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SDLRC - Scientific Articles all years by Author - L-Lh


The Sheahan Diamond Literature Reference Compilation
The Sheahan Diamond Literature Reference Compilation is compiled by Patricia Sheahan who publishes on a monthly basis a list of new scientific articles related to diamonds as well as media coverage and corporate announcementscalled the Sheahan Diamond Literature Service that is distributed as a free pdf to a list of followers. Pat has kindly agreed to allow her work to be made available as an online digital resource at Kaiser Research Online so that a broader community interested in diamonds and related geology can benefit. The references are for personal use information purposes only; when available a link is provided to an online location where the full article can be accessed or purchased directly. Reproduction of this compilation in part or in whole without permission from the Sheahan Diamond Literature Service is strictly prohibited. Return to Diamond Resource Center
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Media/Corporate References by Name for all years
A B C D-Diam Diamonds Diamr+ E F G H I J K L M N O P Q R S T U V W X Y Z
Tips for Users
Posted/Published Reference CodesThe SDLRC provides 3 types of references identified in the reference code. DS for scientific article, DM for a media article, and DC for a corporate announcement. Consider DS0512-0001. The DS stands for "diamond scientific". 05 stands for 2005, the year the reference was posted. 12 represents the month the reference was posted. For all years prior to 2015 the default month is 12. -0001 is the reference's identifier and it does not mean anything. The number below the refence code, ie 2015, is the year the article was published. Note that the posted year may sometimes be later than the published year.
Sort OrderReferences are sorted by the "author" name and when the reference was posted to the compilation.
Most RecentIf the reference code is highlighted yellow, the reference was made available through the most recent monthly compilation of new literature. Use this to check out new references. When new references are posted, we make it our priority to track down an online link and obtain an abstract. With regard to older references, tracking down an abstract and an online link is a work in progress.
Link to external location of article: If the title has a link, it means we have found a location online where you can either retrieve the full article free, or purchase access to it. The Sheahan Diamond Literature Service is not a technical article procurement service; if you want a restricted article, you must deal directly with the vendor who controls the copyright to the article.
Searching this page for a specific term or authorIn your Firefox browser click Edit in the menu bar and then Find. In the Find box that shows up at the bottom of the web page enter your search term. Firefox will highlight all occurrences. This is particularly helpful when the author you are seeking was not the lead author by whom the compilation is sorted.
Sending or sharing a referenceThe left column (Posted/Published) has an embedded hyperlink for each reference. In Firefox, if you right click on it, you can obtain the link url for that reference's location within the page, which you can copy and paste into an email or any other document. You can also use the "share this link" option to tweet, facebook etc the link.
Author Index
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
Sheahan Diamond Literature Reference Compilation - Scientific Articles by Author for all years - L-Lh
Posted/
Published
AuthorTitleSourceRegionKeywords
DS201907-1555
2019
LKupenko, G.A., Vasilukov, D.M., McCammon, C., Charleton, S., Cerantola, V., Kantor, I., Chumakov, A.I.., Ruffer, R., Dubrovinsky, L, Sanchez-Valle, C.Magnetism in cold subducting slabs at mantle transition zone depths.Nature, Vol. 570, 7759, p. 102.Mantlesubduction

Abstract: The Earth’s crust-mantle boundary, the Mohorovi?i? discontinuity, has been traditionally considered to be the interface between the magnetic crust and the non-magnetic mantle1. However, this assumption has been questioned by geophysical observations2,3 and by the identification of magnetic remanence in mantle xenoliths4, which suggest mantle magnetic sources. Owing to their high critical temperatures, iron oxides are the only potential sources of magnetic anomalies at mantle depths5. Haematite (?-Fe2O3) is the dominant iron oxide in subducted lithologies at depths of 300 to 600 kilometres, delineated by the thermal decomposition of magnetite and the crystallization of a high-pressure magnetite phase deeper than about 600 kilometres6. The lack of data on the magnetic properties of haematite at relevant pressure-temperature conditions, however, hinders the identification of magnetic boundaries within the mantle and their contribution to observed magnetic anomalies. Here we apply synchrotron Mössbauer source spectroscopy in laser-heated diamond anvil cells to investigate the magnetic transitions and critical temperatures in Fe2O3 polymorphs7 at pressures and temperatures of up to 90 gigapascals and 1,300 kelvin, respectively. Our results show that haematite remains magnetic at the depth of the transition zone in the Earth’s mantle in cold or very cold subduction geotherms, forming a frame of deep magnetized rocks in the West Pacific region. The deep magnetic sources spatially correlate with preferred paths of the Earth’s virtual geomagnetic poles during reversals8 that might not reflect the geometry of the transitional field. Rather, the paths might be an artefact caused by magnetized haematite-bearing rocks in cold subducting slabs at mid-transition zone depths. Such deep sources should be taken into account when carrying out inversions of the Earth’s geomagnetic data9, and especially in studies of planetary bodies that no longer have a dynamo10, such as Mars.
DS1910-0068
1910
L.G.L.G.Alluvial Gold and Diamonds in the Earlier Days. #2South Africa Majority Special Issue., PP. 136-137.South AfricaHistory
DS201511-1838
2007
La Ferrara, E.Guidolin, M., La Ferrara, E.Diamonds are forever, war is not: is conflict bad for private firms?The American Economic Review, Vol. 97, 5, pp. 1978-1993.GlobalEconomics

Abstract: This paper studies the relationship between civil war and the value of firms in a poor, resource abundant country using microeconomic data for Angola. We focus on diamond mining firms and conduct an event study on the sudden end of the conflict, marked by the death of the rebel movement leader in 2002. We find that the stock market perceived this event as “bad news” rather than "good news" for companies holding concessions in Angola, as their abnormal returns declined by 4 percentage points. The event had no effect on a control portfolio of otherwise similar diamond mining companies. This finding is corroborated by other events and by the adoption of alternative methodologies. We interpret our findings in the light of conflict-generated entry barriers, government bargaining power and transparency in the licensing process.
DS1993-0870
1993
La Fleche, M.R.La Fleche, M.R., Schrijver, K., Tremblay, A.Geochemistry, origin and provenance of upper Proterozoic to upper Cambrian alkaline to transitional basaltic rocks in and contiguous to sector HumberzoneAmerican Journal of Science, Vol. 293, November pp. 980-1009AppalachiaGeochemistry, Humber Zone
DS1994-0972
1994
la Moigne, J.Lagabrielle, Y., la Moigne, J., Maury, R.C., Cotten, J.Volcanic record of the subduction of an active spreading ridge, Taitao Peninsula (southern Chile)Geology, Vol. 22, No. 6, June pp. 515-518ChileSubduction, Tectonics
DS200812-0282
2008
La Nuez, J.deDemeny, A., Casillas, R., Ahijado, A., La Nuez, J.de, Milton, J.A., Nagy, G.Carbonate xenoliths in La Palma: carbonatite or alteration product?Chemie der Erde, Vol. 68, 4, pp. 369-381.Europe, Canary IslandsGeochronology
DS2003-0767
2003
La Pierre, H.La Pierre, H., Bosch, D., Tardy, M., Struik, L.C.Late Paleozoic and Triassic plume derived magmas in the Canadian Cordillera played aChemical Geology, Vol. 201, 3-4, Nov. 14, pp. 55-89.British ColumbiaTectonics, Cache Creek, Slide Mountain Terrane, geochem
DS2003-0768
2003
La Pierre, H.La Pierre, H., Bosch, D., Tardy, M., Struik, L.C.Late Paleozoic and Triassic plume derived magmas in the Canadian Cordillera played aChemical Geology, Vol. 201, 1-2, pp. 55-89.British Columbia, Yukon, Alberta, Northwest TerritoriesMagmatism, tectonics
DS200412-1077
2003
La Pierre, H.La Pierre, H., Bosch, D., Tardy, M., Struik, L.C.Late Paleozoic and Triassic plume derived magmas in the Canadian Cordillera played a key role in continental crust growth.Chemical Geology, Vol. 201, 1-2, pp. 55-89.Canada, British Columbia, Yukon, Alberta, Northwest TerritoriesMagmatism, tectonics
DS200412-1078
2003
La Pierre, H.La Pierre, H., Bosch, D., Tardy, M., Struik, L.C.Late Paleozoic and Triassic plume derived magmas in the Canadian Cordillera played a key role in continental crust growth.Chemical Geology, Vol. 201, 3-4, Nov. 14, pp. 55-89.Canada, British ColumbiaTectonics, Cache Creek, Slide Mountain Terrane, geochem
DS1994-0114
1994
la Pointe, P.R.Barton, C.C., la Pointe, P.R.Fractals in the earth sciences #1Plenum Press, 261pGlobalBook -ad, Fractals
DS1995-0111
1995
la Pointe, P.R.Barton, C.C., la Pointe, P.R.Fractals in the earth sciences #2Plenum Press, GlobalBook -ad, Fractals
DS1999-0390
1999
La Prairie, L.F.La Prairie, L.F., Vuori, H.F., Dowsett, J.S.Darnley Bay: part 1. historical perspectives on exploration. part 2: theproject... mentions anomalies.8th. Calgary Mining forum, 5p. abstractNorthwest TerritoriesNews item, Darnley Bay
DS200812-0944
2008
La Prairie, L.L.Reford, S.W., La Prairie, L.L.Exploring for metals and diamonds at Darnley Bay. NT.Northwest Territories Geoscience Office, p. 51. abstractCanada, NunavutBrief overview - Darnley Bay
DS201112-0666
2011
La Terra, E.F.Menezes, P.T.L., La Terra, E.F.3D magnetic interpretation of the Regis kimberlite pipe, Minas Gerais, Brazil.Near Surface Geophysics, In press,South America, Brazil, Minas GeraisGeophysics - Regis
DS201312-0600
2011
La Terra, E.F.Menezes, P.T.L., La Terra, E.F.3 D magnetic interpretation of the Regis kimberlite pipe, Minas Gerais.Near Surface Geophysics, Vol. 9, 4, pp. 331-337.South America, BrazilDeposit - Regis
DS1994-0941
1994
Laaioki, K.Korobeynikov, A.N., Laaioki, K.Petrological aspects of the evolution of clinopyroxene composition in intrusive rocks Lovozero Alkali Massif.Geochemistry International, Vol. 31, No. 3, pp. 69-76.RussiaAlkaline rocks
DS1998-0790
1998
LaajokiKorobeinikov, A.N., Mitrofanov, Gehor, Laajoki, PavlovGeology and copper sulphide mineralization of the Salmagorskii ring igneouscomplex, Kola Peninsula.Journal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 2033-41.Russia, Kola PeninsulaAlkaline rocks, Salmagorsky Complex
DS1989-0840
1989
Laajoki, K.Laajoki, K.Stratigraphic classification and nomenclature of igneous and metamorphic rock bodies: discussion and replyGeological Society of America (GSA) Bulletin, Vol. 101, No. 5, May pp. 753-754GlobalClassification, Igneous/Metamorphic
DS1999-0719
1999
Laajoki, K.Strand, K., Laajoki, K.Application of the parasequence concept to the Paleoproterozoic record Of the northern FennoscandianPrecambrian Research, Vol. 97, No. 3-4, Sept. 1, pp. 253-68.Norway, FennoscandiaShield - history
DS2002-0441
2002
Laajoki, K.Evins, P.M., Mansfeld, J., Laajoki, K.Geology and geochronology of the Suomujarvi Complex: a new Archean gneiss region in the NE Baltic Shield, Finland.Precambrian Research, Vol. 116, No. 3-4, pp. 285-306.FinlandGeneral geology - not specific to diamonds
DS200612-0437
2005
Lab NotesGems &.Gemology, Lab NotesStrongly coloured natural type IIb blue diamonds.Gems & Gemology, Vol. 41, 3, Fall, p.258-9..TechnologyDiamond - colour
DS200612-0438
2005
Lab NotesGems &.Gemology, Lab NotesDiamond dyed rough.Gems & Gemology, Vol. 41, 3, Fall, p.257-258.TechnologyDiamond - colour
DS200812-0622
2007
Lab NotesLab NotesPhenakite as a rough diamond imitation.Gems & Gemology, Fall, p. 250.TechnologyPhenakite
DS200812-0623
2007
Lab NotesLab NotesNatural type IIb blue diamond with atypical electroluminescence.Gems & Gemology, Fall, pp. 246-48.TechnologyType IIa
DS201906-1309
2019
Lab notesLab notesThe largest diamond ever discovered in North America 552.7 ct. DiavikGems & Gemology, Vol. 55, 1, p. 91-2.Canada, Northwest Territoriesdeposit - Diavik

Abstract: In October 2018, a diamond weighing a remarkable 552.7 ct was recovered from the Diavik mine in Canada. This is by far the largest known gem diamond found to date in North America. It is nearly three times larger than the 187.63 ct Diavik Foxfire which was unearthed from the same mine in August 2015, and about twice the size of a 271 ct white diamond mined from the Victor mine in Canada. GIA’s New York laboratory had the opportunity to examine this notable diamond in late January 2019, before it went on public display at the Phillips Auctions in New York...(no abstract, full article)
DS201906-1310
2019
Lab notesLab notesCVD layer grown on natural diamondGems & Gemology, Vol. 55, 1, pp. 97-99.Globalsynthetic

Abstract: A 0.64 ct Fancy grayish greenish blue cushion modified brilliant (figure 1) was recently found to be a composite of synthetically grown and natural diamond. During testing, the infrared spectrum showed both strong absorption of nitrogen and the absorption of uncompensated boron, features characteristic of type Ia and type IIb diamonds, respectively (figure 2). The UV-Vis-NIR spectrum showed “cape” peaks, which are nitrogen-related defects, but also a sloping absorption into the red portion of the spectrum caused by uncompensated boron. It is very unusual for boron- and nitrogen-related defects to be seen together in natural diamonds, though an example has been seen before (Spring 2009 Lab Notes, pp. 55-57). Mixed-type diamonds always call for additional scrutiny...(no abstract, full article)
DS2001-0645
2001
Labbe, J-Y.Labbe, J-Y.Crustal lineaments and kimberlite discovery potential in western Nouveau-QuebecRessources Naturelle Quebec, PRO 2001-02, 7 p.Quebeccrustal lineaments, mineral potential maps, northeastern Superior craton
DS2001-0646
2001
Labbe, J-Y.Labbe, J-Y.Crustal lineaments and kimberlite discovery potential in western Nouveau Quebec.24EQuebec Department of Mines, No. PRO 2001-02, 7p.Quebec, UngavaStructure, tectonics, rifting, Lac Aigneau area
DS202205-0701
2022
Labdidi, J.Labdidi, J.The origin of nitrogen in Earth's mantle: constraints from basalts 15N/14N and N2/3He ratios.Chemical Geology, 10.1016/j.chemgeo.2022.120780Europe, Iceland, Galapogos, Hawaiibasalts

Abstract: Plate tectonics is thought to be a major driver of volatile redistribution on Earth. The budget of nitrogen in Earth's mantle has been suggested to be almost entirely surface-derived. Recycling would contribute nitrogen with relatively heavy 15N/14N isotope ratios to Earth's mantle. This could explain why the Earth's mantle 15N/14N isotope ratio is substantially higher than both solar gases and chondritic parent bodies akin to enstatite chondrites. Here, published nitrogen isotope data of mid-ocean ridge and ocean island basalts are compiled and used to evaluate the nitrogen subduction hypothesis. Nitrogen isotope ratios are used in conjunction with published N2/3He and K2O/TiO2 ratios on the same basalts. Assuming that 3He is not recycled, N2/3He ratios are argued to trace nitrogen addition to mantle sources via subduction. Various mantle source enrichments for basalts are tracked with K2O/TiO2 ratios: elevated K2O/TiO2 ratios are assumed to primarily reflect the contributions of recycled components in the basalts mantle sources. The main result of our data compilation is that for most basalts, ?15N and N2/3He remain constant across a vast range of K2O/TiO2 ratios. Mid-ocean ridge basalts have ?15N signatures that are lower than air by ~4‰ and an average N2/3He ratio of 3.7 (±1.2) x106 (95% confidence, n = 30). Published ?15N and N2/3He are invariant across K2O/TiO2 ratios that vary over a factor of ~20. Using estimates of slab K2O/TiO2 and [TiO2], the observed invariant ?15N and N2/3He may be fit with slabs containing ~0.1 ppm N. A mass balance shows that adding ~10% recycled slabs to the convective mantle only raises the N2/3He by <5%. Lavas from Iceland, Galapagos and Hawaii have high 3He/4He and 15N/14N ratios relative to the convective mantle. Only seven samples show nitrogen isotopic signatures that are unaffected by air contamination, although those samples are poorly characterized for N2/3He. The seven basalts show ?15N between ?2 and 0‰ that do not vary systematically with K2O/TiO2 ratios that vary over a factor of ~5. The N2/3He ratios of these seven basalts is unknown, but the high 3He/4He mantle may be estimated by combining published N2/36Ar to 3He/36Ar ratios. This yields a N2/3He of 2.3 (±1.2) x 106 (1? uncertainty). This is indistinguishable from the MORB estimate of 3.7 (±1.2) x 106. Invariant ?15N across variable degrees of mantle enrichments and MORB-like N2/3He for the high 3He/4He mantle are not consistent with nitrogen addition to plume sources with elevated 3He/4He ratios. A ?15N between ?2 and 0‰ for plume sources, only marginally higher than MORB, could be a primordial feature of undegassed mantle reservoirs. Nonetheless, nitrogen subduction may have contributed to a specific array of mantle sources, as revealed by the few published data on basalts with low 3He/4He ratios. Lavas from the Society plume with low 3He/4He ratios show an enriched mantle source, and they have elevated ?15N ? +0.5‰ and N2/3He > 107. For those, the addition of slabs with concentrations of ~0.1 ppm N to a mantle source can account for the integrated dataset. To summarize, the published data suggest that nitrogen subduction may explain a sub-set of published N isotope data on basalts, but that N recycling has an overall more limited impact on mantle nitrogen than previously thought.
DS1994-0968
1994
Laberge, G.Laberge, G.Geology of the Lake Superior RegionGeoscience Press, 300pWisconsin, MichiganGreenstone belt, Keweenawan, Table of contents
DS1970-0949
1974
Laberge, G.L.Laberge, G.L.Major Structural Lineaments in the Precambrian of Central Wisconsin.First International Conference On Basement Tectonics., WisconsinMid-continent
DS1984-0442
1984
Laberge, G.L.Laberge, G.L., Myers, P.E.Two Early Proterozoic Successions in Central Wisconsin and Their Tectonic Significance.Geological Society of America (GSA) Bulletin., Vol. 95, No. 2, FEBRUARY PP. 246-253.United States, WisconsinMid Continent
DS1984-0636
1984
Laberge, G.L.Schulz, K.J., Laberge, G.L., Sims, P.K., Peterman, Z.E., Klasner.The Volcanic Plutonic Terrane of Northern Wisconsin: Implications for Early Proterozoic Tectonism, Lake Superior Region.Geological Association of Canada (GAC), Vol. 9, P. 103. (abstract.).MichiganMid-continent
DS1988-0394
1988
Laberge, G.L.Laberge, G.L.Exploration drill cores in the Wisconsin magmatic terraneUnited States Geological Survey (USGS) Open File, No. 88-0536, 72p. paper copy $ 11.25WisconsinBasement, Tectonics
DS1994-0969
1994
LaBerge, G.L.LaBerge, G.L.Geology of the Lake Superior regionPhoenix Press, 313p.Michigan, WisconsinGeneral geology -not specific to diamonds, Book -ad
DS201212-0112
2012
Labidi, J.Cartigny, P., Palot, M., Clog, M., Labidi, J., Thomassot, E., Aubaud, C., Busigny, V., Harris, J.W.On overview of the deep carbon cycle and its isotope heterogeneity.Goldschmidt Conference 2012, abstract 1p.MantleCarbon cycle
DS201606-1130
2016
Labidi, J.Zhang, Z., Dorfman, S.M., Labidi, J., Zhang, S., Li, M., Manga, M., Stixrude, L., McDonough, W.F., Williams, Q.Primordial metallic melt in the deep mantle.Geophysical Research Letters, Vol. 43, 8, pp. 3693-3697.MantleMelting

Abstract: Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3-3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
DS201607-1323
2016
Labidi, J.Zhang, Z., Dorfman, S.M., Labidi, J., Zhang, S., Li, M., Manga, M., Stixrude, L., McDonough, W.F., Williams, Q.Primordial metallic melt in the deep mantle.Geophysical Research Letters, Vol. 43, 8, pp. 3693-3699.MantleMelting

Abstract: Seismic tomography models reveal two large low shear velocity provinces (LLSVPs) that identify large-scale variations in temperature and composition in the deep mantle. Other characteristics include elevated density, elevated bulk sound speed, and sharp boundaries. We show that properties of LLSVPs can be explained by the presence of small quantities (0.3 -3%) of suspended, dense Fe-Ni-S liquid. Trapping of metallic liquid is demonstrated to be likely during the crystallization of a dense basal magma ocean, and retention of such melts is consistent with currently available experimental constraints. Calculated seismic velocities and densities of lower mantle material containing low-abundance metallic liquids match the observed LLSVP properties. Small quantities of metallic liquids trapped at depth provide a natural explanation for primitive noble gas signatures in plume-related magmas. Our model hence provides a mechanism for generating large-scale chemical heterogeneities in Earth's early history and makes clear predictions for future tests of our hypothesis.
DS202005-0744
2020
Labidi, J.Labidi, J., Barry, P.H., Bekaert, D.V., Broadley, M.W., Marty, B., Giunta, T., Warr, O., Sherwood Lollar, B., Fischer, T.P., Avice, G., Caracusi, A., Ballentine, C.J., Halldorsson, S.A., Stefansson, A., Kurz, M.D., Kohl, I.E., Young, E.D.Hydrothermal 15N15N abundances constrain the origins of mantle nitrogen.Nature, Vol. 580, 7803 pp. 367-371. Mantlenitrogen

Abstract: Nitrogen is the main constituent of the Earth’s atmosphere, but its provenance in the Earth’s mantle remains uncertain. The relative contribution of primordial nitrogen inherited during the Earth’s accretion versus that subducted from the Earth’s surface is unclear1,2,3,4,5,6. Here we show that the mantle may have retained remnants of such primordial nitrogen. We use the rare 15N15N isotopologue of N2 as a new tracer of air contamination in volcanic gas effusions. By constraining air contamination in gases from Iceland, Eifel (Germany) and Yellowstone (USA), we derive estimates of mantle ?15N (the fractional difference in 15N/14N from air), N2/36Ar and N2/3He. Our results show that negative ?15N values observed in gases, previously regarded as indicating a mantle origin for nitrogen7,8,9,10, in fact represent dominantly air-derived N2 that experienced 15N/14N fractionation in hydrothermal systems. Using two-component mixing models to correct for this effect, the 15N15N data allow extrapolations that characterize mantle endmember ?15N, N2/36Ar and N2/3He values. We show that the Eifel region has slightly increased ?15N and N2/36Ar values relative to estimates for the convective mantle provided by mid-ocean-ridge basalts11, consistent with subducted nitrogen being added to the mantle source. In contrast, we find that whereas the Yellowstone plume has ?15N values substantially greater than that of the convective mantle, resembling surface components12,13,14,15, its N2/36Ar and N2/3He ratios are indistinguishable from those of the convective mantle. This observation raises the possibility that the plume hosts a primordial component. We provide a test of the subduction hypothesis with a two-box model, describing the evolution of mantle and surface nitrogen through geological time. We show that the effect of subduction on the deep nitrogen cycle may be less important than has been suggested by previous investigations. We propose instead that high mid-ocean-ridge basalt and plume ?15N values may both be dominantly primordial features.
DS202107-1091
2021
Labidi, J.Bekaert, D.V., Turner, S.J., Broadley, M.W., Barnes, J.D., Halldorsson, S.A., Labidi, J., Wade, J., Walowski, K.J., Barry, P.H.Subduction-driven volatile recycling: a global mass balance.Annual Review of Earth and Planetary Sciences, Vol. 49, pp. 37-70.Mantlesubduction

Abstract: Volatile elements (water, carbon, nitrogen, sulfur, halogens, and noble gases) played an essential role in the secular evolution of the solid Earth and emergence of life. Here we provide an overview of Earth's volatile inventories and describe the mechanisms by which volatiles are conveyed between Earth's surface and mantle reservoirs, via subduction and volcanism. Using literature data, we compute volatile concentration and flux estimates for Earth's major volatile reservoirs and provide an internally balanced assessment of modern global volatile recycling. Using a nitrogen isotope box model, we show that recycling of N (and possibly C and S) likely began before 2 Ga and that ingassing fluxes have remained roughly constant since this time. In contrast, our model indicates recycling of H2O(and most likely noble gases) was less efficient in the past. This suggests a decoupling of major volatile species during subduction through time, which we attribute to the evolving thermal regime of subduction zones and the different stabilities of the carrier phases hosting each volatile. This review provides an overview of Earth's volatile inventory and the mechanisms by which volatiles are transferred between Earth reservoirs via subduction. The review frames the current thinking regarding how Earth acquired its original volatile inventory and subsequently evolved through subduction processes and volcanism.
DS1994-0970
1994
Labonne, B.Labonne, B.Small and medium scale mining... the Harare seminar and guidelinesNatural Resources forum, Vol. 18, No. 1, pp. 13-16ZimbabweMining -small scale
DS1994-0971
1994
Labonne, B.Labonne, B.Small and medium scale mining.. notes from the Harare seminar andguidelines.Natural Resources forum, Vol. 18, No. 1, February pp. 13-16.ZimbabweMining -small scale, Economics
DS200812-1000
2008
Laboucan, A.B.Sandeman, H.A., Barnett, R.L., Laboucan, A.B.An overview of the Mud Lake kimberlite, SW Slave Craton, Northwest Territories, and implications of the presence of high Cr2O3, CaO rich green garnets.9IKC.com, 3p. extended abstractCanada, Northwest TerritoriesDeposit - Mud Lake petrography
DS200712-0935
2007
Laboucan, B.Sandeman, H.A., Barnett, R.L., Laboucan, B., Flemming, R., Tubrett, M.Unique garnet compositions from the Mud Lake kimberlite SW Slave Province, NWT: an occurrence of rare high Cr-Ca green garnets.Geological Association of Canada, Gac-Mac Yellowknife 2007, May 23-25, 1 pg. abstract p.70-71.Canada, Northwest TerritoriesGarnet analyses
DS1982-0356
1982
Labrecque, J.J.Labrecque, J.J., Nagata, K., Ishizaki, C., Ishizaki, K.Environmental Impact of Diamond Mining in the Guanamo Riverbasin.Agid Report No. 7, Hidden Wealth: Mineral Exploration Techni, PAPER F3, P. 185. (abstract.)GlobalChemistry, Waters
DS2001-0647
2001
Labroose, S.Labroose, S., Poirier, J.P., Lemouel, J.L.The age of the inner coreEarth and Planetary Science Letters, Vol. 190, No. 3-4, pp. 111-123.MantleCore - boundary, Geochronology
DS200712-0591
2007
Labroose, S.Labroose, S., Jaupart, C.Thermal evolution of the Earth: secular changes and fluctuations of plate characteristics.Earth and Planetary Science Letters, Vol. 260, 3-4, pp. 465-481.MantleDynamics, tectonics, geothermometry
DS201012-0323
2010
LabrosseJavoy, M., Kaminski, E., Guyot,Andrault, Sanloup, Moreira, Labrosse, Jambon, Agrinier.Davaille, JaupartThe chemical composition of the Earth: enstatite chondrite models.Earth and Planetary Science Letters, Vol. 293, 3-4, pp. 259-268.MantleChemistry
DS2002-0909
2002
Labrosse, S.Labrosse, S.Hotspots, mantle plumes and core heat lossEarth and Planetary Science Letters, Vol.199,1-2,pp.147-56., Vol.199,1-2,pp.147-56.MantlePlumes
DS2002-0910
2002
Labrosse, S.Labrosse, S.Hotspots, mantle plumes and core heat lossEarth and Planetary Science Letters, Vol.199,1-2,pp.147-56., Vol.199,1-2,pp.147-56.MantlePlumes
DS200712-0384
2007
Labrosse, S.Grigne, C., Labrosse, S., Tackley, P.J.Convection under a lid of finite conductivity in wide aspect ratio models: effect of continents on the rate of mantle flow.Journal of Geophysical Research, Vol. 112, B8, B08403MantleConvection
DS200712-0385
2007
Labrosse, S.Grigne, C., Labrosse, S., Tackley, P.J.Convection under a lid of finite conductivity in wide aspect ratio models: heat flux scaling and application to continents.Journal of Geophysical Research, Vol. 112, B8, B08402MantleConvection
DS200712-0429
2007
Labrosse, S.Hernlund, J.W., Labrosse, S., Coltice, N.The energy balance at the core-mantle boundary.Plates, Plumes, and Paradigms, 1p. abstract p. A399.MantleGeothermometry
DS201312-0388
2013
Labrosse, S.Hirose, K., Labrosse, S., Hernlund, J.Composition and state of the core.Annual Review of Earth and Planetary Sciences, Vol. 41, pp. 657-691.MantleMineralogy
DS2003-1218
2003
Labrousse, L.Scharer, U., Labrousse, L.Dating the exhumation of UHP rocks and associated crustal melting in the NorwegianContributions to Mineralogy and Petrology, Vol. 144, 6, pp. 758-70.NorwayGeochronology, UHP
DS2003-1219
2003
Labrousse, L.Scharer, U., Labrousse, L.Dating the exhumation of UHP rocks and associated crustal melting in the NorwegianContributions to Mineralogy and Petrology, Vol. 144, 6, March pp. 758-77.NorwayUHP - ultra high pressure, Geochronology
DS200412-1741
2003
Labrousse, L.Scharer, U., Labrousse, L.Dating the exhumation of UHP rocks and associated crustal melting in the Norwegian Caledonides.Contributions to Mineralogy and Petrology, Vol. 144, 6, pp. 758-70.Europe, NorwayGeochronology, UHP
DS200512-0485
2005
Labrousse, L.Jolivet, L., Raimbourg, H., Labrousse, L., Avigad, D., Leroy, Y., Austrheim, H., Andersen, T.B.Softening triggered by eclogitization, the first step toward exhumation during continental subduction.Earth and Planetary Science Letters, Vol. 237, 3-4, Sept. 15, pp. 532-547.Europe, NorwayEclogite, subduction
DS202104-0579
2021
Labrousse, L.Godet, A., Guilmette, C.,Labrousse, L., Smit, M.A., Cutts, J.A., Davis, D.W., Vanier, M-A.Lu-Hf garnet dating and the timing of collisions: Paleoproterozoic accretionary tectonics revealed in the southeastern Churchill Province Trans-Hudson Orogen, Canada. Torngat, New QuebecJournal of Metamorphic Geology, doi:10.1111/jmg.12599Canada, Quebeccratons

Abstract: Dating the onset of continental collision is fundamental in defining orogenic cycles and their effects on regional tectonics and geodynamic processes through time. Part of the Palaeoproterozoic Trans?Hudson Orogen, the Southeastern Churchill Province (SECP) is interpreted to result from the amalgamation of Archean to Palaeoproterozoic crustal blocks (amalgamated as the central Core Zone) that diachronically collided with the margins of the North Atlantic and Superior cratons, resulting in two bounding transpressive orogens: the Torngat and New Quebec Orogens. The SECP exposes mainly gneissic middle to lower orogenic crust in which deformation and amphibolite to granulite facies metamorphism and anatexis overprinted the early geological features classically used to constrain the timing of collisional events. To enable improved tectonic models for the development of the SECP, and the Trans?Hudson as a whole, we investigated granulite facies supracrustal sequences from the Tasiuyak Complex (TC) accretionary prism and the western margin of the North Atlantic Craton-that is, Saglek Block (upper plate)-using a multi?chronometer approach coupled with trace element geochemistry. In particular, the use of garnet Lu-Hf geochronology provides an important minimal time constraint for crustal thickening and collision. Garnet growth in the TC is constrained at 1885 ± 12 Ma (Lu-Hf), indistinguishable from U-Pb age of prograde monazite at 1873 ± 5 Ma. Zircon growth during melt crystallization occurred at 1848 ± 12 Ma. Garnet from the overriding Saglek Block is dated at 2567 ± 4.4 Ma (Lu-Hf) and indicates that gneissic rocks from the upper plate did not record the metamorphic imprint of the Torngat Orogeny. The diachronicity of the integrated metamorphic record across the strike of the SECP is explained by the location of terrane boundaries, consistent with the westward growth of the Churchill plate margin through sequential amalgamation of narrow crustal blocks during accretionary tectonics from c. 1.9 to 1.8 Ga.
DS202111-1767
2021
Labrousse, L.Godet, A., Guilmette, C., Labrousse, L., Smit, M.A., Cutts, J.A., Davis, D.W., Vanier, M-A.Lu-Hf garnet dating and the timing of collisions: Paleoproterozoic accretionary tectonics revealed in the southeastern Churchill Province, Trans-Hudson orogen, Canada.Journal of Metamorphic Geology, Vol. 39, 8, 31p. PdfCanadageochronology

Abstract: Dating the onset of continental collision is fundamental in defining orogenic cycles and their effects on regional tectonics and geodynamic processes through time. Part of the Palaeoproterozoic Trans-Hudson Orogen, the Southeastern Churchill Province (SECP) is interpreted to result from the amalgamation of Archean to Palaeoproterozoic crustal blocks (amalgamated as the central Core Zone) that diachronically collided with the margins of the North Atlantic and Superior cratons, resulting in two bounding transpressive orogens: the Torngat and New Quebec Orogens. The SECP exposes mainly gneissic middle to lower orogenic crust in which deformation and amphibolite to granulite facies metamorphism and anatexis overprinted the early geological features classically used to constrain the timing of collisional events. To enable improved tectonic models for the development of the SECP, and the Trans-Hudson as a whole, we investigated granulite facies supracrustal sequences from the Tasiuyak Complex (TC) accretionary prism and the western margin of the North Atlantic Craton—that is, Saglek Block (upper plate)—using a multi-chronometer approach coupled with trace element geochemistry. In particular, the use of garnet Lu-Hf geochronology provides an important minimal time constraint for crustal thickening and collision. Garnet growth in the TC is constrained at 1885 ± 12 Ma (Lu-Hf), indistinguishable from U-Pb age of prograde monazite at 1873 ± 5 Ma. Zircon growth during melt crystallization occurred at 1848 ± 12 Ma. Garnet from the overriding Saglek Block is dated at 2567 ± 4.4 Ma (Lu-Hf) and indicates that gneissic rocks from the upper plate did not record the metamorphic imprint of the Torngat Orogeny. The diachronicity of the integrated metamorphic record across the strike of the SECP is explained by the location of terrane boundaries, consistent with the westward growth of the Churchill plate margin through sequential amalgamation of narrow crustal blocks during accretionary tectonics from c. 1.9 to 1.8 Ga.
DS2000-0717
2000
Labudia, H.C.Ntaflos, Th., Gunther, M., Labudia, H.C., Bjerg, E.A.Isotopic and geochemical evolution of the Cenozoic basalts from Rio Negro Patagonia Argentina.Igc 30th. Brasil, Aug. abstract only 4p.ArgentinaGeochronology, Basanites
DS1960-1149
1969
Labuz, A.L.Labuz, A.L.The Herkimer Diamond Grounds Former Schrader Property and Related Properties.Rocks And Minerals, Vol. 44, PP. 243-250.United States, Appalachia, New YorkHerkimer Diamonds
DS201412-0778
2014
Lacalamita, M.Schingaro, E., Kullerud, K., Lacalamita, M., Mesto, E., Scordari, F., Zozulya, D., Erambert, M., Ravna, E.J.K.Yangzhumgite and phlogopite from the Kvaloya lamproite ( North Norway): structure, composition and origin.Lithos, Vol. 210-211, pp. 1-13.Europe, NorwayLamproite
DS201212-0392
2012
Lacamita, M.Lacamita, M., Mesto, E., Scordari, F., Schingaro, E.Chemical and structural study of 1M and 2M1 phlogopites coexisting in the same Kaseny kamafugitic rock ( SW Uganda).Physics and Chemistry of Minerals, Vol. 39, 8, pp. 601-611.Africa, UgandaKamafugite
DS1991-0947
1991
Lacazette, A.Lacazette, A.A new stereo graphic technique for the reduction of scanline survey dat a of geologic fracturesComputers and Geosciences, Vol. 17, No. 3, pp. 445-464GlobalStereographic technique
DS1900-0147
1903
Lace Diamond CompanyLace Diamond CompanyThe Lace Diamond Mine Company ReportSouth Africa Mines Commerce and Industry, Vol. 1, MAY 23RD. PP. 238-239.Africa, South AfricaCompany Report
DS2001-1295
2001
Lacelle, D.Zdanowicz, C., Fisher, D., Clark, I., Lacelle, D.Ice marginal studies on Barnes Ice Cap, Baffin Island: clues to the history of the Laurentide ice sheet.29th. Yellowknife Geoscience Forum, Nov. 21-23, abstract p. 97.Northwest Territories, Baffin IslandGeomorphology
DS1990-0898
1990
Lachenbruch, A.H.Lachenbruch, A.H., Morgan, P.Continental extension, magmatism and elevation; formal extensions and rules of thumbTectonophysics, special issue on heat and detachment in continental, Vol. 174, No. 1-2, pp. 39-62GlobalCrustal extension, Magmatism
DS201707-1360
2017
Lachhman, D.Reis, N.J., Nadeau, S., Fraga, L.M., Menezes Betiollo, L., Telma Lins Faraco, M., Reece, J., Lachhman, D., Ault, R.Stratigraphy of the Roraima Supergroup along the Brazil Guyana border in the Guiana shield, northern Amazonian craton - results of the Brazil Guyana geology and geodiversity mapping project.Brazil Journal of Geology, Vol. 47, 1, pp. 43-57.South America, Brazil, Guyanacraton

Abstract: The Geological and Geodiversity Mapping binational program along the Brazil?Guyana border zone allowed reviewing and in? tegrating the stratigraphy and nomenclature of the Roraima Supergroup along the Pakaraima Sedimentary Block present in northeastern Brazil and western Guyana. The area mapped corresponds to a buffer zone of approximately 25 km in width on both sides of the border, of a region extending along the Maú?Ireng River between Mount Roraima (the tri? ple?border region) and Mutum Village in Brazil and Monkey Mountain in Guyana. The south border of the Roraima basin is overlain exclusively by effusive and volcaniclastic rocks of the Surumu Group of Brazil and its correlated equivalent the Burro?Burro Group of Guyana.
DS201810-2371
2018
Lachhman, D.Reis, N.J., Nadeau, S., Fraga, L.M., Betiollo, L.M., Faraco, M.T.L., Reece, J., Lachhman, D., Ault, R.Stratigraphy of the Roraima Supergroup along the Brazil-Guyana border in the Guiana shield, northern Amazonian craton- results of the Brazil-Guyana geology and geodiversity mapping project.Brazilian Journal of Geology, Vol. 47, 1, pp. 43-57.South America, Brazil, Guyanacraton

Abstract: The Geological and Geodiversity Mapping binational program along the Brazil?Guyana border zone allowed reviewing and in? tegrating the stratigraphy and nomenclature of the Roraima Supergroup along the Pakaraima Sedimentary Block present in northeastern Brazil and western Guyana. The area mapped corresponds to a buffer zone of approximately 25 km in width on both sides of the border, of a region extending along the Maú?Ireng River between Mount Roraima (the tri? ple?border region) and Mutum Village in Brazil and Monkey Mountain in Guyana. The south border of the Roraima basin is overlain exclusively by effusive and volcaniclastic rocks of the Surumu Group of Brazil and its correlated equivalent the Burro?Burro Group of Guyana.
DS201904-0772
2017
Lachhman, D.Reis, N.J., Nadeau, S., Fraga, L.M., Menezes Betiollo, L., Telma Lins, Faraco, M., Reece, J., Lachhman, D., Ault, R.Stratigraphy of the Roraima Supergroup along the Brazil-Guyana border in the Guiana shield, northern Amazonian craton - results of the Brazil Guyana geology and geodiversity mapping project.Brazilian Journal of Geology, Vol. 41, 1, pp. 43-57.South America, Brazil, GuyanaGuiana shield

Abstract: The Geological and Geodiversity Mapping binational program along the Brazil-Guyana border zone allowed reviewing and integrating the stratigraphy and nomenclature of the Roraima Supergroup along the Pakaraima Sedimentary Block present in northeastern Brazil and western Guyana. The area mapped corresponds to a buffer zone of approximately 25 km in width on both sides of the border, of a region extending along the Maú-Ireng River between Mount Roraima (the triple-border region) and Mutum Village in Brazil and Monkey Mountain in Guyana. The south border of the Roraima basin is overlain exclusively by effusive and volcaniclastic rocks of the Surumu Group of Brazil and its correlated equivalent the Burro-Burro Group of Guyana.
DS200612-1460
2005
Lackey, J.S.Valley, J.W., Lackey, J.S., Cavosie, A.J., Clechenko, C.C., Spicuzza, M.J., Basei, M.A.S., Bindeman, I.N.4.4 billion years of crustal maturation: oxygen isotope ratios.Contributions to Mineralogy and Petrology, Vol. 150, 8, Dec. pp. 561-580.MantleGeochronology
DS200812-0372
2008
Lackey, J.S.Fu, B., Page, F.Z., Cavosie, A.J., Fournelle, J., Kita, N.T., Lackey, J.S., Wilde, S.A., Valley, J.W.Ti in zircon thermometry: applications and limitations.Contributions to Mineralogy and Petrology, 37p. in press availableTechnologyGeothermometry - kimberlites
DS201611-2132
2016
Lackey, J.S.Poletti, J.E., Cottle, J.M., Hagen-Peter, G.A., Lackey, J.S.Petrochronological constraints on the origin of the Mountain Pass ultrapotassic and carbonatite intrusive suite, California.Journal of Petrology, In press available, 44p.United States, CaliforniaCarbonatite

Abstract: Rare earth element (REE) ore-bearing carbonatite dikes and a stock at Mountain Pass, California, are spatially associated with a suite of ultrapotassic plutonic rocks, and it has been proposed that the two are genetically related. This hypothesis is problematic, given that existing geochronological constraints indicate that the carbonatite is ?15-25 Myr younger than the ultrapotassic rocks, requiring alternative models for the formation of the REE ore-bearing carbonatite during a separate event and/or via a different mechanism. New laser ablation split-stream inductively coupled plasma mass spectrometry (LASS-ICP-MS) petrochronological data from ultrapotassic intrusive rocks from Mountain Pass yield titanite and zircon U-Pb dates from 1429?±?10 to 1385?±?18?Ma, expanding the age range of the ultrapotassic rocks in the complex by ?20 Myr. The ages of the youngest ultrapotassic rocks overlap monazite Th-Pb ages from a carbonatite dike and the main carbonatite ore body (1396?±?16 and 1371?±?10?Ma, respectively). The Hf isotope compositions of zircon in the ultrapotassic rocks are uniform, both within and between samples, with a weighted mean ?Hfi of 1•9?±?0•2 (MSWD?=?0•9), indicating derivation from a common, isotopically homogeneous source. In contrast, in situ Nd isotopic data for titanite in the ultrapotassic rocks are variable (?Ndi?=?-3•5 to -12), suggesting variable contamination by an isotopically enriched source. The most primitive ?Ndi isotopic signatures, however, do overlap ?Ndi from monazite (?Ndi?=?-2•8?±?0•2) and bastnäsite (?Ndi?=?-3•2?±?0•3) in the ore-bearing carbonatite, suggesting derivation from a common source. The data presented here indicate that ultrapotassic magmatism occurred in up to three phases at Mountain Pass (?1425, ?1405, and ?1380?Ma). The latter two stages were coeval with carbonatite magmatism, revealing previously unrecognized synchronicity in ultrapotassic and carbonatite magmatism at Mountain Pass. Despite this temporal overlap, major and trace element geochemical data are inconsistent with derivation of the carbonatite and ultrapotassic rocks by liquid immiscibility or fractional crystallization from common parental magma. Instead, we propose that the carbonatite was generated as a primary melt from the same source as the ultrapotassic rocks, and that although it is unique, the Mountain Pass ultrapotassic and carbonatite suite is broadly similar to other alkaline silicate-carbonatite occurrences in which the two rock types were generated as separate mantle melts.
DS2001-0648
2001
Lackie, M.Lackie, M., Clark, D.A key paleomagnetic pole for the Early Permian for Australia and GondwanaGemoc Annual Report 2000, p. 31.Australia, GondwanaGeophysics - Paleomagnetism
DS201502-0096
2014
laclamita, M.Schingaro, E., Kullerud, K., laclamita, M., Mesto, E., Scordari, F., Zozulya, D., Erambert, M., Ravna, E.J.K.Yangzhumingite and phlogopite from the Kvaloya lamproite (North Norway): structure, composition and origin.Lithos, Vol. 210-211, pp. 1-13.Europe, NorwayLamproite
DS2002-0911
2002
Lacombe, O.Lacombe, O., Mouthereau, F.Basement involved shortening and deep detachment tectonics in forelands of orogens insights from recent collision belts. (Taiwan, Western Alps, Pyrenees)Tectonics, Vol. 21, No. 6, 10.1029/2001TC001018EuropeTectonics - not specific to diamonds
DS201510-1811
2015
Lacrampe, J.Vandenberg, J.A., Herrell, M., Faithful, J.W., Snow, A.M., Lacrampe, J., Bieber, C., Dayyani, S., Chisholm, V.Multiple modeling approach for the aquatic effects assessment of a proposed northern diamond mine development. Gahcho KueMine Water and the Environment, in press available, 19p.Canada, Northwest TerritoriesDeposit - Gahcho Kue

Abstract: Eight water models were used to assess potential aquatic environmental effects of the proposed Gahcho Kué diamond mine on groundwater and surface water flow and quality in the Northwest Territories, Canada. This sequence of models was required to cover different spatial and temporal domains, as well as specific physico-chemical processes that could not be simulated by a single model. Where their domains overlapped, the models were interlinked. Feedback mechanisms amongst models were addressed through iterative simulations of linked models. The models were used to test and refine mitigation plans, and in the development of aquatic component monitoring programs. Key findings generated by each model are presented here as testable hypotheses that can be evaluated after the mine is operational. This paper therefore offers a record of assumptions and predictions that can be used as a basis for post-validation.
DS201609-1754
2016
Lacrampe, J.Vandenberg, J.A., Herrell, M., Faithful, J.W., Snow, A.M., Lacrampe, J., Bieber, C., Dayyani, S., Chisholm, V.Multiple modeling approach for the aquatic effects assessment of a proposed northern diamond mine development.Mine Water and the Environment, Vol. 35, pp. 350-368.Canada, Northwest TerritoriesDeposit - Gahcho Kue

Abstract: Eight water models were used to assess potential aquatic environmental effects of the proposed Gahcho Kué diamond mine on groundwater and surface water flow and quality in the Northwest Territories, Canada. This sequence of models was required to cover different spatial and temporal domains, as well as specific physico-chemical processes that could not be simulated by a single model. Where their domains overlapped, the models were interlinked. Feedback mechanisms amongst models were addressed through iterative simulations of linked models. The models were used to test and refine mitigation plans, and in the development of aquatic component monitoring programs. Key findings generated by each model are presented here as testable hypotheses that can be evaluated after the mine is operational. This paper therefore offers a record of assumptions and predictions that can be used as a basis for post-validation.
DS201501-0031
2014
Lacrampe-Couloume, G.Lollar, B.S., Onstott, T.C., Lacrampe-Couloume, G., Ballentine, C.J.The contribution of the Precambrian continental lithosphere to global H2 production.Nature, Vol. 516, Dec. 18, pp. 379-382.MantleHydrogeology
DS1860-0946
1896
Lacroix, A.Lacroix, A.Diamant, 1896Mineralogie de la France et des Colonies, pp. 354-6.Africa, AlgeriaDiamond Synthesis
DS1860-1037
1898
Lacroix, M.A.Lacroix, M.A.Note sur Les Mineraux et Les Roches du Gisement Diamantifere de Monastery (etat Libre D'orange) et sur Ceux du Griqualand.Soc. Min. France (paris) Bulletin., Vol. 21, PP. 22-29. ALSO: Neues Jahrbuch f?r Mineralogie, P. 12. BD. 1, (Africa, South Africa, Orange Free StateMineralogy
DS2001-0649
2001
Lacroix, S.Lacroix, S., Doucet, P., Jean, A.Diamond and nickel potential of northern Quebec attracts attentionProspectors and Developers Association of Canada (PDAC) Exploration and development Highlights, pp. 10-11.Quebec, Ungava, LabradorKimberlites, Exploration - discoveries
DS2002-0912
2002
Lacroix, S.Lacroix, S.Diamond discoveries in the far north bolster exploration spendingProspectors and Developers Association of Canada (PDAC) Exploration and Development Highlights, pp. 10-11.QuebecNews item - brief review
DS2003-0769
2003
Lacroix, S.Lacroix, S.Diamond discoveries launch biggest-ever map staking rushExploration and Development Highlights, March 2003, p. 12-14QuebecNews item, Ashton, Renard, James Bay area - Majescor, Canabrava, BHPBilliton
DS200412-1079
2004
Lacroix, S.Lacroix, S.Cape Smith and Otish have them exploring la belle province.PDAC Exploration and Developments Highlights, pp. 10-12.Canada, Quebec, Otish MountainsBrief overview - diamond mentioned
DS1860-1093
1899
Lacy, G.Lacy, G.Pictures of Travel, Sport and AdventureLondon: C.A. Pearson, 420P.Africa, South AfricaTravelogue
DS1998-0823
1998
Lacy, W.Lacy, W.Introduction to geology and hard rock miningMountain Mineral Law Foundation, $ 25.00GlobalBook - ad, Geology for non-geologists
DS1992-0973
1992
Ladeira, E.A.Machado, N., Noce, C.M., Ladeira, E.A., Belo de Oliveira, O.uranium-lead (U-Pb) (U-Pb) geochronology of Archean magmatism and Proterozoic metamorphism in the Quadrilatero Ferrifero, southern Sao Francisco craton, BrasilGeological Society of America (GSA) Bulletin, Vol. 104, No. 9, September pp. 1221-1227BrazilGeochronology, Proterozoic
DS201604-0617
2016
Ladenburger, S.Ladenburger, S., Marks, M.A.W., Upton, B., Hill, P., Wenzel, T., Markl, G.Compositional variation of apatite from rift related alkaline igneous rocks of the Gardar Province, South Greenland.American Mineralogist, Vol. 101, pp. 612-626.Europe, GreenlandAlkalic

Abstract: Textural and compositional variations of apatite from four intrusions with different characteristic features of the rift-related alkaline Gardar Province were investigated: dyke rocks that belong to the most primitive rocks of the Province (Isortoq), nepheline-syenites associated with a carbonatite (Grønnedal-Ika), SiO2-saturated and SiO2-oversaturated syenites (Puklen) and nepheline-syenites displaying the transition from miaskitic to agpaitic mineral assemblages (Motzfeldt, Fig.1). Additionally, apatites from these intrusions were compared with other apatites of the Gardar Province. These include apatites from the Older Giant Dyke Complex, the Younger Giant Dyke Complex (both from the Tugtutôq region) and a narsarsukite-bearing trachytic dyke (Igdlutalik), as well as apatites from the Kûngnât, the North Qôroq and the Ilímaussaq intrusive complexes. This results in a complete overview of rift-related magmatites of the Gardar Province, ranging from primitive to highly evolved rocks. Backscattered electron images reveal the presence of various types of apatite textures including (i) growth zonation (concentric and oscillatory) that formed during magmatic differentiation and (ii) overgrowth and secondary textures (rounded cores, patchy zonation and overgrowth rims) due to fluid/melt induced metasomatic overprint and intracrystalline diffusion (Fig.2). Additionally, apatite compositions were analyzed with wavelength-dispersive electron microprobe analyses. During the crystallization history of the different intrusions, as well as within samples (documented by zoning patterns), increasing concentrations are observed for Si, REE, Na and F, whereas Cl shows a decreasing trend. However, for F, Cl and Na these trends are only observed in dyke rocks. Compositional variation of the investigated apatites is mainly due to substitution of Ca and P by variable amounts of Si, Na and REE. This study reveals that variations in the chemical composition of apatite are useful tools to obtain geochemical information about the host magma and its magmatic evolution. Here, Si and REE were found to be reliable petrogenetic indicators, whereas Na, F and Cl are only applicable in fast cooling systems to avoid redistribution of those elements.
DS1985-0377
1985
Laderoue, D.G.Laderoue, D.G., Evans, N.J., Mitchell, R.H.Lamprophyres Associated with the Coldwell Alkaline Complex, n.w. Ontario.Geological Association of Canada (GAC)., Vol. 10, P. A 33, (abstract.).Canada, OntarioMineralogy
DS1991-1175
1991
Laderoute, D.G.Mitchell, R.H., Platt, R.G., Downey, M., Laderoute, D.G.Petrology of alkaline lamprophyres from the Coldwell alkaline complex, northwestern OntarioCanadian Journal of Earth Sciences, Vol. 28, No. 10, October pp. 1653-1663OntarioAlkaline lamprophyres, Petrology, Coldwell
DS2001-0307
2001
Ladygina, M.Y.Evdokimov, M.D., Ladygina, M.Y., Nesterov, A.R.Morphology of diamonds as a possible indicator of their genesisNeues Jahrbuch f?r Mineralogie Abh., Vol. 176, No. 2, pp. 153-177.GlobalDiamond - morphology, Diamond - genesis
DS2001-0308
2001
Ladygina, M.Y.Evdorkimov, M.D., Ladygina, M.Y., Nesterov, A.R.Morphology of diamonds as possible indicator of their genesisNeues Jahrbuch Mineralogische Abhandlung, Vol. 176, No. 3, pp. 153-77.RussiaDiamond - morphology, Genesis
DS1998-0824
1998
LaFehr, T.R.LaFehr, T.R.On Talwani's errors in the total Bouguer reductionGeophysics, Vol. 63, No. 4, July-Aug. pp. 1125-36GlobalGeophysics - bouguer
DS201703-0424
2017
LaFlamme, C.LaFlamme, C., McFarlane, C.R.M., Fisher, C.M., Kirkland, C.L.Multi-mineral geochronology: insights into crustal behaviour during exhumation of an orogenic root.Contributions to Mineralogy and Petrology, in press available, 18p.CanadaCraton, Rae, Hearne
DS1989-1037
1989
Laflamme, J.H.G.Mitchell, R.H., Laflamme, J.H.G., Cabri, L.J.Rhenium sulphide from the Coldwell Complex,northwestern Ontario, CanadaMineralogical Magazine, Vol. 53, No. 373, Pt. 5, December pp. 635-636OntarioCarbonatite, Coldwell Complex -sulphid
DS2000-0198
2000
LafonDallagnol, R., Lafon, Fraga, Scandolara, BarrosThe Precambrian evolution of the Amazonian Craton: one of the last unknown Precambrian terranes in the world.Igc 30th. Brasil, Aug. abstract only 1p.Brazil, Guyana ShieldCraton - Amazon, Tectonics
DS200612-0302
2006
Lafon, J.M.Da Rosa Costa, L., Lafon, J.M., Delor, C.Zircon geochronology and Sm Nd isotopic study: further constraints for the Archean and Paleoproterozoic geodynamical evolution of southe eastern Guiana Shield.Gondwana Research, Vol. 10, 3-4, pp. 277-300.South America, GuyanaGeochronology
DS201112-0756
2011
Lafon, J.M.Oliveira, E.P., Souza, Z.S., McNaughton, N.J., Lafon, J.M., Costa, F.G., Figueiro, A.M.The Rio Capim volcanic plutonic sedimentary belt, Sao Francisco craton, Brazil: geological, geochemical and isotopic evidence for oceanic accretion during....Gondwana Research, Vol. 19, 3, pp. 735-750.South America, BrazilPaleoproterozoic continental collision
DS201809-2055
2018
Lafon, J.M.Leal, R.E., Lafon, J.M., da Ros Costa, L.T., Dantas, E.L.Orosirian magmatic episodes in the erepercuru-trombetas domain ( southeastern Guyana shield: implications for the crustal evolution of the Amazonian craton.South American Earth Sciences, Vol. 85, pp. 278-297.South America, Guyanacraton - Amazonian
DS1994-0367
1994
Lafon, J-M.Dall'Agnol, R., Lafon, J-M., Macambira, M.J.B.Proterozoic anorogenic magmatism in the central Amazonian Province, Amazonian craton: geochronological, petrological and geochemical aspectsMineralogy and Petrology, Vo. 50, No. 1-3, pp. 113-138South AmericaGeochemistry, Petrology
DS200912-0772
2009
Lafon, J-M.Travassos da Rosa Costa, L., Monie, P., Lafon, J-M., Arnaud, N.C.40 Ar 39 Ar geochronology across Archean and Paleoproterozoic terranes from southeastern Guiana Shield: evidence for contrasting cooling histories.Journal of South American Earth Sciences, Vol. 27, 2-3, pp. 113-128.South America, BrazilGeochronology
DS201812-2833
2016
Lafon, J-M.Kroonenberg, S.B., de Roever, E.W.F., Fraga, L.M., Faraco, T., Lafon, J-M., Cordani, U., Wong, T.E.Paleoproterzoic evolution of the Guiana Shield in Suriname: a revised model.Netherlands Journal of Geolsciences, Vol. 95, 4, pp. 491-522.South America, SurinameGuiana shield

Abstract: The Proterozoic basement of Suriname consists of a greenstone-tonalite-trondhjemite-granodiorite belt in the northeast of the country, two high-grade belts in the northwest and southwest, respectively, and a large granitoid-felsic volcanic terrain in the central part of the country, punctuated by numerous gabbroic intrusions. The basement is overlain by the subhorizontal Proterozoic Roraima sandstone formation and transected by two Proterozoic and one Jurassic dolerite dyke swarms. Late Proterozoic mylonitisation affected large parts of the basement. Almost 50 new U-Pb and Pb-Pb zircon ages and geochemical data have been obtained in Suriname, and much new data are also available from the neighbouring countries. This has led to a considerable revision of the geological evolution of the basement. The main orogenic event is the Trans-Amazonian Orogeny, resulting from southwards subduction and later collision between the Guiana Shield and the West African Craton. The first phase, between 2.18 and 2.09 Ga, shows ocean floor magmatism, volcanic arc development, sedimentation, metamorphism, anatexis and plutonism in the Marowijne Greenstone Belt and the adjacent older granites and gneisses. The second phase encompasses the evolution of the Bakhuis Granulite Belt and Coeroeni Gneiss Belt through rift-type basin formation, volcanism, sedimentation and, between 2.07 and 2.05 Ga, high-grade metamorphism. The third phase, between 1.99 and 1.95 Ga, is characterised by renewed high-grade metamorphism in the Bakhuis and Coeroeni belts along an anticlockwise cooling path, and ignimbritic volcanism and extensive and varied intrusive magmatism in the western half of the country. An alternative scenario is also discussed, implying an origin of the Coeroeni Gneiss Belt as an active continental margin, recording northwards subduction and finally collision between a magmatic arc in the south and an older northern continent. The Grenvillian collision between Laurentia and Amazonia around 1.2-1.0 Ga caused widespread mylonitisation and mica age resetting in the basement.
DS202012-2236
2020
Lafon, J-M.Neto, J.M.M., Lafon, J-M.Crustal growth and reworking of Archean crust within the Rhyacian domains of the southeastern Guiana Shield, Brazi: evidence from zircon U-Pb-Hf and whole rock Sm-Nd geochronology.Journal of South American Earth Sciences, Vol. 103, 102740 29p pdfSouth America, Brazilcraton

Abstract: The southeastern Guiana Shield, northern Amazonian Craton, is part of a Paleoproterozoic orogenic belt that was built up during the Transamazonian orogenic cycle (2.26-1.95 Ga). This cycle includes large segments of Rhyacian juvenile crust and some reworked Archean terranes. The geology in this region consists mainly of Paleoproterozoic granulitic-migmatitic-gneissic complexes, deformed and metamorphosed metavolcanic and metasedimentary rocks, and granitoids (granitic and TTG magmatism). Three tectonic domains are distinguished in the Brazilian territory of the southeastern Guiana Shield. They are known as the Amapá Block, Lourenço Domain, and Carecuru Domain. The Amapá Block is a Meso-Neoarchean continental block that was intensely reworked during the Transamazonian orogeny. The other two domains represent Rhyacian landmasses, the evolution of which involved several stages of subduction of oceanic lithosphere in magmatic arc environments. There are also relics of reworked Archean continental crust, the formation of which was followed by a collisional stage of tectonic accretion of the magmatic arcs. Whole-rock Sm-Nd and U-Pb zircon geochronology have confirmed the juvenile character of much of this Transamazonian orogenic belt. However, for the Lourenço and Carecuru domains, Nd isotopic signatures indicate the participation of Meso-Neoarchean crustal material in the sources of the magmatic rocks. Combined zircon U-Pb and Lu-Hf isotopic analyses by LA-ICP-MS were performed on eleven Rhyacian granitoids and orthogneisses from the Lourenço and Carecuru domains. The aim was to verify the extension of the influence of the Archean continental crust in the adjacent Paleoproterozoic domains. The main magmatic episodes were identified in the Lourenço Domain (~2.17-2.18, 2.14 and 2.12-2.09 Ga) and Carecuru Domain (2.14 Ga) by U-Pb zircon geochronology. The Lu-Hf isotope data point to the predominance of crustal reworking processes (?Hf(2.2-2.1 Ga) < 0; 67% of zircon crystals) during the formation of Lourenço and Carecuru domains. Hf model ages were found to be mostly Archean (98.4%), even for zircon grains that have positive ?Hf(2.2-2.1 Ga) values. For the terrane at the border of the Lourenço and Carecuru domains with the Amapá Block, assimilation of Archean crust of different ages and proportions in a magmatic arc environment accounts for the Hf-Nd isotopic signatures and Hf model ages of Rhyacian magmatism. In the northwestern part of the Lourenço Domain, more than 100 km north of the Amapá Block, the Hf-Nd isotopic signatures and Hf model ages indicate the participation of Archean crustal material, either as continental fragments and/or through incorporation of continental sediments in island arc environments, similar to what has been recorded for some Birimian terranes of the West African Craton in Ghana.
DS1975-0068
1975
Lafountain, L.J.Dobecki, T.L., Lafountain, L.J.Seismicity and Structure Along a Portion of the Midcontinent Geophysical Anomaly.Eos, Vol. 56, No. 9, PP. 602-603. (abstract.).KansasMid-continent
DS201812-2836
2018
Lafranchi, R.A.Lafranchi, R.A.A view of the potential of diamondiferous mineralization in Bahia using multi-source data.7th Symposio Brasileiro de Geologia do Diamante , Title only South America, Brazil, Bahiatechnology
DS1994-0972
1994
Lagabrielle, Y.Lagabrielle, Y., la Moigne, J., Maury, R.C., Cotten, J.Volcanic record of the subduction of an active spreading ridge, Taitao Peninsula (southern Chile)Geology, Vol. 22, No. 6, June pp. 515-518ChileSubduction, Tectonics
DS1996-0159
1996
Lagabrielle, Y.Bourgopis, J., Martin, H., Lagabrielle, Y., et al.Subduction erosion related to spreading ridge subduction: Titao peninsula(Chile triple junction)Geology, Vol. 24, No. 8, August pp. 723-726ChileSubduction, Tectonics
DS201012-0190
2010
Lagabrielle, Y.Faccenna, C., Becker, T.W., Lallemand, S., Lagabrielle, Y., Funiciello, F., Piromallo, C.Subduction triggered magmatic pulses: a new class of plumes?Earth and Planetary Science Letters, Vol. 299, 1-2, Oct. 15, pp. 54-68.MantleMagmatism
DS1992-0041
1992
Lager, G.A.Armbruster, T., Geiger, C.A., Lager, G.A.Single-crystal x-ray structure study of synthetic pyrope almandine garnet sat 100 and 293 kAmerican Mineralogist, Vol. 77, No. 5, 6, May-June pp. 512-521GlobalGarnet mineralogy, Synthetic pyrope
DS1996-1120
1996
LagnyPinna, P., Cocherie, A., Thieblemont, Feybesse, LagnyEvolution geodynamique du craton est-Africain et determinisme gitologueChron. Recherche Miniere, No, 525, pp. 33-43Tanzania, Kenya, UgandaTectonics, Metallogeny
DS201112-0534
2011
Lagos, M.Konig, S., Munker, C., Hohl, S., Paulick, H., Barth, A.R., Lagos, M., Pfander, J., Buchl, A.The Earth's tungsten budget during mantle melting and crust formation.Geochimica et Cosmochimica Acta, Vol. 78, 8, pp. 2119-2136.MantleMelting - not specific to diamonds
DS201312-0053
2013
Lagos, M.Ballhaus, C., Laurenz, V., Munker, C., Fonseca, R.O.C., Albarede, F., Rohrbach, A., Lagos, M., Schmidt, M.W., Jochum, K-P., Stoll, B., Weis, U., Helmy, H.M.The U /Pb ratio of the Earth's mantle - a signature of late volatile addition.Earth and Planetary Interiors, Vol. 362, pp. 237-245.MantleMelting
DS1920-0187
1924
Lagrange, E.Lagrange, E.Les Mines Diamantiferes de Kimberley, Les Degagements Gazeux et la Pression Atmospherique.Ciel Et Terre., Vol. 40, NOVEMBER and DECEMBER PP. 307-308.South Africa, Kimberley AreaMining Engineering
DS2003-0134
2003
Lagroix, F.Borradaile, G.J., Werner, T., Lagroix, F.Differences in paleomagnetic interpretations due to the choice of statisticalTectonophysics, Vol. 363, 1-2, Feb. 20, pp. 103-26.OntarioGeophysics - magnetics
DS2003-0135
2003
Lagroix, F.Borradaile, G.J., Werner, T., Lagroix, F.Difference in paleomagnetic interpretations due to choice of statistical, demagnetizationTectonophysics, Vol. 363, No. 1-2, Feb. 20, pp. 103-125.OntarioPaleomagnetics, tectonics
DS200412-0184
2003
Lagroix, F.Borradaile, G.J., Werner, T., Lagroix, F.Differences in paleomagnetic interpretations due to the choice of statistical, demagnetization and correction techniques: KapuskTectonophysics, Vol. 363, 1-2, Feb. 20, pp. 103-26.Canada, OntarioGeophysics - magnetics
DS1992-1754
1992
Laguta, O.N.Zolotukhin, V.V., Laguta, O.N., Malyuk, B.I.Genesis of komatiites of different continents, as inferred from dat a on their chemical compositionDoklady Academy of Science USSR, Earth Science Section, Vol. 312, No. 3, pp. 177-180RussiaKomatiites, Geochemistry
DS1992-1755
1992
Laguta, O.N.Zolotukhin, V.V., Malyuk, B.I., Laguta, O.N.Genetic aspects of deep seated petrogenesis of komatiite magmasSoviet Geology and Geophysics, Vol. 33, No. 1, pp. 29-39Russia, Commonwealth of Independent States (CIS)Komatiite, Petrology
DS1992-1756
1992
Laguta, O.N.Zolotukin, V.V., Malyuk, B.I., Laguta, O.N.Komatiites and the problem of basalt genesisRussian Geology and Geophysics, Vol. 33, No. 3, pp. 48-56Russia, Commonwealth of Independent States (CIS)Komatiites, Genesis -basalt
DS1998-1523
1998
Laguta, O.N.Vasilev, Y.R., Zolotukhin, V.V., Laguta, O.N.Shoshonites of the Northern Siberian PlatformDoklady Academy of Sciences, Vol. 361A, No. 6, pp. 799-03.Russia, SiberiaMagmatism, Shoshonites
DS1995-1044
1995
Lahaye, Y.Lahaye, Y., Arndt, N., Gruau, G.The influence of alteration on the trace element and neodymium isotopic compositions of komatiitesChemical Geology, Vol. 126, No. 1, Nov. 20, pp. 43-64AustraliaKomatiites, Alteration, Metasomatism
DS2003-0549
2003
Lahaye, Y.Hanrahan, M., Stachel. T., Brey, G.P., Lahaye, Y.Garnet peridotite xenoliths from the Koffiefontein mine, South Africa8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractSouth AfricaDeposit - Koffiefontein
DS2003-0770
2003
Lahaye, Y.Lahaye, Y., Brey, G.P.Scale and timing constraints on chemical redistribution between minerals of a composite8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractSouth AfricaMantle geochemistry, Deposit - Kimberley
DS200412-0784
2003
Lahaye, Y.Hanrahan, M., Stachel,T., Brey, G.P., Lahaye, Y.Garnet peridotite xenoliths from the Koffiefontein mine, South Africa.8 IKC Program, Session 6, POSTER abstractAfrica, South AfricaMantle petrology Deposit - Koffiefontein
DS200512-0960
2004
Lahaye, Y.Seitz, H-M., Brey, G.P., Lahaye, Y., Durali, S., Weyer, S.Lithium isotopic signatures of peridotite xenoliths and isotopic fractionation at high temperature between olivine and pyroxenes.Chemical Geology, Vol. 212, 1-2, pp. 163-177.MantlePetrology - not specific to diamonds
DS200612-0464
2006
Lahaye, Y.Girnis, A.V., Bulatov, V.K., Lahaye, Y., Brey, G.P.Partitioning of trace elements between carbonate silicate melts and mantle minerals: experiment and petrological consequences.Petrology, Vol. 14, 5, pp. 492-514.MantleMelts
DS200612-0708
2006
Lahaye, Y.Klama, K., Lahaye, Y., Weyer, S., Brey, G.P.Episodic versus long tern recycling processes within the Archean South African crust.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 21. abstract only.Africa, South AfricaSubduction
DS200612-0776
2006
Lahaye, Y.Lazarov, M., Brey, G., Lahaye, Y.Mapping of the Kaapvaal craton lithosphere with garnets from a polymict peridotite.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 345. abstract only.Africa, South AfricaGeochemistry - garnets
DS200812-0141
2008
Lahaye, Y.Brey, G.P., Bulatov, V.K., Girnis, A.V., Lahaye, Y.Experimental melting of carbonated peridotite at 6-10 GPa.Journal of Petrology, Vol. 49, 4, pp. 797-821.MantleMelting
DS200812-0624
2008
Lahaye, Y.Lahaye, Y., Kogarko, L.N., Brey, G.P.Isotopic (Nd, Hf, Sr) composition of super large rare metal deposits from the Kola Peninsula using in-situ LA MC ICPMS9IKC.com, 3p. extended abstractRussia, Kola PeninsulaDeposit - Khibina, Lovosero
DS200912-0393
2009
Lahaye, Y.Kogarko,N.,Lahaye, Y., Brey, G.P.Plume related mantle source of super large rare metal deposits from the Lovozero and Khibin a massifs on the Kola Peninsula, east Baltic Shield: Sr, Nd, Hf isotope ssytematics.Mineralogy and Petrology, in press availableEurope, Baltic Shield, Kola PeninsulaAlkalic
DS201112-0895
2011
Lahaye, Y.Saalmann, K., Gerdes, A., Lahaye, Y., Hartmann, L.A., Remus, M.V.D., Laufer, A.Multiple accretion at the eastern margin of the Rio de la Plat a craton: the prolonged Brasiliano orogeny in southernmost Brazil.International Journal of Earth Sciences, Vol. 100, 2, pp. 355-378.South America, BrazilCraton, not specific to diamonds
DS202008-1405
2020
Lahaye, Y.Kara, J., Vaisanen, M., Heinonen, J.S., Lahaye, Y., O'Brien, H., Huhma, H.Tracing arcologites in the Paleoproteroic era - a shift from 1.88 Ga calc-alkaline to 1.86 Ga high-Nb and adakite-like magmatism in central Fennoscandian shield.Lithos, in press available, 68p. PdfEurope, Fennoscandiaalkaline
DS200612-0098
2005
Lahiri, A.K.Basu, A., Das, L.K., Moitra, M., Bhattacharya, D., Lahiri, A.K.On the occurrence of rocks of lamproitic affinity in Singhbhum granite, near Rajnaga Tiring area, district of Singhbhum, Jharkland.Journal of the Geological Society of India, Vol. 65, pp. 15-16.IndiaLamproite
DS200412-1080
2004
Lahiri-Dutt, K.Lahiri-Dutt, K.Informality in mineral resource management in Asia: raising questions relating to community economics and sustainable developmenNatural Resources Forum, Vol. 28, 4, May, pp. 123-132.AsiaSocio-economics - not specific to diamonds
DS202109-1457
2021
Lahiri-Dutt, K.Choudhury, A.R., Lahiri-Dutt, K.Extractive capital and multi-scalar environmental politics: interpreting the exit of Rio Tinto from the diamond fields of Central India.Third World Quarterly, Vol. 42, 8, pp. 1770-1787. Indiaeconomics

Abstract: Rio Tinto had been developing a diamond mining project in Madhya Pradesh for a decade when in 2017 it hastily abandoned the project. We analyse this counterintuitive exit through an ethnographic approach nested within a qualitative case study framework. We argue that the exit was caused by multi-scalar politics. Local protests over livelihood and labour issues -pre-emptively rearticulated by regional civil society groups through an ecological ‘framing’ - led to litigation. The national forest bureaucracy posed regulatory hurdles, and a change in the national political regime in 2014 brought to power a party that leveraged national capital of a certain variety, which weakened Rio Tinto’s political position. Lastly, a slump in the global diamond market created economic uncertainties, finally leading to its exit. It has not, however, deterred the government from facilitating investment by Indian mega-corporate houses in mining diamonds, once again ignoring local dissent. Under the current regime in India, the space for activism is increasingly restricted, and that restriction, we contend, can lead to the disarray in strategising alliances and goals between ecological and social justice concerns.
DS202112-1924
2021
Lahiri-Dutt, K.Chowdhury, A.R., Lahiri-Dutt, K.Extractive capital and multi-scalar environmental politics: interpreting the exit of Rio Tinto from the diamond fields of central India.Third World Quarterly, Vol. 42, 8, pp. 1770-1787. pdfIndiaeconomics

Abstract: Rio Tinto had been developing a diamond mining project in Madhya Pradesh for a decade when in 2017 it hastily abandoned the project. We analyse this counterintuitive exit through an ethnographic approach nested within a qualitative case study framework. We argue that the exit was caused by multi-scalar politics. Local protests over livelihood and labour issues -pre-emptively rearticulated by regional civil society groups through an ecological ‘framing’ - led to litigation. The national forest bureaucracy posed regulatory hurdles, and a change in the national political regime in 2014 brought to power a party that leveraged national capital of a certain variety, which weakened Rio Tinto’s political position. Lastly, a slump in the global diamond market created economic uncertainties, finally leading to its exit. It has not, however, deterred the government from facilitating investment by Indian mega-corporate houses in mining diamonds, once again ignoring local dissent. Under the current regime in India, the space for activism is increasingly restricted, and that restriction, we contend, can lead to the disarray in strategising alliances and goals between ecological and social justice concerns.
DS1990-0590
1990
Lahmeyer, B.Gotze, H-J., Lahmeyer, B., Schmidt, S., Strunk, S., Araneda, M.Central Andes gravity dat a baseEos, Vol. 71, No. 16, April 17, pp. 401, 406-407Andes, Chile, ArgentinaGeophysics- gravity, Database
DS201805-0952
2017
Lahna, A.A.Ikenne, M., Lahna, A.A., Soderlund, U., Tassinar, C.C.G., Ernst, R.E., Pin, Ch., Youbi, N., El Aouli, EH., Hafid, A., Admou, H., Mata, J., Bouougri, EH., Boumehdi, M.A.New Mesoproterozoic age constraints for the Taghdout Group, Anti-Atlas ( Morocco): toward a new lithostratigra[hic framework for the Precambrian in the NW margin of the West African Craton.The First West African Craton and Margins International Workshop WACMA, Held Apr. 24-29. 1p. AbstractAfrica, Moroccogeochronology
DS202111-1768
2021
Lahna, A.A.Gong, Z., Evans, D.A.D., Youbi, N., Lahna, A.A., Sodelund, U., Malek, M.A., Wen, B., Jing, X., Ding, J., Boumedhdi, M.A., Ernst, R.E.Reorienting the West African craton in Paleoproterozoic-Msoproterozoic supercontinent Nuna.Geology, Vol. 49, 10, pp. 1171-1176. pdfAfrica, west AfricaNuna

Abstract: The location of the West African craton (WAC) has been poorly constrained in the Paleoproterozoic-Mesoproterozoic supercontinent Nuna (also known as Columbia). Previous Nuna reconstruction models suggested that the WAC was connected to Amazonia in a way similar to their relative position in Gondwana. By an integrated paleomagnetic and geochronological study of the Proterozoic mafic dikes in the Anti-Atlas Belt, Morocco, we provide two reliable paleomagnetic poles to test this connection. Incorporating our new poles with quality-filtered poles from the neighboring cratons of the WAC, we propose an inverted WAC-Amazonia connection, with the northern WAC attached to northeastern Amazonia, as well as a refined configuration of Nuna. Global large igneous province records also conform to our new reconstruction. The inverted WAC-Amazonia connection suggests a substantial change in their relative orientation from Nuna to Gondwana, providing an additional example of large-magnitude cumulative azimuthal rotations between adjacent continental blocks over supercontinental cycles.
DS1985-0068
1985
Lahner, L.Bluemel, G., Lahner, L.Minas Gerais, Brasil; Myths and Realities.(in German)Geologische Blaetter Fuer Nordost Bayern Und Angrenzende Gebiete, Vol. 34-35, pp. 735-754BrazilDiamonds Discussed, Overview
DS200612-0757
2005
Lahti, I.Lahti, I., Korja, T., Kaikkonen, P., Vaittinen, K.Decomposition analysis of the BEAR magnetotelluric data: implications for the upper mantle conductivity in the Fennoscandian Shield.Geophysical Journal International, Vol. 163, 3, Dec. pp. 900-914.Europe, Fennoscandia, Finland, SwedenGeophysics - magnetotelluric
DS201212-0742
2012
Lahti, I.Vaittinen, K., Korja, T., Kaikkonen, P., Lahti, I., Smirnov, M.Yu.High resolution magnetotelluric studies of the Archean Proterozoic border zone in the Fennoscandian shield, FinlandGeophysical Journal International, inpress availableEurope, FinlandGeophysics, magetics
DS200612-0758
2005
Lahti, S.I.Lahti, S.I.Orbicular rocks in Finland..... brief mentions of peridotites.Geological Survey of Finland, 176p.Europe, FinlandBook - occurrences, features, terminology - not diamond
DS1997-0642
1997
Lahtinen, R.Lahtinen, R., Huhma, H.Isotopic and geochemical constraints on the evolution of 1.93 - 1.79 Ga Svecofennian crust and mantle.Precambrian Research, Vol. 82, No. 1-2, Mar. 1, pp. 13-34.FinlandGeochronology, Mantle
DS1997-0643
1997
Lahtinen, R.Lahtinen, R., Huhma, H.Isotopic and geochemical constraints on the evolution of the 1.93-1.79 Ga Svecofennian crust and mantle.Precambrian Research, Vol. 82, No. 1-2, March pp. 13-34.FinlandTectonics, crust, mantle, Geochronology
DS2000-0548
2000
Lahtinen, R.Lahtinen, R.Archean Proterozoic transition: geochemistry, provenance, tectonic setting of metasedimentary rocksPrecambrian Research, Vol. 104, No. 3-4, Nov.pp. 147-74.Finland, FennoscandiaTectonics
DS200612-1517
2005
Lahtinen, R.Weihed, P., Arndt, N., Billstrom, K., Duschesne, J-C., Eilu, P., Martinsson, O., Papunen, H., Lahtinen, R.Precambrian geodynamics and ore formation: the Fennoscandian shield.Ore Geology Reviews, Vol. 27, pp. 273-322.Europe, FennoscandiaMetallogeny - tectonics
DS201906-1311
2019
Lahtinen, R.Lahtinen, R., Huhma, H.A revised geodynamic model for the Lapland - Kola Orogen.Precambrian Research, Vol. 330, pp. 1-19.Europe, Fennoscandia, Russia, Kola Peninsulatectonics

Abstract: The Paleoproterozoic Lapland-Kola Orogen in Fennoscandia has been studied for decades and several plate tectonic models have been proposed including one-sided subduction zone, either towards SW or NW, or two opposite-verging subduction zones before the collision. Based on new structural and isotope data from Finland and recently published data from Russia, we propose a revised tectonic model for the Paleoproterozoic Lapland-Kola Orogen. The main components are foreland in the NE followed by cryptic suture, Inari arc, retro-arc basin and retro-arc foreland in the SW. The latter three constitute the Inari Orocline. Subduction towards present SW and subsequent arc magmatism (Inari arc) started at ca. 1.98?Ga followed by voluminous sedimentation in the deepening retro-arc basin. Underplating of a mid-ocean ridge caused flat subduction and magmatic flare at 1.92?Ga over a broad distance in the retro-arc basin. Rapid heating led to melting of the retro-arc basin sediments and voluminous amounts of granulite-facies diatexites formed. During collision (D1) at 1915-1910?Ma, large thrust nappes formed on the foreland. Deformation in the retro-arc basin is seen as recumbent folding and shearing of diatexites in the lower parts of the basin and thrusting of metatextite-diatexite packages in the upper parts. A post-collisional stage is seen as 1904?Ma appinites and decompression derived granites at 1.90-1.89?Ga. Renewed shortening (D2), due to far-field effects in SW at 1.88-1.87?Ga, led to thick-skin shortening of the Archean middle crust, large-scale crustal duplexing of already cooled granulites towards the retro-arc foreland and inclined upright folding of granulites in the opposite direction towards the Inari arc. A switch in the stress field from NE-SW to NW-SE led to orogen-parallel contraction and buckling started along a dextral strike-slip fault zone to form the Inari Orocline. Buckling is seen in the bending of pre-orocline fabrics and formation of syn-orocline fabrics: radial conical folds (D3), radial fractures, a strike-slip fault zone and thrusting at the hinge zone. The end-result is a mega-scale parallel multi-layer fold composed of the Inari arc, retro-arc basin and possibly also the heated retro-arc foreland.
DS2001-0639
2001
Lahtinen R.Kukkonen, I.T., Lahtinen R.Variation of radiogenic heat production rate in 2.8 - 1.8 Ga old rocks in the central Fennoscandian shield.Physics of the Earth and Planetary Interiors, Vol. 126, No. 3-4, Nov. 1, pp. 279-94.Finland, Sweden, Baltica, FennoscandiaGeothermometry
DS1997-0644
1997
Lahtinent, R.Lahtinent, R., Huhma, H.Isotopic and geochemical constraints on the evolution of the 1.93 and 1.79Ga Svecofennian crust and mantlePrecambrian Research, Vol. 82, pp. 13-34FinlandGeochronology, Geochemistry
DS2002-1757
2002
LaiYamamoto, J., Kagi, H., Kaneoka, Lai, Prikhodko,AraiFossil pressures of fluid inclusions in mantle xenoliths exhibiting rheology of mantle minerals...Earth and Planetary Science Letters, Vol.198,3-4,pp.511-19., Vol.198,3-4,pp.511-19.MantleSpectroscopy, Geobarometry - mantle minerals
DS2002-1758
2002
LaiYamamoto, J., Kagi, H., Kaneoka, Lai, Prikhodko,AraiFossil pressures of fluid inclusions in mantle xenoliths exhibiting rheology of mantle minerals...Earth and Planetary Science Letters, Vol.198,3-4,pp.511-19., Vol.198,3-4,pp.511-19.MantleSpectroscopy, Geobarometry - mantle minerals
DS202204-0540
2022
LaiVan Rythoven, A.D., Schulze, D.J., Stern, R.A., Lai, M, Y.Composition of diamond from the 95-2 pipe, Lake Timiskaming kimberlite cluster, Superior craton, Canada.The Canadian Mineralogist, Vol. 60, pp. 67-90. pdfCanada, Ontariocathodluminenescence

Abstract: Forty-one samples of diamond from the Jurassic 95-2 kimberlite pipe in the Lake Timiskaming Kimberlite Cluster, Superior Craton, Canada, were imaged using cathodoluminescence and analyzed by secondary ion mass spectrometry and Fourier-transform infrared absorbance spectrometry to determine carbon stable isotope composition, total nitrogen abundance, and nitrogen aggregation state. The carbon isotope compositions results (?13CVPDB) range from -9.11 to -3.57‰, with a mean value of -5.8‰. Intra-stone variation is small (maximum ?2.2‰, and in most individual diamond samples <1‰). Nitrogen contents range from 0.5 to 2040 ppm (mean of 483 ppm). The greatest range of values in a single stone is 825 ppm. The samples are poorly aggregated in terms of nitrogen. The samples are mostly type IaA or IaAB, with a few bordering on type Ib. Diamond growth was episodic, with nitrogen behaving highly compatibly (i.e., D = [N]diamond/[N]fluid >> 1). Precipitation was likely from a carbonate-rich fluid in a peridotitic (lherzolitic) environment within the mantle of the central Superior Craton. This generation of diamond growth is very similar to those reported from the Jurassic age Victor and U2 pipes of the Attawapiskat Kimberlite Cluster, and distinct from a possibly much older (>1.1 Ga) generation of diamond reported in other older host rocks (T1, Wawa, Lynx, and Renard). This older generation of diamond at these other localities is also predominantly of the peridotitic (harzburgitic) paragenesis but contains far less nitrogen (although typically more aggregated as B centers) and has higher ?13CVPDB. The younger generation of diamond formed after mantle heating during formation of the Mid-Continental Rift (ca. 1.1 Ga) destroyed any proximal prior generation(s) of diamond. Igneous activity after 1.1 Ga subsequently refertilized the cratonic mantle to a lherzolitic paragenesis in which the younger generation precipitated.
DS202009-1676
2020
Lai, C-K.Zheng, H., Chen, H., Wu, C., Jiang, H., Gao, C., Kang, Q., Yang, C., Wang, D., Lai, C-K.Genesis of the supergiant Huayangchuan carbonatite-hosted uranium polymetallic deposit in the Qinling orogen, central China.Gondwana Research, Vol. 86, pp. 250-265.ChinaREE

Abstract: The newly-discovered supergiant Huayangchuan uranium (U)-polymetallic deposit is situated in the Qinling Orogen, Central China. The deposit contains economic endowments of U, Nb, Pb, Se, Sr, Ba and REEs, some of which (e.g., U, Se, and Sr) reaching super-large scale. Pyrochlore, allanite, monazite, barite-celestite and galena are the major ore minerals at Huayangchuan. Uranium is mainly hosted in the primary mineral of pyrochlore, and the mineralization is mainly hosted in or associated with carbonatite dikes. According to the mineral assemblages and crosscutting relationships, the alteration/mineralization at Huayangchuan comprises four stages, i.e., pegmatite REE mineralization (I), main mineralization (II), skarn mineralization (III) and post-ore alteration (IV). Coarse-grained euhedral allanite is the main Stage I REE mineral, and the pegmatite-hosted REE mineralization (ca. 1.8 Ga) occurs mostly in the shallow-level of northwestern Huayangchuan, corresponding to the Paleoproterozoic Xiong'er Group volcanic rocks (1.80-1.75 Ga) in the southern margin of North China Block. Carbonatite-hosted Stage II mineralization contributes to the majority of U-Nb-REE-Ba-Sr resources, and is controlled by the Huayangchuan Fault. Stage II mineralization can be further divided into the sulfate mineralization (barite-celestite) (II-A), alkali-rich U mineralization (aegirine-augite + pyrochlore + uraninite + uranothorite) (II-B) and REE (allanite + monazite + chevkinite)-U (pyrochlore + uraninite) mineralization (II-C) substages. Stage II mineralization may have occurred during the Late Triassic Mianlue Ocean closure. Skarn mineralization contributed to the majority of Pb and minor U-REE (uraninite-allanite) resources at Huayangchuan, and is spatially associated with the Late Cretaceous-Early Jurassic (Yanshanian) Huashan and Laoniushan granites. We suggested that hydrothermal fluids derived from the Laoniushan and Huashan granites may have reacted with the Triassic carbonatites, and formed the Huayangchuan Pb skarn mineralization. The mantle-derived Triassic carbonatites may have been fertilized by the U-rich subducting oceanic sediments, and were further enriched through reacting with the Proterozoic U-REE-rich pegmatite wallrocks at Huayangchuan. Ore-forming elements were likely transported in metal complexes (F?, and ), and deposited with the dilution of the complex concentration. This may have formed the distinct vertical mineralization zoning, i.e., sodic fenite-related alkali-U mineralization at depths and potassic fenite-related REE-U mineralization at shallow level.
DS202012-2258
2020
Lai, C-k.Zheng, H., Chen, H., Wu, C., Jiang, H., Gao, C., Kang, Q., Yang, C., Wang, D., Lai, C-k.Genesis of the supergiant Huayanchuan carbonatite-hosted uranium-plymetallic deposit in the Qinling Orogen, central China.Gondwana Research, Vol. 86, pp. 250-265. pdfChinadeposit - Huayangchuan

Abstract: The newly-discovered supergiant Huayangchuan uranium (U)-polymetallic deposit is situated in the Qinling Orogen, Central China. The deposit contains economic endowments of U, Nb, Pb, Se, Sr, Ba and REEs, some of which (e.g., U, Se, and Sr) reaching super-large scale. Pyrochlore, allanite, monazite, barite-celestite and galena are the major ore minerals at Huayangchuan. Uranium is mainly hosted in the primary mineral of pyrochlore, and the mineralization is mainly hosted in or associated with carbonatite dikes. According to the mineral assemblages and crosscutting relationships, the alteration/mineralization at Huayangchuan comprises four stages, i.e., pegmatite REE mineralization (I), main mineralization (II), skarn mineralization (III) and post-ore alteration (IV). Coarse-grained euhedral allanite is the main Stage I REE mineral, and the pegmatite-hosted REE mineralization (ca. 1.8 Ga) occurs mostly in the shallow-level of northwestern Huayangchuan, corresponding to the Paleoproterozoic Xiong'er Group volcanic rocks (1.80-1.75 Ga) in the southern margin of North China Block. Carbonatite-hosted Stage II mineralization contributes to the majority of U-Nb-REE-Ba-Sr resources, and is controlled by the Huayangchuan Fault. Stage II mineralization can be further divided into the sulfate mineralization (barite-celestite) (II-A), alkali-rich U mineralization (aegirine-augite + pyrochlore + uraninite + uranothorite) (II-B) and REE (allanite + monazite + chevkinite)-U (pyrochlore + uraninite) mineralization (II-C) substages. Stage II mineralization may have occurred during the Late Triassic Mianlue Ocean closure. Skarn mineralization contributed to the majority of Pb and minor U-REE (uraninite-allanite) resources at Huayangchuan, and is spatially associated with the Late Cretaceous-Early Jurassic (Yanshanian) Huashan and Laoniushan granites. We suggested that hydrothermal fluids derived from the Laoniushan and Huashan granites may have reacted with the Triassic carbonatites, and formed the Huayangchuan Pb skarn mineralization. The mantle-derived Triassic carbonatites may have been fertilized by the U-rich subducting oceanic sediments, and were further enriched through reacting with the Proterozoic U-REE-rich pegmatite wallrocks at Huayangchuan. Ore-forming elements were likely transported in metal complexes (F?, and ), and deposited with the dilution of the complex concentration. This may have formed the distinct vertical mineralization zoning, i.e., sodic fenite-related alkali-U mineralization at depths and potassic fenite-related REE-U mineralization at shallow level.
DS1989-0841
1989
Lai, D.Lai, D.An important source of 4 He (and 3 He) in diamondsEarth and Planetary Science Letters, Vol. 96, pp. 1-7GlobalDiamond morphology, Helium, Noble gases -helium isoto
DS1989-1624
1989
Lai, D.Wiens, R.C., Lai, D., Craig, H.Helium and carbon isotope ratios in Indian diamondsEos, Vol. 70, No. 43, October 24, p. 1411. AbstractIndiaGeochronology, Diamond
DS1990-0899
1990
Lai, D.Lai, D., Craig, H.Sorting out the helium isotopes in diamonds: primordial, cosmogenic and implanted componentsEos, Vol. 71, No. 28, July 10, p. 849. AbstractGlobalDiamond morphology, Noble gases -helium isoto
DS1994-1914
1994
Lai, D.Wiens, R.C., Lai, D., Rison, W., Wacker, J.F.Helium isotope diffusion in natural diamondsGeochimica et Cosmochimica Acta, Vol. 58, No. 7, April pp. 1747-1758.GlobalDiamond morphology, Natural diamonds
DS201312-0539
2013
Lai, J.Liang, Q., Meng, Y., Yan, C., Krasnicki, S., Lai, J., Hemawan, K., Shu,H., Popov, D., Yu,T., Yang, W., Mao, H., Hemley, R.Developments in synthesis, characterization, and application of large high-quality CVD single crystal diamond.Journal of Superhard Materials, Vol. 35, 4, pp. 195-213.TechnologyDiamond synthetics
DS201906-1340
2019
Lai, M.Qiao, X., Zhou, Z., Schwarz, D.T., Qi, L., Gao, J., Nong, P., Lai, M., Guo, K., Li, Y.Study of the differences in infrared spectra of emerald from different mining areas and the controlling factors.The Canadian Mineralogist, Vol. 57, pp. 65-79.Globalemerald genesis

Abstract: Natural emeralds from 11 mining areas were studied using an infrared spectrometer. The results showed different spectroscopic characteristics for emerald from different mine regions. Infrared absorption is mainly attributed to the vibration of Si-O lattice, channel water, alkaline cations, and molecules such as CO2, [Fe2(OH)4]2+, etc. Both near-infrared and mid-infrared spectra showed that the differences in band positions, intensities, and shapes are related to the mixed ratio of the two types of channel water. Accordingly, emerald and its mining regions can be divided into 3 types: H2O I, H2O II, and transition I-II. Furthermore, the study indicates that the relative amounts of the two different orientations of channel water molecules are mainly affected by the presence of (Mg + Fe)2+ in the host rock or in the mineralizing fluid. Therefore, the mineralization environment type (alkali-poor, alkali-rich, and transitional types) of emerald can be preliminarily identified from IR spectroscopy. This can be useful for determining the origin of emeralds.
DS201812-2837
2018
Lai, M.Y.Lai, M.Y.Spectroscopic analysis of yellow diamonds. ( Chidliak, Ekati, Qilalugaq)Thesis, Msc. University of Alberta, 142p. Pdf availableCanada, Nunavut, Northwest Territoriesdeposit - Chidliak, Ekati, Qilalugaq
DS202002-0199
2020
Lai, M.Y.Lai, M.Y., Breeding, C.M., Stachel, T., Stern, R.A.Spectroscopic features of natural and HPHT treated yellow diamonds. EkatiDiamonds & Related Materials, Vol. 101, 107642, 8p. PdfCanada, Northwest Territoriesdeposit - Ekati

Abstract: High pressure high temperature (HPHT) treatment has long been applied in the gem trade for changing the body colour of diamonds. The identification of HPHT-treated diamonds is a field of on-going research in gemological laboratories, as different parameters of treatment will result in either the creation or the destruction of a variety of lattice defects in diamonds. Some features that exist in treated diamonds can also be found in natural diamonds, and consequently must not be employed for the separation of treated and natural diamonds. In this research, we investigated the properties of 11 natural yellow diamonds (directly obtained from the Ekati Diamond Mine to ensure that they are untreated) before and after HPHT treatment, conducted at a temperature of 2100 °C and a pressure of 6 GPa for 10 min. We report spectroscopic data and fluorescence characteristics, collected using PL mapping, FTIR mapping and fluorescence imaging showing the distribution of lattice defects and internal growth structures. PL mapping indicates SiV defects exist in one of the nitrogen-rich natural diamonds prior to treatment. Silicon-related defects can also be created by HPHT treatment, and they seem to show a relationship with pre-existing NV? centres. SIMS analysis was conducted to confirm the presence of silicon in these diamonds. The increase in the hydrogen-related infrared absorption peak at 3107 cm?1 (VN3H) is very strong in some diamonds that do not form B-centres during treatment. NVH was observed in our HPHT-treated natural diamonds, so it is possible that this strong increase in VN3H suppresses the aggregation of A- to B-centres as the newly formed A-centres were captured by NVH lattice defects to form VN3H. HPHT-altered and HPHT-induced platelet peaks are different from their natural counterparts in peak width and shape. Strong green fluorescence over a large area of a diamond, which is linked to relatively high concentration of H3 centres, was produced after HPHT treatment. We are confident that the unusual platelet peaks and strong emission of H3 centres are reliable indicators for HPHT-treated diamonds as they are not observed in untreated natural diamonds.
DS202003-0347
2020
Lai, M.Y.Lai, M.Y., Stachel, T., Breeding, C.M., Stern, R.A.Yellow diamonds with colourless cores - evidence for episodic diamond growth beneath Chidliak and Ekati mine, Canada.Mineralogy and Petrology, in press available 13p. PdfCanada, Northwest Territoriesdeposit - Chidliak, Ekati

Abstract: Yellow diamonds from the CH-7 (Chidliak) and the Misery (Ekati Mine) kimberlites in northern Canada are characterised for their nitrogen characteristics, visible light absorption, internal growth textures, and carbon isotope compositions. The diamonds are generally nitrogen-rich, with median N contents of 1230 (CH-7) and 1030 at.ppm (Misery). Normally a rare feature in natural diamonds, single substitutional nitrogen (C centres) and related features are detected in infrared absorption spectra of 64% of the studied diamonds from CH-7 and 87% from Misery and are considered as the major factor responsible for their yellow colouration. Episodically grown diamonds, characterised by colourless cores containing some nitrogen in the fully aggregated form (B centres) and yellow outer layers containing C centres, occur at both localities. Carbon isotope compositions and N contents also are significantly different in such core and rim zones, documenting growth during at least two temporally distinct events and involving different diamond forming fluids. Based on their nitrogen characteristics, both the yellow diamonds and yellow rims must have crystallized in close temporal proximity (<<1 Ma) to kimberlite activity at CH-7 and Misery.
DS202204-0527
2022
Lai, M.Y.Lai, M.Y., Stachel, T., Stern, R.A., Hardman, M.F., Pearson, D.G., Harris, J.W.Formation of mixed paragenesis diamonds during multistage growth - constraints from- in situ Delta 13C-delta 15N-[N] analyses of Koidu diamonds.Geochimica et Cosmochimica Acta, Vol. 323, pp. 20-39.Africa, Sierra Leonedeposit - Koidu

Abstract: Inclusion-bearing diamonds from the Koidu kimberlite complex, Sierra Leone (West African Craton) were analyzed in situ for carbon and nitrogen isotope compositions, nitrogen concentrations and nitrogen aggregation states. In a suite of 105 diamonds, 78% contain eclogitic mineral inclusions, 17% contain peridotitic mineral inclusions, and 5% - an unusually high proportion - contain co-occurring eclogitic and peridotitic mineral inclusions indicating a mixed paragenesis. Major and trace element compositions of mineral inclusions from two mixed paragenesis diamonds (one with omphacite + Mg-chromite, the other with eclogitic garnet + forsteritic olivine) were determined. The presence of positive Eu anomalies in centrally located omphacite and eclogitic garnet inclusions indicates derivation from subducted protoliths, formed as igneous cumulates in lower oceanic crust. Mg-chromite (Cr# 85.5; Mg# 65.2) and olivine (Mg# 94.5) inclusions, located in outer portions of the mixed paragenesis diamonds, have compositions indicative of derivation from strongly depleted cratonic peridotites. Given that the olivine Mg# of 94.5 is the highest reported to date for the West African Craton, the eclogitic and peridotitic inclusions in these mixed paragenesis diamonds cannot have precipitated during infiltration of peridotitic substrates by eclogite-derived fluids, as the consequent fluid-rock interaction should lead to Mg# lower than that for the original peridotitic diamond substrate. The different origins of eclogitic and peridotitic inclusions could be explained by physical transport of their host diamonds from eclogitic into peridotitic substrates, possibly along high-strain shear zones, before renewed diamond growth. Based on the ?¹³C-?¹?N systematics of the entire inclusion-bearing diamond suite from Koidu, three major compositional clusters are identified. Cluster 1 (eclogitic diamond cores; ?¹³C = -33.2 to -14.4 ‰ and ?¹?N = -5.3 to +10.1 ‰) bears the isotopic signature of recycled crustal material (± a mantle component). Cluster 2 (peridotitic diamonds and including the core of a diamond containing omphacite + Mg-chromite; ?¹³C = -6.0 to -1.1 ‰ and ?¹?N = -4.2 to +9.7 ‰) likely involves mixing of carbon and nitrogen from subducted and mantle sources. Cluster 3 (rims of eclogitic diamonds and including the eclogitic garnet + olivine included diamond and the rim of the omphacite + Mg-chromite included diamond; ?¹³C = -7.8 to -3.6 ‰ and ?¹?N = -7.9 to -2.1 ‰) matches convecting mantle-derived fluids/melts. The distinct isotopic signatures of the three diamond clusters, together with differences in nitrogen aggregation and cathodoluminescence response between diamond cores and rims, suggest episodic diamond growth during multiple fluid/melt pulses.
DS201312-0528
2013
Lai, X.Lai, X., Yang, X.Geochemical characteristics of the Bayan Obo giant REE Nb Fe deposit: constraints on its genesis.Journal of South American Earth Sciences, Vol. 41, pp. 99-112.ChinaDeposit - Bayan Obo
DS201702-0256
2017
Lai, X.Yang, X., Lai, X., Pirajno, F., Liu, Y., Mingxing, L., Sun, W.Genesis of the Bayan Obo Fe_REE-Nb formation in Inner Mongolia, North Chin a craton: a perspective review.Precambrian Research, Vol. 288, pp. 39-71.ChinaDeposit - Bayan Obo

Abstract: The Bayan Obo deposit in Inner Mongolia, North China Craton (NCC) is the largest rare-earth element (REE) resource in the world. Due to the complex element and mineral compositions and the activity of several geological events, the ore-forming mechanism is still controversial. Previous models are reviewed here to provide information for further investigation on the Bayan Obo deposit. In this study, we summarize all different types of Fe-REE-Nb mineralization using field observations and microscope work, in which we recognize 9 types of Fe-REE-Nb ores in the Bayan Obo ore district. By compiling and re-evaluating a large number of published geochemical data, this paper provides solid evidence that the Bayan Obo deposit formed through interaction between sedimentary rocks and carbonatite magmatism. From the results of our review, it can be conjectured that the formation of iron ores was originated from sedimentation (Pt1), whereas the formation of REE mineralized dolomite might be related to interaction and reaction between the carbonatite magmas and/or associated fluids with sedimentary carbonate rocks, with the REE-bearing carbonatite magmas having undergone intense fractionation enrichment process. The C-O-S-Fe-Mg isotopes indicate that the REE-Nb mineralization was derived from metasomatism (fenitic alteration) of sedimentary carbonate. A new model is proposed for this unique REE-Nb mineralization, which is related to the subduction of Siberian Craton beneath the North China Craton since Early Paleozoic period. We interpret that the Bayan Obo Fe-REE-Nb ore deposits and their massive barren host, H8 dolomite, were generated as a result of interaction of fluids expelled from a subcontinental lithospheric mantle (SCLM)-derived carbonatite magma with sedimentary carbonates.
DS201709-2021
2017
LaI, X.Li, J., Xhu, F., Dong, J., Liu, J., LaI, X., Chen, B., Meng, Y.Experimental investigations into the fate of subducted carbonates and origin of super deep diamonds.Goldschmidt Conference, abstract 1p.Mantlepetrology

Abstract: Carbonates are common rock-forming minerals in the Earth’s crust and act as sinks of atmospheric carbon dioxide. Subduction of hydrothermally altered oceanic lithosphere returns carbon to the interior, where more than three quarters of Earth’s carbon is stored. The contribution of subducted carbonates to the Earth's long-term deep carbon cycle is uncertain and has recently emerged as a topic of intense debate [1]. Moreover, mantle-slab interaction has been proposed as a mechanism to produce super-deep diamonds, thus questioning the use of certain mineral inclusions to infer lower-mantle origin [2]. Here we report new data on the chemical stability and reaction kinetics of carbonates in the mantle from multianvil and diamond-anvil-cell experiments. Our results suggest that carbon can be sequestered into deep Earth through reaction freezing and that the index minerals for super-deep diamonds are not reliable indicators for their formation depths.
DS201809-2085
2018
Lai, X.Sharma, S.K., Chen, B., Gao, J., Lai, X.Micro-Raman investigations of diamond genesis during slab-mantle interaction.Goldschmidt Conference, 1p. AbstractMantlediamond genesis

Abstract: Magnesite is proposed to be a major oxidized carbon storage phase in the mantle due to its wide P-T range of stability [1-2]. The presence of magnesite in the Earth's interior will depend on the redox state of the Earth's interior. Large part of the deep mantel is considered to be significantly reduced with considerable amount of FeO dispersed in rocks [3]. During slab-mantle interaction, subducted carbonates in the slab will undergo redox reactions with metallic Fe. However, the mechanism of this interaction is not well understood. In order to understand diamond genesis during the slabmantle interactions, we have conducted high-pressure and high-temperature experiments in a 2000-ton multi-anvil highpressure press on samples containing MgCO3 and iron foils (50 ?m thick) in BN capsules. The samples under pressures from 10 to 16 GPa were heated to 1200-1700 K. The samples were quenched under pressure and the quenched samples were polished and then analyzed with multi-wavelength micro-Raman spectrometers using 785, 514.5 and 532 nm laser excitations. Micro-Raman investigations show that the iron foils reduce MgCO3 to various sp2 carbon phases, mainly graphite, followed by the transformation to diamond upon long-duration heating. The transformation to diamond is driven by the temperature. For example, in the Run number PL066 with staring material containing magnesite and two Fe foils heated to 1400 K at 10 GPa for 24 hrs, and quenched, the run products were [Mg,Fe]O, and diamond and graphite. The sample PL044 with staring material containing magnesite and three Fe foils heated to 1600 K at 14 GPa for 12 hrs, the run products were larger size (~10 ?m) diamonds, iron carbide and small amount of graphite. Our results indicate that in slow subduction (T~1500 K) all carbonates will be converted in diamond and iron carbide. Under rapid subduction of the slab, the carbonate will survive and be carried to greater depth. The inclusions of [Mg,Fe]O in diamonds, however, do not necessarily indicate that this phase is of lower mantle origin.
DS201811-2587
2018
Lai, X.Lai, X., Zhu, F., Zhang, D., Hu, Y., Finkelstein, G.J., Dera, P., Chen, B.The high pressure anisotropic thermelestic properties of a potential inner core carbon bearing phase, Fe-C3, by single crystal X-ray diffraction.American Mineralogist, Vol. 103, pp. 1568-1574.Mantlecarbon

Abstract: Carbon has been suggested as one of the light elements existing in the Earth's core. Under core conditions, iron carbide Fe7C3 is likely the first phase to solidify from a Fe-C melt and has thus been considered a potential component of the inner core. The crystal structure of Fe7C3, however, is still under debate, and its thermoelastic properties are not well constrained at high pressures. In this study, we performed synchrotron-based single-crystal X-ray diffraction experiment using an externally heated diamond-anvil cell to determine the crystal structure and thermoelastic properties of Fe7C3 up to 80 GPa and 800 K. Our diffraction data indicate that Fe7C3 adopts an orthorhombic structure under experimentally investigated conditions. The pressure-volume-temperature data for Fe7C3 were fitted by the high-temperature Birch-Murnaghan equation of state, yielding ambient-pressure unit-cell volume V0 = 745.2(2) Å3, bulk modulus K0 = 167(4) GPa, its first pressure derivative K0? = 5.0(2), dK/dT = -0.02(1) GPa/K, and thermal expansion relation ?T = 4.7(9) × 10-5 + 3(5) × 10-8 × (T - 300) K-1. We also observed anisotropic elastic responses to changes in pressure and temperature along the different crystallographic directions. Fe7C3 has strong anisotropic compressibilities with the linear moduli Ma > Mc > Mb from zero pressure to core pressures at 300 K, rendering the b axis the most compressible upon compression. The thermal expansion of c3 is approximately four times larger than that of a3 and b3 at 600 and 700 K, implying that the high temperature may significantly influence the elastic anisotropy of Fe7C3. Therefore, the effect of high temperature needs to be considered when using Fe7C3 to explain the anisotropy of the Earth's inner core.
DS201904-0805
2019
Lai, X.Zhu, F., Li, J., Liu, J., Lai, X., Chen, B., Meng, Y.Kinetic control on the depth of superdeep diamonds.Geophysical Research Letters, Vol. 46, 4, pp. 1984-1992.Mantlediamond genesis

Abstract: Superdeep diamonds originate from great depths inside Earth, carrying samples from inaccessible mantle to the surface. The reaction between carbonate and iron may be an important mechanism to form diamond through interactions between subducting slabs and surrounding mantle. Interestingly, most superdeep diamonds formed in two narrow zones, at 250-450 and 600-800 km depths within the ~2,700?km?deep mantle. No satisfactory hypothesis explains these preferred depths of diamond formation. We measured the rate of a diamond forming reaction between magnesite and iron. Our data show that high temperature promotes the reaction, while high pressure does the opposite. Particularly, the reaction slows down drastically at about 475(±55) km depth, which may explain the rarity of diamond formation below 450 km depth. The only exception is the second zone at 600-800 km, where carbonate accumulates and warms up due to the stagnation of subducting slabs at the top of lower mantle, providing more reactants and higher temperature for diamond formation. Our study demonstrates that the depth distribution of superdeep diamonds may be controlled by reaction rates.
DS202002-0200
2019
Lai, X.Lai, X., Yang, X.U-Pb ages and Hf isotope of zircons from a carbonatite dyke in the Bayan Obo Fe-REE deposit in Inner Mongolia: its geological significance.Acta Geologica Sinica, Vol. 93, 6, pp. 1783-1796.China, MongoliaREE

Abstract: Detailed studies on U?Pb ages and Hf isotope have been carried out in zircons from a carbonatite dyke associated with the Bayan Obo giant REE?Nb?Fe deposit, northern margin of the North China Craton (NCC), which provide insights into the plate tectonic in Paleoproterozoic. Analyses of small amounts of zircons extracted from a large sample of the Wu carbonatite dyke have yielded two ages of late Archaean and late Paleoproterozoic (with mean 207Pb/206Pb ages of 2521±25 Ma and 1921±14 Ma, respectively). Mineral inclusions in the zircon identified by Raman spectroscopy are all silicate minerals, and none of the zircon grains has the extremely high Th/U characteristic of carbonatite, which are consistent with crystallization of the zircon from silicate, and the zircon is suggested to be derived from trapped basement complex. Hf isotopes in the zircon from the studied carbonatite are different from grain to grain, suggesting the zircons were not all formed in one single process. Majority of ?Hf(t) values are compatible with ancient crustal sources with limited juvenile component. The Hf data and their TDM2 values also suggest a juvenile continental growth in Paleoproterozoic during the period of 1940-1957 Ma. Our data demonstrate the major crustal growth during the Paleoproterozoic in the northern margin of the NCC, coeval with the assembly of the supercontinent Columbia, and provide insights into the plate tectonic of the NCC in Paleoproterozoic.
DS202202-0229
2022
Lai, X.Zhou, W-Y., Zhang, J.S., Huang, Q., Lai, X., Chen, B., Dera, P., Schmandte, B.High pressure-temperature single crystal elasticity of ringwoodite: implications for detecting the 520 discontinuity and metastable ringwoodite at depths greater than 660 km.Earth and planetary Science Letters, Vol. 579, 117359, 11p. PdfMantleringwoodite

Abstract: The 520 km discontinuity (the 520) and the 660 km discontinuity (the 660) are primarily caused by the wadsleyite to ringwoodite and ringwoodite to bridgmanite + ferropericlase phase transitions, respectively. Global seismic studies show significant regional variations of the 520, which are likely due to chemical and thermal heterogeneities in the Mantle Transition Zone (MTZ). However, the effects of chemical composition and temperature on the detectability of the 520 are unclear. Additionally, it remains unknown whether the possibly existing metastable ringwoodite in the core of the cold and fast subducting slabs could create a detectable seismic signature near the top of the lower mantle. Our understanding of both issues is hindered by the lack of single-crystal elasticity measurements of ringwoodite at simultaneous high pressure-temperature (P-T) conditions. In this study, we measured the single-crystal elasticity of an anhydrous Fe-bearing ringwoodite up to 32 GPa and 700 K by Brillouin spectroscopy, and then modeled the composition-dependent elastic properties of ringwoodite to calculate the compositional effects on the velocity jumps at the 520. We found that opposite to the effect of Fe, water enhances the Vp (P-wave velocity) jump, yet decreases the Vs (S-wave velocity) jump of the 520 across the wadsleyite to ringwoodite transition. Higher temperature increases both Vp and Vs contrasts across the 520. At depths between 660-700 km in the lower mantle, the existence of metastable ringwoodite may only result in ?1-2% low velocity anomaly, which is seismically difficult to resolve. The low velocity anomaly caused by metastable ringwoodite increases to 5-7% at 750 km depth due to the weak pressure dependence of Vs in ringwoodite at lower mantle conditions, but whether it is seismically detectable depends on the extension of the regions in subducted slabs that are sufficiently cold to host metastable ringwoodite.
DS201212-0393
2012
Lai, X-D.Lai, X-D., Yang, X-Y.Geochemical characteristics of the Bayan Obo giant REE-Nb-Fe deposit: constraints on its genesis.Journal of South American Earth Sciences, in press available 58p.ChinaCarbonatite
DS200912-0716
2009
Lai, Y.Song, S., Su, L., Niu, Y., Lai, Y., Zhang, L.CH4 inclusions in orogenic harzburgite: evidence for reduced slab fluids and implication for redox melting in mantle wedge.Geochimica et Cosmochimica Acta, Vol. 73, 6, pp. 1737-1754.MantleSubduction
DS1992-0354
1992
Lai ShaocongDeng Jinfu, Zhao Hailing, Lai Shaocong, Molan, E., Lou Zaohua, Mo XuanxueThe mantle plume beneath the northern part of Chin a continentInternational Symposium Cenozoic Volcanic Rocks Deep seated xenoliths China and its, Abstracts pp. 15ChinaMantle, Plume
DS1982-0320
1982
Lai.Keller, G.R., Kruger, J.M., Schneider, R.V., Aiken, C.L.V., Lai.Regional Geophysical Studies of the Southern Oklahoma Aulocogen and Ouachita SystemGeological Society of America (GSA), Vol. 14, No. 3, P. 115, (abstract.).OklahomaMid-continent, Geophysics
DS201811-2619
2018
Laia, S.Xu, J., Melgarejo, J.C., Castillo, O., Montgarri, A., Laia, S., Santamaria, J.Ilmenite generations in kimberlite from Banankoro, Guinea. ConakryNeues Jahrbuch fur Mineralogie, doi:.org/10.1127/njma/2018/0096Africa, Guineadeposit - Banakoro

Abstract: A complex mineral sequence in a kimberlite from the Banankoro Cluster (Guinea Conakry) has been interpreted as the result of magma mixing processes. The composition of the early generations of phlogopite and spinel suggest direct crystallisation of a kimberlitic magma. However, the compositional trends found in the late generations of phlogopite and spinels could suggest magma mixing. In this context, four ilmenite generations formed. The first generations (types 1 and 2) are geikielitic and are associated with spinel and phlogopite which follow the kimberlitic compositional trends. They are interpreted as produced by crystallization from the kimberlite magma. A third generation of euhedral tabular Mg-rich ilmenite (type 3) formed during the interval between two generations of serpentine. Finally, a late generation of Mn-rich ilmenite (type 4) replaces all the Ti-rich minerals and is contemporaneous with the last generation of serpophitic non-replacing serpentine. Therefore, the formation of type 3 and type 4 ilmenite took place after the crystallization of the groundmass, during late hydrothermal process. Our results suggest a detailed textural study is necessary when use Mg-rich and Mn-rich ilmenites as KIMs.
DS1998-1002
1998
Laiba, A.A.Mikhalsky, E.V., Laiba, A.A., Surina, N.P.The Lambert Province of alkaline basic and alkaline ultrabasic rocks of East Antarctica: geochemistry...Petrology, Vol 6, No. 5, Sept-Oct. p. 466-479.GlobalAlkaline rocks
DS200812-0103
2008
Laiba, A.A.Belyatsky, B.V., Antonov, A.V., Rodionov, N.V., Laiba, A.A., Sergeev, S.A.Age and composition of carbonatite kimberlite dykes in the Prince Charles Mountains, East Antarctica9IKC.com, 3p. extended abstractAntarcticaCarbonatite
DS200912-0422
2009
Laiginhas, F.Laiginhas, F., Pearson, D.G., Phillips, D., Burgess, R., Harris, J.W.Re Os and 40Ar 39Ar isotope measurements of inclusions in alluvial diamonds from the Ural Mountains: constraints on diamond genesis and eruption ages.Lithos, in press availableRussia, UralsGeochronology
DS201812-2831
2018
Laiginhas, F.Krebs, M.Y., Pearson, D.G., Stachel, T., Laiginhas, F., Woodland, S., Chinn, I., Kong, J.A common parentage - Low abundance trace element data of gem diamonds reveals similar fluids to fibrous diamonds. ( silicate/sulphide)Lithos, doi.org/10.1016/ jlithos.2018.11.025 49p.Canada, Ontario, Attawapiskat, Africa, South Africadeposit - Victor, Finsch, Newlands

Abstract: Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. “Planed” and “ribbed” trace element patterns characterize not only the high-density fluid (HDF) inclusions in fibrous diamonds but also in gem diamonds. Two diamonds from two Finsch harzburgite xenoliths show trace element patterns similar to those of saline fluids, documenting the involvement of saline fluids in the precipitation of gem diamonds, further strengthening the link between the parental fluids of both gem and fibrous diamonds. Differences in trace element characteristics are evident between Victor diamonds containing silicate inclusions compared with Victor diamonds containing sulphide inclusions. The sulphide-bearing diamonds show lower levels of inter-element fractionation and more widely varying siderophile element concentrations - indicating that the silicate and sulphide-bearing diamonds likely formed by gradations of the same processes, via melt-rock reaction or from a subtly different fluid source. The shallow negative LREEN-HREEN slopes displayed by the Victor diamonds establish a signature indicative of original derivation of the diamond forming agent during major melting (~10% melt). Consequently, this signature must have been passed on to HDFs separating from such silicate melts.
DS201902-0288
2019
Laiginhas, F.Krebs, M.Y., Pearson, D.G., Stachel, T., Laiginhas, F., Woodland, S., Chinn, I., Kong, J.A common parentage low abundance trace element data of gem diamonds reveals similar fluids to fibrous diamonds.Lithos, Vol. 324, 1, pp. 356-370.Canada, Ontario, Africa, South Africadeposit - Victor, Finsch, Newlands

Abstract: Quantitative trace element data from high-purity gem diamonds from the Victor Mine, Ontario, Canada as well as near-gem diamonds from peridotite and eclogite xenoliths from the Finsch and Newlands mines, South Africa, acquired using an off-line laser ablation method show that we see the same spectrum of fluids in both high-purity gem and near-gem diamonds that was previously documented in fibrous diamonds. "Planed" and "ribbed" trace element patterns characterize not only the high-density fluid (HDF) inclusions in fibrous diamonds but also in gem diamonds. Two diamonds from two Finsch harzburgite xenoliths show trace element patterns similar to those of saline fluids, documenting the involvement of saline fluids in the precipitation of gem diamonds, further strengthening the link between the parental fluids of both gem and fibrous diamonds. Differences in trace element characteristics are evident between Victor diamonds containing silicate inclusions compared with Victor diamonds containing sulphide inclusions. The sulphide-bearing diamonds show lower levels of inter-element fractionation and more widely varying siderophile element concentrations - indicating that the silicate and sulphide-bearing diamonds likely formed by gradations of the same processes, via melt-rock reaction or from a subtly different fluid source. The shallow negative LREEN-HREEN slopes displayed by the Victor diamonds establish a signature indicative of original derivation of the diamond forming agent during major melting (~10% melt). Consequently, this signature must have been passed on to HDFs separating from such silicate melts.
DS201803-0439
2006
Laiginhas-Fernando, A.T.P.Correia Eugenio, A., Laiginhas-Fernando, A.T.P.Garnets from the Camafuca Camazambo kimberlite.Anais da Academia Brasileira de Ciencas, Vol. 78, 2, pp. 309-315.Africa, Angoladeposit - Camafuca

Abstract: This work presents a geochemical study of a set of garnets, selected by their colors, from the Camafuca-Camazambo kimberlite, located on northeast Angola. Mantle-derived garnets were classified according to the scheme proposed by Grütter et al. (2004) and belong to the G1, G4, G9 and G10 groups. Both sub-calcic (G10) and Ca-saturated (G9) garnets, typical, respectively, of harzburgites and lherzolites, were identified. The solubility limit of knorringite molecule in G10D garnets suggests they have crystallized at a minimum pressure of about 40 to 45 kbar (4-4.5 GPa). The occurrence of diamond stability field garnets (G10D) is a clear indicator of the potential of this kimberlite for diamond. The chemistry of the garnets suggests that the source for the kimberlite was a lherzolite that has suffered a partial melting that formed basaltic magma, leaving a harzburgite as a residue.
DS1996-1526
1996
Laili, J.Wen, Su, Shutong, Xu, Laili, J., Yican, LiuCoesite from quartz jadeitite in the Dabie Mountains, eastern ChinaMineralogical Magazine, Vol. 60, pp. 659-662.ChinaCoesite
DS200812-0625
2008
Laine, H.M.Laine, H.M., O'Brien, H.E.Alteration and primary kimberlite rock type classification for Lahtojoki kimberlite, Finland.9IKC.com, 3p. extended abstractEurope, FinlandDeposit - Lahtojoki
DS1970-0118
1970
Laing, E.M.Laing, E.M.Report on the Geology of Part of the Nimini Hills Schist Belt and Associated Sialic Rocks.Geological Survey SIERRA LEONE., UNPUBL. ReportWest Africa, Sierra LeoneGeology
DS1998-0825
1998
Laing, G.Laing, G.Discovery and evaluation of the Jericho kimberlites, NorthwestTerritories.Calgary Mining Forum, Apr. 8-9, p. 26. abstractNorthwest TerritoriesDeposit - Jericho, Lytton Minerals
DS1999-0391
1999
Laing, G.Laing, G.Tahera Corporation: developing the Jericho kimberlite field8th. Calgary Mining forum, 1p. abstractNorthwest TerritoriesNews item
DS200812-0626
2008
Laing, T.Laing, T.Diamonds are forever.... Eira Thomas and Ellen Clements are interviewed.Mining and Exploration ( BC), Summer. p. 4-5.CanadaNews item - history
DS2003-1515
2003
Lai-Xiang, L.Xue-Cheng, Y., Klemperer, S.L., Wen-Bang, T., Lai-Xiang, L., Chetwin, E.Crustal structure and exhumation of the Dabie Shan ultrahigh pressure orogen, easternGeology, Vol. 31, 5, pp. 435-8.ChinaGeophysics - seismics, UHP - ultra high pressure
DS200412-2164
2003
Lai-Xiang, L.Xue-Cheng, Y., Klemperer, S.L., Wen-Bang, T., Lai-Xiang, L., Chetwin, E.Crustal structure and exhumation of the Dabie Shan ultrahigh pressure orogen, eastern China, from seismic reflection profiling.Geology, Vol. 31, 5, pp. 435-8.ChinaGeophysics - seismics UHP - ultra high pressure
DS1991-0948
1991
Laj, C.Laj, C., Mazaud, A., Weeks, R., Fuller, M., Herrero Bervera, E.Geomagnetic reversal pathsNature, Vol. 351, June 6, p. 447GlobalGeophysics, Geomagnetics, Paleomagnetics
DS1997-0645
1997
Lajaunie, C.Lajaunie, C., Courrioux, G., Manuel, L.Foliation fields and 3D cartography in geology: principles of a method based on potential interpolationMath. Geol, Vol. 29, No. 4, pp. 571-584GlobalGeostatistics, Kriging
DS2000-0525
2000
Lajoki, K.Korobeinikov, A.N., Lajoki, K., Gehor, S.Nepheline bearing feldspar syenite (pulaskite) Khibin a pluton, Kola Peninsula -petrological investigationJournal of Asian Earth Science, Vol. 18, No.2, Apr. pp.205-12.Russia, Kola PeninsulaPetrology, Pulaskite
DS201112-1045
2011
Lake, G.Tien, Y., Zhou, Y., Sigloch, K., Nolet, G., Lake, G.Structure of North American mantle constrained by simultaneous inversion of multiple frequency SH, SS and Love waves.Journal of Geophysical Research, Vol. 116, B2, B02307..MantleGeophysics - seismics
DS1860-0667
1890
Lake, P.Lake, P.The Supposed Matrix of the Diamond at Wajrakarur, MadrasIndia Geological Survey Records, Vol. 23, PP. 69-72.India, Andhra PradeshPetrography
DS1992-0906
1992
Lakefield ResearchLakefield ResearchMineralogy: diamond exploration samples. Brochure outlining procedures they use and fee structure for microdiamond extraction.briefLakefield Research, 2p. ( total 1p. info)CanadaBrochure, Lakefield Research
DS1900-0779
1909
Lakes, A.Lakes, A.Precious Stones 1909Mining Science., Vol. 60, Nov. 4TH. PP. 414-416.United States, CanadaGemstones
DS200712-0478
2007
Lakes, R.S.Jaglinski, T., Kochmann, D., Stone, D., Lakes, R.S.Composite materials with viscoelastic stiffness greater than diamond.Science, No. 5812, Feb. 2, pp. 620-621.TechnologyChemistry
DS202108-1288
2021
Lakey, S.Hermann, J., Lakey, S.Water transfer to the deep mantle through hydrous, Al-rich silicates in subduction zones.Geology, Vol. 49, pp. 911-915.Mantlewater

Abstract: Constraining deep-water recycling along subduction zones is a first-order problem to understand how Earth has maintained a hydrosphere over billions of years that created conditions for a habitable planet. The pressure-temperature stability of hydrous phases in conjunction with slab geotherms determines how much H2O leaves the slab or is transported to the deep mantle. Chlorite-rich, metasomatic rocks that form at the slab-mantle interface at 50-100 km depth represent an unaccounted, H2O-rich reservoir in subduction processes. Through a series of high-pressure experiments, we investigated the fate of such chlorite-rich rocks at the most critical conditions for subduction water recycling (5-6.2 GPa, 620-800 °C) using two different natural ultramafic compositions. Up to 5.7 GPa, 740 °C, chlorite breaks down to an anhydrous peridotite assemblage, and H2O is released. However, at higher pressures and lower temperatures, a hydrous Al-rich silicate (11.5 Å phase) is an important carrier to enable water transfer to the deep mantle for cold subduction zones. Based on the new phase diagrams, it is suggested that the deep-water cycle might not be in secular equilibrium.
DS201806-1239
2018
Lakhotia, S.C.Patwardhan, B., Nagarkar, S., Gadre, S.R., Lakhotia, S.C., Katoch, V.M., Moher, D.A critical analysis of the 'UGC' approved list of journals.Current Science, Vol. 114, 6, Mar. 25, pp. 1299-1303.Indialegal

Abstract: Scholarly journals play an important role in maintaining the quality and integrity of research by what they publish. Unethical practices in publishing are leading to an increased number of predatory, dubious and low-quality journals worldwide. It has been reported that the percentage of research articles published in predatory journals is high in India. The University Grants Commission (UGC), New Delhi has published an 'approved list of journals', which has been criticized due to inclusion of many substandard journals. We have developed a protocol with objective criteria for identifying journals that do not follow good publication practices. We studied 1336 journals randomly selected from 5699 in the university source component of the 'UGC-approved list'. We analysed 1009 journals after excluding 327 indexed in Scopus/Web of Science. About 34.5% of the 1009 journals were disqualified under the basic criteria because of incorrect or non-availability of essential information such as address, website details and names of editors; another 52.3% of them provided false information such as incorrect ISSN, false claims about impact factor, claimed indexing in dubious indexing databases or had poor credentials of editors. Our results suggest that over 88% of the non-indexed journals in the university source component of the UGC-approved list, included on the basis of suggestions from different universities, could be of low quality. In view of these results, the current UGC-approved list of journals needs serious reconsideration. New regulations to curtail unethical practices in scientific publishing along with organization of awareness programmes about publication ethics at Indian universities and research institutes are urgently needed.
DS201012-0391
2010
Lakin, D.A.Kislyakov, V.E., Korzon, O.A., Lakin, D.A.Shelf placer deposits: a new technology for winter mining.Russian Geology and Geophysics, Vol. 51, pp. 143-145.RussiaMining - coolants related to placer gold deposits
DS201412-0941
2013
Lakshimi, V.N.Vani, T., Lakshimi, V.N., Ramakrishnarao, M.V., Keller, G.R., Subbarao, K.V.Integration of geophysical and geological dat a of kimberlites in Narayanpet-Maddur field, Andhra Pradesh, India.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 229-240.India, Andhra PradeshDeposit - Narayanpet- Maddur
DS1970-0268
1971
Lakshmanan, S.Das, K.N., Lakshmanan, S.Repositories of the Panna Diamond Deposits and Age of the Majhgawan Volcanic Pipe.India Geological Survey Miscellaneous Publishing, No. 19, PP. 95-101.IndiaGeochronology
DS1990-0900
1990
Lakshmanan, V.I.Lakshmanan, V.I., Miller, J.D.Advanced materials- application of mineral and metallurgical processingAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Book, 400p. approx. 60.00GlobalMineral processing, Advanced materials
DS200512-0051
2005
Lakshmi, M.P.Babu, H.V.R., Lakshmi, M.P.Aeromagnetic image of a part of peninsular India and its relation to geology and geophysics.Exploration Geophysics, Vol. 36, 2, pp. 250-258.India, AsiaGeophysics - magnetics (not specific to diamonds)
DS200712-0630
2007
Lakshtanov, D.Litasov, K.D., Kagi, H., Shatskiy, A., Lakshtanov, D., Bass, J.D., Ito, E.High hydrogen solubility in Al rich stishovite and water transport in the lower mantle.Earth and Planetary Science Letters, Vol. 262, 3-4, Oct. 30, pp. 620-634.MantleWater
DS200612-0097
2006
Lakshtanov, D.L.Bass, J.D., Sanchez-Valle, C., Lakshtanov, D.L., Brenizer, J., Wang, J., Matas, J.Elastic properties of high pressure phases and implications for the temperature and mineralogy of Earth's lower mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.MantleGeothermometry
DS200612-0824
2006
Lakshtanov, D.L.Litasov, K.D., Ohtain, E., Kagi, H., Lakshtanov, D.L., Bass, J.D.Hydrogen solubility in Al rich stidhovite and water transport to the lower mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 23. abstract only.MantleWater
DS1987-0392
1987
Lal, D.Lal, D., Nishizumi, K., Klein, J., Middleton, R., Craig, H.Cosmogenic 13Be in Zaire alluvial diamonds: implications for Helium contents of diamondsNature, Vol. 328, No. 6126, July 9, pp. 139-141Democratic Republic of CongoDiamond, Mineral Chemistry
DS1989-0842
1989
Lal, D.Lal, D., Craig, H., Wacker, J.F., Poreda, R.He-3 diamonds- the cosmogenic component (letter)Geochimica et Cosmochimica Acta, Vol. 53, No. 2, Feb. pp. 569-574GlobalDiamond morphology
DS1990-1148
1990
Lal, D.Ozima, M., Lal, D.Comment on an important source of 4He (and 3He) in diamonds, by D. Lal. and reply by LalEarth and Planetary Science Letters, Vol. 101, No. 1, November pp. 107-111GlobalDiamonds, helium
DS1990-1556
1990
Lal, D.Wiens, R., Lal, D., Craig, H.Helium and carbon isotopes in Indian diamondsGeochimica et Cosmochimica Acta, Vol. 54, pp. 2587-2591IndiaGeochronology, Diamond inclusions - H and
DS1996-0801
1996
Lal, D.Lal, D.On nuclear studies of processes and time scales in the evolution of an alluvial fan.Geochemistry International, Vol. 33, No. 5, pp. 77-93.RussiaAlluvials, Geomorphology, cosmic ray geophysics
DS1990-1368
1990
Lal, K.Singh, B.P., Gupta, S.K., Dhawan, U., Lal, K.Characterization of synthetic diamonds by EPR and X-raydiffractiontechniquesJournal of Material Science, Vol. 25, No. 28, February pp. 1487-1490GlobalDiamond synthesis, EPR and X-ray diffraction
DS200812-0627
2008
Lal, R.K.Lal, R.K.An updated calibration of garnet clinopyroxene Fe Mg exchange geothermometer: application to mantle xenoliths in kimberlite and related rocks.Indian Dykes: editors Srivastava, Sivaji, Chalapathi Rao, pp. 354-366.IndiaKimberlite geothermometry
DS200412-0669
2004
Lalancette, J.Girard, R., Parent,M., Aubin, A., Belley, J.M., Lalancette, J.Glacial dispersion of lithological indicators in the Otish Mountain area.Quebec Exploration Conference, Canada, Quebec, Otish MountainsGeochemistry, geomorphology
DS1860-0805
1893
Lalanne, E.Lalanne, E.Les Mines de Diamant du Cap (1893) - the Diamond Mines of the CapeScience Illustrated., Vol. 11, Jan.14TH. PP. 114-115.Africa, South AfricaGeology
DS200612-0759
2005
Lalemant, H.G.A.Lalemant, H.G.A., Sisson, V.B.Caribbean South American plate interactions, Venezuela.Geological Society of America, No. 394, 335p.South America, VenezuelaBook - eclogites,allochthonous belts - not specific diamonds
DS1995-1045
1995
Lalleman, S.Lalleman, S.High rates of arc consumption by subduction processes: some consequencesGeology, Vol. 23, No. 6, June pp. 551-554Japan, PeruMantle, Subduction, arc consumption
DS1995-1046
1995
Lallemand, S.Lallemand, S.High rates of arc consumption by subduction processes: some consequencesGeology, Vol. 23, No. 6, June pp. 551-554.Japan, PeruSubduction
DS200512-0430
2005
Lallemand, S.Heuret, A., Lallemand, S.Plate motions, slab dynamics and back arc deformation.Physics of the Earth and Planetary Interiors, Vol. 149, 1-2, March 15, pp. 31-51.MantleSubduction
DS200512-0596
2005
Lallemand, S.Lallemand, S., Heuret, A., Boutelier, D.On the relationship between slab dip, back arc stress, upper plate absolute motion, and crustal nature in subduction zones.Geochemistry, Geophysics, Geosystems: G3, Vol. 6, Q12J14, doi:10.1029/2005 GC000917MantleSubduction, geodynamics
DS200812-0373
2008
Lallemand, S.Funiciello, F., Faccenna, C., Heuret, A., Lallemand, S., Di Guiseppe, E., Becker, T.W.Trench migration, net rotation and slab mantle decoupling.Earth and Planetary Science Letters, Vol. 271, 1-4, pp. 233-240.MantleSubduction
DS200812-0628
2008
Lallemand, S.Lallemand, S., Heuret, A., Faccenna, C., Funiciello, F.Subduction dynamics as revealed by trench migration.Tectonics, Vol. 27, TC3014MantleSubduction
DS200812-1271
2008
Lallemand, S.Wu, B., Conrad, C.P., Heuret, A., Lithgow Bertollini, C., Lallemand, S.Reconciling strong slab pull and weak plate bending: the plate motion constraint on the strength of mantle slabs.Earth and Planetary Science Letters, Vol. 272, 1-2, pp. 412-421.MantleSubduction
DS200812-1273
2008
Lallemand, S.Wu, C., Conrad, C.P., Heuret, A., Lithgow-Bertelloni, C., Lallemand, S.Reconciling strong slab pull and weak plate bending: the plate motion constraint on the strength of mantle slabs.Earth and Planetary Science Letters, Vol. 272, 1-2, July 30, pp. 412-421.MantleSubduction
DS201012-0190
2010
Lallemand, S.Faccenna, C., Becker, T.W., Lallemand, S., Lagabrielle, Y., Funiciello, F., Piromallo, C.Subduction triggered magmatic pulses: a new class of plumes?Earth and Planetary Science Letters, Vol. 299, 1-2, Oct. 15, pp. 54-68.MantleMagmatism
DS1993-0895
1993
Lallemant, S.Le Pichon, X., Henry, P., Lallemant, S.Accretion and erosion in subduction zones: the role of fluidsAnnual Review of Earth and Planetary Sciences, Vol. 21, pp. 307-332MantleTectonics
DS200512-0617
2005
Lallukka, H.M.Lehtonen, M.L., Pakkanen, L.K., Johanson, B.S., Lallukka, H.M.EMP analyses of kimberlite indicator minerals from Pipe 7 and Dyke 16 kimberlites and the basal till surrounding them.Geological Survey of Finland, Open File M 41.2/2005/2.Europe, FinlandGeochemistry
DS1994-0105
1994
Lally, J.H.Barker, D.J., Lally, J.H.Use of geostatistics to model geology -vein distribution in a complex pegmatite type depositInstitute of Mining and Metallurgy (IMM) Bulletins, pp. B 97-102GlobalGeostatistics, Pegmatites
DS200612-0801
2006
Lalonde, A.Lenz, D., Lalonde, A., Salvi, S., Paquette, J.Alkaline igneous systems: dissecting magmatic to hydrothermal mineralizing processes.Mineralogical Association of Canada, www.gacmac2006.caCanada, QuebecTechnical meeting - volcanism, alkaline rocks
DS1981-0258
1981
Lalonde, A.E.Lalonde, A.E.The Baie des Mountons Syenitic Complex, la Tabatiere, QuebecMsc. Thesis, Mcgill University, Canada, QuebecBlank
DS1994-0973
1994
Lalonde, A.E.Lalonde, A.E., Rancourt, D.G., Chao, G.Y.iron bearing trioctahedral micas from Mont Saint Hilaire, QuebecGeological Association of Canada (GAC) Abstract Volume, Vol. 19, p.QuebecMineralogy, Mont Saint Hilaire
DS1996-0802
1996
Lalonde, A.E.Lalonde, A.E., Rancourt, D.G., Chao, G.Y.iron bearing trioctahedral micas from Mont Saint Hilaire Quebec, CanadaMineralogical Magazine, Vol. 60, pp. 447-460.QuebecAlkaline rocks, Deposit -Mont St. Hilaire region
DS1985-0378
1985
LamLam, CHI-KIN, Yarger, H.L.Preliminary Investigation of New Kansas Gravity MapGeological Society of America (GSA), Vol. 17, No. 5, MARCH P. 297. (abstract.).United States, Central States, KansasGravity, Geophysics
DS1988-0395
1988
Lam, C.Lam, C., Yarger, H.The structure of the central North American rift system in Kansas as interpreted from gravity dataGeological Society of America Abstracts with Program, Vol. 20, No. 2, January p. 121. Sth. Central, LawrenceKansasMid continent
DS1989-0843
1989
Lam, C.Lam, C.New gravity dat a in northeastern IndianaGeological Society of America (GSA) Abstract Volume, Vol. 21, No. 4, p. 39. (abstract.)Indiana, MidcontinentGeophysics
DS1983-0640
1983
Lam, C.K.Yarger, H.L., Lam, C.K.New Gravity Dat a in Eastern KansasGeological Society of America (GSA), Vol. 15, No. 6, P. 724. (abstract.)KansasMid Continent
DS1986-0479
1986
Lam, C.K.Lam, C.K., Yarger, H.L.Kansas basement age terrane boundary from gravity and magnetic dataGeological Society of America (GSA) Abstact Volume, Vol. 18, No. 6, p. 664. (abstract.)GlobalGeochronology, Geophysics
DS1989-0844
1989
Lam, H-L.Lam, H-L.On the prediction of low frequency geomagnetic pulsations for geophysicalprospectingGeophysics, Vol. 54, No. 5, May pp. 635-642GlobalGeophysics, electromagnetic
DS2000-0969
2000
LaMarUSGS, Hearns, P., Hare, Schruber, Sherrill, LaMarGlobal GIS database: digital atlas of Central and South AmericaUsgs, DDS-62-A ( CD ROM)Central America, South AmericaDigital Data series - atlas
DS201902-0289
2018
Lamarque, G.Lamarque, G., Agostinetti, N.P., Julia, J., Evain, M.Joint interpretation of SKS-splitting measurements and receiver function data for detecting seismic anisotropy in the upper mantle: feasibility and limitations.AGU, 1p. abstract Mantlegeophysics -seismic

Abstract: Measuring seismic anisotropy within the Earth is essential as it constitutes a proxy for inferring upper mantle deformation related to mantle flow, that develops preferred orientations of the minerals in response to tectonic strain. The most-used method to detect anisotropy beneath a seismic station is the measurement of teleseismic SKS wave splitting on two horizontal recordings, i.e. measuring the delay time (?t) between two fast- and slow- polarized shear-waves and the orientation of polarization (?). This technique allows a integrative measurement (SKS data, hereinafter) that estimates the average ? and ?t along the entire SKS ray-path. Despite its importance for large-scale anisotropy within the upper mantle, the analysis of SKS data suffers from several limitations : (1) SKS data become difficult to interpret in regions where several anisotropic layers occur; (2) SKS waves fail to provide robust information about anisotropy related to thin layers; and (3) SKS data can investigate rock volumes with an horizontal symmetry axis only. During the last decade a new method, called harmonic decomposition of teleseismic Receiver Functions (RFs) has been developed in order to detect more complex anisotropic layering. This methodology is based on the extraction of back-azimuth harmonics of the RF dataset. Briefly, it constitutes a tool to appreciate the value of ? and ?t at every depth-level affording a detailed study of the rock anisotropy with both plunging and horizontal symmetry axis. RFs studies are however commonly limited to the first 10-15s of the signal and do not sample the deepest anisotropy. In this work we investigate in details both SKS data and RFs harmonic decomposition for a pool of stations deployed in northeastern Brasil, in order to understand how results from the analysis of these two observables can be jointly interpreted. We focus our study on the permanent station RCBR and on temporary seismic stations deployed in the area. We show that comparison and/or joint interpretation is not straightforward as both results can vary according to the amount of data available and their distribution in back-azimuth, and filtering. However, tacking into account those issues, the integration of these two observables represent a great step-forward for robust detection of upper mantle anisotropy.
DS1975-0107
1975
Lamb, G.C.Howard, J.M., Lamb, G.C.Transition Element Geochemistry of the Potash Sulfur Springs Intrusion, Garland County, Arkansaw.Geological Society of America (GSA), Vol. 7, No. 2, P. 174. (abstract.).United States, Gulf Coast, Arkansas, Garland CountyGeochemistry
DS201708-1700
2017
Lamb, K.Lamb, K.Kimberlite intrusions, Kimberlitic as dispersal, diamond transport and diamond deposition: the potential role of Earth Systems Modelling in diamond exploration.11th. International Kimberlite Conference, PosterTechnologyEarth Systems Modelling
DS1990-0885
1990
Lamb, L.D.Kratschmer, W., Lamb, L.D., Fostiropoulos, K., Huffman, D.R.Solid C 60: a new form of carbonNature, Vol. 347, No. 6291, September 27, pp. 354-358GlobalExperimental petrology, Carbon- Solid C 60
DS201611-2109
2016
Lamb, M.P.Ganti, V., Von Hagke, C., Scherler, D., Lamb, M.P., Fischer, W.W., Avouac, J-P.Time scale bias in erosion rates of glaciated landscapes.Science Advances, Vol. 2, 10, 3p.GlobalGlaciology

Abstract: Deciphering erosion rates over geologic time is fundamental for understanding the interplay between climate, tectonic, and erosional processes. Existing techniques integrate erosion over different time scales, and direct comparison of such rates is routinely done in earth science. On the basis of a global compilation, we show that erosion rate estimates in glaciated landscapes may be affected by a systematic averaging bias that produces higher estimated erosion rates toward the present, which do not reflect straightforward changes in erosion rates through time. This trend can result from a heavy-tailed distribution of erosional hiatuses (that is, time periods where no or relatively slow erosion occurs). We argue that such a distribution can result from the intermittency of erosional processes in glaciated landscapes that are tightly coupled to climate variability from decadal to millennial time scales. In contrast, we find no evidence for a time scale bias in spatially averaged erosion rates of landscapes dominated by river incision. We discuss the implications of our findings in the context of the proposed coupling between climate and tectonics, and interpreting erosion rate estimates with different averaging time scales through geologic time.
DS1993-0685
1993
Lamb, S.Hoke, L., Lamb, S., Entenmann, J.Volcanic rocks from the Bolivian Altiplano: insights into crustalstructure, contamination, and magma genesis: comment and replyGeology, Vol. 21, No. 12, December pp. 1147-1149BoliviaTectonics, Magma
DS1993-0871
1993
Lamb, S.Lamb, S.Going with the flow...tectonicsNature, Vol. 362, No. 6418, March 25, pp. 294-295MantleTectonics, Brittle crust
DS1993-0872
1993
Lamb, S.Lamb, S.Tectonics... going with the flowNature, Vol. 362, No. 6418, March 25, pp. 294-295MantleTectonics, Continental lithosphere, plate boundary
DS1995-0935
1995
Lamb, S.Kennan, L., Lamb, S., Rundle, C.Potassium-Argon dates from the Altiplano and Cordillera oriental of Bolivia: implications for Cenozoic stratigraphyJournal of South American Earth Sciences, Vol. 8, No. 2, pp. 163-186BoliviaStratigraphy, Geochronology
DS1997-0646
1997
Lamb, S.Lamb, S., Hoke, L.Origin of the high pressurelateau in the Central Andes, Bolivia, South AmericaTectonics, Vol. 16, No. 4, August pp. 623-49BoliviaBolivian Altiplano, chronostratigraphy, tectonics, Structure, Tambo Tambilla, deformation, crustal
DS2000-0417
2000
Lamb, S.Hoke, L., Lamb, S., Poreda, R.J.Southern limit of mantle derived geothermal helium emissions in Tibet: implications for lithospheric ...Earth and Planetary Science Letters, Vol. 180, No. 3-4, pp.297-308.Tibet, MantleGeothermometry
DS2002-0913
2002
Lamb, S.Lamb, S.Is it all in the crust?Nature, No. 6912, Nov. 14, p. 130.MantleGeochemistry
DS200612-0760
2006
Lamb, S.Lamb, S.Shear stresses on megathrusts: implications for mountain building behind subduction zones.Journal of Geophysical Research, Vol. 111, B07401, 24p.South America, ChileSubduction zone - not specific to diamonds
DS201708-1574
2017
Lamb, S.Lamb, S., Moore, J.D., Smith, E., Stern, T.Episodic kinematics in continental rifts modulated by changes in mantle melt fraction.Nature, Vol. 547, 7661, pp. 84-88.Mantlemelting

Abstract: Oceanic crust is created by the extraction of molten rock from underlying mantle at the seafloor ‘spreading centres’ found between diverging tectonic plates. Modelling studies have suggested that mantle melting can occur through decompression as the mantle flows upwards beneath spreading centres, but direct observation of this process is difficult beneath the oceans. Continental rifts, however—which are also associated with mantle melt production—are amenable to detailed measurements of their short-term kinematics using geodetic techniques. Here we show that such data can provide evidence for an upwelling mantle flow, as well as information on the dimensions and timescale of mantle melting. For North Island, New Zealand, around ten years of campaign and continuous GPS measurements in the continental rift system known as the Taupo volcanic zone reveal that it is extending at a rate of 6-15?millimetres per year. However, a roughly 70-kilometre-long segment of the rift axis is associated with strong horizontal contraction and rapid subsidence, and is flanked by regions of extension and uplift. These features fit a simple model that involves flexure of an elastic upper crust, which is pulled downwards or pushed upwards along the rift axis by a driving force located at a depth greater than 15?kilometres. We propose that flexure is caused by melt-induced episodic changes in the vertical flow forces that are generated by upwelling mantle beneath the rift axis, triggering a transient lower-crustal flow. A drop in the melt fraction owing to melt extraction raises the mantle flow viscosity and drives subsidence, whereas melt accumulation reduces viscosity and allows uplift—processes that are also likely to occur in oceanic spreading centres.
DS202007-1181
2020
Lamb, S.Stern, T., Lamb, S., Moore, J.D.P., Okaya, D., Hichmuth, K.High mantle seismic P-wave speeds as a signature for gravitational spreading of superplumes. Science Adavances, Vol. 6, eaba7118 May 27, 9p. PdfAsia, Javageophysics -seismic

Abstract: New passive- and active-source seismic experiments reveal unusually high mantle P-wave speeds that extend beneath the remnants of the world’s largest known large igneous province, making up the 120-million-year-old Ontong-Java-Manihiki-Hikurangi Plateau. Sub-Moho Pn phases of ~8.8 ± 0.2 km/s are resolved with negligible azimuthal seismic anisotropy, but with strong radial anisotropy (~10%), characteristic of aggregates of olivine with an AG crystallographic fabric. These seismic results are the first in situ evidence for this fabric in the upper mantle. We show that its presence can be explained by isotropic horizontal dilation and vertical flattening due to late-stage gravitational collapse and spreading in the top 10 to 20 km of a depleted, mushroom-shaped, superplume head on a horizontal length scale of 1000 km or more. This way, it provides a seismic tool to track plumes long after the thermal effects have ceased.
DS1995-2040
1995
Lamb, S.H.Watts, A.B., Lamb, S.H., Fairhead, J.D.Lithospheric flexing and bending of the central AndesEarth and Planetary Science Letters, Vol. 134 No. 1-2, Aug 15, pp. 9-22AndesTectonics
DS1997-0581
1997
Lamb, S.H.Kennan, L., Lamb, S.H., Hoke, L.High altitude paleosurfaces in the Bolivian Andes: evidence for late Cenozoic surface upliftWiddowson, M. Paleosurfaces, Geological Society of London, No. 120, pp. 307-323BoliviaCentral Andes, Tectonics
DS200412-1081
2004
Lamb, W.Lamb, W.Mineral characterization to metallurgical design.PDAC 2004, 1p. abtract.TechnologyMining
DS200512-0597
2005
Lamb, W.Lamb, W.Parameters affecting dense medium process efficiency.CIM Mining Rocks April 24-27th. Toronto Annual Meeting, Paper# 1750 AbstractNews item - mineral processing
DS201609-1709
2010
Lamb, W.Campbell, J.A.H., Lamb, W., Clarke, J., Petersen, K.The development of AK6.The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 20p.Africa, BotswanaDeposit - AK6
DS200912-0423
2009
Lamb, W.M.Lamb, W.M., Popp, R.K.Amphibole equilibration temperatures in mantle rocks: determining values of mantle alpha H2O and implications for mantle H2O contents.American Mineralogist, Vol. 94, 1, pp. 41-52.MantleWater
DS201904-0748
2019
Lamb, W.M.Hunt, L.E., Lamb, W.M.Application of mineral equilibria to estimate fugacities of H2O, H2, and O2 in mantle xenoliths from the southwestern U.S.A.American Mineralogist, Vol. 104, pp. 333-347.United Statesxenoliths

Abstract: Small amounts of H2O, on the order of tens to hundreds of parts per million, can significantly influence the physical properties of mantle rocks. Determining the H2O contents of nominally anhydrous minerals (NAMs) is one relatively common technique that has been applied to estimate mantle H2O contents. However, for many mantle NAMs, the relation between H2O activity and H2O content is not well known. Furthermore, certain mantle minerals may be prone to H2O loss during emplacement on Earth’s surface. The goal of this study is to apply mineral equilibria to estimate values of aH2O in rocks that originated below the Moho. The chemical compositions of olivine + orthopyroxene + clinopyroxene + amphibole + spinel ± garnet were used to estimate values of temperature (T), pressure (P), aH2O, hydrogen fugacity (fH2), and oxygen fugacity (fO2) in 11 amphibole-bearing mantle xenoliths from the southwestern U.S.A. Application of amphibole dehydration equilibria yields values of aH2O ranging from 0.05 to 0.26 for these 11 samples and the compositions of coexisting spinel + olivine + orthopyroxene yield ?logfO2 (FMQ) of -1 to +0.6. For nine of the samples, values of fH2 were estimated using amphibole dehydrogenation equilibria, and these values of fH2 ranged from 6 to 91 bars. Values of fH2 and fO2 were combined, using the relation 2H2O = 2H2 + O2, to estimate a second value of aH2O that ranged from 0.01 to 0.57 for these nine samples. Values of aH2O, estimated using these two methods on the same sample, generally agree to within 0.05. This agreement indicates that the amphibole in these samples has experienced little or no retrograde H-loss and that amphibole equilibria yields robust estimates of aH2O that, in these xenoliths, are generally <0.3, and are often 0.1 or less.
DS201212-0394
2012
Lambart, S.Lambart, S., Laporte, D., Provost, A., Schinao, P.Fate of pyroxenite derived melts in the periodotitic mantle: thermodynamic and experimental constraints.Journal of Petrology, Vol 53, 3, pp. 451-476.MantlePeridotite
DS201412-0498
2014
Lambart, S.Laporte, D., Lambart, S., Schiano, P., Ottolini, L.Experimental derivation of nepheline syenite and phonolite liquids by partial melting of upper mantle peridotites.Earth and Planetary Science Letters, Vol. 404, pp. 319-331.MantleMelting
DS201907-1557
2018
Lambart, S.Lambart, S., Koorneef, J., Millet, M-A., Davies, G.R., Cook, M., Lissenberg, J.Mantle heterogeneity revealed in the Lower Oceanic crust.American Geophysical Union, Fall Meeting. , V23A-05 1p.Mantlegeophysics

Abstract: Variations in radiogenic isotopes in mid-ocean ridge basalts (MORB) are interpreted to reflect the presence of enriched and depleted mantle components in their source regions and have been used to infer the abundance and time scales of crustal recycling. However, MORB are homogenized via magma mixing prior to eruption and may not capture the full heterogeneity of melts generated in their upper mantle source. Here we show that primitive cumulate minerals, formed by crystallization of mantle melts in the lower crust, retain the signature of the recycled material. We performed high spatial resolution Nd and Sr isotopic analyses on clinopyroxene and plagioclase of gabbroic cumulates from the Atlantis massif, located on a depleted ridge segment on the northern Mid-Atlantic Ridge, and compared these data with whole rock isotopic compositions of diabase and microgabbros collected on the same core, associated basalts flows, and MORB data from the literature. We find that cumulate minerals: (1) are significantly more isotopically heterogeneous than the associated diabase and lavas, exceeding the range of 143Nd/144Nd in MORB by a factor of seven; and (2) contain the full Nd isotopic heterogeneity of all of North Atlantic MORB. Furthermore, we find that isotopic heterogeneity occurs down to the sample scale, with plagioclase and clinopyroxene from individual samples commonly not in isotopic equilibrium. We further demonstrate that the MORB and cumulate mineral data can be reconciled with constant high magnitude, small length scale heterogeneity through the North Atlantic upper mantle, with limited magma mixing in the mantle and extensive mixing in the oceanic crust.The isotopic heterogeneity revealed in the lower oceanic crust provides strong evidence that MORB is not an accurate representation of the heterogeneity of its mantle source. Hence, the true isotopic variation of the upper mantle requires rigorous further examination, and models of convective thinning and stretching and melt migration must be re-evaluated to account for greater local variation.
DS1989-0525
1989
Lambeck, K.Goleby, B.R., Shaw, R.D., Wright, C., Kennett, B.L.N., Lambeck, K.Geophysical evidence for thick skinned crustal deformation incentralAustraliaNature, Vol. 337, No. 6205, January 26, pp. 325-330AustraliaGeophysics, Tectonics
DS1991-1562
1991
Lambeck, K.Shaw, R.D., Etheridge, M.A., Lambeck, K.Development of the Late Proterozoic to mid-Paleozoic intracratonic Amadeus Basin in central Australia: a key to understanding tectonic forces in plateinteriorsTectonics, Vol. 10, No. 4, August pp. 688-721AustraliaTectonics, Basin -Amadeus
DS1996-0803
1996
Lambeck, K.Lambeck, K., Smither, C.Shoreline evolution over the Northwest Shelf Australia for the past 20, 000years.Australia Nat. University of Diamond Workshop July 29, 30., 1/8p. brief.AustraliaGeomorphology, Sea level
DS2000-0474
2000
Lambeck, K.Kaufmann, G., Lambeck, K.Mantle dynamics, Post glacial rebound and radial viscosity profilePhysical Earth and Planetary Interiors, Vol. 121, No. 3-4, pp. 301-24.MantleGeodynamics, Geomorphology - glacial
DS201212-0823
2012
Lambeck, K.Zhao, S., Lambeck, K., Lidberg, M.Lithosphere thickness and mantle viscosity inverted from GPS - derived deformation rates in Fennoscandia.Geophysical Journal International, Vol. 190, 1, pp. 278-292.Europe, Finland, SwedenGeophysics - seismics
DS1991-1756
1991
Lambert, A.Tushingham, A.M., Lambert, A., Liard, J.O., Peltier, W.R.Secular gravity changes: measurements and predictions for selected CanadiansitesCanadian Journal of Earth Sciences, Vol. 28, No. 4, April pp. 557-560CanadaGeophysics -gravity, General
DS201612-2343
2016
Lambert, C.W.Thomas, R.J., Macey, P.H., Spencer, C., Dhansay, T., Diener, J.F.A., Lambert, C.W., Frei, D., Nguno, A.The Sperrgebeit Domain, Aurus Mountains, SW Namibia: a ~2020-850 Ma window within the Pan-African Gariep Orogen.Precambrian Research, Vol. 286, pp. 35-58.Africa, NamibiaGeochronology
DS1999-0261
1999
Lambert, D.Graham, S., Lambert, D., Shee, S., Smith, C.B., ReevesRe Os isotopic evidence for Archean lithospheric mantle beneath the Kimberley Block, Western Australia.Geology, Vol. 27, No. 5, May pp. 431-34.AustraliaGeochronology, Deposit - Argyle, Seppelt
DS1991-0949
1991
Lambert, D.D.Lambert, D.D., Shirey, S.B., Carlson, R.W., Weaver, B.L., GilbertRhenium- Osmium (Re-Os) and samarium-neodymium (Sm-Nd) isotopic systematics of lamproites and basalts from theEos Transactions, Vol. 72, No. 44, October 29, abstract p. 543Arkansas, MidcontinentLamproites, Geochemistry, geochronology
DS1993-0215
1993
Lambert, D.D.Carlson, R.W., Esperanca, S., Lambert, D.D., Svisero, D.P.The electromagnetic-I component in the South Atlantic: clues to the origin from isotope and trace element dat a for Brazilian kimberlites.American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 633.BrazilGeochronology, Kimberlite
DS1993-0421
1993
Lambert, D.D.Esperanca, S., Carlson, R.W., Lambert, D.D., Svisero, D.P.The petrology and geochemistry of deep crustal granulite xenoliths in an ultrapotassic host, Minas Gerais State, Brasil.The Xenolith window into the lower crust, abstract volume and workshop, p. 8.BrazilUltrapotassic rocks
DS1994-0974
1994
Lambert, D.D.Lambert, D.D., Shirey, S.B., Bergman, S.C.Re Os and Sm neodymium isotope geochemistry of the Prairie Creek lamproites:evidence subduction related mantle.Geological Society of Australia Abstracts, No. 37, p. 231-232.ArkansasLamproites, Geochemistry
DS1995-1047
1995
Lambert, D.D.Lambert, D.D., Shirey, S.B., Bergman, S.C.Proterozoic lithospheric mantle source for the Prairie Creek lamproites:Rhenium- Osmium (Re-Os) and samarium-neodymium (Sm-Nd) isotopic evidence.Geology, Vol. 23, No. 3, March pp. 273-276.ArkansasGeochronology, Deposit -Prairie Creek
DS1996-0463
1996
Lambert, D.D.Foster, J.G., Lambert, D.D., Maas, R.Rhenium- Osmium (Re-Os) isotopic evidence for genesis of Archean nickel ores from uncontaminated komatiitesNature, Vol. 382, No. 6593, Aug. 22, pp. 703-705AustraliaNickel, komatiites, Geochronology
DS1996-0559
1996
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R., Hamilton, R., FosterAlkaline ultramafic rocks as probes of lithospheric mantle enrichment events in the eastern Yilgarn craton.Australia Nat. University of Diamond Workshop July 29, 30. abstract, 1p.AustraliaCraton, Alkaline rocks, geochronology
DS1996-0911
1996
Lambert, D.D.McBride, J.S., Lambert, D.D., Greig, A., Nicholls, I.A.Multistage evolution of Australian subcontinental mantle: Rhenium- Osmium (Re-Os) isotopic constraints from Victorian...Geology, Vol. 24, No. 7, July pp. 631-634.Australia, VictoriaMantle xenoliths, Geochronology
DS1997-0436
1997
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R., Hamilton, R.ReOs and SmNd evidence for Archean lithosphere mantle modification byorogenesis, Norseman, Western AustraliaGeological Society of Australia Abstracts, No. 44, p. 35. 1p.Australia, Western AustraliaGeochronology, picroilmentites, melnoite, Diamond exploration
DS1998-0529
1998
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R., Smith, HamiltonRe Os and Sm neodymium isotope systematics of alkaline ultramafic rocks, xenoliths and macrocrysts...7th International Kimberlite Conference Abstract, pp. 262-4.AustraliaAlkaline rocks, Yilgarn Craton, Earaheedy Basin area
DS1998-0530
1998
Lambert, D.D.Graham, S., Lambert, D.D., Smith, C.B., Shee, ReevesRhenium- Osmium (Re-Os) isotope systematics of oxide xenocrysts and peridotite xenoliths From the kimberlites - Argyle7th International Kimberlite Conference Abstract, pp. 265-7.AustraliaMantle - lithosphere, lamproite, Deposit - Argyle
DS1998-0826
1998
Lambert, D.D.Lambert, D.D., Alard, O., Costa, S., Frick, BodinierEvidence for interaction of Proterozoic (2 Ga) sub-continental mantle wit han enriched mantle plume...Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 848-9.FranceMelt depletion, peridotite xenoliths, Franch Massif Central
DS2001-0743
2001
Lambert, D.D.McBride, J.S., Lambert, D.D., Nicholls, I.A., Price, R.Osmium isotopic evidence for crust mantle interaction in the genesis of continental intraplate basalts ...Journal of Petrology, Vol. 42, No. 6, pp. 1197-1218.Australia, southeastNewer Volcanic Province, Geochronology
DS2002-0606
2002
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R., Pearson, N.J.Juvenile lithospheric mantle enrichment and the formation of alkaline ultramafic magmaChemical Geology, Vol. 186, No. 2-4, pp. 215-33.Australia, westernMelnoites, Geochronology
DS2003-0492
2003
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R.Geochemical and isotopic evidence of a kimberlite - melnoite - carbonatite genetic link8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, AbstractAustraliaKimberlite petrogenesis, Geochronology, Leonora alkalic province
DS2003-0493
2003
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R., Pearson, N.J.Erratum to juvenile lithospheric mantle enrichment and the formation of alkalineChemical Geology, Vol. Sept. 15, p.. 361. Original Vol. 186, pp. 215-233.AustraliaMelnoites, Geochronology
DS200412-0707
2003
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R.Geochemical and isotopic evidence of a kimberlite - melnoite - carbonatite genetic link.8 IKC Program, Session 7, AbstractAustraliaKimberlite petrogenesis Geochronology, Leonora alkalic province
DS200412-0708
2003
Lambert, D.D.Graham, S., Lambert, D.D., Shee, S.R., Pearson, N.J.Erratum to juvenile lithospheric mantle enrichment and the formation of alkaline ultramafic magma sources: Re Os Lu Hf and Sm NdChemical Geology, Vol. Sept. 15, p.. 361. Original Vol. 186, pp. 215-233.AustraliaMelnoites, geochronology
DS1997-0305
1997
Lambert, I.East, J., Lambert, I., Wood, P., Veitch, S.Recent trends in access to Australian mineral resourcesAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 4, June pp. 84-88AustraliaBrief overview, Resources, discoveries, economics
DS2001-0650
2001
Lambert, I.B.Lambert, I.B.Mining and sustainable development: considerations for minerals supplyNatural Res. Forum, Vol. 25, No. 4, pp. 275-84.GlobalLegal - economics
DS1989-0845
1989
Lambert, M.B.Lambert, M.B., Ernst, R.E.Mafic dyke swarms of the Cameron and Beaulieur River volcanic belts, SlaveProvince, N.W.T.Geological Society of Canada (GSC) Forum 1989, P. 16 abstractNorthwest TerritoriesDykes
DS1991-0253
1991
Lambert, R. St.J.Chamberlain, V.E., Lambert, R. St.J., McKerrow, W.S.Mesozoic sedimentation rates in the Western Canada basin as indicators Of the time and place of tectonic activityBasin Research, Vol. 2, No. 3, September pp. 189-202Western Canada, AlbertaTectonics, Peace River Arch, Basin
DS1987-0393
1987
Lambert, R.St. J.Lambert, R.St. J.Mid-Cretaceous alkaline igneous rocks in the southern Canadian Rockies And related areasEos, Vol. 68, No. 44, November 3, p. 1517. Abstract onlyBritish ColumbiaBlank
DS1986-0130
1986
Lambert, R.St.J.Cavell, P.A., Baadsgaard, H., Lambert, R.St.J.Samarium-Neodymium, Rubidium-Strontium, and Uranium-Lead systematics of the Big Spruce Lake alkaline carbonatiteGeological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 53-54. (abstract.)OntarioFoyalite, ijolite, geochronology, Carbonatite
DS201906-1312
2019
Lambert, S.Lambert, S., Koornneef, J.M., Millet, M-A., Davies, G.R., Cook, M., Lissenberg, C.J.Highly heterogeneous depleted mantle recorded in the lower oceanic crust. ( MAR)Nature Geoscience, https://doi.org/10.1038/s41561-019-0368-9 8p.Mantleplate tectonics

Abstract: The Earth’s mantle is heterogeneous as a result of early planetary differentiation and subsequent crustal recycling during plate tectonics. Radiogenic isotope signatures of mid-ocean ridge basalts have been used for decades to map mantle composition, defining the depleted mantle endmember. These lavas, however, homogenize via magma mixing and may not capture the full chemical variability of their mantle source. Here, we show that the depleted mantle is significantly more heterogeneous than previously inferred from the compositions of lavas at the surface, extending to highly enriched compositions. We perform high-spatial-resolution isotopic analyses on clinopyroxene and plagioclase from lower crustal gabbros drilled on a depleted ridge segment of the northern Mid-Atlantic Ridge. These primitive cumulate minerals record nearly the full heterogeneity observed along the northern Mid-Atlantic Ridge, including hotspots. Our results demonstrate that substantial mantle heterogeneity is concealed in the lower oceanic crust and that melts derived from distinct mantle components can be delivered to the lower crust on a centimetre scale. These findings provide a starting point for re-evaluation of models of plate recycling, mantle convection and melt transport in the mantle and the crust.
DS202007-1185
2020
Lambert, S.Xu, R., Liu, Y., Lambert, S.Melting of a hydrous peridotite mantle source under the Emeishan large igneous province.Earth Science Reviews, in press available 30p. PdfChinapicrites

Abstract: Large igneous provinces on Earth result from anomalously enormous volcanic eruptions at high melt production rates. These eruptions are often linked to catastrophic events such as mass extinctions, global climate changes, or continental break-up. Decoding their petrogenesis is therefore of great importance for our comprehensive understanding of the evolution and geodynamics of our planet. The ~260 Ma Emeishan large igneous province is an important geological feature of SW China with world-class ore deposits and is also suggested to be linked with the Capitanian mass extinction. However, fundamental aspects of the genesis of Emeishan province's most primitive lavas (picrites), such as the source lithology (pyroxenite or peridotite), the origin of compositional variations of olivines and the melting temperature and pressure conditions, remain poorly constrained. Here, we compile information on melt inclusion and host olivine, and whole-rock compositions from the ELIP picrites and show that these data are consistent with decompression melting of a relatively homogeneous peridotitic mantle plume, with a potential temperature higher than 1560 °C. The compositional variability of the olivines and picrites can be explained by varying the equilibrium depth of primary magma segregation and does not require the contribution of a pyroxenite component as previously suggested. Our results favor a scenario for the origin of the Emeishan large igneous province in which the decompression melting during upwelling of a hot hydrous and oxidized mantle plume is accompanied by catastrophic lithospheric thinning. In combination with the now extensive multi-element geochemical data, our findings provide a starting point for re-evaluation of the petrogenesis models for large igneous provinces.
DS1989-0846
1989
Lambiase, J.J.Lambiase, J.J.The framweork of African rifting during the PhanerozoicJournal of African Earth Sciences, Vol. 8, No. 2/3/4, pp. 183-190AfricaTectonics, Rifting -Phanerozoic
DS1993-0873
1993
Lambrecht, W.R.Lambrecht, W.R., Lee, C.H., Segall, B., Angus, J.C., Sunkara, M.Diamond nucleation by hydrogenation of the edges of graphitic precursorsNature, Vol. 364, August 12, pp. 607-610.GlobalDiamond morphology
DS1993-0874
1993
Lambrect, W.R.L.Lambrect, W.R.L., Lee, C.H., Segall, B., Angus, J.C., Li, Z.Diamond nucleation by hydrogenation of the edges of graphitic precursorsNature, Vol. 364, No. 6438, August 12, pp. 607-610GlobalDiamond morphology, Graphite
DS1995-1048
1995
Lambrinos, D.Lambrinos, D.Taxation and accounting issues relating to mining projects in RussiaWorld Mining Congress, Institute International Research held May, 26pRussiaEconomics -investment
DS201112-0566
2011
Lamcaster, P.J.Lamcaster, P.J., Storey, C.D., Hawkesworth, C.J., Dhuime, B.Understanding the roles of crustal growth and preservation in the detrital zircon record.Earth and Planetary Science Letters, In press, availableMantleGeochronology
DS200812-1045
2008
Lamenetsky, V.S.Sharygin, V.V., Lamenetsky, V.S., Kamenetsky, M.B.Potassium sulfides in kimberlite hosted chloride nyereite and chloride clasts of the Udachnaya East pipe, Yakutia, Russia.Canadian Mineralogist, Vol. 46, 4, August pp.Russia, YakutiaDeposit - Udachnaya
DS1989-0847
1989
Lameyre, J.Lameyre, J., Black, R., Giret, A.Le magmatism alcalin: donnees geologiques sur quelques provinces oceaniques et continentales.(in French)Geological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A49. (abstract.)West Africa, NigeriaAlkaline rocks
DS1999-0211
1999
Lamge R.A.Feldstein, S.N., Lamge R.A.Pliocene potassic magmas from the Kings River Basin, Sierra Nevada:evidence for melting subduction mantleJournal of Petrology, Vol. 40, No. 8, Aug. pp. 1301-20.CaliforniaTectonics - subduction
DS1991-1087
1991
Laming, D.McCall, G., Laming, D., Scott, S.GeohazradsChapman and Hall, 236p. approx. $ 40.00 United StatesGlobalBook -ad, Geohazards
DS1988-0396
1988
Lammer, A.Lammer, A.Mechanical properties of polycrystalline diamondsMater. Sci. Technol, Vol. 4, No. 11, pp. 949-955GlobalDiamond morphology
DS1950-0408
1958
Lamont, G.T.Lamont, G.T.Report on the Prospecting of the Tuli Block, Bechuana land Protectorate.De Beers Prospecting (rhodesia) Ltd., (UNPUBL.)BotswanaDiamond Prospecting
DS1950-0485
1959
Lamont, G.T.Lamont, G.T.Report on the Prospecting of the Gaberone Block, Bechuana land Protectorate.De Beers Prospecting (rhodesia) Ltd., (UNPUBL.)BotswanaDiamond Prospecting
DS1970-0119
1970
Lamont, G.T.Lamont, G.T.Prospecting MethodsIn: Diamonds, Editor Bruton, E., P. 119.South AfricaProspecting
DS201812-2850
2018
Lamontagne, M.McPeak, S., Samson, C., Lamontagne, M., Elliott, B.Application of passive seismic methodologies to the determination of overburden thickness.2018 Yellowknife Geoscience Forum , p. 111-112. abstractCanada, Northwest Territoriesgeophysics - seismics

Abstract: Diamond mining is central to the economic development of the Canadian North. Innovative methods are needed to identify new prospective targets, as many of them are hidden beneath a thick overburden of glacial sediments. Passive seismics is an emerging method used to map the thickness of near-surface geological layers. Vibrations from distant earthquakes are used as a source of signal and data is processed to estimate the depth of the interface between the overburden and the underlying bedrock. In July 2018, four Tromino seismographs were taken to a study site located approximately ten minutes driving north of Yellowknife. A total of 146 Tromino measurements and associated GPS elevation measurements were taken at 6 m intervals along a dirt road. Elevation measurements were averaged over the course of four days and the survey line was approximately 740 m long. Results indicated that depth to bedrock decreases near outcrops and increases in valleys however; another geophysical dataset is needed to validate the passive seismic data.
DS1996-0742
1996
Lamontagne, Y.King, A., Fullagar, P., Lamontagne, Y.Borehole geophysics in exploration, development and productionProspectors and Developers Association of Canada (PDAC) Short Course, pp. 239-252CanadaGeophysics -borehole, drillhole, Short course -Exploration technology
DS1997-0647
1997
LaMoreaux, P.E.LaMoreaux, P.E., Powell, W.J., LeGrand, H.E.Environmental and legal aspects of karst areasEnvironmental Geology, Vol. 29, No. 1-2, Jan. 1, pp. 23-36GlobalEnvironment, Karst
DS1995-1049
1995
Lamorey, G.Lamorey, G., Jacobson, E.Estimation of semivariogram parameters and evaluation of the effects ofdat a sparcityMathematical Geology, Vol. 27, No. 3, pp. 327-358GlobalGeostatistics, Jackknife kriging
DS1970-0461
1972
Lamorre, B.Alt, D., Hyndman, D.W., Ferguson, J.A., Lamorre, B.Pleistocene Maar Craters Near Drummond, MontanaNorthwest Geology, Vol. 1, PP. 33-37.United States, Montana, Rocky MountainsDiatreme
DS1993-0948
1993
LamotheMachado, N., David, Scott, Lamothe, Philipe, Gariepyuranium-lead (U-Pb) geochronology of the western Cape Smith Belt: new insights on age of initial rifting and arc magmatismGeological Association of Canada (GAC), Annual Meeting, Vol. 16, p. A78. abstract.Quebec, Ungava, LabradorGeochronology, Tectonics
DS1990-1180
1990
Lamothe, D.Picard, C., Lamothe, D., Piboule, M., Oliver, R.Magmatic and geotectonic evolution of a Proterozoic oceanic basin system:the Cape Smith Thrust- Fold Belt.Precambrian Research, Vol. 47, pp. 223-249.Quebec, Labrador, New QuebecTectonics, Structure
DS1993-0875
1993
Lamothe, D.Lamothe, D., Dion, D-J., Choiniere, J., Rivard, P.Localisation d'anomalies magnetiques circulaires entre le 56 et 58 parallel Territoire du Nouveau Quebec.(in French)Quebec Department of Mines, MB 93-62, 23p.QuebecGeophysics -magnetics, Diatremes
DS1994-0975
1994
Lamothe, D.Lamothe, D., Dion, D.J., Choiniere, J., Rivard, P.Localisation d'anomalies magnetiques circulaires entre le 56eme et le 58emeparralele-Territoire du Nouveau Quebec. (in French)Quebec Department of Mines, No. MB 93-62, 24p. $ paper copy 6.00QuebecGeophysics -magnetics, Circular anomalies
DS202109-1472
2021
Lamothe, K.G.Hoffman, P.F., Halverson, G.P., Schrag, D.P., Higgins, J.A., Domack, E.W., Macdonald, F.A., Pruss, S.B., Blattler, C.L., Crockford, P.W., Hodgin, E.B., Bellefroid, E.J., Johnson, B.W., Hodgskiss, M.S.W., Lamothe, K.G., LoBianco, S.J.C., Busch, J.F., HowesSnowballs in Africa: sectioning a long-lived Neoproterozoic carbonate platform and its bathyal foreslope ( NW Namibia). (Octavi Group)Earth Science Reviews , Vol. 219, 103616 231p. PdfAfrica, NamibiaCraton - Congo

Abstract: Otavi Group is a 1.5-3.5-km-thick epicontinental marine carbonate succession of Neoproterozoic age, exposed in an 800-km-long Ediacaran?Cambrian fold belt that rims the SW cape of Congo craton in northern Namibia. Along its southern margin, a contiguous distally tapered foreslope carbonate wedge of the same age is called Swakop Group. Swakop Group also occurs on the western cratonic margin, where a crustal-scale thrust cuts out the facies transition to the platformal Otavi Group. Subsidence accommodating Otavi Group resulted from S?N crustal stretching (770-655?Ma), followed by post-rift thermal subsidence (655-600?Ma). Rifting under southern Swakop Group continued until 650-635?Ma, culminating with breakup and a S-facing continental margin. No hint of a western margin is evident in Otavi Group, suggesting a transform margin to the west, kinematically consistent with S?N plate divergence. Rift-related peralkaline igneous activity in southern Swakop Group occurred around 760 and 746?Ma, with several rift-related igneous centres undated. By comparison, western Swakop Group is impoverished in rift-related igneous rocks. Despite low paleoelevation and paleolatitude, Otavi and Swakop groups are everywhere imprinted by early and late Cryogenian glaciations, enabling unequivocal stratigraphic division into five epochs (period divisions): (1) non-glacial late Tonian, 770-717?Ma; (2) glacial early Cryogenian/Sturtian, 717-661?Ma; (3) non-glacial middle Cryogenian, 661-646?±?5?Ma; (4) glacial late Cryogenian/Marinoan, 646?±?5-635?Ma; and (5) non-glacial early Ediacaran, 635-600?±?5?Ma. Odd numbered epochs lack evident glacioeustatic fluctuation; even numbered ones were the Sturtian and Marinoan snowball Earths. This study aimed to deconstruct the carbonate succession for insights on the nature of Cryogenian glaciations. It focuses on the well-exposed southwestern apex of the arcuate fold belt, incorporating 585?measured sections (totaling >190?km of strata) and?>?8764 pairs of ?13C/?18Ocarb analyses (tabulated in Supplementary On-line Information). Each glaciation began and ended abruptly, and each was followed by anomalously thick ‘catch-up’ depositional sequences that filled accommodation space created by synglacial tectonic subsidence accompanied by very low average rates of sediment accumulation. Net subsidence was 38% larger on average for the younger glaciation, despite its 3.5-9.3-times shorter duration. Average accumulation rates were subequal, 4.0 vs 3.3-8.8?m Myr?1, despite syn-rift tectonics and topography during Sturtian glaciation, versus passive-margin subsidence during Marinoan. Sturtian deposits everywhere overlie an erosional disconformity or unconformity, with depocenters ?1.6?km thick localized in subglacial rift basins, glacially carved bedrock troughs and moraine-like buildups. Sturtian deposits are dominated by massive diamictite, and the associated fine-grained laminated sediments appear to be local subglacial meltwater deposits, including a deep subglacial rift basin. No marine ice-grounding line is required in the 110 Sturtian measured sections in our survey. In contrast, the newly-opened southern foreslope was occupied by a Marinoan marine ice grounding zone, which became the dominant repository for glacial debris eroded from the upper foreslope and broad shallow troughs on the Otavi Group platform, which was glaciated but left nearly devoid of glacial deposits. On the distal foreslope, a distinct glacioeustatic falling-stand carbonate wedge is truncated upslope by a glacial disconformity that underlies the main lowstand grounding-zone wedge, which includes a proximal 0.60-km-high grounding-line moraine. Marinoan deposits are recessional overall, since all but the most distal overlie a glacial disconformity. The Marinoan glacial record is that of an early ice maximum and subsequent slow recession and aggradation, due to tectonic subsidence. Terminal deglaciation is recorded by a ferruginous drape of stratified diamictite, choked with ice-rafted debris, abruptly followed by a syndeglacial-postglacial cap-carbonate depositional sequence. Unlike its Sturtian counterpart, the post-Marinoan sequence has a well-developed basal transgressive (i.e., deepening-upward) cap dolomite (16.9?m regional average thickness, n?=?140) with idiosyncratic sedimentary features including sheet-crack marine cements, tubestone stromatolites and giant wave ripples. The overlying deeper-water calci-rhythmite includes crystal-fans of former aragonite benthic cement ?90?m thick, localized in areas of steep sea-floor topography. Marinoan sequence stratigraphy is laid out over ?0.6?km of paleobathymetric relief. Late Tonian shallow-neritic ?13Ccarb records were obtained from the 0.4-km-thick Devede Fm (~770-760?Ma) in Otavi Group and the 0.7-km-thick Ugab Subgroup (~737-717?Ma) in Swakop Group. Devede Fm is isotopically heavy, +4-8‰ VPDB, and could be correlative with Backlundtoppen Fm (NE Svalbard). Ugab Subgroup post-dates 746?Ma volcanics and shows two negative excursions bridged by heavy ?13C values. The negative excursions could be correlative with Russøya and Garvellach CIEs (carbon isotope excursions) in NE Laurentia. Middle Cryogenian neritic ?13C records from Otavi Group inner platform feature two heavy plateaus bracketed by three negative excursions, correlated with Twitya (NW Canada), Taishir (Mongolia) and Trezona (South Australia) CIEs. The same pattern is observed in carbonate turbidites in distal Swakop Group, with the sub-Marinoan falling-stand wedge hosting the Trezona CIE recovery. Proximal Swakop Group strata equivalent to Taishir CIE and its subsequent heavy plateau are shifted bidirectionally to uniform values of +3.0-3.5‰. Early Ediacaran neritic ?13C records from Otavi Group inner platform display a deep negative excursion associated with the post-Marinoan depositional sequence and heavy values (??+?11‰) with extreme point-to-point variability (?10‰) in the youngest Otavi Group formation. Distal Swakop Group mimics older parts of the early Ediacaran inner platform ?13C records, but after the post-Marinoan negative excursion, proximal Swakop Group values are shifted bidirectionally to +0.9?±?1.5‰. Destruction of positive and negative CIEs in proximal Swakop Group is tentatively attributed to early seawater-buffered diagenesis (dolomitization), driven by geothermal porewater convection that sucks seawater into the proximal foreslope of the platform. This hypothesis provocatively implies that CIEs originating in epi-platform waters and shed far downslope as turbidites are decoupled from open-ocean DIC (dissolved inorganic carbon), which is recorded by the altered proximal Swakop Group values closer to DIC of modern seawater. Carbonate sedimentation ended when the cratonic margins collided with and were overridden by the Atlantic coast-normal Northern Damara and coast-parallel Kaoko orogens at 0.60-0.58?Ga. A forebulge disconformity separates Otavi/Swakop Group from overlying foredeep clastics. In the cratonic cusp, where the orogens meet at a right angle, the forebulge disconformity has an astounding ?1.85?km of megakarstic relief, and km-thick mass slides were displaced gravitationally toward both trenches, prior to orogenic shortening responsible for the craton-rimming fold belt.
DS1988-0397
1988
Lamothe, M.Lamothe, M.Dating till using thermoluminescenceQuaternary Science Reviews, Vol. 7, pp. 273-276. Database # 17543GlobalTill, Thermoluminescence
DS1988-0398
1988
Lamothe, M.Lamothe, M.Dating till using thermoluminesenceQuaternary Science Reviews, Vol. 7, pp. 273-276QuebecBecancoeur Till Wisconsinian or Illinoian
DS201312-0229
2013
Lamothe, M.Dube-Loubert, H., Roy, M., Allard, G., Lamothe, M., Veilette, J.J.Glacial and nonglacial events in the eastern James Bay lowlands, Canada.Canadian Journal of Earth Sciences, Vol. 50, 4, pp. 379-396.Canada, Ontario, QuebecGeomorphology
DS1989-0848
1989
Lampietti, F.Lampietti, F.Reports on the 28th. International Geological Congress meeting held Washington ,D.C. Part II. a commentary upon the Geological Workshop ondiamondsIndiaqua, No. 54, 1989/III, p. 19, 21GlobalConference -Diamond Workshop, Report on Diamond Worksho
DS1900-0427
1906
Lamplugh, G.W.Lamplugh, G.W.Note on the Occurrence of Dwyka Conglomerate in Kimberley Mines.British Association Advanced Science Report For 1905, Kimberley Meeting, P. 408.Africa, South AfricaDetailed Geology
DS200712-0592
2007
Lamprecht, G.H.Lamprecht, G.H., Human, H.G.C., Snyman, L.W.Detection of diamond in ore using pulsed laser Raman spectroscopy.International Journal of Mineral processing, Vol. 84, 1-4, October, pp. 262-273.TechnologySorting, laser excitation
DS200812-0629
2007
Lamprecht, G.H.Lamprecht, G.H., Human, H.G.C., Synman, L.W.Detection of diamond in ore using pulsed laser Raman Spectroscopy.International Journal of Mineral Processing, Vol. 84, pp. 262-273.TechnologySpectroscopy
DS200912-0424
2009
Lamprecht, G.H.Lamprecht, G.H., Human, H.G.C., Snyman, L.W.Diamond detection in ore using laser Raman spectrosopy: comparison between pulsed and continuous wave lasers as excitation source at 532 nm.Transactions of the Institution of Mining and Metallurgy, Vol. 118, 1, March pp. 60-62.TechnologyDiamond processing
DS2001-0651
2001
Lan, C.Y.Lan, C.Y., Chung, S.L., Lo, Lee, Wang, Li, Van ToanFirst evidence for Archean continental crust in northern Vietnam and its implications for crustal ...Geology, Vol. 29, No. 3, Mar. pp.219-22.GlobalTectonic evolution, Geochronology, Yangtze Craton
DS200612-0761
2006
Lan, C.Y.Lan, C.Y., Izuka,T., Usuki, T., Wang, K.L., Anh, T.T., Van lOng ,T., O'Reilly, S.Y.Petrology and geochemistry of peridotite xenoliths from Vietnam Indochin a block.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 2. abstract only.ChinaXenolith - geochemistry
DS1995-0830
1995
Lan, L.Hudleston, P.J., Lan, L.Rheological information from geological structuresPure and Applied Geophysics, Vol. 145, No. 3-4, Dec. 1, pp. 605-620.MantleGeodynamics
DS201112-0567
2011
Lan, T-G.Lan, T-G., Fan, H-R., Santosh, M., Hu, F-F., Yang, Y-H, Liu, Y.Geochemistry and Sr Nd Pb Hf isotopes of the Mesozoic Dadian alkaline intrusive complex in the Sulu orogenic belt, eastern China: implications for crust mantle interaction.Chemical Geology, Vol. 285, 1-4, pp. 97-114.ChinaAlkalic
DS201602-0217
2016
Lan, Y.Lan, Y., Liang, R., Lu, T.Identification of a CVD synthetic diamond with a tree ring growth pattern.Journal of Gemmology, Vol. 34, 8, pp. 702-710.TechnologySynthetics
DS201901-0043
2018
Lan, Y.Ke, J., Lu, T., Lan, Y., Song, Z., Tang, S., Zhang, J., Chen, H.Recent developments in detection and gemology in China, particularly for Chinese synthetic diamonds.Gems & Gemology, Sixth International Gemological Symposium Vol. 54, 3, 1p. Abstract p. 268.Chinasynthetics

Abstract: China is the world’s largest producer of HPHT-grown industrial diamonds. Its 2016 production of about 20 billion carats accounted for 98% of the global supply. Since the beginning of 2015, meleesized colorless HPHT synthetic diamonds have been tested at the National Gemstone Testing Center’s (NGTC) Shenzhen and Beijing laboratories in parcels submitted by different clients, which means that colorless HPHT synthetic diamonds have entered the Chinese jewelry market and may be mistaken for natural diamonds. CVD synthesis technology has grown rapidly in recent years. Large colorless and colored (blue, pink) CVD-grown diamonds have been entering the market, and a few have been fraudulently sold as natural diamonds. China has independently developed gem-grade HPHT synthetic diamond production technology since 2002, and can grow gem-grade type Ib, IIa, and IIb and high-nitrogen-content synthetic diamonds in volume, depending on market needs. Gemgrade type Ib, IIa, and IIb HPHT synthetic diamonds have been grown using the temperature gradient method, under a cubic press at high pressure (e.g., 5.4 GPa) and high temperature (1300-1600°C). Driven by a specific temperature gradient, the carbon source from high-purity graphite (>99.9%) located at the high-temperature zone can diffuse into the seed crystals in the cubic press, resulting in the crystallization of synthetic diamonds. Chinese production of melee-sized colorless to near-colorless HPHT synthetic diamonds accounts for about 90% of the global output. Gem-grade type IIa and IIb CVD synthetic diamonds are grown using the microwave plasma chemical vapor deposition (MPCVD) and direct current (DC) arc plasma methods. Faceted colorless CVD diamonds can be grown in sizes up to 6 ct by at least two Chinese companies (table 1). After testing and analyzing thousands of natural and synthetic diamonds collected directly from the Chinese companies, NGTC independently developed the GV5000, PL5000, DS5000, and ADD6000 instruments for rapidly screening and identifying the diamonds based on the gemological characteristics obtained. Besides HPHT and CVD synthetic diamonds, a thickly layered hybrid diamond consisting of both natural and CVD material was identified at the NGTC Beijing laboratory (figure 1). The identification features and properties of regrown CVD synthetic diamonds using natural type Ia diamond crystals as seeds will be reported. The current status and features of colored stones examined at NGTC laboratories, including several cases studies, will be discussed.
DS201312-0994
2013
Lan, Z-W.Ye, H-M., Li, X-H., Lan, Z-W.Geochemical and Sr-Nd-Hf-O-C isotopic constraints on the origin of the Neoproterozoic Qieganbulake ultramafic carbonatite complex from the Tarim block, northwest China.Lithos, Vol. 182, pp. 150-164.ChinaCarbonatite
DS2003-0771
2003
Lana, C.Lana, C., Gibson, R.L., Kisters, A.F., Reimold, W.U.Archean crustal structure of the Kaapvaal Craton, South Africa - evidence from theEarth and Planetary Science Letters, Vol. 206, 1-2, pp. 133-44.South AfricaTectonics
DS200412-1082
2004
Lana, C.Lana, C., Reimold, W.U., Gibson, R.L., Koeberl, C., Siegesmund, S.Nature of the Archean midcrust in the core of the Vredfort dome, Central Kaapvaal Craton, South Africa.Geochimica et Cosmochimica Acta, Vol. 68, 3, pp. 623-42.Africa, South AfricaCraton, not specific to diamonds
DS200612-0037
2006
Lana, C.Armstrong, R.A., Lana, C., Reimold, W.U., Gibson, R.L.Shrimp zircon age constraints on Mesoarchean crustal development in the Vredefort dome, central Kaapvaal Craton, South Africa.Geological Society of America, Special Paper 405, pp. 233-254.Africa, South AfricaGeochronology
DS201112-0959
2011
Lana, C.Silva, D., Lana, C., Stevens, G., Souza Filho, C.R.Effects of shock induced incongruent melting within Earth's crust: the case of biotite melting.Terra Nova, in press availableMantleMelting
DS202109-1458
2021
Lana, C.de Caravlho, L.D.V., Jalowitzki, T., Scholz, R., de Oliveira Gonzales, G., Rocha, M.P., Peeira, R.S., Lana, C., de Castro, P., Queiroga, G., Fuck, R.A.An exotic Cretaceous kimberlite linked to metasomatized lithospheric mantle beneath the southwestern margin of the Sao Francisco Craton, Brazil.Geoscience Frontiers, doi,org/101016/j.gsf.2021.101.28South America, Brazildeposit - Osvaldo Franca 1

Abstract: We present major and trace element compositions of mineral concentrates comprising garnet xenocrysts, ilmenite, phlogopite, spinel, zircon, and uncommon minerals (titanite, calzirtite, anatase, baddeleyite and pyrochlore) of a newly discovered Late Cretaceous kimberlite (U-Pb zircon age 90.0 ± 1.3 Ma; 2?) named Osvaldo França 1, located in the Alto Paranaíba Igneous Province (APIP), southeastern Brazil. Pyrope grains are lherzolitic (Lherz-1, Lherz-2 and Lherz-3), harzburgitic (Harz-3) and wehrlitic (Wehr-2). The pyrope xenocrysts cover a wide mantle column in the subcratonic lithosphere (66-143 km; 20-43 kbar) at relatively low temperatures (811-875 °C). The shallowest part of this mantle is represented by Lherz-1 pyropes (20-32 kbar), which have low-Cr (Cr2O3 = 1.74-6.89 wt.%) and fractionated middle to heavy rare earth elements (MREE-HREE) pattern. The deepest samples are represented by Lherz-2, Lherz-3, Harz-3, and Wehr-2 pyropes (36-43 kbar). They contain high-Cr contents (Cr2O3 = 7.36-11.19 wt.%) and are characterized by sinusoidal (Lherz-2 and Wehr-2) and spoon-like (Lherz-3 and Harz-3) REE patterns. According to their REE and trace elements, pyrope xenocrysts have enriched nature (e.g., Ce and Yb vs. Cr2O3), indicating that the cratonic lithosphere has been affected by a silicate melt with subalkaline/tholeiite composition due to their low Zr, Ti and Y concentrations. Besides minerals with typical kimberlitic signatures, such as ilmenite and zircon, the exotic compositions of phlogopite and ulvöspinel suggest an enriched component in the magma source. The formation of rare mineral phases with strong enrichment of light-REE (LREE) and high field strength elements (HFSE) is attributed to the late-stage kimberlitic melt. We propose a tectonic model where a thermal anomaly, represented by the low-velocity seismic anomaly observed in P-wave seismic tomography images, supplied heat to activate the alkaline magmatism from a metasomatized cratonic mantle source during the late-stages of Gondwana fragmentation and consequent South Atlantic Ocean opening. The metasomatism recorded by mineral phases is a product of long-lived recycling of subducted oceanic plates since the Neoproterozoic (Brasiliano Orogeny) or even older collisional events, contributing to the exotic character of the Osvaldo França 1 kimberlite, as well as to the cratonic lithospheric mantle.
DS1997-0648
1997
Lanardic, A.Lanardic, A.On the heat flow variation from Archean craton to Proterozoic mobilebelts.Journal of Geophysical Research, Vol. 102, No. B1, Jan. 10, pp. 709-746.GlobalCraton, Mobile belts
DS201803-0446
2017
Lanari, P.Engi, M., Lanari, P., Jokn, M.J.Significant ages - an introduction to petrochronology.Reviews in Mineralogy & Geochemistry, Vol. 83, Chap. 1, pp. 1-12.Technologygeochronology

Abstract: Question: Why "Petrochronology"? Why add another term to an already cluttered scientific lexicon? Answer: Because petrologists and geochronologists need a term that describes the unique, distinctive way in which they apply geochronology to the study of igneous and metamorphic processes. Other terms just won’t do.
DS201806-1222
2018
Lanari, P.Engi, M., Giuntoli, F., Lanari, P., Burn, M., Kunz, B., Bouvier, A.S.Pervasive eclogization due to brittle deformation and rehydration of subducted basement: effects on continental recycling?Geochemistry, Geophysics, Geosystems, Vol. 19, 3, pp. 865-881.Mantlesubduction

Abstract: The buoyancy of continental crust opposes its subduction to mantle depths, except where mineral reactions substantially increase rock density. Sluggish kinetics limit such densification, especially in dry rocks, unless deformation and hydrous fluids intervene. Here we document how hydrous fluids in the subduction channel invaded lower crustal granulites at 50-60 km depth through a dense network of probably seismically induced fractures. We combine analyses of textures and mineral composition with thermodynamic modeling to reconstruct repeated stages of interaction, with pulses of high-pressure (HP) fluid at 650-6708C, rehydrating the initially dry rocks to micaschists. SIMS oxygen isotopic data of quartz indicate fluids of crustal composition. HP growth rims in allanite and zircon show uniform U-Th-Pb ages of 65 Ma and indicate that hydration occurred during subduction, at eclogite facies conditions. Based on this case study in the Sesia Zone (Western Italian Alps), we conclude that continental crust, and in particular deep basement fragments, during subduction can behave as substantial fluid sinks, not sources. Density modeling indicates a bifurcation in continental recycling: Chiefly mafic crust, once it is eclogitized to >60%, are prone to end up in a subduction graveyard, such as is tomographically evident beneath the Alps at 550 km depth. By contrast, dominantly felsic HP fragments and mafic granulites remain positively buoyant and tend be incorporated into an orogen and be exhumed with it. Felsic and intermediate lithotypes remain positively buoyant even where deformation and fluid percolation allowed them to equilibrate at HP.
DS2001-0037
2001
Lanat, J-F.Annen, C., Lanat, J-F., Provost, A.The long term growth of volcanic edifices: numerical modelling of the roleof dike intrusion and lava flow..Journal of Volcan. Geotherm Res., Vol. 105, pp. 263-89.GlobalDyke intrusions - not specific to diamond
DS1970-0950
1974
Lancaster, I.N.Lancaster, I.N.Pans of the Southern KalahariBotswana Notes And Records, Vol. 6, PP. 157-169.BotswanaGeomorphology
DS1988-0163
1988
Lancaster, N.Deacon, J., Lancaster, N.Late Quaternary Paleoenvironments of southern AfricaOxford University of Press, 236p. APPROX. $65.00USSouth AfricaPaleogeography
DS2003-0161
2003
Lancaster, N.Bristow, C.S., Lancaster, N., Duller, G.A.Combining ground penetrating radar and optical dating to determine dune migration inGeological Society of America, Annual Meeting Nov. 2-5, Abstracts p.300.NamibiaGPR, geomorphology
DS200412-0209
2003
lancaster, N.Bristow, C.S., lancaster, N.,Duller, G.A.Combining ground penetrating radar and optical dating to determine dune migration in Namibia.Geological Society of America, Annual Meeting Nov. 2-5, Abstracts p.300.Africa, NamibiaGPR, geomorphology
DS201112-0568
2011
Lancaster, P.J.Lancaster, P.J., Storey, C.D., Hawkesworth, C.J., Dhuime, B.Understanding the roles of crustal growth and preservation in the detrital zircon record.Earth and Planetary Science Letters, Vol. 305, 3-4, pp. 405-412.MantleGeochronology
DS201412-0496
2014
Lancaster, P.J.Lancaster, P.J., Dey, S., Storey, C.D., Mitra, A., Bhunia, R.K.Contrasting crustal evolution processes in the Dharwar craton: insights from detrial zircon U-Pb and Hf isotopes.Gondwana Research, in press availableIndiaCraton, geodynamics
DS1940-0121
1946
Lancsweert, P.Lancsweert, P.Belgian Congo Diamond MinesRoy. Col. Institute, Vol. 17, No. 2, P. 732.Democratic Republic of Congo, Central AfricaMining
DS1997-1098
1997
Land, B.A.Stapleton, J., Land, B.A.Metallic and industrial mineral assessment report, lamprophyres of Peace River District, ashes ...Alberta Geological Survey, MIN 19970006AlbertaExploration - assessment, TUL Petroleums Ltd.
DS1998-1403
1998
Land, P.Stapleton, M.J., Land, P.Metallic and industrial mineral assessment report on the West River diamond indicator geochemistryAlberta Geological Survey, MIN 19980014, pt.3.AlbertaExploration - assessment, Hawk Hills Magnetic Anomaly, TUL Petroleums
DS1999-0708
1999
Land, P.Stapleton, M.J., Land, P.Exploration of the West Peace River diamond indicator mineral trendAlberta Geological Survey, MIN 19990025AlbertaExploration - assessment, New Claymore Resources Ltd.
DS1999-0709
1999
Land, P.Stapleton, M.J., Land, P.Exploration of thew West Peace River diamond indicator mineral trendAlberta Geological Survey, MIN 19990025AlbertaExploration - assessment, New Claymore Resources Ltd.
DS1993-0876
1993
Landa, E.Landa, E., Thore, P., Reshef, M.Model based stack: a method for constructing an accurate zero-offsetsection for complex overburdensGeophysical Prospecting, Vol. 41, pp. 661-670GlobalGeophysics -experimental not practical, Overburden
DS1981-0088
1981
Landa, E.A.Bogdasarov, E.A., Landa, E.A., Markovskiy, A.A.Chemical Composition and Crystallization Conditions of Chrome Spinels of Volcanic Ultramafics and Other Rocks of the Mafic Ultramafic Series.International Geology Review, Vol. 23, No. 9, PP. 931-RussiaKimberlite, Spinels, Mineralogy
DS1983-0382
1983
Landa, E.A.Landa, E.A., Krashnova, N.I., Tarhovskaya, A.N., Shergina, Y.P.The distribution of rare earths and yttrium in apatite from alkali-ultrabasic and carbonatite intrusions and the origin ofapatitemineralizationGeochemistry International, Vol. 20, No. 1, pp. 77-87Russia, FennoscandiaCarbonatite, Rare Earth
DS1983-0383
1983
Landa, E.A.Landa, E.A., Lyapunov, S.M., Markovskiy, B.A.Characteristics of rare earth distribution in volcanicultrabasites.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 272, No. 2, pp. 462-464RussiaKamchatka Pen., Anabar Shield, Meymechite, Picrite, Rare Earth
DS1983-0384
1983
Landa, E.A.Landa, E.A., Murina, G.A, SHERAGINA, Yu.p., KRASNOVA, N.i.Isotopic Composition of Strontium in Apatite and Apatite Bearing Rocks of Carbonatite Complexes.Geochemistry International (Geokhimiya), Vol. 20, No. 3, PP. 214-216.RussiaRelated Rocks
DS1992-0092
1992
Landefeld, L.A.Barriga, F.J.A.S., Fyfe, W.S., Landefeld, L.A., Munha, J., RibeiroMantle eduction: tectonic fluidisation at depthEarth Science Reviews, Vol. 32, pp. 123-129MantleTectonic fluidization, Seismics
DS2001-0652
2001
Landen, L.S.Landen, L.S., Ramo, O.T.Silicic magmatism and Early Paleoproterozoic continental rifting, east FIn land and adjacent RussiaGeological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.81.abstract.Finland, RussiaMagmatism
DS2002-0778
2002
Landenberger, B.Jenkins, R.B., Landenberger, B., Collins, W.J.Late Paleozoic retreating and advancing subduction boundary in the New England fold belt, New South Wales.Australian Journal of Earth Sciences, Vol.49, No. 3, pp. 467-90.AustraliaSubduction
DS1930-0073
1931
Landes, K.K.Landes, K.K.A Paragenetic Classification of the Magnet Cove MineralsAmerican MINERALOGIST., Vol. 16, No. 8, PP. 313-326.United States, Gulf Coast, Arkansas, Hot Spring CountyMineralogy
DS1950-0114
1952
Landes, K.K.Oesterling, W.A. , Landes, K.K.Geologic and Economic Significance of the Huston Zinc Mine, salem Kentucky Fluorspar District.Economic Geology, Vol. 47, No. 3, PP. 316-338.GlobalKimberlite, Western Kentucky, Central States
DS1930-0141
1933
Landes, K.R.Landes, K.R., Ockepan, J.W.Origin of Domes in Lincoln and Mitchell Counties, KansasGeological Society of America (GSA) Bulletin., Vol. 44, No. 3, PP. 529-540.KansasKimberlite, Central States, Wilson, Woodson
DS201212-0781
2012
Landgrade, T.C.W.Williams, S.E., Muller, R.D., Landgrade, T.C.W., Whittaker, J.M.An open source software environment for visualizing and refining plate tectonic reconstructions using high resolution geological and geophysical dat a sets.Geology Today, Vol. 22, no. 4/5, pp. -9.TechnologyGplates
DS201212-0645
2012
Landgrebe, T.C.W.Shephard, G.E., Bunge, H-P., Schuberth, B.S.A., Muller, R.D., Talsma, A.S., Moder, C., Landgrebe, T.C.W.Testing absolute plate reference frames and the implications for the generation of geodynamic mantle heterogeneity stucture.Earth and Planetary Science Letters, Vol. 317-318, pp. 204-217.MantleGeodynamics
DS1992-0082
1992
Landi, P.Barberi, F., Bertagnini, A., Landi, P., Principe, C.A review on phreatic eruptions and their precursorsJournal of Volcanology and Geothermal Research, Vol. 52, pp. 231-246GlobalVolcanics, Phreatomagmatics
DS201112-0981
2010
Landim Dominguez, J.M.Soares Lima, E., Landim Dominguez, J.M.Analise de minerais pesados como ferramenta na avaliacao de possiveis depositos diamantiferos na platforma continental no sul da Bahia.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 62.South America, Brazil, BahiaPlacer diamonds
DS1975-0331
1976
Landis, G.P.Mansker, W.L., Brookins, D.G., Landis, G.P., et al.Post Devonian Distremes in Southeast Missouri, Investigation of the Avon Kimberlite and Some Emplacement Parameters.Eos, Vol. 57, No. 10, P. 761, (abstract.).GlobalKimberlite, Central States, Alnoite
DS1996-0804
1996
Landol, J.D.Landol, J.D., Foland, K.A.The formation of quartz syenite by crustal contamination at Mont Shefford and other MontregianCanadian Mineralogist, Vol. 34, pt. 2, April pp. 301-324.QuebecMetasomatism, Montregian Complexes
DS1994-0529
1994
Landoll, .J.D.Foland, K.A., Landoll, .J.D., Henderson, C.M.B.Some consequences of interaction between mantle magmas and crust in the formation of epizonal alkaline complexes.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.MantleAlkaline rocks
DS1994-0976
1994
Landoll, J.D.Landoll, J.D., Foland, K.A., Chen, J-F., Henderson, C.M.B.The role of crustal contamination in the formation of silica oversaturated rocks in the Montregian Hills province, Quebec.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p. posterQuebecAlkaline rocks, Montregian Hills
DS1992-0843
1992
Landon, S.M.Kerr, S.D., Landon, S.M.Proterozoic Midcontinent rift system, an overviewGeological Society of America (GSA) Abstracts with programs, 1992 Annual, Vol. 24, No. 7, abstract p. A328MidcontinentGeophysics -gravity, Tectonics, rifting
DS200612-1169
2006
Landonio, M.Rolandi, V., Brajkovic, A., Adamo, I., Landonio, M.Diamonds from Udachnaya pipe, Yakutia. Their morphology, optical and Raman characteristics, FTIR and CL features.Australian Gemmologist, Vol. 22, no. 9 Jan-Mar, pp.RussiaDiamond morphology
DS201012-0422
2010
Landreth, J.O.Landreth, J.O., Dockweiler, P.J.Mountain Pass carbonatite project.International Workshop Geology of Rare Metals, held Nov9-10, Victoria BC, Open file 2010-10, extended abstract pp. 19-20.United States, CaliforniaCarbonatite
DS2002-0154
2002
Landrgebe, D.Biehl, L., Landrgebe, D.MultiSpec - a tool for multispectral hyper spectral image dat a analysesComputers and Geosciences, Vol. 28, 10, pp.1153-59.GlobalComputers - programs
DS201012-0423
2010
Landry, F.Landry, F., Denholm, E., Hanks, C.Fish habitat compensation and mining in the North. Ekati has two compensation programs.38th. Geoscience Forum Northwest Territories, Abstract p. 60.Canada, Northwest TerritoriesEkati
DS200812-0630
2008
Landuyt, W.Landuyt, W., Bercovici, D., Ricard, Y.Plate generation and two phase damage theory in a model of mantle convection.Geophysical Journal International, Vol. 174, 3, pp. 1065-1080.MantleConvection
DS201212-0536
2012
Landuyt, W.Paczkowski, K., Bercovici, D., Landuyt, W., Brandon, M.T.Drip instabilities of continental lithosphere: acceleration and entrainment by damage.Geophysical Journal International, in press availableMantleRheology
DS2001-0653
2001
Landwehr, D.Landwehr, D., Blundy, J., Chamorro-Perez, Hill, E., WoodU series disequilibration temperatures generated by partial melting of spinel lherzoliteEarth and Planetary Science Letters, Vol. 188, No. 3-4, pp. 329-48.MantleMelting, lherzolite
DS1989-0322
1989
Lane, A.Dagbert, M., de l'Etolie, R., McLean, P., Lane, A.SECTCAD: un programme de C.A.O. pour l'evaluation desgisements.*FRENCHThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Annual Meeting Preprint and Outline of slides *FRENCH, 22p. Database # 18041GlobalComputer, Program -SECTCAD.
DS1992-0348
1992
Lane, D.E.Day, W.C., Lane, D.E.Strategic and critical minerals in the midcontinent regionUnited States Geological Survey (USGS) Bulletin, 1989 A-C, 42p. $ 3.00Midcontinentmineral resources, Economics
DS201609-1728
2010
Lane, G.R.Lane, G.R., Milovanovic, B., Bondi, E.Economic modelling and its application in strategic planning.The 4th Colloquium on Diamonds - source to use held Gabarone March 1-3, 2010, 14p.GlobalEconomics - strategic planning

Abstract: Mining executives often have a difficult task detennining what the strategic objective of the business should be as this can be impacted by the prevailing market conditions. In addition, they have no mechanism to quantitatively 'test' the impact of this strategic decision on the business and understand the underlying dynamics. During the commodities bull run of 2003 to 2008 the strategic objective may have been to grow the long term value of the business (NPV) tluough increased tonnage, acquisition and finding new reserves, which all came with an increasing fixed cost base. Now with the financial crisis upon us and the collapse of commodity prices and demand, executives have adjusted their strategies as 'cash is king' and short-tenn cash flow, in some instances at the expense of long terms value, is the order of the day. For many mining companies, mine closures, reductions in production and cost cutting exercisers are now the focus. In many instances, management do not have an ability to rapidly test different strategic alternatives to 'test' the impact on value, unit costs, reserves and profitability at the operational level and optimise the underlying trade-off variables. Economic modelling of the complete business value chain is a means of linking the operational 'reality ' and strategic choices, so that the full impact can be assessed. This paper describes some of the challenges facing mining executives and how economic modelling can be applied to make decision making more rigorous.
DS1994-1688
1994
Lane, L.SStephenson, R.A., Coflin, K.C., Lane, L.S, DietrichCrustal structure and tectonics of the southeast Beaufort Sea continentalmargin.Tectonics, Vol. 13, No. 2, Apr. pp. 389-400.Northwest Territories, Beaufort SeaTectonics - structure
DS2000-0149
2000
Lane, L.S.Cecile, M.P., Lane, L.S., Morrow, StockmalMajor basement controlled features of the Central Foreland north of Peace River Arch.Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000 Conference, 4p. abstractAlberta, Cordillera, British Columbia, Western CanadaTectonics, Basin - activity
DS1960-0164
1961
Lane, M.Lane, M.A Calabash of Diamonds: an African Treasure HuntLondon: Heinemann., 215P.South AfricaTravelogue, History, Kimberley
DS200612-1306
2005
Lane, R.Simandl, G.J., Ferbey, T., Levson, V.M., Robinson, N.D., Lane, R., Smith, R., Demchuk, Raudsepp, HickinKimberlite and diamond indicator minerals in northeast British Columbia, Canada - a reconnaissance survey.British Columbia Geological Survey, Geofile 2005-25, 25p.Canada, British ColumbiaGeochemistry, geochronology, Buffalo Head Terrane
DS202112-1936
2021
Lanese, N.Lanese, N.Earth's 1st continents arose hundreds of millions of years earlier than thought.livescience.com, Nov. 8, 5p.Globalcratons

Abstract: Earth's first continents, known as the cratons, emerged from the ocean between 3.3 billion and 3.2 billion years ago, a new study hints. This pushes back previous estimates of when the cratons first rose from the water, as various studies suggested that large-scale craton emergence took place roughly 2.5 billion years ago. "There was no uncertainty that continents were partly sticking out of water as early as 3.4 billion years ago," said Ilya Bindeman, a professor of geology at the University of Oregon, who was not involved in the new study. That's because scientists have found sedimentary rocks - which form from the broken-up bits of other rocks that have undergone erosion and weathering — that date back to that era. Such sedimentary rocks could only form once land broke through the surface of early Earth's oceans.
DS1995-1050
1995
Lane-Serff, G.F.Lane-Serff, G.F.Partial recycling in hydrothermal plumes.. commentEarth and Planetary Science Letters, Vol. 132, pp. 233-234GlobalPlumes, Hot spots
DS1988-0371
1988
Lanev, V.S.Kozlovskiy, Ye.A., Guberman, D.M., Kazanskiy, V.I., Lanev, V.S.The ore potential of deep seated zones of ancient continental crust Based on dat a from the Kola Superdeep drillholeInternational Geology Review, Vol. 30, No. 7, July pp. 763-771. Database # 17694RussiaOre deposits, Genesis
DS200912-0757
2009
Lang, A.Thrasher, I.M., Mauz, B., Chiverrell, R.C., Lang, A.Luminescence dating of glaciofluvial deposits: a review.Earth Science Reviews, Vol. 97, pp. 145-158.TechnologyNot specific to diamonds
DS1960-0855
1967
Lang, A.R.Lang, A.R.Causes of Birefringence in DiamondNature., Vol. 213, No. 5073, PP. 248-251.GlobalDiamond Morphology
DS1970-0966
1974
Lang, A.R.Moore, A.M., Lang, A.R.Correlations between Habit, Ultraviolet Transparency and Birefringence Features in South African Microdiamonds.Diamond Research, 1974, PP. 16-15.South AfricaCrystallography, Micro-diamonds
DS1975-0321
1976
Lang, A.R.Lang, A.R., Woods, G.S.Finger Printing Diamonds by X Ray TopographyIndustrial Diamond Review., MARCH PP. 96-103.GlobalDiamond Morphology
DS1981-0001
1981
Lang, A.R.Adams, R.C.G., Bielicki, T.A., Lang, A.R.Correlation of Electrostatic Charging Patterns with Internal Structure in Diamonds.Journal of MATERIALS SCIENCE., Vol. 16, No. 9, PP. 2369-2380.GlobalDiamond Morphology
DS1982-0586
1982
Lang, A.R.Sumida, N., Lang, A.R.On Spike Diffuse Reflections in Electron Diffraction Patterns of Diamonds.Journal of APPL. CRYSTALLOGRAPHY, Vol. 15, No. 3, PP. 266-274.GlobalDiamond Crystallography
DS1983-0385
1983
Lang, A.R.Lang, A.R., Walmsley, J.C.Apatite Inclusions in Natural Diamond CoatPhysics And Chemistry of Metals, Vol. 9, No. 1, PP. 6-9.GlobalBlank
DS1985-0379
1985
Lang, A.R.Lang, A.R., Kowalski, G., Makepeace, A.P.Recording Diffuse X-ray Reflections with Continuous Synchroton Radiation - an Application to Type 1a Diamond.Phil. Magazine, SECT. A, Vol. 52, No. 1, JULY, PP. 1-L. (LETTER).GlobalMineralogy
DS1988-0677
1988
Lang, A.R.Sumida, N., Lang, A.R.On the measurement of population density and size of platelets in type 1Adiamond and its implications for platelet structure modelsProceedings of the Royal Society of London, Section A, Vol. 419, No. 1857, pp. 235-257GlobalDiamond morphology, Nitrogen
DS1991-0950
1991
Lang, A.R.Lang, A.R., Moore, M., Makepeace, A.P., Wierzchov, W.On the dilation of synthetic type 1B diamond by substitutional nitrogenimpurityPhil. Transactions Roy. A., Vol. A 337, No. 1648, Dec. 16, pp. 497-520GlobalDiamond synthesis, Nitrogen impurity
DS1992-1627
1992
Lang, A.R.Walmsley, J.C., Lang, A.R.On sub-micrometre inclusions in diamond coat: crystallography and composition of ankerites and related rhombohedral carbonates.Mineralogical Magazine, Vol. 56, December pp. 533-543.GlobalDiamond CVD., Inclusions in CVD.
DS1992-1628
1992
Lang, A.R.Walmsley, J.C., Lang, A.R.Oriented biotite inclusions in diamond coatMineralogical Magazine, Vol. 56, March pp. 108-111GlobalDiamond morphology, Natural diamonds, biotite
DS1993-0779
1993
Lang, A.R.Kaneka, K., Lang, A.R.Chlorine and optical microtopographic studies of Argyle diamondsIndustrial Diamond Review, # MX681, Vol. 53, No. 6, pp. 334-337.AustraliaDiamond morphology, Deposit -Argyle
DS1993-0877
1993
Lang, A.R.Lang, A.R.Topographic methods for studying defects in diamondsDiamond Relat, Vol. 2, No. 2-4, March 31, pp. 106-114GlobalDiamond inclusions
DS1994-0977
1994
Lang, A.R.Lang, A.R.Lattice parameter determinations in diamond: an overviewProperties and growth of diamond, G. Davies, pp. 106-110.GlobalDiamond, Properties of nitrogen in diamond
DS1994-0978
1994
Lang, A.R.Lang, A.R.Effect of nitrogen on the lattice parameter of diamondProperties and growth of diamond, G. Davies, pp. 111-115.GlobalDiamond, Properties of nitrogen in diamond
DS1994-0979
1994
Lang, A.R.Lang, A.R.Topographial studies of nitrogen in diamondProperties and growth of diamond, G. Davies, pp. 116-120.GlobalDiamond, Properties of nitrogen in diamond
DS1994-0980
1994
Lang, A.R.Lang, A.R.An unusual octahedral diamondMineralogical Magazine, Vol. 58, No. 392, Sept. 508-512.GlobalMineralogy, Diamond morphology
DS200812-0631
2007
Lang, A.R.Lang, A.R., Bulanova, G.P., Fisher, D., Fukert, S., Saruna, A.Defects in a mixed habit Yakutian diamond: studies by optical and cathodluminescence microscopy, infrared absorption, Raman Scattering and photoluminesence spectJournal of Crystal Growth, Vol. 309, 2, pp. 170-180.TechnologySpectroscopy
DS1989-0986
1989
Lang, H.R.McGuffie, B.A., Johnson, L.F., Alley, R.E., Lang, H.R.IGIS Computer aided photogeologic mapping with image processing, graphic sand CAD/CAM capabilitiesGeobyte, Vol. 4, No. 5, pp. 8, 10-14. Database #18194GlobalComputer, Program -IGIS
DS1994-0981
1994
Lang, H.R.Lang, H.R., Paylor, E.D.Spectral stratigraphy: remote sesning lithostratigraphic procedures for basin analysis, Central Wyoming examplesNonrenewable Resources, Vol. 3, No. 1, Spring, pp. 25-45WyomingRemote sensing, Stratigraphy
DS1990-0854
1990
Lang, J.Kogbe, C.A., Lang, J.Great African continental complexes. Special issue -major African continental Phanerozoic complexes and dynamics of sedimentationJournal of African Earth Sciences, Vol. 10, No. 1/2 pp. 1-400AfricaContinetal complexes, Sediments
DS1992-0230
1992
Lang, J.Cessier, C., Lang, J.La Formation glaciaire de la Mambere (Republique Centrafricaine):reconstitution paleogeographique et implications a l'echelle du Paleozoiqueafricain.(in French)Geologische Rundschau, (in French), Vol. 81, No. 3, pp. 769-789Central African RepublicGeomorphology, Glacial till
DS1995-1051
1995
Lang, J.R.Lang, J.R., Lueck, B., Mortensen, J.K., Russell, J.K.Triassic Jurassic silica undersaturated and silica saturated alkalic intrusions in Cordillera-arc magmaGeology, Vol. 23, No. 5, May pp. 451-454.British ColumbiaAlkalic intrusives, Arc magmatism, Quesnellia terrane, Stikinia terrane
DS1988-0399
1988
Lang, L.Lang, L.Are CAD and GIS evolving toward the same answer?Geobyte, Vol. 3, No. 4, November pp. 12-15. Database # 17519GlobalComputer, Program-CAD-GIS
DS2000-0963
2000
Lang, M.Ulrych, J., Pivec, E., Lang, M., Lloyd, F.E.Ijolite segregations in melilite nephelinite of Podhorni arch volcano, western Bohemia.Neues Jahr. Min. Abh., No. 175, No. 3, pp. 317-48.Europe, BohemiaOlivine nephelinite
DS1910-0198
1911
Lang, P.Lang, P.Discovery of Diamonds in CanadaU.s. Monthly Consular And Trade Reports, No. 134, JUNE 9TH. P. 1087.Canada, QuebecBlank
DS1985-0380
1985
Lang, R.D.Lang, R.D.Argyle - a New DevelopmentAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) PREPRINT., No. 85-40, 6P.Australia, Western AustraliaHistory, Exploration Techniques, Mining Methods, Marketing, Prod
DS1986-0480
1986
Lang, R.D.Lang, R.D.Development of Australia's first major diamond discovery outlinedMining Engineering, Vol. 38, No. 1, January pp. 13-16GlobalArgyle, treatment plant, Economics
DS202203-0346
2021
Lang, S.France, L., Brouillet, F., Lang, S.Early carbonatite magmatism at Oldoinyo Lengai volcano ( Tanzania): carbonatite-silicate melt immiscibility in Lengai 1 melt inclusions.Comptes Rendus Geoscience, Vol. 353, no S2, pp. 273-288. pdfAfrica, Tanzaniadeposit - Oldoinyo Lengai

Abstract: Carbonatites are unusual C-rich alkaline magmas that have been reported throughout the geological record. Nevertheless, there is only one currently active carbonatite system on Earth: Oldoinyo Lengai stratovolcano in northern Tanzania (God’s mountain in Maasai culture). Present-day Lengai carbonatites are natrocarbonatites, peculiar Na-rich carbonatites that, under atmospheric conditions, alter and leach to compositions similar to the more common Ca-carbonatites within weeks, preventing any long-term geological record of such Na-rich magmas. It follows that the oldest report of natrocarbonatites at Oldoinyo Lengai dates to the 19th century. Here, by using samples from the Lengai I cone (11 ka), we show that immiscible silicate-carbonatite melts were already present at reservoir conditions at that time. Measurements of three-phase (carbonatite silicate gas) melt inclusions from Lengai I highlight that their chemical compositions were similar to those of immiscible melts recently present in the reservoir. Alkaline carbonatites in melt inclusions from both Lengai I and historical explosive eruptions are enriched in Ca relative to those historically effused at the surface and likely record higher equilibrium temperatures (1100 °C). We also report chemical maps that qualitatively document elemental partitioning between immiscible silicate-carbonatite melts. We show that at the melt inclusions’ entrapment conditions Si, Fe, K, Na, and Cl are compatible with the silicate phase when C, Ca, P, Sr, Ba, and F are compatible with the carbonate phase.
DS201412-0497
2014
Langdon, J.Langdon, J.Diamonds will shine brightly in 2014 .. Experts agree.International Resource Journal, Jan. pp. 26-29.GlobalEconomics
DS2003-0772
2003
Lange, G.M.Lange, G.M., Hassan, R., Alfieri, A.Using environmental accounts to promote sustainable development: experience inNatural Resources Forum, Vol. 27, 1, pp. 19-31.South AfricaSustainability - not specific to diamonds
DS200412-1083
2003
Lange, G.M.Lange, G.M., Hassan, R., Alfieri, A.Using environmental accounts to promote sustainable development: experience in southern Africa.Natural Resources Forum, Vol. 27, 1, pp. 19-31.Africa, South AfricaSustainability - not specific to diamonds
DS1994-0982
1994
Lange, R.Lange, R.Subcontinental lithosphere: preservation of complex interactions, asthenospheric plumes and subducted slabs.Eos, Vol. 75, No. 16, April 19, p. 188.MantlePlumes, Subduction
DS1990-0901
1990
Lange, R.A.Lange, R.A., Carmichael, I.S.E.Hydrous basaltic andesites associated with minette and related lavas in western MexicoJournal of Petrology, Vol. 31, pt. 6, pp. 1225-1259MexicoMinettes, Petrology
DS1991-0951
1991
Lange, R.A.Lange, R.A., Carmichael, I.S.E.A potassic volcanic front in western Mexico: the lamprophyric and related lavas of San SebastianGeological Society of America Bulletin, Vol. 103, No. 7, July pp. 928-940MexicoMinette, absarokite, Volcanics, Geochemistry
DS1993-0435
1993
Lange, R.A.Feldstein, S.N., Lange, R.A., Vennemann, T., O'Neil, J.R.Complete chemical analyses and D/H ratios of phlogopite: the importance Of the Oxy-annite component.American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 636.GlobalExperimental petrology, Phlogopite
DS2000-0549
2000
Lange, R.A.Lange, R.A.Plio-Pleistocene paleomagnetism of the Leucite Hills volcanics revisited (Wyoming).Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-173.WyomingLamproite, Deposit - Leucite Hills
DS201212-0726
2012
Lange, R.A.Thoma, C.W., Liu, Q., Agee, C.B., Asimov, P.D., Lange, R.A.Multi-technique equation for Fe2SiO4 melt and the density of Fe bearing silicate melts from 0 to 161 Gpa.Journal of Geophysical Research, Vol. 117, 18p. B10206TechnologyMantle mineralogy
DS201508-0370
2015
Lange, R.A.O'Leary, M.C., Lange, R.A., Ai, Y.The compressability of CaCO3-Li2CO3-Na2CO3-K2CO3 liquids: application to natrocarbonatite and CO2- bearing nephelinite liquids from Oldoinyo Lengai.Contributions to Mineralogy and Petrology, Vol. 170, 18p.Africa, TanzaniaDeposit - Oldoinyo Lengai
DS202010-1859
2020
Lange, T.Lorenz, V., Lange, T.The volcanic field of the Swabian Alb in southern Germany. *** GERJber. Mitt. oberrhein. Geol. Ver. N.F. English abstract, Vol. 102, pp. 153-174. 22p. PdfEurope, Germanymelilitite
DS202010-1860
2020
Lange, T.Lorenz, V., Lange, T., Buchel, G.The volcanoes of the Westeifel, Germany. ***GERJber. Mitt. oberrhein. Geol. Ver. N.F. English abstract, Vol. 102, pp. 379-411. 33p. PdfEurope, Germanymaars
DS202010-1855
2019
Lange, V.T.Lange, V.T., Lorenz, V., Koppen, K-H, Buchel, G.New aspects of the volcanism of the West Eifel. *** GERJber. Mitt. oberrhein. Geol. Ver. N.F. English abstract, Vol. 101, pp. 227-250. 24p. PdfEurope, Germany guidebook
DS1983-0236
1983
Langel, R.Frey, H., Langel, R., et al.Pogo and PangeaTectonophysics, Vol. 95, No. 3-4, PP. 181-190.South Africa, Africa, South AmericaTectonics, Magsat
DS1991-0952
1991
Langel, R.A.Langel, R.A.Study of the crust and mantle using magnetic surveys by magsat and othersatellitesP.il.a.s.-ear, Vol. 99, No. 4, December pp. 581-618GlobalGeophysics -magnetics, Remote sensing
DS1995-1550
1995
Langel, R.A.Ravat, D., Langel, R.A., Alsdorf, D.E.Global vector and scalar MAGSAT magnetic anomaly mapsJournal of Geophysical Research, Vol. 100, No. 10, Oct, 10, pp. 111-136.GlobalGeophysics -magnetics, Magsat
DS1996-1144
1996
Langel, R.A.Purucker, M.E., Sabaka, T.J., Langel, R.A.Conjugate gradient analyses - a new tool for studying satellite magneticdat a setsGeophys. Research Letters, Vol. 23, No. 5, March 1, pp 507-510GlobalRemote sensing, Geophysics -magnetics
DS1975-0322
1976
Lange-Mechlen, S.Lange-Mechlen, S.Edelstein. #1Stuttgart: Belser Verlag, 120P.GlobalKimberlite
DS1996-0805
1996
Langenberg, C.W.Langenberg, C.W., Skupinski, A.The provenance of diamond indicator minerals in bedrock of the Hinton @ Alberta Foothills.Alberta Geological Survey, MIN 19960008, 66p. $ 10.00Alberta, west centralExploration - assessment
DS1998-0827
1998
Langenberg, C.W.Langenberg, C.W., Skupinski, A.Indications of ultramafic volcanism in bedrock of the Wapiti area, west central Alberta.Calgary Mining Forum, Apr. 8-9, p. 62. poster abstractAlbertaSampling - heavy minerals, Diatremes, dikes
DS1999-0284
1999
Langenberg, C.W.Hamilton, W.N., Price, M.C., Langenberg, C.W.Geological map of AlbertaAlberta Geological Survey, 1:1, 000, 000AlbertaMap - not specific to diamonds
DS1999-0392
1999
Langenberg, C.W.Langenberg, C.W., Skupunski, A.Remnants of ultramafic igneous rocks in bedrock of the Wapiti area, west central Alberta.8th. Calgary Mining forum, 1p. abstractAlbertaGeochemistry - indicator minerals
DS2000-0550
2000
Langenberg, C.W.Langenberg, C.W., Skupinski, A.Remnants of (possibly diamondiferous) ultramafic igneous rocks in bedrock of Kakwa/Wapiti area.Alberta Geological Survey, Earth Science Report 00-03, 45p. $15.00Alberta, west centralExploration - assessment
DS200912-0758
2009
Langenheim, V.Thurber, C., Zhang, H., Brocher, T., Langenheim, V.Regional three dimensional seismic velocity model of the crust and uppermost mantle of northern California.Journal of Geophysical Research, Vol. 114, B01304.United States, CaliforniaGeophysics - seismics
DS1995-1052
1995
Langenheim, V.E.Langenheim, V.E.Gravity of the New Madrid seismic zone - a preliminary studyUnited States Geological Survey (USGS) Prof. paper, No. 1538- L, 18p.MidcontinentGeophysics - seismics, Mississippi Embayment
DS1995-1053
1995
Langenheim, V.E.Langenheim, V.E.Gravity of the New Madrid seismic zone: a preliminary studyUnited States Geological Survey (USGS) Prof. Paper, No. P1538-L, L1-18Missouri, Arkansas, Kentucky, TennesseeGeophysics -gravity, Midcontinent
DS1997-0523
1997
LangenhorstHough, R.M., Gilmour, I., Pillinger, C.T., LangenhorstDiamonds from the iridium rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico.Geology, Vol. 25, No. 11, Nov. pp. 1019-22.MexicoK-T boundary, Diamonds - mineralogy, techniques
DS1999-0813
1999
Langenhorst, A.Wysession, M.E., Langenhorst, A., Clarke, T.J.Lateral variations in compressional/shear veolocities at the base of themantle.Science, Vol. 284, No. 5411, Apr. 2, pp. 120-4.MantleGeophysics - seismics, Tectonics
DS1999-0393
1999
Langenhorst, F.Langenhorst, F., Shafranovsky, Masaitis, KoivistoDiscovery of impact diamonds in a Fennoscandian crater and evidence #NAME? solid state transformation.Geology, Vol. 27, No. 8, Aug. pp. 747-50.Finland, Baltic StatesDiamond genesis, Lappajarvi Crater
DS2002-0914
2002
Langenhorst, F.Langenhorst, F., Poirier, J.P.Transmission electron microscopy of coesite inclusions in the Dora Maira high pressure metamorphic pyrope quartzite.Earth and Planetary Science Letters, Vol. 203, 3-4, pp. 793-803.EuropeCoesite - inclusions, UHP, ultra high pressure
DS2002-1023
2002
Langenhorst, F.McCammon, C., Lauterbach, S., Van Akern, P., Langenhorst, F., Seifert, F.EELS studies of lower mantle mineral assemblages: a window to redox conditions18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.77.MantleUHP mineralogy - perovskite
DS2003-0354
2003
Langenhorst, F.Dubrovinsky, L., Dubrovinskaia, N., Langenhorst, F., Dobson, D., Robie, D.Iron silica interaction at extreme conditions and the electrically conducting layer at theNature, No. 6927, March 6, pp. 58-60.MantleCore mantle boundary, Geochemistry
DS2003-0823
2003
Langenhorst, F.Litasov, K., Ohtani, E., Langenhorst, F., Yurimoto, H., Kubo, T., Kondo, T.Water solubility in Mg perovskites and water storage capacity in the lower mantleEarth and Planetary Science Letters, Vol. 211, 1-2, June 15, pp. 189-203.MantleWater storage
DS2003-0824
2003
Langenhorst, F.Litasov, K., Ohtani, E., Langenhorst, F., Yurimoto, H., Kubo, T., Kondo, T.Water solubility in Mg perovskites and water storage capacity in the lower mantleEarth and Planetary Science Letters, Vol. 211, 1-2, pp. 189-203.MantleBlank
DS2003-1300
2003
Langenhorst, F.Smyth, J.R., Holl, C.M., Frost, D.J., Jacobsen, S.D., Langenhorst, F.Structural systematics of hydrous ring woodite and water in Earth's interiorAmerican Mineralogist, Vol. 88, 10, Oct. pp. 1402-7.MantleMineralogy
DS200412-0585
2004
Langenhorst, F.Frost, D.J., Liebske, C., Langenhorst, F., McCammon, C.A., Tronnes, R.G., Rubie, D.C.Experimental evidence for the existence of iron rich metal in the Earth's lower mantle.Nature, No. 6981, March 25, pp. 409-411.MantleSulphides
DS200412-0586
2004
Langenhorst, F.Frost, D.J., Liebske, C., McCammon, C.A., Langenhorst, F., Tronnes, R., Rubie,D.C.Experimental evidence for the existence of a metallic iron rich phase in the Earth's mantle.Lithos, ABSTRACTS only, Vol. 73, p. S38. abstractMantleRedox conditions
DS200412-1144
2003
Langenhorst, F.Litasov, K., Ohtani, E., Langenhorst, F., Yurimoto, H., Kubo, T., Kondo, T.Water solubility in Mg perovskites and water storage capacity in the lower mantle.Earth and Planetary Science Letters, Vol. 211, 1-2, June 15, pp. 189-203.MantleWater storage
DS200412-1258
2004
Langenhorst, F.McCammon, C.A., Lauterbach, S., Seifert, F., Langenhorst, F., Van Aken, P.A.Iron oxidation state in lower mantle mineral assemblages. Part 2.Earth and Planetary Science Letters, Vol. 222, 2, pp. 435-449.MantleMineral chemistry
DS200412-1269
2004
Langenhorst, F.McEnroe, S.A., Langenhorst, F., Robinson, P., Bromiley, G.D., Shaw, C.S.J.What is magnetic in the lower crust?Earth and Planetary Science Letters, Vol. 226, 1-2, Sept. 30, pp.175-192.MantleMagnetic anomalies, hematite-ilmenite, Curie isotherm
DS200412-1863
2003
Langenhorst, F.Smyth, J.R., Holl, C.M., Frost, D.J., Jacobsen, S.D., Langenhorst, F., McCammon, C.A.Structural systematics of hydrous ring woodite and water in Earth's interior.American Mineralogist, Vol. 88, 10, Oct. pp. 1402-7.MantleMineralogy
DS200512-0444
2005
Langenhorst, F.Holzapel, C., Rubie, D.C., Frost, D.J., Langenhorst, F.Geophysics: Fe Mg interdiffusion in (Mg,Fe) SiO3 perovskite and lower mantle requilibration.Science, No. 5741, Sept. 9, pp. 1707-1710.MantleGeophysics
DS200712-0593
2007
Langenhorst, F.Langenhorst, F., Solozhenko, V.L.ATEM-EELS study of diamond like phases in the B-C-N system.Plates, Plumes, and Paradigms, 1p. abstract p. A542.TechnologyB-C-N compounds
DS200712-0726
2007
Langenhorst, F.Mierdel, K., Keppler, H., Smyth, J.R., Langenhorst, F.Water solubility in aluminous orthopyroxene and the origin of the Earth's asthenosphere.Science, Vol. 315, Jan. 19, pp. 364-368.MantleTectonics
DS201112-0635
2010
Langenhorst, F.Malaspina, N., Scambelluri, M., Poli, S., Van Roermund, H.L.M., Langenhorst, F.The oxidation state of mantle wedge majoritic garnet websterites metasomatised by C-bearing subduction fluids.Earth and Planetary Science Letters, Vol. 298, 3-4, pp. 417-426.MantleMetasomatism
DS201212-0098
2012
Langenhorst, F.Bureau, H., Langenhorst, F., Auzende, A-L., Frost, D.J., Esteve, I., Siebert, J.The growth of fibrous, cloudy and polycrystalline diamonds.Geochimica et Cosmochimica Acta,, Vol. 77, pp. 202-214.TechnologyDiamond morphology
DS201212-0187
2012
Langenhorst, F.Escudero, A., Miyajima, N., Langenhorst, F.Microstructure, composition and P-T conditions of rutile from Diamondiferous gneiss of the Saxonian Erzgebirge Germany.Chemie der Erde, Vol. 72, 1, pp. 25-30.Europe, GermanyUHP
DS201212-0188
2012
Langenhorst, F.Escudero, A., Myyajima, N., Langenhorst, F.Microstructure, composition and P-T conditions of rutile from Diamondiferous gneiss of the Saxonian Ezgebirge, Germany.Chemie Der Erde, Vol. 72, 1, pp. 25-30.Europe, GermanyUHP , geothermometry
DS201212-0395
2012
Langenhorst, F.Langenhorst, F., Deutsch, A.Shock metamorphism of minerals.Elements, Vol. 8, 1, Feb. pp. 31-36.TechnologyHP, melting
DS201212-0433
2012
Langenhorst, F.Malaspina, N., Langenhorst, F., Fumagalli, P., Tumiati, S., Poli, S.Fe 3+ distribution between garnet and pyroxenes in mantle wedge carbonate bearing garnet peridotites ( Sulu, China) and implications for their oxidation state.Lithos, Vol. 146-147, pp. 11-17.ChinaUHP
DS201212-0434
2012
Langenhorst, F.Malaspina, N., Langenhorst, F., Fumagalli, P., Tumiati, S., Poli, S.Fe 3 + distribution between garnet and pyroxenes in mantle wedge carbonate bearing garnet peridotites ( Sulu China) and implications for their oxidation state.Lithos, Vol. 146-147, pp. 11-17.ChinaUHP
DS201212-0435
2012
Langenhorst, F.Malaspina, N., Langenhorst, F., Poli, S.C-O-H metasomatism and redox processes in the mantle at subduction zones.emc2012 @ uni-frankfurt.de, 1p. AbstractChinaSulu area
DS201312-0569
2013
Langenhorst, F.Malaspina, N., Langenhorst, F.Fluid induced redox processes at the slab mantle interface: insights from ultrahigh pressure garnet peridotites.Goldschmidt 2013, AbstractMantleRedox
DS201412-0711
2014
Langenhorst, F.Prescher, C., Langenhorst, F., Dubrovinsky, L.S., Prakapenka, V.B., Miyajima, N.The effect of Fe spin crossovers on its partitioning behavior and oxidation state in a pyrolitic Earth's lower mantle system.Earth and Planetary Science Letters, Vol. 399, pp. 86-91.MantleOxidation
DS201904-0755
2018
Langenhorst, F.Langenhorst, F., Campione, M.Ideal and real structures of different forms of carbon, with some remarks on their geological significance.Journal of the Geological Society of London, Vol. 176, pp. 337-347.Globalcarbon

Abstract: Carbon is found in nature in a huge variety of allotropic forms and recent research in materials science has encouraged the development of technological materials based on nanocarbon. Carbon atoms with sp2 or sp3 hybridization can be thought of as building blocks. Following a bottom-up approach, we show how graphene and diamond molecules are built up and how their properties vary with size, reaching an upper limit with bulk graphite and diamond. Carbon atoms with sp2 hybridization give rise to an impressive number of different materials, such as carbon nanotubes, graphene nanoribbons, porous carbon and fullerene. As in any crystalline phase, the crystal structures of natural carbon allotropes (i.e. graphite and diamond) contain various types of imperfections. These so-called lattice defects are classified by their dimensions into 0D (point), 1D (line), 2D (planar) and 3D (volume) defects. Lattice defects control the physical properties of crystals and are often a fingerprint of the geological environment in which they formed and were modified. Direct observations of lattice defects are commonly accomplished by transmission electron microscopy. We present and discuss the ideal and real structures of carbon allotropes, the energetics of lattice defects and their significance in understanding geological processes and conditions.
DS201605-0872
2016
Langenhoven, J.Mokgalaka, L., Langenhoven, J., du Toit, R.Progress update on the Petra Diamonds' MTS 3D SpatialDB integration and reporting project.Diamonds Still Sparkling SAIMM 2016 Conference, Mar. 14-17, pp. 239-250.Africa, South AfricaMining - applied
DS1991-1356
1991
Langer, K.Platonov, A.N., Langer, K., Matsuk, S.S., Taran, M.N., Hu, X.iron 2 Ti4 Charge transfer in garnets from mantle eclogitesEuropean Journal of Mineralogy, Vol. 3, No. 1, pp. 19-26GlobalMineralogy, Eclogites -garnet
DS1993-0878
1993
Langer, K.Langer, K., et al.Single crystal spectra of garnets from Diamondiferous high-pressure metamorphic rocks from Kazakhstan; indications for Oh, H2O and FeTi chargetransfer.European Journal of Mineralogy, Vol. 5, No. 6, Dec. pp. 1091-1100.GlobalMineral chemistry, Kokchetav Massif
DS1993-0879
1993
Langer, K.Langer, K., Robarick, E., Sobolev, N.V., Shatsky, V.S.Single crystal spectra of garnets from Diamondiferous high pressure metamorphic rocks from Kazakhstan -indications for OH-,H2O, and FeTi chargetransfer.European Journal of Mineralogy, Vol. 5, No. 6, Nov-Dec pp. 1091-1100.Russia, KazakhstanMetamorphic rocks, Mineralogy -garnets
DS1998-0965
1998
Langer, K.Matsyuk, S.S., Langer, K., Hosch, A.Hydroxyl defects in garnets from mantle xenoliths in kimberlites of the Siberian Platform #2Contributions to Mineralogy and Petrology, Vol. 132, No. 2, pp. 163-179.Russia, SiberiaMantle xenoliths, Petrology
DS1998-0966
1998
Langer, K.Matsyuk, S.S., Langer, K., Hosch, A.Hydroxyl defects in garnets from mantle xenoliths in kimberlites of the Siberian Platform #1Contributions to Mineralogy and Petrology, Vol. 133, No. 4, pp. 418-.Russia, SiberiaXenoliths, Garnets
DS2001-0597
2001
Langer, K.Khisina, N.R., Wirth, R., Langer, K., Andrut, UkhanovMicrostructure of experimentally oxidized olivine from a mantle nodule 1. modes of Fe3 and OH occurrence.Geochemistry International, Vol. 39, No. 4, pp. 327-35.GlobalPetrology - experimental, Nodule
DS200412-1247
2004
Langer, K.Matsyuk, S.S., Langer, K.Hydroxl in olivines from mantle xenoliths in kimberlites of the Siberian platform.Contributions to Mineralogy and Petrology, Vol. 147, 4, pp. 413-437.Russia, SiberiaMineral chemistry
DS200412-1965
2004
Langer, K.Taran, M.N., Kvasnytsya, V.M., Langer, K.On unusual deep violet microcrystals of diamonds from placers of Ukraine.European Journal of Mineralogy, Vol. 16, 2,pp. 241-245.Europe, UkraineDiamond morphology
DS200612-1415
2006
Langer, K.Taran, M.N., Kvasnytsya, V.M., Langer, K., Ilchenko, K.O.Infrared spectroscopy study of nitrogen centers in microdiamonds from Ukrainian Neogene placers.European Journal of Mineralogy, Vol. 18, 1, pp. 71-81.Europe, Ukraine, RussiaMicrodiamonds
DS1995-0978
1995
Langer, W.H.Knepper. D.H., Langer, W.H., Miller, S.Survey of natural aggregate properties characteristics important in remotesensing, Air- geophysics.Nonrenewable Resources, Vol. 4, No. 1, Spring pp. 99-120.GlobalRemote sensing, airborne geophysics, Alluvials - gravels not specific to diamonds
DS1997-0506
1997
Langereis, C.G.Hilgen, F.J., Krijgsman, W., Langereis, C.G., Lourens, L.Breakthrough made in dating of the geological recordEos, Vol. 78, No. 28, July 15, p. 285, 288, 289GlobalTimescale, Sedimentary cycles
DS2003-1342
2003
Langereis, C.G.Strik, G., Blake, T.S., Zegers, T.E., White, S.H., Langereis, C.G.Paleomagnetism of flood basalts in the Pilbara Craton, Western Australia: Late ArcheanJournal of Geophysical Research, Vol. 108, No. B 12, Dec. 3, 10.1029/2003JB002475AustraliaGeophysics - paleomagnetics, tectonics
DS200412-1937
2003
Langereis, C.G.Strik, G., Blake, T.S., Zegers, T.E., White, S.H., Langereis, C.G.Paleomagnetism of flood basalts in the Pilbara Craton, Western Australia: Late Archean continental drift and the oldest known reJournal of Geophysical Research, Vol. 108, No. B 12, Dec. 3, 10.1029/2003 JB002475AustraliaGeophysics - paleomagnetics, tectonics
DS1997-0649
1997
Langerheim, V.E.Langerheim, V.E., Hildenbrand, T.G.Commerce geophysical lineament - its source, geometry and relationship to Reelfoot Rift and New Madrid zone.Geological Society of America (GSA) Bulletin., Vol. 109, No. 5, May pp. 580-595.Arkansas, Tennessee, Kentucky, MissouriTectonics, Rifting
DS200712-1048
2007
Langeris, C.G.Strik, G., De Wit, M.J., Langeris, C.G.Paleomagnetism of the NeoArchean Pongola and Ventersdorp Supergroups and an appriasal of the 3.0 - 1.9 Ga apparent polar wander path of Kaapvaal CratonPrecambrian Research, Vol. 153, 1-2, pp. 96-115.Africa, South AfricaPaleomagnetism
DS1994-0983
1994
Langfield, J.Langfield, J.Gem of gems... diamondAustralian Gold Gem and Treasure, pp. 31-33.AustraliaNews item, Argyle -layman's notes
DS2002-0915
2002
Langford, C.Langford, C.Man vs manufacturing... high cost environment and difficulties in finding skilled labourCanadian Diamonds, Fall, pp. 34-6.CanadaDiamond - cutting
DS2002-0916
2002
Langford, C.Langford, C.A cut above... risky business but diamond manufacturing has become a part of daily life in the north.Canadian Diamonds, p. 36.Northwest TerritoriesNews item, Diamond cutters
DS2003-0773
2003
Langford, C.Langford, C., Kennedy, J.Diavik: Canada's next big stepCanadian Diamonds, Spring, pp. 30-38, 49.Northwest TerritoriesDeposit - Diavik
DS200412-1084
2003
Langford, C.Langford, C., Kennedy, J.Diavik: Canada's next big step.Canadian Diamonds, Spring, pp. 30-38, 49.Canada, Northwest TerritoriesMining Deposit - Diavik
DS201201-0854
2011
Langford, N.K.Lee, K.C., Sprague, M.R., Sussman, B.J., Nunn, J., Langford, N.K., Jin, X-M., Champoin, T., et al.Entangling microscopic diamonds at room temperature. ( quantum technology)Science, Vol. 334, no. 6060, Dec. 2, pp. 1253-1256.TechnologyQuantum state of diamonds
DS1970-0951
1974
Langford, R.E.Langford, R.E.A Study of the Origin of Arkansaw Diamonds by Mass Spectrometry.Ph.d. Thesis, University of Georgia, Athens, United States, Gulf Coast, Arkansas, PennsylvaniaGenesis, Isotope Chemistry
DS1975-0789
1978
Langford, R.E.Langford, R.E.The Origin of Diamonds, Theoretical StudyJournal of KOREAN CHEMICAL SOCIETY, Vol. 22, No. 3, PP. 138-149.GlobalChemistry, Genesis, Theory, Natural Diamond, Spectrometry, Inclusions
DS1989-0849
1989
Langford, R.P.Langford, R.P., Chan, M.A.Fluvial-aeolian interactions: Part 1. modern systems Part II. ancientsystemsSedimentology, Vol. 36, No. 6, December pp. 1023-1052GlobalGeomorphology, Sedimentology -fluvial systems
DS1989-1416
1989
Langham, C.D.Sneath, P.H.A., Langham, C.D.OUTLIER: a BASIC program for detecting outlying members of multivariate clusters based on presence-absencedataComputers and Geosciences, Vol. 15, No. 6, pp. 939-964GlobalComputer, Program -OUTLIER.
DS201809-2035
2018
Langhof, J.Holtstam, D., Camara, F., Skogby, H., Karlsson, A., Langhof, J.Description and recognition of potassic richterite, an amphibole supergroup mineral from the Pajsberg ore field, Varmland, Sweden.Mineralogy and Petrology, doi.org/101007/ s00710-018-0623-6 10p.Europe, Swedenalkaline

Abstract: Potassic-richterite, ideally AKB(NaCa)CMg5TSi8O22W(OH)2, is recognized as a valid member of the amphibole supergroup (IMA-CNMNC 2017-102). Type material is from the Pajsberg Mn-Fe ore field, Filipstad, Värmland, Sweden, where the mineral occurs in a Mn-rich skarn, closely associated with mainly phlogopite, jacobsite and tephroite. The megascopic colour is straw yellow to grayish brown and the luster vitreous. The nearly anhedral crystals, up to 4 mm in length, are pale yellow (non-pleochroic) in thin section and optically biaxial (?), with ??=?1.615(5), ??=?1.625(5), ??=?1.635(5). The calculated density is 3.07 g•cm?1. VHN100 is in the range 610-946. Cleavage is perfect along {110}. EPMA analysis in combination with Mössbauer and infrared spectroscopy yields the empirical formula (K0.61Na0.30Pb0.02)?0.93(Na1.14Ca0.79Mn0.07)?2(Mg4.31Mn0.47Fe3+0.20)?5(Si7.95Al0.04Fe3+0.01)?8O22(OH1.82F0.18)?2 for a fragment used for collection of single-crystal X-ray diffraction data. The infra-red spectra show absorption bands at 3672 cm?1 and 3736 cm?1 for the ? direction. The crystal structure was refined in space group C2/m to R1?=?3.6% [I >?2?(I)], with resulting cell parameters a?=?9.9977(3) Å, b?=?18.0409(4) Å, c?=?5.2794(2) Å, ??=?104.465(4)°, V?=?922.05(5) Å3 and Z?=?2. The A and M(4) sites split into A(m) (K+), A(2/m) (Na+), A(2) (Pb2+), and M(4?) (Mn2+) subsites, respectively. The remaining Mn2+ is strongly ordered at the octahedrally coordinated M(2) site, possibly together with most of Fe3+. The skarn bearing potassic-richterite formed at peak metamorphism, under conditions of low SiO2 and Al2O3 activities and relatively high oxygen fugacities.
DS1920-0289
1926
Langley, C.E.H.Langley, C.E.H.The Union Diamond Industry in 1925Mining Engineering Journal of South Africa, Vol. 37, PT. 2, No. 1835, NOVEMBER 27TH. P. 333.South AfricaCurrent Activities
DS201709-2072
2017
Langman, J.Wilson, D., Amos, R., Blowes, D., Langman, J., Smith, L., Sego, D.Diavik waste rock project: scale up of a reactive transport conceptual model for temperature and sulfide dependent geochemical evolution.Goldschmidt Conference, abstract 1p.Canada, Northwest Territoriesdeposit, Diavik
DS201801-0081
2018
Langman, J.B.Wilson, D., Amos, R.T., Blowes, D.W., Langman, J.B., Ptacek, C.J., Smith, L., Sego, D.C.Diavik waste rock project: a conceptual model for temperature and sulfide content dependent geochemical evolution of waste rock - Laboratory scale.Applied Geochemistry, Vol. 89, pp. 160-172.Canada, Northwest Territoriesdeposit - Diavik

Abstract: The Diavik Waste Rock Project consists of laboratory and field experiments developed for the investigation and scale-up of the geochemical evolution of sulfidic mine wastes. As part of this project, humidity cell experiments were conducted to assess the long-term geochemical evolution of a low-sulfide waste rock. Reactive transport modelling was used to assess the significant geochemical processes controlling oxidation of sulfide minerals and their dependence on temperature and sulfide mineral content. The geochemical evolution of effluent from waste rock with a sulfide content of 0.16 wt.% and 0.02 wt.% in humidity cells was simulated with the reactive transport model MIN3P, based on a conceptual model that included constant water flow, sulfide mineral content, sulfide oxidation controlled by the availability of oxidants, and subsequent neutralization reactions with carbonate and aluminosilicate minerals. Concentrations of Ni, Co, Cu, Zn, and SO4 in the humidity cell effluent were simulated using the shrinking core model, which represented the control of oxidant diffusion to the unreacted particle surface in the sulfide oxidation process. The influence of temperature was accounted for using the Arrhenius relation and appropriate activation energy values. Comparison of the experiment results, consisting of waste rock differentiated by sulfide mineral content and temperature, indicated surface area and temperature play important roles in rates of sulfide oxidation and release of sulfate and metals. After the model was calibrated to fit the effluent data from the higher sulfide content cells, subsequent simulations were conducted by adjusting only measured parameters, including sulfide mineral content and surface area.
DS201809-2115
2018
Langman, J.B.Wilson, D., Amos, R.T., Blowes, D.W., Langman, J.B., Smith, L., Sego, D.C.Diavik waste rock project: Scale up of a reactive transport model for temperature and sulfide content dependent geochemical evolution of waste rock.Applied Geochemisty, Vol. 96, pp. 177-190.Canada, Northwest Territoriesdeposit - Diavik

Abstract: The Diavik Waste Rock Project, located in a region of continuous permafrost in northern Canada, includes complementary field and laboratory experiments with the purpose of investigating scale-up techniques for the assessment of the geochemical evolution of mine waste rock at a large scale. As part of the Diavik project, medium-scale field experiments (?1.5?m high active zone lysimeters) were conducted to assess the long term geochemical evolution and drainage of a low-sulfide waste rock under a relatively simple (i.e. constrained by the container) flow regime while exposed to atmospheric conditions. A conceptual model, including the most significant processes controlling the sulfide-mineral oxidation and weathering of the associated host minerals as observed in a laboratory humidity cell experiment, was developed as part of a previous modelling study. The current study investigated the efficacy of scaling the calibrated humidity cell model to simulate the geochemical evolution of the active zone lysimeter experiments. The humidity cell model was used to simulate the geochemical evolution of low-sulfide waste rock with S content of 0.053?wt.% and 0.035?wt.% (primarily pyrrhotite) in the active zone lysimeter experiments using the reactive transport code MIN3P. Water flow through the lysimeters was simulated using temporally variable infiltration estimated from precipitation measurements made within 200?m of the lysimeters. Flow parameters and physical properties determined during previous studies at Diavik were incorporated into the simulations to reproduce the flow regime. The geochemical evolution of the waste-rock system was simulated by adjustment of the sulfide-mineral content to reflect the values measured at the lysimeters. The temperature dependence of the geochemical system was considered using temperature measurements taken daily, adjacent to the lysimeters, to correct weathering rates according to the Arrhenius equation. The lysimeter simulations indicated that a model developed from simulations of laboratory humidity cell experiments, incorporating detailed representations of temporally variable temperature and water infiltration, can be scaled to provide a reasonable assessment of geochemical evolution of the medium-scale field experiments.
DS200612-0762
2006
Langmuir, C.Langmuir, C., Goldstein, S.Recycled eclogite as the fertile component of the depleted MORB source.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 3. abstract only.MantleEclogite
DS1988-0546
1988
Langmuir, C.H.Plank, T., Langmuir, C.H.An evaluation of the global variations in the major element chemistry of arc basaltsEarth and Planetary Science Letters, Vol. 90, No. 4, November 25, pp. 349-370GlobalBasalts- arc, Geochemistry
DS1989-0850
1989
Langmuir, C.H.Langmuir, C.H.Geochemical consequences of in situ crystallizationNature, Vol. 340, No. 6230, July 20, pp. 199-204GlobalGeochemistry, Crystallization
DS1990-0902
1990
Langmuir, C.H.Langmuir, C.H.Ocean ridges spring surprisesNature, Vol. 344, No. 6267, April 12, p. 585GlobalMantle, Plate tectonics -ocean ridges
DS1993-0880
1993
Langmuir, C.H.Langmuir, C.H.Deep thoughts on the mantleNature, Vol. 364, July 15, pp. 191-192MantlePetrology
DS1993-1244
1993
Langmuir, C.H.Plank, T., Langmuir, C.H.Tracing trace elements from sediment input to volcanic output at subductionzonesNature, Vol. 362, No. 6422, April 22, pp. 739-742GlobalSubduction, Tectonics
DS1994-0305
1994
Langmuir, C.H.Christie, D.M., Langmuir, C.H.Automated XY plots from microsoft EXCELComputers and Geosciences, Vol. 20, No. 1, pp. 47-52GlobalComputer Program, Program -Excel
DS1994-0984
1994
Langmuir, C.H.Langmuir, C.H.Petrogenesis: water and the solid earthNature, Vol. 369, No. 6483, June 30, p. 704MantlePetrology
DS1994-1195
1994
Langmuir, C.H.Miller, D.M., Goldstein, S.L., Langmuir, C.H.Cerium/lead and lead isotope ratios in arc magmas and the enrichment of lead in the continentsNature, Vol. 368, No. 6471, April 7, p. 514MantleGeochronology, Arc magmas
DS1995-0959
1995
Langmuir, C.H.Kinzler, R.J., Langmuir, C.H.Minute mantle meltsNature, Vol. 375, No. 6529, May 25, p. 274MantleMelts, Geochemistry
DS1995-0960
1995
Langmuir, C.H.Kinzler, R.J., Langmuir, C.H.Geochemistry -minute mantle meltsNature, Vol. 375, No. 6529, May 25, p. 274.MantleMelt, Geochemistry
DS1995-0961
1995
Langmuir, C.H.Kinzler, R.J., Langmuir, C.H.Minute mantle meltsNature, Vol. 375, May 25, pp. 274-275.MantleMelting, Olivine
DS1996-1236
1996
Langmuir, C.H.Ryan, J.G., Leeman, W.P., Morris, J.D., Langmuir, C.H.The boron systematics of intraplate lavas: implications for crust and mantle evolution.Geochimica et Cosmochimica Acta, Vol. 60, No. 3, Feb. pp. 415-422.MantleBoron
DS1997-0850
1997
Langmuir, C.H.Niu, Y., Langmuir, C.H., Kinzler, R.J.The origin of abyssal peridotites: a new perspectiveEarth and Plan. Sci. Letters, Vol. 152, No. 1-4, pp. 251-265.Mantle, ridgesMelting, Peridotites
DS1998-1169
1998
Langmuir, C.H.Plank, T., Langmuir, C.H.The chemical composition of subducting sediment and its consequences For the crust and mantle.Chemical Geology, Vol. 145, No. 3-4, Apr. 15, pp. 325-394.MantleMineral chemistry
DS2003-0046
2003
Langmuir, C.H.Asimov, P.D., Langmuir, C.H.The importance of water to oceanic mantle melting regimesNature, No. 6925, Feb. 20, pp. 815-20.MantleMelt - subduction
DS200412-0469
2004
Langmuir, C.H.Donnelly,K.E., Goldstein, S.L., Langmuir, C.H., Spiegelman, M.Origin of enriched ocean ridge basalts and implications for mantle dynamics.Earth and Planetary Science Letters, Vol. 226, 3-4, Oct. 15, pp. 347-366.MantleE-MORB, geochemistry, isotope, trace, convective mixing
DS200512-0500
2003
Langmuir, C.H.Katz, R.F., Spiegelman, M., Langmuir, C.H.A new parameterization of hydrous mantle melting.Geochemistry, Geophysics, Geosystems: G3, Vol. 4, 9, p. 1073 10.1029/2002 GC000433MantleMelting, water
DS201412-0162
2014
Langmuir, C.H.Dalton, C.A., Langmuir, C.H., Gale, A.Report geophysical and geochemical evidence for deep temperature variations beneath mid-Ocean ridges.Science, Vol. 344, no. 6179, pp. 80-83.MantleGeophysics - seismics
DS202204-0539
2022
Langmuir, C.H.Turner, S.J., Langmuir, C.H.Sediment and ocean crust both melt at subduction zones.Earth and Planetary Science Letters, Vol. 584, 13p. 117424Mantlesubduction

Abstract: Hydrous arc magmas are produced when water-bearing materials from subducted oceanic plates are transported to the mantle beneath volcanic arcs, though the mechanism of mass transport remains debated. The geochemical characteristics of the slab component have important implications for the thermal structures of down-going plates and the fluxes of elements into the deep mantle. If slab temperatures are low, then elemental fluxes from the slab will be carried in a dilute fluid. If temperatures are high, the slab may melt instead. While a long-standing paradigm for arc volcanism has been that sediments melt and ocean crust dehydrates, a growing body of evidence from arc geochemistry and experimental petrology suggests both sediment and ocean crust melt. The low solubility of many elements in aqueous fluids prevents them from making a substantial contribution to arc mass-balance. Constraints from Sr concentrations and 87Sr/86Sr ratios require a large flux of Sr from the ocean crust, which is only possible if the crust melts. H2O/Sr ratios of arc volcanics are also inconsistent with slab fluids. These conclusions are supported by thermo-mechanical models indicating that slab temperatures exceed the hydrous solidus for both ocean crust and sediments. Examination of experimental data shows a likely strong effect of oxygen fugacity on residual phases during slab melting. Arc data are best explained if the ocean crust melts beneath all arcs under oxidizing conditions somewhere between FMQ and NNO+2. Experimental constraints on sediments also require melting and that sediment melt compositions depend on bulk composition as well as temperature. If these experiments serve as analogs to sediment melting beneath arcs, then sediment bulk compositions are a necessary input for any rare earth element-based slab thermometer. We present compositions for ocean crust partial melts and partition coefficients for sediment melting based on existing experiments, physical models, and arc data, that can be used in geochemical models of arc volcanism.
DS1989-0851
1989
Langran, G.Langran, G.A review of temporal database research and its use in GIS applicationsInternational Journal of Geographical Information Systems, Vol. 3, No. 3, July-September pp. 215-232GlobalGIS, Database research
DS1995-2035
1995
Langridge, R.J.Wasteneys, H.A., Clark, A.H., Farrar, E., Langridge, R.J.Grevillian granulite facies metamorphism in the Arequipa Massif Peru: a Laurentia Gondwana linkEarth and Plan. Sci. Letters, Vol. 132, pp. 63-73PeruCentral Andean orogenic basement, Arica Bight, Bolivian anticline
DS1990-0903
1990
Langseth, M.G.Langseth, M.G., Moore, J.C.Fluids in accretionary prisMEos, Vol. 71, No. 5, January 30, pp. 245-246GlobalTectonics, Subduction zones
DS2000-0722
2000
LangstonNyblade, A.A., Owens, T.J., Gurrola, Ritsema, LangstonSeismic evidence for a deep upper mantle thermal anomaly beneath east AfricGeology, Vol. 28, No. 7, July, pp. 599-602.Tanzania, Uganda, Kenya, East AfricaGeophysics - seismics, mantle, plume rift, Craton - Tanzanian
DS1990-0339
1990
Langston, C.A.Clouser, R.H., Langston, C.A.Upper mantle structure of southern Africa from PNI wavesJournal of Geophysical Research, Vol. 95, No. B 11, October 10, pp. 17403-17416South AfricaStructure, Mantle
DS1995-1368
1995
Langston, C.A.Nyblade, A.A., Langston, C.A.East African earthquakes below 20 km depth and their implications for crustal structure.Geophys. Journal, Vol. 121, pp. 49-62.East Africa, Kenya, Tanzania, Mozambique, Zaire, ZambiaTectonics
DS1996-1045
1996
Langston, C.A.Nyblade, A.A., Birt, C., Langston, C.A., Owens, T.J., LastSeismic experiment reveals rifting of Craton in TanzaniaEos, Vol. 77, No. 51, Dec. 17, p. 517, 521.TanzaniaGeophysics - seismics, Craton
DS1996-1046
1996
Langston, C.A.Nyblade, A.A., Vogfjord, K.S., Langston, C.A.P wave velocity of Proterozoic upper mantle beneath central and southernAsia.Journal of Geophysical Research, Vol. 101, No. 5, May 10, pp. 1159-72.AsiaMantle, Proterozoic
DS1999-0832
1999
Langston, C.A.Zhao, M., Langston, C.A., Owens, T.J.Upper mantle velocity structure beneath southern Africa from modeling regional seismic data.Journal of Geophysical Research, Vol. 104, No.3, Mar. 10, pp. 4783-94.South Africa, Botswana, TanzaniaGeophysics - seismics, Structure
DS2000-0721
2000
Langston, C.A.Nyblade, A.A., Langston, C.A., Owens, T.J.Seismic structure of the Tanzania Craton: implications for the stability of cratonic lithosphere.Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-164.Tanzania, East AfricaGeophysics - seismics, Craton - Tanzanian
DS1982-0357
1982
Langton, G.Langton, G.The South African Mining IndustryErzmetall., Vol. 35, No. 1, JANUARY PP. 20-26.South AfricaMining, Diamonds
DS1975-0790
1978
Langworthy, A.P.Langworthy, A.P., Black, L.P.The Mordor Complex: a Highly Differentiated Potassic Intrusion with Kimberlitic Affinities in Central Australia.Contributions to Mineralogy and Petrology, Vol. 67, PP. 51-62.AustraliaKimberlite, Carbonatite
DS1900-0578
1907
Lanier, R.S.Lanier, R.S.Has Arkansas a Diamond Field?Review of Reviews, Vol. 36, P. 301.United States, Gulf Coast, Arkansas, PennsylvaniaHistory, Geology, News Item
DS202012-2223
2020
Lanigan, P.M.P.Jones, D.C., Kumar, S., Lanigan, P.M.P., McGuiness, C.D., Dale, M.W., Twichen, D.J., Fisher, D., Martineau, P.M., Neil, M.A., Dunsby, C., French, P.M.W.Multidemensional luminescence microscope for imaging defect colour centres in diamond.Methods and Applications in Flouresence, Vol. 8, 1, 01404 htpp:dx.doi.org/10.1088/2050-6120/ab4eacGloballuminescence

Abstract: We report a multidimensional luminescence microscope providing hyperspectral imaging and time-resolved (luminescence lifetime) imaging for the study of luminescent diamond defects. The instrument includes crossed-polariser white light transmission microscopy to reveal any birefringence that would indicate strain in the diamond lattice. We demonstrate the application of this new instrument to detect defects in natural and synthetic diamonds including N3, nitrogen and silicon vacancies. Hyperspectral imaging provides contrast that is not apparent in conventional intensity images and the luminescence lifetime provides further contrast.
DS202012-2231
2020
Lanigan, P.M.P.McGuinness, C.D., Wassell, A.M., Lanigan, P.M.P., Lynch, S.A.Seperation of natural from laboratory-grown diamond using time -gated luminescence imaging.Gems & Gemology, Vol. 56, 2, summer pp. 220-229. pdfGloballuminescence
DS1989-0852
1989
Lankston, R.W.Lankston, R.W.The seismic refraction method: a viable tool for mapping shallow targets into the 1990'sGeophysics, Vol. 54, No. 12, December pp. 1535-1542GlobalGeophysics, Seismics
DS1970-0263
1971
Lanphere, M.A.Coleman, R.G., Lanphere, M.A.Distribution and Age of High-grade Blueschists, Associated Eclogites and Amphibolites from Oregon and California.Geological Society of America (GSA) Bulletin., Vol. 82, No. 9, PP. 2397-2412.GlobalEclogite
DS1975-0791
1978
Lanthier, L.R.Lanthier, L.R.Stratigraphy and Structure of the Lower Part of the Precambrian Libby Creek Group, Central Medicine Bow Mountains #1Msc. Thesis, University Wyoming, 30P.United States, Wyoming, Rocky Mountains, Medicine Bow MountainsRegional Studies
DS1975-1108
1979
Lanthier, R.Lanthier, R.Stratigraphy and Structure of the Lower Part of the Precambrian Libby Creek Group, Central Medicine Bow Mountains, Wyoming #2University WYOMING Contributions to Geology, Vol. 17, No. 2, PP. 135-147.GlobalKimberlite, Medicine Bow Mountains Rocky Mountains
DS1988-0400
1988
Lantuejoul ChLantuejoul ChOn the importance of choosing a change of support model for global reservesestimationMathematical Geology, Vol. 20, No. 8, November pp. 1001-1020. Database # 1757GlobalComputer, Program -Ore reserves
DS1995-1054
1995
Lanyon, R.Lanyon, R., Crawford, A.J., Eggins, S.M.Westward migration of Pacific Ocean upper mantle into Southern Ocean region between Australia and AntarcticaGeology, Vol. 23, No. 6, June pp. 511-514.Australia, AntarcticaTectonics, discordance, mantle, Geochronology
DS1995-1055
1995
Lanyon, R.Lanyon, R., Le Roex, A.P.Petrology of the alkaline and ultramafic lamprophyre associated with Okenyenya igneous complex, northeastSouth. African Journal of Geology, Vol. 98, No. 2, June pp. 140-156.NamibiaAlkaline rocks, Deposit -Okenyenya complex
DS1995-1056
1995
Lanyon, R.Lanyon, R., Le Roex, A.P.Petrogenesis of the lamprophyric intrusions associated with Damaral and igneous complexes, liquid immiscibilityEos, Vol. 76, No. 46, Nov. 7. p.F642-3. Abstract.NamibiaCarbonatite, lamprophyric diatremes, dikes, Damaraland
DS1998-0838
1998
Lanyon, R.Le Roex, A.P., Lanyon, R.Isotope and trace element geochemistry of Cretaceous Damaral and lamprophyres and carbonatites...Journal of Petrology, Vol. 39, No. 6, June 1, pp. 1117-46.NamibiaPlume - lithosphere interactions, Carbonatite, lamprophyres
DS1993-1139
1993
Lanz, T.Noakes, M., Lanz, T.Cost estimation handbook for the Australian mining industryAusIMM Sydney Branch, Mincost 90, Monograph No. 20 approx. $120.00AustraliaBook -table of contents, Cost estimation -Economics
DS201707-1307
2017
Lanzirotti, A.Bell, A.S., Shearer, C., Burger, P., Ren, M., Newville, M., Lanzirotti, A.Quantifying and correcting the effects of anisotropy in Xanes measurements of chromium valence in olivine: implications for a new olivine oxybarometer.American Mineralogist, Vol. 102, pp. 1165-1172.Technologyolivine

Abstract: Chromium valence ratios in igneous olivine may hold a wealth of redox information about the melts from which they crystallized. It has been experimentally shown that the Cr2+/?Cr of olivine varies systematically with fO2, therefore measurements of Cr valence in olivine could be employed as a quantitative oxybarometer. In situ synchrotron ?-XANES analyses of Cr valence ratios of individual olivine phenocrysts in thin section have the potential to unlock this stored magmatic redox information on a fine spatial scale. However, there are still obstacles to obtaining accurate XANES measurements of cation valence in crystalline materials, as the results from these measurements can be compromised by anisotropic absorption effects related to the crystallographic orientation of the sample. Improving the accuracy of XANES measurements of Cr valence ratios in olivine by calibrating an anisotropy correction is a vital step in developing Cr valence measurements in olivine as a rigorous oxybarometer. To accomplish this goal, we have used an integrated approach that combined experiments, electron backscatter diffraction analysis, and XANES measurements in olivine to systematically examine how orientation affects the resultant Cr K-edge XANES spectra and the Cr valence ratios that are calculated from them. The data set generated in this work was used to construct a model that mitigates the effects of anisotropy of the calculated Cr2+/?Cr values. The application of this correction procedure as a part of spectral processing improves the overall accuracy of the resultant Cr2+/?Cr values by nearly a factor of five. The increased accuracy of the XANES measured Cr valence ratios afforded by the anisotropy correction reduces the error on calculated fO2 values from approximately ±1.2 to ±0.25
DS201805-0984
2018
Lanzirotti, A.Tschauner, O., Huang, S., Greenberg, E., Prakapenka, V.B., Ma, C., Rossman, G.R., Shen, A.H., Zhang, D., Newville, M., Lanzirotti, A., Tait, K.Ice-VII inclusions in diamonds: evidence for aqueous fluid in the Earth's deep mantle. Orapa, ShandongScience, Vol. 359, pp. 1136-1139.Africa, South Africa, Botswana, Congo, Sierra Leone, Chinadiamond inclusions
DS201809-2021
2018
Lao-Davila, D.A.Fletcher, A.W., Abdelsalam, M.G., Emishaw, L., Atekwana, E.A., Lao-Davila, D.A., Ismail, A.Lithospheric controls on the rifting of the Tanzanian Craton at the Eyasi Basin, eastern branch of the East African Rift system.Tectonics, Aug 14, doi: 10.1029/2018 TC005065Africa, Tanzaniacraton

Abstract: Continental rifts most often nucleate within orogenic belts. However, some studies in the East African Rift System (EARS) have shown that continental rifts can also develop withincratons. This work investigated the ~1.5 Ma Eyasibasin,which propagates in a WSW direction into the Tanzanian craton. The basin is located where the Eastern Branch of the EARS transitions from a narrow rift (~70 km wide) thewider(~300 km wide) North Tanzanian Divergence. Unlike the rest of the Eastern Branch segments, the Eyasibasindoes not follow the Mozambique orogenic belt located on the eastern margin of the Tanzanian craton. This work generatedlithospheric?scale sections across the basinusing: (1) Digital Elevation Model to map surface rift?related brittle structures; (2) Aeromagnetic data to determine the depth to the Precambrian basement;and (3) World Gravity Model 2012 to estimatecrustal and lithospheric thickness by applying the two?dimensional(2D) radially?averaged power spectral analysis and 2D forward gravity modeling. These cross?sectionsshow that the Eyasibasinnucleates within a previously unidentified suture zone within the Tanzanian cratonand that this suture zone is characterized by thinner lithospherethat can be as thin as ~95 km. This zone ofthinner lithosphere is offset southeastwardfrom the surface expression of the Eyasibasinand might have facilitated the formation of other basins further south. Furthermore, the lithospheric thickness map indicates that the Tanzanian craton is heterogeneous and possibly composed of multiplesmaller cratonic fragments.
DS201412-0088
2014
Laouar, R.Caby, R., Bruguier, O., Fernandez, L., Hammor, D., Bosch, D., Mechati, M., Laouar, R., Ouabadi, A., Abdallah, N., Douchet, C.Metamorphic diamonds in a garnet megacryst from the Edough Massif (northeastern Algeria)… Recognition and geodynamic consequences.Tectonophysics, Vol. 637, pp. 341-353.Africa, AlgeriaEdough Massif
DS201709-1965
2017
Laouar, R.Bruguier, O., Bosch, D., Caby, R., Vitale-Brovarone, A., Fernadez, L., Hammor, D., Laouar, R., Ouabadi, A., Abdallah, N., Mechanti, M.Age of UHP metamorphism in the Western Mediterranean: insight from rutile and minute zircon inclusions in a diamond bearing garnet megacryst ( Edough Massif, NE Algeria).Earth and Planetary Science Letters, Vol. 474, pp. 215-225.Africa, Algeriadiamond inclusions

Abstract: Diamond-bearing UHP metamorphic rocks witness for subduction of lithospheric slabs into the mantle and their return to shallow levels. In this study we present U-Pb and trace elements analyses of zircon and rutile inclusions from a diamond-bearing garnet megacryst collected in a mélange unit exposed on the northern margin of Africa (Edough Massif, NE Algeria). Large rutile crystals (up to 300 ?m in size) analyzed in situ provide a U-Pb age of 32.4 ± 3.3 Ma interpreted as dating the prograde to peak subduction stage of the mafic protolith. Trace element analyses of minute zircons (?30 ?m) indicate that they formed in equilibrium with the garnet megacryst at a temperature of 740-810 °C, most likely during HP retrograde metamorphism. U-Pb analyses provide a significantly younger age of 20.7 ± 2.3 Ma attributed to exhumation of the UHP units. This study allows bracketing the age of UHP metamorphism in the Western Mediterranean Orogen to the Oligocene/early Miocene, thus unambiguously relating UHP metamorphism to the Alpine history. Exhumation of these UHP units is coeval with the counterclockwise rotation of the Corsica-Sardinia block and most likely resulted from subduction rollback that was driven by slab pull.
DS200612-0763
2005
Lapen, T.J.Lapen, T.J., Medaris, L.G., Johnson, C.M., Beard, B.L.Archean to middle Proterozoic evolution of Baltica subcontinental lithosphere:Contributions to Mineralogy and Petrology, Vol. 150, 2, pp. 131-145.Europe, Baltic ShieldTectonics
DS201212-0550
2012
Lapen, T.J.Peslier, A.H., Woodland, A.B., Bell, D.R., Lazarov, M., Lapen, T.J.Metasomatic control of water contents in the Kaapvaal cratonic mantle.Geochimica et Cosmochimica Acta, Vol. 97, pp. 213-246.Africa, South Africa, LesothoDeposit - Finsch, Kimberley, Jagersfontein, Letseng, Liqhobong
DS201312-0592
2013
Lapen, T.J.McCelland, W.C., Lapen, T.J.Linking time to the pressure temperature path of ultrahigh pressure rocks.Elements, Vol. 9, 4, August in pressMantleUHP
DS201412-0015
2014
Lapen, T.J.Armytage, R.M.G., Brandon, A.D., Peslier, A.H., Lapen, T.J.Osmium isotope evidence for Early to Middle Proterozoic mantle lithosphere stabilization and concommitant production of juvenile crust in Dish Hill, CA peridotite xenoliths.Geochimica et Cosmochimica Acta, Vol. 137, pp. 113-133.United States, CaliforniaSCLM, subduction
DS201702-0238
2017
Lapen, T.J.Righter, K., Nickodem, K., Pando, K., Danielson, L., Boujibar, A., Righter, M., Lapen, T.J.Distribution of Sb, As, Ge and in between metal and silicate during acccretion and core formation in the Earth.Geochimica et Cosmochimica Acta, Vol. 198, pp. 1-16.MantleCore chemistry

Abstract: A large number of siderophile (iron-loving) elements are also volatile, thus offering constraints on the origin of volatile elements in differentiated bodies such as Earth, Moon, Mars and Vesta. Metal-silicate partitioning data for many of these elements is lacking, making their overall mantle concentrations in these bodies difficult to model and origin difficult to distinguish between core formation and volatile depletion. To address this gap in understanding, we have undertaken systematic studies of four volatile siderophile elements - Sb, As, Ge and In - at variable temperature and variable Si content of metal. Several series were carried out at 1 GPa, and between 1500 and 1900 °C, for both C saturated and C-free conditions. The results show that temperature causes a decrease in the metal/silicate partition coefficient for all four elements. In addition, activity coefficients for each element have been determined and show a very strong dependence on Si content of Fe alloy. Si dissolved in metal significantly decreases the metal/silicate partition coefficients, at both 1600 and 1800 °C. The combination of temperature and Si content of the metal causes reduction of the metal-silicate partition coefficient to values that are close to those required for an origin of mantle As, Sb, Ge, and In concentrations by metal-silicate equilibrium processes. Combining these new results with previous studies on As, Sb, Ge, and In, allowed derivation of predictive expressions for metal/silicate partition coefficients for these elements which can then be applied to Earth. The expressions are applied to two scenarios for continuous accretion of Earth; specifically for constant and increasing fO2 during accretion. The results indicate that mantle concentrations of As, Sb, Ge, and In can be explained by metal-silicate equilibrium during an accretion scenario. The modeling is not especially sensitive to either scenario, although all element concentrations are explained better by a model with variable fO2. The specific effect of Si is important and calculations that include only S and C (and no Si) cannot reproduce the mantle As, Sb, Ge, and In concentrations. The final core composition in the variable fO2 model is 10.2% Si, 2% S, and 1.1% C (or XSi = 0.18, XS = 0.03, and XC = 0.04. These results suggest that core formation (involving a Si, S, and C-bearing metallic liquid) and accretion were the most important processes establishing many of Earth’s mantle volatile elements (indigenous), while post-core formation addition or re-equilibration (exogenous) was of secondary or minor importance.
DS2001-1152
2001
Lapenna, V.Telesca, L., Cuomo, V., Lapenna, V., Macchiato, M.Statistical analysis of fractal properties of point processes modeling seismic sequencesPhysics of the Earth and Planetary Interiors, Vol. 125, No. 1-4, pp. 65-83.GlobalGeophysics - seismics, Experimental
DS1960-0365
1963
Lapham, D.M.Lapham, D.M., Mckague, H.L.Deformation of Serpentinites in the Piedmont of PennsylvaniaGeological Society of America (GSA) SPECIAL PAPER., No. 73, P. 45. (abstract.).Appalachia, PennsylvaniaGeology
DS1960-0469
1964
Lapham, D.M.Lapham, D.M., Bassett, W.A.Potassium-argon Dating of Rocks and Tectonic Events in Piedmont of Southeastern Pennsylvania.Geological Society of America (GSA) SPECIAL PAPER., No. 73, PP. 661-667.Appalachia, PennsylvaniaGeochronology
DS2001-0907
2001
LapidoPereira, F., Bilal, E., Moutte, Lapido, Gruffat, AlbertDissolution of apatite ore from Angico Dos Dias carbonatite Complex and recovery of rare earth elementsJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 28.(abs)BrazilCarbonatite, Angico Dos Dias
DS1983-0386
1983
Lapido loureiro, F.E.Lapido loureiro, F.E., Tavares, J.R.Duas Novas Ocorrencias de Carbonatitos: Mato Preto E Barra Do Rio Itapirapua.Revista Brasileira De Geociencias, Vol. 13, No. 1, PP. 7-11.BrazilCarbonatite, Related Rocks
DS1991-0479
1991
Lapido-LoureiroFilho, A.I., Dos Santos, A.B.R.M., Riffel, B.F., Lapido-LoureiroAspects of the geology, petrology and chemistry of Angolan carbonatitesJournal of Geochemical Exploration, Special Publications Geochemical Exploration, Vol. 40, No. 1-3, pp. 205-226AngolaCarbonatite, Petrology
DS1970-0744
1973
Lapido-Loureiro, F.E.Lapido-Loureiro, F.E.Carbonatitis de AngolaMems Trab. Institute Invest. Cient. Angola., No. 11, 42P.Angola, West AfricaCarbonatite
DS1993-0077
1993
Lapido-Loureiro, F.E.Barbosa, J., Lapido-Loureiro, F.E.Rare earths in Brasil: deposits, identified resources and politicsRare earth Minerals: chemistry, origin and ore deposits, International Geological Correlation Programme (IGCP) Project, pp. 7-9. abstractBrazilRare earths, Economics
DS2003-0958
2003
Lapidus, I.V.Mironov, Y.V., Ryakhovsky, V.M., Putovoy, A.A., Lapidus, I.V.Mantle plumes and isotopic heterogeneity of the mantle: evidence from the Atlantic andDoklady Earth Sciences, Vol. 391, 5, pp. 714-17.MantleGeochemistry, Alrosa
DS200412-1332
2003
Lapidus, I.V.Mironov, Y.V., Ryakhovsky, V.M., Putovoy, A.A., Lapidus, I.V.Mantle plumes and isotopic heterogeneity of the mantle: evidence from the Atlantic and adjacent continents.Doklady Earth Sciences, Vol. 391, 5, pp. 714-17.MantleGeochemistry
DS2002-1356
2002
LapierreRolland, Y., Picard, C., Pecher, Lapierre, Bosch, KellerThe Cretaceous Ladakh arc of NW Himalaya slab melting and melt mantle interaction during fast northward driftChemical Geology, Vol.182, 2-4, Feb.15, pp.139-78.India, northwest HimalayasMelting, slab subduction, Indian Plate
DS1987-0170
1987
Lapierre, H.Dupont, P.L., Lapierre, H., Gravelle, BertrandCaracterisation du magmatism Proterozoique superieur en Afrique de l'ouestet implications geodynamiques: rrifts intracratoniques au Panafricain?Canadian Journal of Earth Sciences, Vol. 24, pp. 96-109.GlobalAlkaline rocks, magmatism
DS1996-0214
1996
Lapierre, H.Campos, C., Charvet, J., Lapierre, H.Evidence of a Middle Late Devonian tectonic event in the Eastern Klamathterrane, northern CaliforniaGsn Proceedings Geol. Ore Dep. American Cordillera, Vol. 2, pp. 823-838CaliforniaTectonics
DS1998-0828
1998
Lapierre, H.Lapierre, H., Arculus, R., Ballevre, M., Bosch, D.Accreted eclogites with oceanic plateau basalt affinities in EcuadorMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 852-3.EcuadorRaspas Formation, MetmorphisM., Eclogites
DS1999-0018
1999
Lapierre, H.Arculus, R.J., Lapierre, H., Jaillard. E.Geochemical window into subduction and accretion processes: Raspas metamorphic complex, Ecuador.Geology, Vol. 27, No. 6, June, pp. 547-50.EcuadorLithosphere, subduction, Geochemistry - Raspas
DS2001-1150
2001
Lapierre, H/. StruikTardy, M., Lapierre, H/. Struik, Bosch, BrunetThe influence of mantle plume in the genesis of Cache Creek oceanic igneous rocks: geodynamic evolution...Canadian Journal of Earth Sciences, Vol. 38, No. 4, Apr. pp. 515-34.British Columbia, CordilleraMantle plume - not specific to diamonds
DS200712-0594
2007
Lapin, A.Lapin, A., Tolstov, A., Antonov, A.Sr and Nd isotopic compositions of kimberlites and associated rocks of the Siberian Craton.Doklady Earth Sciences, Vol. 413, 3, pp. 557-560.RussiaGeochronology
DS200712-0595
2007
Lapin, A.Lapin, A., Tolstov, A., Antonov, A.Sr and Nd isotopic compositions of kimberlites and associated rocks of the Siberian Craton.Doklady Earth Sciences, Vol. 413, 3, pp. 557-560.RussiaGeochronology
DS1985-0381
1985
Lapin, A.P.Lapin, A.P.Significance of Limited Miscibility in Silicate Carbonate Melts in the Petrology and Genesis of Carbonatites.International Geology Review, Vol. 26, No. 7, JULY PP. 779-794.RussiaPetrology
DS1980-0208
1980
Lapin, A.V.Lapin, A.V.Carbonatites of Explosive and Dike Facies; the Classification of Geologic Facies of Carbonatites.Geol. Rud. Mestorozhd., Vol. 22, No. 3, PP. 15-33.RussiaBlank
DS1980-0209
1980
Lapin, A.V.Lapin, A.V., Kharkiv, A.D.Geochemistry of Ultramafic Ilmenite Phlogopite Inclusions In Kimberlite and the Effect of Fluids on Differentiation of The Mantle.Doklady Academy of Science USSR, Earth Science Section., Vol. 255, PP. 234-236.RussiaGeochemistry, Petrography
DS1982-0358
1982
Lapin, A.V.Lapin, A.V.Carbonatite Differentiation ProcessesInternational Geology Review, Vol. 24, No. 9, PP. 1079-1089.RussiaClassification, Genesis
DS1984-0443
1984
Lapin, A.V.Lapin, A.V., Marshintsev, V.K.Carbonatites and Kimberlitic Carbonatites.(russian)Geol. Rudn. Mestorozh., (RUS), Vol. 26, No.3, pp. 28-42RussiaCarbonatite, Genesis
DS1986-0481
1986
Lapin, A.V.Lapin, A.V.The relationships between carbonatites and kimberlites and some problems of deep seated magma formationInternational Geology Review, Vol. 28, No. 8, August pp. 955-964RussiaCarbonatite, Kimberlites
DS1986-0482
1986
Lapin, A.V.Lapin, A.V.Relationship between kimberlites and carbonatites and some problems of deep magma genesis.(Russian)Izv. Akad. Nauk SSSR, Ser. Geol., (Russian), Vol. 1986, No. 12, pp. 36-46RussiaCarbonatite-kimberlite, Genesis
DS1986-0483
1986
Lapin, A.V.Lapin, A.V., Gushchin, V.N., Lugovaya, I.P.Isotopic interaction of carbonatites and metamorphosed carbonatite sedimentary rocks.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 7, pp. 979-986RussiaCarbonatite, Geochronology
DS1987-0394
1987
Lapin, A.V.Lapin, A.V.Typomorphism and genesis of strontio- and bariopyrochlores.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 296, No. 6, pp. 1453-1457RussiaBlank
DS1987-0395
1987
Lapin, A.V.Lapin, A.V., Gushin, V.N., Lougovaya, I.P.Isotopic interactions of carbonatites and carbonate metasedimentsGeochemistry International, Vol. 24, No. 2, pp. 73-80RussiaCarbonatite, Isotope
DS1987-0396
1987
Lapin, A.V.Lapin, A.V., Ploshko, V.V., Malyshev, A.A.Carbonatites of the Tatar deep seated fault zone on the Eniseiridge.(Russian)Geol. Rudn. Mestorozd., (Russian), Vol. 29, No. 1, pp. 30-45RussiaCarbonatite
DS1988-0376
1988
Lapin, A.V.Kravchenko, S.M., Bagdasarov, Yu.A., Lapin, A.V.Geological and mineral genetic new dat a on carbonatite formations.(Russian)Geologii i Geofiziki, (Russian), No. 11, PP. 22-31RussiaCarbonatite
DS1988-0401
1988
Lapin, A.V.Lapin, A.V., Malyshev, A.A., Ploshko, V.V., Cherepivskaya, G.Ye.Strontiopyrochlore from lateritic weathered mantle of carbonatiteDoklady Academy of Science USSR, Earth Science Section, Vol. 290, No. 1-6, March pp. 188-192RussiaSupergene alteration, analyses, Carbonatite
DS1988-0402
1988
Lapin, A.V.Lapin, A.V., Ploshko, V.V.Rock association and morphological types of carbonatite and their geotectonic environmentsInternational Geology Review, Vol. 30, No. 4, pp. 390-396RussiaCarbonatite
DS1990-0904
1990
Lapin, A.V.Lapin, A.V.On the composition and ore contents of the products of oxidation and reduction stages of carbonatite erosion.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 314, No. 4, pp. 922-925RussiaCarbonatite, Weathering
DS1992-0907
1992
Lapin, A.V.Lapin, A.V.Carbonatite weathering crusts: geochemical types and mineralizationGeochemistry International, Vol. 29, No. 7, pp. 72-83RussiaCarbonatite, Weathering
DS1992-0908
1992
Lapin, A.V.Lapin, A.V.On the composition and ore potential of the products of oxidizing and reducing stages in the weathering of carbonatitesDoklady Academy of Sciences USSR, Earth Science Section, Vol. 314, No. 1-6, July 1992, pp. 72-75RussiaCarbonatite, Weathering
DS1994-0985
1994
Lapin, A.V.Lapin, A.V.Churchite from lateritic weathered mantles on carbonatites and the behaviour of rare earths.Doklady Academy of Sciences USSR, Vol. 327, Oct. pp. 135-139.RussiaCarbonatite
DS1994-0986
1994
Lapin, A.V.Lapin, A.V.The rare earth elements in carbonatite weathering crusts: distribution, fractionation and mineral forms.Geochemistry International, Vol. 31, No. 10, pp. 34-49.RussiaCarbonatite, Weathering crust
DS1995-1057
1995
Lapin, A.V.Lapin, A.V.The geological setting and genesis of high grade complex rare metal ores Of the Tomtor deposit.Geology of Ore Deposits, Vol. 37, No. 1, Jan-Feb. pp. 17-31.Russia, SiberiaCarbonatite
DS1996-0806
1996
Lapin, A.V.Lapin, A.V.Classification and prediction of ore deposits of carbonatite weatheringcrusts.Geology of Ore Deposits, Vol. 38, No. 2, pp. 151-162.BrazilCarbonatite, NiobiuM., Deposit -Araxa
DS1996-0807
1996
Lapin, A.V.Lapin, A.V.Differential mobility of components in the Supergene zone as main factor information of carbonatite -Geochemistry International, Vol. 33, No. 6, pp. 1-18.RussiaCarbonatite, weathering, Deposit -Belozima, Tatarskoye, Chuktukon, Arasha, Tomto
DS200412-1085
2003
Lapin, A.V.Lapin, A.V., Kharkiv, A.D.Majhgawanites as a special petrochemical type of Diamondiferous igneous rocks.Geochemistry International, Vol. 41, 11, pp. 1081-89.IndiaGeochemistry
DS200612-0764
2005
Lapin, A.V.Lapin, A.V., Divaev, F.K., Kostiysyn, Yu.A.Petrochemical interpretation of carbonatite-like rocks from the Chagatai Complex of the Tien Shan with appllication to the problem of diamond potential.Petrology, Vol. 13, 5, pp. 499-510.Russia, AsiaCarbonatite-kimberlite rocks
DS200612-0765
2006
Lapin, A.V.Lapin, A.V., Verichev, E.M.Kimberlites and related rocks of the Arkhangel'sk Diamondiferous province and adjacent areas: a comparative petrogeochemical analysis.Geochemistry International, Vol. 44, 8, pp. 771-790.Russia, Archangel, Kola PeninsulaPetrology - review
DS200812-0632
2007
Lapin, A.V.Lapin, A.V., Tolstov, A.V., Vasilenko, V.B.Petrochemical characteristics of the kimberlites in the Middle Markha region with application to the problem of the geochemical heterogeneity of kimberlites.Geochemistry International, Vol. 45, 12, Dec. pp. 1197-1209.Russia, YakutiaGeochemistry - comparison Zolotitsa and Grib
DS200912-0425
2009
Lapin, A.V.Lapin, A.V., Belov, S.V.Models of diamond generation in different geodynamic environments.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractGlobalGeodynamics
DS200912-0426
2009
Lapin, A.V.Lapin, A.V., Tolstov, A.V.Geochemical types of kimberlites and their mantle sources.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractRussia, Kola Peninsula, ArchangelDeposits
DS201212-0396
2012
Lapin, A.V.Lapin, A.V., Gusev, G.S.Kimberlitic and non-kimberlitic diamond potential of igneous and metamorphic rocks.Geokart GEOS, Moscow, 448p. In RUSSIANMantleDiamond genesis
DS201807-1520
2018
Lapin, A.V.Nosova, A.A., Sazonova, L.V., Kargin, A.V., Smirnova, M.D., Lapin, A.V., Shcherbakov, V.D.Olivine in ultramafic lamprophyres: chemistry, crystallisation, and melt sources of Siberian pre and post trap aillikites. IlbokichContributions to Mineralogy and Petrology, 10.1007/ s00410-018- 1480-3, 27p.Russia, Siberiakimberlite

Abstract: We studied olivines from the Devonian pre-trap (the Ilbokich occurrence) and the Triassic post-trap (the Chadobets occurrence) carbonate-rich ultramafic lamprophyres (UMLs) in the southwestern portion of the Siberian craton. On the basis of detailed investigations of major, minor, and trace-element distributions, we have reconstructed the main processes that control the origins of these olivines. These include fractional crystallisation from melt, assimilation, and fractional crystallisation processes with orthopyroxene assimilation, melt-reaction diffusive re-equilibration, alkali enrichment, and CO2 degassing of the melt. Furthermore, we inferred the composition of the sources of the primary UML melt and their possible correlations with proto-kimberlitic melts, as well as the influence of the Triassic Siberian plume on the composition of the lithospheric mantle. The main differences between olivines from the Ilbokich and the Chadobets aillikites were that the olivines from the former had more magnesium-rich cores (Mg# = 89.2 ± 0.2), had Mg- and Cr-rich transition zones (Mg# = 89.7 ± 0.2 and 300-500 ppm Cr), had lower Ni (up to 3100 ppm) and Li (1.4-1.5 ppm), and had higher B (0.8-2.6 ppm) contents, all at higher Fo values (90-86), relative to the olivines from the latter (Mg# = 88-75; 200-300 ppm Cr; up to 3400 ppm Ni; 1.4-2.4 ppm Li; 0.4-2.2 ppm B). The Siberian aillikite sources contained a significant amount of metasomatic material. Phlogopite-rich MARID-type veins provided the likely metasomatic component in the pre-trap Devonian Ilbokich aillikite source, whereas the Triassic Chadobets aillikitic post-trap melts were derived from a source with a significant carbonate component. A comparison of UML olivines with olivines from the pre-trap and post-trap Siberian kimberlites shows a striking similarity. This suggests that the carbonate component in the aillikitic source could have been produced by evolved kimberlite melts. The differences in the lithospheric metasomatic component that contributed to pre-trap and post-trap aillikitic melts can be interpreted as reflections of the thermal impact of the Siberian Traps, which reduced phlogopite-bearing metasomes within the southwestern Siberian sub-continental lithospheric mantle.
DS202108-1295
2021
Lapin, A.V.Lapin, A.V., Kulikova, I.M., Nabelkin, O.A.Surface formations in the weathering crusts of carbonatites: implication for the genesis of unique rare metal ores in the Tomtor deposit, Russia.Lithology and Mineral Resources, Vol. 56, pp. 356-374.Russiadeposit - Tomtor

Abstract: A comparative analysis of the composition and structure of the surface facies of carbonatite weathering crusts (profiles) in the Chuktukon (Russia) and Seis Lagos (Brazil) deposits and ultra-rich rare metal ores in the Tomtor deposit (Russia) is presented. It is shown that the main geochemical trends in the formation of the Tomtor-type ultra-rich rare metal ores and the surface facies of weathering profiles are opposite. The obtained results do not confirm the genetic link between the unique Tomtor ores and the surface facies of the crust of carbonatites, but serve as evidence of their later formation due to the reductive epigenesis of carbonatite weathering products under the influence of solutions draining the overlying coaliferous rocks. Wide distribution of the phenomena of colloidal liquid layering into manganese and ferruginous fractions was established for the first time in surface facies of the weathering crust of carbonatites, and active lateral colloidal migration of Ti from the host rocks was revealed.
DS1989-0853
1989
Lapin, A.V. 1989.Lapin, A.V. 1989.Types of ore deposits in weathering crusts of carbonatites.(Russian)Geol. Rudn. Mestorozhd., (Russian), Vol. 31, No. 4, pp. 76-87RussiaCarbonatite, Weathering-laterites
DS1996-0547
1996
LapinaGorshkov, A.I., Seliverstov, V.A., Sivstov, A.V., LapinaThe first discovery of native aluminum in carbonadoGeology of ore deposits, Vol. 38, No. 4, pp. 341-343.RussiaCarbonado, Kedrovka River
DS1998-1547
1998
Lapina, M.I.Vinokurov, S.F., Gorshkov, A.I., Lapina, M.I.Diamonds from kimberlite Diatreme 50, Liaoning Province, China:microtextural, mineralogical, geneticGeochemistry International, Vol. 36, No. 8, Aug. 1, pp. 676-683.ChinaTextures, petrology, Deposit - Diatreme 50
DS200412-0740
2003
Lapina, V.A.Gubarevich, A.V., Akhremkova, G.S., Lapina, V.A.Properties of the surface of ultrafine diamonds.Russian Journal of Physical Chemistry, Vol. 77, 11, pp. 1832-36. Ingenta 1035296891TechnologyDiamond morphology
DS200512-0942
2005
Lapke, C.Schmitt, R.T., Lapke, C., Lingemann, C.M., Siebenschock, M., Stoffler, D.Distribution and origin of impact diamonds in the Ries Carter, Germany.Geological Society of America, Special Paper, No. 384, pp. 299-314.Europe, GermanyMeteorite
DS2003-1178
2003
LapointeRolandone, F., Mareschal, J.C., Jaupart, C., Gosselin, C., Bienfait, G., LapointeHeat flow in the western Superior province of the Canadian ShieldJournal of Geophysical Research, Vol. 30, 12, June 15, 10.1029/2003GLO17386Ontario, Manitoba, SaskatchewanGeothermometry
DS1991-0090
1991
Lapointe, B.Bedard, L.P., Lapointe, B.Global warming: natural or anthropogenicGeoscience Canada, Vol. 18, No. 3, p. 98 onlyGlobalGlobal warming, Overview -climates
DS1994-0987
1994
Lapointe, B.Lapointe, B.L'exploration au Saguenay-Lac Saint Jean: bilan et perspectives.(in French)Seventh Colloque Annuel en Ressources Minerales, Universite du Quebec a, p. 13. abstract in FrenchQuebecBlank
DS1984-0359
1984
Lapointe, P.Hogarth, D.D., Lapointe, P.Amphibole and Pyroxene Development in Fenite from Cantley, Quebec.Canadian Mineralogist., Vol. 22, PP. 281-295.Canada, QuebecRelated Rocks, Carbonatite
DS200412-1682
2003
Lapointe, R.Rolandone, F., Mareschal, J.C., Jaupart, C., Gariepy, C., Bienfait, G., Carbonne, C., Lapointe, R.Surface heat flow, crustal temperatures and mantle heat flow in the Proterozoic Trans Hudson Orogen, Canadian Shield.Journal of Geophysical Research, Vol. 107, 12, Dec. 6, pp. DO1 10.1029/2001 JB000698Canada, OntarioGeothermometry
DS200412-1683
2003
Lapointe, R.Rolandone, F., Mareschal, J.C., Jaupart, C., Gosselin, C., Bienfait, G., Lapointe, R.Heat flow in the western Superior province of the Canadian Shield.Journal of Geophysical Research, Vol. 30, 12, June 15, 10.1029/2003 GLO17386Canada, Ontario, Manitoba, SaskatchewanGeothermometry
DS200512-0686
2005
Lapointe, R.Mareschal, J.C., Jaupart, C., Rolandone, F., Gariepy, C., Fowler, C.M., Bienfait, G., Carbonne, C., Lapointe, R.Heat flow, thermal regime, and elastic thickness of the lithosphere in the Trans-Hudson Orogen.Canadian Journal of Earth Sciences, Vol. 42, 4, April pp. 517-532.Canada, Northwest TerritoriesGeothermometry
DS200412-1249
2004
Laporte, D.Maumus, J., Laporte, D., Schiano, P.Dihedral angle measurements and infiltration property of SIO2 rich melts in mantle peridotite assemblages.Contributions to Mineralogy and Petrology, Vol. 148, 1, pp. 1-12.MantleMineralogy - peridotites
DS201012-0611
2010
Laporte, D.Rapp, R.P., Norman, M.D., Laporte, D., Yaxley, G.M., Martin, H., Foley, S.F.Continent formation in the Archean and chemical evolution of the cratonic lithosphere: melt rock reaction experiments at 3-4 GPa and petrogenesisJournal of Petrology, Vol. 51, 6, pp. 1237-1266.MantleSanukitoids
DS201212-0394
2012
Laporte, D.Lambart, S., Laporte, D., Provost, A., Schinao, P.Fate of pyroxenite derived melts in the periodotitic mantle: thermodynamic and experimental constraints.Journal of Petrology, Vol 53, 3, pp. 451-476.MantlePeridotite
DS201212-0445
2012
Laporte, D.Martin, A.M., Laporte, D., Koga, K.T., Kawamoto, T., Hammouda, T.Experimental study of the stability of a dolomite + coesite assemblage in contact with peridotite: implications for sediment-mantle interaction and diamond formation during subduction.Journal of Petrology, Vol. 53, 2, pp. 391-417.TechnologyUHP, diamond genesis
DS201212-0446
2012
Laporte, D.Martin, A.M., Laporte, D., Koga, K.T., Kawamoto, T., Hammouda, T.Experimental stidy of the stability of a dolomite + coesite assembalge in contact with peridotite: implications for sediment-mantle interaction and diamond formation during subduction.Journal of Petrology, Vol. 53, 2, pp. 391-417.MantleSubduction
DS201312-0169
2013
Laporte, D.Condamine, P., Medard, E., Laporte, D., Nauret, F.Experimental melting of phlogopite peridotite at 1 Gpa - implications for potassic magmatism.Goldschmidt 2013, AbstractMantleSubduction
DS201412-0498
2014
Laporte, D.Laporte, D., Lambart, S., Schiano, P., Ottolini, L.Experimental derivation of nepheline syenite and phonolite liquids by partial melting of upper mantle peridotites.Earth and Planetary Science Letters, Vol. 404, pp. 319-331.MantleMelting
DS201606-1077
2016
Laporte, D.Baasner, A., Medard, E., Laporte, D., Hoffer, G.Partial melting of garnet lherzolite with water and carbon dioxide at 3 Gpa using a new melt extraction technique: implications for intraplate magmatism.Contributions to Mineralogy and Petrology, Vol. 171, 45p.MantleMagmatism

Abstract: The origin and source rocks of alkali-rich and SiO2-undersatured magmas in the Earth’s upper mantle are still under debate. The garnet signature in rare earth element patterns of such magmas suggests a garnet-bearing source rock, which could be garnet lherzolite or garnet pyroxenite. Partial melting experiments were performed at 2.8 GPa and 1345-1445 °C in a piston-cylinder using mixtures of natural lherzolite with either 0.4 wt% H2O and 0.4 wt% CO2 or 0.7 wt% H2O and 0.7 wt% CO2. Different designs of AuPd capsules were used for melt extraction. The most successful design included a pentagonally shaped disc placed in the top part of the capsule for sufficient melt extraction. The degrees of partial melting range from 0.2 to 0.04 and decrease with decreasing temperature and volatile content. All samples contain olivine and orthopyroxene. The amounts of garnet and clinopyroxene decrease with increasing degree of partial melting until both minerals disappear from the residue. Depending on the capsule design, the melts quenched to a mixture of quench crystals and residual glass or to glass, allowing measurement of the volatile concentrations by Raman spectroscopy. The compositions of the partial melts range from basalts through picrobasalts to foidites. Compared to literature data for melting of dry lherzolites, the presence of H2O and CO2 reduces the SiO2 concentration and increases the MgO concentration of partial melts, but it has no observable effect on the enrichment of Na2O in the partial melts. The partial melts have compositions similar to natural melilitites from intraplate settings, which shows that SiO2-undersaturated intraplate magmas can be generated by melting of garnet lherzolite in the Earth’s upper mantle in the presence of H2O and CO2.
DS201912-2798
2019
Laporte, D.Laumonier, M., Laporte, D., Faure, F., Provost, A., Schiano, P., Ito, K.An experimental study of dissolution and precipitation of forsterite in a thermal gradient: implications for cellular growth of olivine phenocrysts in basalt and melt inclusion formation.Contributions to Mineralogy and Petrology, Vol. 174, 21p. PdfMantlebasanite

Abstract: The morphology of crystals in magmas strongly depends on the temperature regime of the system, in particular the degree of undercooling and the cooling rate. To simulate low degrees of undercooling, we developed a new experimental setup based on thermal migration, in which large cylinders of forsterite (single crystals) immersed in haplobasaltic melt were subjected to a temperature gradient. As forsterite solubility is sensitive to temperature, the forsterite on the high-temperature side undergoes dissolution and the dissolved components are transported toward the low-temperature side where a layer of newly grown forsterite forms (up to 340 ?m thick after 101 h). A striking feature is that the precipitation process does not produce a planar front of forsterite advancing at the expense of liquid: the growth front shows a fingered outline in planar section, with solid lobes separated by glass tubes that are perpendicular to the growth front. We ascribe this texture to cellular growth, a type of growth that had not been experimentally produced so far in silicate systems. We find that the development of cellular growth requires low degrees of undercooling (a few °C) and large crystal-liquid interfaces (~?1 mm across or more), and that it occurs at a growth rate of the order of 10?9 m/s. We found natural occurrences of cellular growth on the rims of olivines from basanites, but otherwise cellular textures are poorly documented in natural volcanic rocks. Melt inclusions were produced in our experiments, showing that they can form in olivine at relatively slow rates of growth (10?9 m/s or lower).
DS1995-1058
1995
laporte, N.laporte, N., Lopez-Baeza, E., Moreno, J.F.Mapping the dense humid forest of Cameroon and Zaire using AVHRR satellitedataInternational Journal of Remote Sensing, Vol. 16, No. 6, April pp. 1127-1146Democratic Republic of CongoRemote sensing
DS200412-0884
2003
Lappegard, G.Iverson, N.R., Cohen, D., Hooyer, T.S., Fischer, U.H., Jackson, M., Moore, P.L., Lappegard, G., Kohler, J.Effects of basal debris on glacier flow.Science, No. 5629, July 4, pp. 81-83.TechnologyGeomorphology
DS1983-0387
1983
Lappin, A.V.Lappin, A.V., Vartiainen, H.Orbicular and Spherulitic Carbonatites from Sokli and Vuorijarvi.Lithos, Vol. 16, No. 1, PP. 53-60.GlobalMorphology, Fractionation, Silicates
DS1960-0260
1962
Lappin, M.A.Lappin, M.A.The Eclogites, Dunites and Anorthosites of the Selje and Almklovdalen Districts, Nordfiord, Southwestern Norway.Ph.d. Thesis, University Durham., Norway, ScandinaviaPetrography, Metamorphic Tectonites
DS1960-0856
1967
Lappin, M.A.Lappin, M.A.Structural and Petrofabric Studies of the Dunites of the Almklovdalen Nordfiord, Norway.Wiley Interscience., PP. 183-191.Norway, ScandinaviaPetrography
DS1970-0745
1973
Lappin, M.A.Lappin, M.A., Dawson, J.B.The Chemistry and Mineralogy of Two Eclogites from the Roberts Victor Pipe, Orange Free State.1st International Kimberlite Conference, EXTENDED ABSTRACT VOLUME, PP. 195-198.South AfricaMineral Chemistry
DS1975-0122
1975
Lappin, M.A.Lappin, M.A., Dawson, J.B.Two Roberts Victor Cumulate Eclogites and Their Re-equilibriation.Physics and Chemistry of the Earth., Vol. 9, PP. 351-366.South AfricaMineral Chemistry
DS1975-0792
1978
Lappin, M.A.Lappin, M.A.The Evolution of a Grospydite from the Roberts Victor MineContributions to Mineralogy and Petrology, Vol. 66, PP. 229-241.South AfricaPetrography
DS1975-0793
1978
Lappin, M.A.Lappin, M.A., Smith, D.C.Mantle Equilibrated Orthopyroxene Eclogite Pods Form the Basal Gneisses in the Selje District, Western Norway.Journal of Petrology, Vol. 19, No. 3, PP. 530-584.Norway, ScandinaviaPetrography, Petrogenesis
DS1989-1412
1989
Lappin, M.A.Smith, D.C., Lappin, M.A.Coesite in the Straumen kyanite -eclogite pod, NorwayTerra Nova, Vol. 1, No. 1, pp. 47-56NorwayCoesite background, Eclogite
DS2002-0428
2002
Laptev, A.I.Elyutin, A.V., Ermolaev, A.A., Laptev, A.I., Manukhin, A.V.Effect of boron on the thermal stability of polycrystalline carbonado diamondsDoklady Physics, (language not known), Vol. 47, 9, pp. 651-3.GlobalCarbonados
DS1988-0403
1988
Laptev, V.A.Laptev, V.A., Pomchalov, A.V., Samoilovich, M.I.Diamond crystallization characteristics in a system consisting of a meta land difficulty graphitizable carbonaceous substances. (Russian)Sverkhtverd. Mater., (Russian), No. 4, pp. 13-17RussiaDiamond morphology
DS1988-0608
1988
Laptev, V.A.Samoylovich, M.I., Laptev, V.A.The deformational interactions of impurities and structural defects within the crystallattice of diamond.(Russian)Izv. Akad. Nauk SSSR, (Russian), Vol. 24, No. 8, pp. 1379-1381RussiaDiamond morphology, Diamond crystallography
DS200812-0746
2008
Laptsevich, A.G.Mikhaliov, N.D., Vladykin, N.V., Laptsevich, A.G.Geochemical features of alkali rocks of Paleozoic magmatism of Belarus.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., 2008 pp. 169-180.Russia, BelarusAlkaline rocks, magmatism
DS201112-0674
2010
Laptsevich, A.G.Mikhailov, N.D., Laptsevich, A.G., Vladykin, N.V.Alkali lamprophyres of the Paleozoic igneous complex of Belarus.Vladykin, N.V., Deep Seated Magmatism: its sources and plumes, pp. 187-199.RussiaLamprophyre
DS1988-0710
1988
Lapushkov, V.M.Tugovik, G.I., Kirasirova, V.I., Lapushkov, V.M.Physical properties of diamonds from eclogites of a plutonicmetamorphicregion.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 299, No. 2, pp. 442-444RussiaBlank
DS1998-1215
1998
LaputinaRass, I.T., Gerasimov, Laputina, IllupinDiamond occurrence in kimberlites dependent on melting depths and rates of cooling of parental mantle magmas.7th. Kimberlite Conference abstract, pp. 723-4.South Africa, Siberia, RussiaMagmatism, Deposit - Wesselton, Mir
DS1984-0646
1984
LAPUTINA, I.p.Seliverstov, V.A., Koloskovm a, V., LAPUTINA, I.p., et al.Ist Dat a on the Composition of Minerals of Deep Seated Inclusion in the Meimechites of Kamchatke.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 278, No. 4, PP. 949-952.RussiaBlank
DS1986-0662
1986
Laputina, I.P.Rass, I.T., Kravchenko, S.M., Laputina, I.P.Pyroxene zoning and the genesis of alkalic ultramafic rocksDoklady Academy of Science USSR, Earth Science Section, Vol. 280, No. 1-6, October pp. 117-122RussiaAlkaline rocks
DS1986-0719
1986
Laputina, I.P.Seliverstov, V.A., Koloskov, A.V., Laputina, I.P.First dat a on the composition of minerals of deep seated inclusions in meymechite from Kamchatka #2Doklady Academy of Science USSR, Earth Science Section, Vol. 278, No. 1-6, April, pp. 123-126RussiaMineralogy, Meymechite
DS1986-0720
1986
Laputina, I.P.Seliverstov, V.A., Koloskov, A.V., Laputina, I.P., et al.First dat a on the composition of minerals of deep seated inclusions in meymechite from Kamchatka #1Doklady Academy of Science USSR, Earth Science Section, Vol. 278, No. 10-6, pp. 127-130RussiaInclusions
DS1987-0155
1987
Laputina, I.P.Distler, V.V., Ilupin, I.P., Laputina, I.P.Sulfides of deep seated origin in kimberlites and some Aspects of coppernickel mineralizationInternational Geology Review, Vol. 29, No. 4, April pp. 456-464RussiaBlank
DS1996-1165
1996
Laputina, I.P.Rass, I.T., Laputina, I.P.Composition and zoning of accessory minerals in alkali ultrabasites as indicators of the composition magmas..Geochemistry International, Vol. 33, No. 2, Feb. 1, pp. 62-77RussiaLayered intrusion differentiation, Alkalic rocks, Pervoskite, Carbonatite
DS1997-0636
1997
Laputina, I.P.Kravechenko, S.M., Laputina, I.P., Krasilnikova, I.G.Geochemistry and genesis of rich scandium (Sc) rare earth elements (REE) yttrium niobium ores at the Tomtor deposit, northern Siberian PlatformGeochemistry International, Vol. 34, No. 10, pp. 847-63.Russia, SiberiaCarbonatite, Deposit - Tomtor
DS2002-0917
2002
Lar, U.A.Lar, U.A., Loubet, M.Major, trace element and isotope geochemistry of mafic ultramafic massifs emplaced within gneissic basement..Global Journal of Pure and Applied Geophysics, Vol.8, No.1, pp.75-88.VenezuelaMantle crust interactions, Geochemistry
DS1996-0808
1996
Laramie BountifulLaramie BountifulCompany opens commercial diamond mine... Kelsey LakeLaramie Bountiful, June 14, p. 1, 16.ColoradoNews item, Redaurum Limited
DS2000-0406
2000
Larbi, Y.Henry, P., Stevenson, R.K., Larbi, Y., Gariepy, C.neodymium isotopic evidence for Early to Late Archean (3.4-2.7Ga) crustal growth in Western Superior ProvinceTectonophysics, Vol. 322, No. 1-2, pp.135-51.OntarioGeochronology, Tectonics
DS2001-0718
2001
Larbi, Y.Madore, L., Larbi, Y.Regional structural character of the northeastern Ungava Peninsula: connection between Rae and SuperiorGeological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.93.abstract.Quebec, Ungava, LabradorTectonics - structure
DS200512-0845
2005
Larchenko, V.A.Perov, V.A., Bogomolov, E.S., Larchenko, V.A., Levskii, L.K., Minchenko, G.V., Sablukov, S.M., SZergeev, S.A., Stepanov, V.P.Rb Sr age of kimberlites of the Pionerskaya pipe, Arkangelsk Diamondiferous province.Doklady Earth Sciences, Vol. 400, 1, pp. 67-71.Russia, Kola Peninsula, ArchangelGeochronology -
DS200512-0847
2005
Larchenko, V.A.Pervov, V.A., Bogomolov, E.S., Larchenko, V.A., Levskii, L.K., Minchenko, Sabukov, Sergeev, StepanovRb Sr age of kimberlites of the Pionerskaya pipe, Arkangelsk Diamondiferous province.Doklady Earth Sciences, Vol. 400, 1, pp. 67-71.Russia, Archangel, Kola PeninsulaGeochronology
DS200612-1083
2006
Larchenko, V.A.Pervov, V.A., Larchenko, V.A., Minchenko, G.V., Stepanov, V.P., Bogomolov, E.S., Levskii, SergeevTiming and duration of kimberlitic magmatism in the Zimnii Bereg Diamondiferous province: evidence from Rb Sr age dat a on kimberlitic sills along the Mela River.Doklady Earth Sciences, Vol. 407, 2, Feb-Mar. pp. 304-307.RussiaGeochronology - Zimnii Bereg
DS200812-0123
2008
Larchenko, V.A.A.A.Bogatikov, O.A.A.A., Larchenko, V.A.A.A., Kononova, V.A.A.A., Nosova, A.A.A.A., Minchenko, G.A.V.A.New kimberlite bodies in the Zimnii Bereg field, Archangelsk district: petrography and prognostic estimates.Doklady Earth Sciences, Vol. 418, 1, pp. 68-72.Russia, Archangel, Kola PeninsulaDeposit - Zimnii Bereg
DS200912-0660
2009
Larchenko, V.A.A.A.Samsonov, A.A.V.A., Nosova, A.A.A.A., Tretyachenko, V.A.V.A., Larchenko, V.A.A.A., Larionova, Y.A.O.A.Collisional sutures in the early Precambrian crust as a factor for localization of Diamondiferous kimberlites in the northern east European platform.Doklady Earth Sciences, Vol. 425, 2, pp. 226-230.RussiaTectonics
DS201212-0595
2012
LardeauxRolland, Y., Lardeaux, J-M, Jolivet, L.Deciphering orogenic evolution.Journal of Geodynamics, Vol. 56-57, pp. 1-6.MantleTectonics
DS1997-0293
1997
Lardeaux, J.M.Duchene, S., Lardeaux, J.M., Albarade, F.Exhumation of eclogites: insights from depth time path analysisTectonophysics, Vol. 280, No. 1-2, Oct. 26, pp. 125-140.MantleEclogites, Subduction
DS1997-0909
1997
Lardeaux, J.M.Pili, E., Ricard, Y., Lardeaux, J.M.Lithospheric shear zones and mantle crust connectionsTectonophysics, Vol. 280, No. 1-2, Oct. 26, pp. 15-30.MantleLithosphere, Tectonics
DS2000-0621
2000
Lardeaux, J.M.Martelat, J.E., Lardeaux, J.M., Rakotondrazafy, R.Strain pattern and late Precambrian deformation history in southern MadagascarPrecambrian Research, Vol. 102, No. 1-2, July 1, pp. 1-20.MadagascarTectonics
DS2003-1067
2003
Lardeaux, J.M.Perrilat, J.P., Daniel, I., Lardeaux, J.M., Cardon, H.Kinetics of the coesite quartz transition: application to the exhumation of ultrahighJournal of Petrology, Vol. 44, 4, pp. 773-88.GlobalUHP
DS200412-1529
2003
Lardeaux, J.M.Perrilat, J.P., Daniel, I., Lardeaux, J.M., Cardon, H.Kinetics of the coesite quartz transition: application to the exhumation of ultrahigh pressure rocks.Journal of Petrology, Vol. 44, 4, pp. 773-88.TechnologyUHP
DS1991-1805
1991
Lardeaux, J-M.Villeurbanne, J.V., Von Roermund, H., Lardeaux, J-M.The clinopyroxene/plagioclase symplectite in retrograde eclogites: a potential geothermobarometerGeologische Rundschau, Vol. 80, No. 2, pp. 303-320GlobalEclogites, Petrology
DS201212-0596
2012
Lardeaux, J-M.Rolland, Y., Lardeaux, J-M., Jolivet, L.Deciphering orogenic evolution.Journal of Geodynamics, Vol. 56-57, pp. 1-6.MantleSubduction
DS202007-1162
2020
Lardeaux, J-M.Martelat, J-E., Cardon, H., Lardeaux, J-M., Nicollet, C., Schulmann, K., Pili, E.Geophysical evidence for large scale mullion type structures at the mantle crust interface in southern Madagascar: implications for Neoproterozoic orogeny.International Journal of Earth Science, Vol. 109, 4, pp. 1487-1500.Africa, Madagascartectonics

Abstract: This study uses gravimetric data integrated with recent seismic data published on south Madagascar to investigate geometry of crust-mantle interface. The regional tectonic framework of Madagascar is characterised by anastomosing network of up to 15-km-wide, 600-km-long and north-oriented high-strain zones, which originated during Neoproterozoic convergence. The studied Bouguer anomalies obtained from the International Gravimetric Bureau were high-pass filtered to emphasise short-wavelength gravimetric variations (shorter than 200 km). The Pan-African high-strain zones coincide with the positive gravimetric anomalies suggesting a link with deep seated high-density material. Considering the present-day thickness of the crust (35 km) and its seismic velocity record, the gravimetric anomalies can be visualised as narrow vertical tabular bodies located at the base of the Moho. Modelling further confirmed that such narrow vertical bodies could be stable over geologic time scale since these structures are relatively small (10 to 30 km wide). The vertical tabular bodies possibly reflect material transfer such as vertical motion of sub-crustal weak and possibly partially molten mantle along vertical deformation zones. It is proposed that these structures were initiated by folding of weak mantle-crust interface characterised by low-viscosity contrast between weak mantle and stronger granulitized lower crust during bulk pure shear-dominated horizontal shortening. It is proposed that the cuspate-lobate "mullion-type" geometry mimics rheological inversions of mafic and felsic rocks and shape of folds of variable scale observed in southern Madagascar. The formation of such mega-mullion structures is possibly an expression of "crème brulée" rheological model, where the deformation of the lithosphere is governed by stronger granulitic lower crust and weaker partially molten and/or hydrated mantle.
DS1995-1727
1995
Larehence, V.A.Shchukin, V.S., Sobolev, V., Larehence, V.A., Makhin, A.I.Geology of the diamond deposits in the Arkhangelsk region, RussiaSociety for Mining, Metallurgy and Exploration (SME) Meeting, Denver March 1995, abstractRussia, Commonwealth of Independent States (CIS), RussiaDiamond deposits
DS1998-1418
1998
Laresen, H.C.Storey, M., Duncan, R.A., Laresen, H.C.40 Ar-39 Ar geochronology of the West Greenland Tertiary volcanicprovince.Earth and Planetary Science Letters, Vol. 160, No. 3-4, Aug. 1, pp. 569-586.GreenlandGeochronology, Argon
DS2003-0724
2003
Laresen, H.C.Klausen, M.B., Laresen, H.C.East Greenland coast parallel dike swarm and its role in continental breakupGeological Society of America Special Paper, No. 362, chapter 9.GreenlandDike swarm, magmatism, Tectonics
DS200912-0732
2009
Laresen, L.M.Starkey, N.A., Stuart, F.M., Ellam, R.M., Fitton, J.G., Basu, S., Laresen, L.M.Helium isotopes in early Iceland plume picrites: constraints on the composition of high 3he/4He mantle.Earth and Planetary Science Letters, Vol. 277, 1-2, pp. 91-100.MantlePicrite
DS201802-0247
2017
Larianov, A.Koreshkova, M., Downes, H., Millar, I., Levsky, L., Larianov, A.Geochronology of metamorphic events in the lower crust of NW Russia: a xenolith Hf isotope study.Journal of Petrology, Vol. 58, 8, pp. 1567-1589.Russia, Kola Peninsulageochronology

Abstract: Hf isotope data for zircons and whole-rocks from lower crustal mafic granulite and pyroxenite xenoliths from NW Russia are presented together with the results of U-Pb zircon dating, Sm-Nd and Rb-Sr isotopic compositions of bulk-rocks and minerals, and trace element compositions of minerals. Most zircons preserve a record of only the youngest metamorphic events, but a few Grt-granulite xenoliths retain Archean magmatic zircons from their protolith. Metamorphic zircons have highly variable ?Hf(t) values from -25 to -4. The least radiogenic zircons were formed by recrystallization of primary magmatic Archean zircons. Zircons with the most radiogenic ?Hf grew before garnet or were contemporaneous with its formation. Zircons with ?Hf(t) from -15 to -9 formed by various mechanisms, including recrystallization of pre-existing metamorphic zircons, subsolidus growth in the presence of garnet and exsolution from rutile. They inherited their Hf isotopic composition from clinopyroxene, pargasite, rutile and earlier-formed zircon that had equilibrated with garnet. Subsolidus zircons were formed in response to a major change in mineral association (i.e. garnet- and zircon-producing reactions including partial melting). Recrystallized zircons date the onset of high-temperature conditions without a major change in mineral association. Age data for metamorphic zircons fall into five groups: >1•91 Ga, 1•81-1•86 Ga, 1•74-1•77 Ga, 1•64-1•67 Ga and <1•6 Ga. Most ages correlate with metamorphic events in the regional upper crust superimposed onto rocks of the Belomorian belt during formation of the Lapland Granulite Belt. Zircon formation and resetting at 1•64-1•67 Ga significantly postdates Lapland-Kola orogenic events and may relate to the onset of Mesoproterozoic rifting. The youngest ages (1•6-1•3 Ga) correspond to an event that affected only a few grains in some samples and can be explained by interaction with a localized fluid. The observed garnet-granulite associations were formed at 1•83 Ga in Arkhangelsk xenoliths and 1•74-1•76 Ga in most Kola xenoliths. By the end of the Lapland-Kola orogeny, the rocks were already assembled in the lower crust. However, no addition of juvenile material has been detected and preservation of pre-Lapland-Kola metamorphic zircon indicates that some xenoliths represent an older lower crust. Granulites, pyroxenites and Phl-rich rocks have a common metamorphic history since at least c. 1•75 Ga. At about 1•64 Ga metasomatic introduction of phlogopite took place; however, this was only one of several phlogopite-forming events in the lower crust.
DS1993-0881
1993
Larianov, N.P.Larianov, N.P.Equipment for gravity concentration of kimberlitesDiamonds of Yakutia, Russia, Extended Abstracts, Volume in English $ 115.00, pp. 171-172.Russia, YakutiaMineral processing, Mining -gravity concentration
DS200712-0596
2007
Larikova, T.Larikova, T.Geochemical characteristics of eclogites from the Eastern part of the Kokchetav Complex N. Kazakhstan.Plates, Plumes, and Paradigms, 1p. abstract p. A544.Russia, KazakhstanEclogite
DS200612-0189
2006
Larin, A.M.Buchko, I.V., Salnikova, E.B., Kotov, A.B., Larin, A.M., Velikoslavinskii, Sorokin, Sorokin, YakovlevaPaleoproterozoic gabbro anorthosites of the Selenga Superterrane, southern framing of the Siberian Craton.Doklady Earth Sciences, Vol. 407, 3, pp. 372-375.Russia, SiberiaTectonics
DS201712-2686
2017
Larin, A.M.Gladkochub, D.P., Donskaya, T.V., Sklyarov, E.V., Kotov, A.B., Vladykin, N.V., Pisarevsky, S.A., Larin, A.M., Salnikova, E.B., Saveleva, V.B., Sharygin, V.V., Starikova, A.E., Tolmacheva, E.V., Velikoslavinsky, S.D., Mazukabzov, A.M., Bazarova, E.P., KovaThe unique Katugin rare metal deposit ( southern Siberia): constraints on age and genesis.Ore Geology Reviews, in press available, 18p.Russia, Siberiadeposit - Katugin

Abstract: We report new geological, mineralogical, geochemical and geochronological data about the Katugin Ta-Nb-Y-Zr (REE) deposit, which is located in the Kalar Ridge of Eastern Siberia (the southern part of the Siberian Craton). All these data support a magmatic origin of the Katugin rare-metal deposit rather than the previously proposed metasomatic fault-related origin. Our research has proved the genetic relation between ores of the Katugin deposit and granites of the Katugin complex. We have studied granites of the eastern segment of the Eastern Katugin massif, including arfvedsonite, aegirine-arfvedsonite and aegirine granites. These granites belong to the peralkaline type. They are characterized by high alkali content (up to 11.8?wt% Na2O?+?K2O), extremely high iron content (FeO?/(FeO??+?MgO)?=?0.96-1.00), very high content of most incompatible elements - Rb, Y, Zr, Hf, Ta, Nb, Th, U, REEs (except for Eu) and F, and low concentrations of CaO, MgO, P2O5, Ba, and Sr. They demonstrate negative and CHUR-close ?Nd(t) values of 0.0…?1.9. We suggest that basaltic magmas of OIB type (possibly with some the crustal contamination) represent a dominant part of the granitic source. Moreover, the fluorine-enriched fluid phases could provide an additional source of the fluorine. We conclude that most of the mineralization of the Katugin ore deposit occurred during the magmatic stage of the alkaline granitic source melt. The results of detailed mineralogical studies suggest three major types of ores in the Katugin deposit: Zr mineralization, Ta-Nb-REE mineralization and aluminum fluoride mineralization. Most of the ore minerals crystallized from the silicate melt during the magmatic stage. The accessory cryolites in granites crystallized from the magmatic silicate melt enriched in fluorine. However, cryolites in large veins and lens-like bodies crystallized in the latest stage from the fluorine enriched melt. The zircons from the ores in the aegirine-arfvedsonite granite have been dated at 2055?±?7?Ma. This age is close to the previously published 2066?±?6?Ma zircon age of the aegirine-arfvedsonite granites, suggesting that the formation of the Katugin rare-metal deposit is genetically related to the formation of peralkaline granites. We conclude that Katugin rare-metal granites are anorogenic. They can be related to a Paleoproterozoic (?2.05?Ga) mantle plume. As there is no evidence of the 2.05?Ga mantle plume in other areas of southern Siberia, we suggest that the Katugin mineralization occurred on the distant allochtonous terrane, which has been accreted to Siberian Craton later.
DS200912-0259
2009
Larin, N.V.Gorbatikov, A.V., Larin, N.V., Moiseev, E.I., Belyashov, A.V.The microseismic sounding method: application for the study of the buried diatreme structure.Doklady Earth Sciences, Vol. 428, 1, pp. 1222-1226.TechnologyGeophysics - seismics
DS200712-0397
2007
Larinov, A.Gusvea, N., Sergeev, S., Lobach-Zhuchenko, S., Larinov, A., Berezhnaya, N.Archean age of miaskite lamproites from the Panzero complex, Karelia.Doklady Earth Sciences, Vol. 413, 3, pp. 420-423.RussiaLamproite
DS200712-0398
2007
Larinov, A.Gusvea, N., Sergeev, S., Lobach-Zhuchenko, S., Larinov, A., Berezhnaya, N.Archean age of miaskite lamproites from the Panzero complex, Karelia.Doklady Earth Sciences, Vol. 413, 3, pp. 420-423.RussiaLamproite
DS202107-1104
2021
Larinova, Y.O.Kargin, A.V., Nosova, A.A., Sazonova, L.V., Tretyachenko, V.V., Larinova, Y.O., Kovalchuk, E.V.Ultramafic alkaline rocks of Kepino cluster, Arkhangelsk, Russia: different evolution of kimberlite melts in sills and pipes.Minerals MDPI, Vol. 11, 540, 33p. PdfRussia, Arkhangelskdeposit - Kepino

Abstract: To provide new insights into the evolution of kimberlitic magmas, we have undertaken a detailed petrographic and mineralogical investigation of highly evolved carbonate-phlogopite-bearing kimberlites of the Kepino cluster, Arkhangelsk kimberlite province, Russia. The Kepino kimberlites are represented by volcanoclastic breccias and massive macrocrystic units within pipes as well as coherent porphyritic kimberlites within sills. The volcanoclastic units from pipes are similar in petrography and mineral composition to archetypal (Group 1) kimberlite, whereas the sills represent evolved kimberlites that exhibit a wide variation in amounts of carbonate and phlogopite. The late-stage evolution of kimberlitic melts involves increasing oxygen fugacity and fluid-phase evolution (forming carbonate segregations by exsolution, etc.). These processes are accompanied by the transformation of primary Al- and Ti-bearing phlogopite toward tetraferriphlogopite and the transition of spinel compositions from magmatic chromite to magnesian ulvöspinel and titanomagnetite. Similar primary kimberlitic melts emplaced as sills and pipes may be transitional to carbonatite melts in the shallow crust. The kimberlitic pipes are characterised by low carbonate amounts that may reflect the fluid degassing process during an explosive emplacement of the pipes. The Kepino kimberlite age, determined as 397.3 ± 1.2 Ma, indicates two episodes of ultramafic alkaline magmatism in the Arkhangelsk province, the first producing non-economic evolved kimberlites of the Kepino cluster and the second producing economic-grade diamondiferous kimberlites.
DS200812-1209
2008
LarionovVernikovsky, V.A.A., Vernikovskaya, A.A.E.A., Salanikova, E.A.B.A., Berezhnaya, Larionov, Kotov, KovachLate Riphean alkaline magmatism in the western margin of the Siberian craton: a result of continental rifting or accretionary events?Doklady Earth Sciences, Vol. 419, 2, pp. 226-230.RussiaMagmatism
DS201112-0831
2010
LarionovProskurnin, V.F., Petrov, Bagdasarov, Rozinov, Tolmacheva, Larionov, Bilskaya, Gavrish, Mozoleva, PetrushkovOrigin of carbonatites of eastern Taimyr deduced from an isotopic and geochemical study of zircons.Geology of Ore Deposits, Vol. 52, 8, pp. 711-724.RussiaPetrology - carbonatites
DS200712-0568
2007
Larionov, A.Kontinen, A., Kapyaho, A., Huhma, H., Karhu, J., Matukov, D.I., Larionov, A., Sergeev, S.A.Nurmes paragneisses in eastern Finland, Karelian Craton: provenance, tectonic setting and implications for Neoarchean craton correlation.Precambrian Research, Vol. 152, 3-4, pp. 119-148.Europe, FinlandKarelian Craton
DS201801-0030
2017
Larionov, A.Koreshkova, M., Downes, H., Millar, I., Levsky, L., Larionov, A., Sergeev, S.Geochronology of metamorphic events in the lower crust beneath NW Russia: a xenolith Hf isotope study.Journal of Petrology, Vol. 58, 8, pp. 1567-1589.Russia, Kola Peninsulageochronology

Abstract: Hf isotope data for zircons and whole-rocks from lower crustal mafic granulite and pyroxenite xenoliths from NW Russia are presented together with the results of U-Pb zircon dating, Sm-Nd and Rb-Sr isotopic compositions of bulk-rocks and minerals, and trace element compositions of minerals. Most zircons preserve a record of only the youngest metamorphic events, but a few Grt-granulite xenoliths retain Archean magmatic zircons from their protolith. Metamorphic zircons have highly variable ?Hf(t) values from -25 to -4. The least radiogenic zircons were formed by recrystallization of primary magmatic Archean zircons. Zircons with the most radiogenic ?Hf grew before garnet or were contemporaneous with its formation. Zircons with ?Hf(t) from -15 to -9 formed by various mechanisms, including recrystallization of pre-existing metamorphic zircons, subsolidus growth in the presence of garnet and exsolution from rutile. They inherited their Hf isotopic composition from clinopyroxene, pargasite, rutile and earlier-formed zircon that had equilibrated with garnet. Subsolidus zircons were formed in response to a major change in mineral association (i.e. garnet- and zircon-producing reactions including partial melting). Recrystallized zircons date the onset of high-temperature conditions without a major change in mineral association. Age data for metamorphic zircons fall into five groups: >1•91 Ga, 1•81-1•86 Ga, 1•74-1•77 Ga, 1•64-1•67 Ga and <1•6 Ga. Most ages correlate with metamorphic events in the regional upper crust superimposed onto rocks of the Belomorian belt during formation of the Lapland Granulite Belt. Zircon formation and resetting at 1•64-1•67 Ga significantly postdates Lapland-Kola orogenic events and may relate to the onset of Mesoproterozoic rifting. The youngest ages (1•6-1•3 Ga) correspond to an event that affected only a few grains in some samples and can be explained by interaction with a localized fluid. The observed garnet-granulite associations were formed at 1•83 Ga in Arkhangelsk xenoliths and 1•74-1•76 Ga in most Kola xenoliths. By the end of the Lapland-Kola orogeny, the rocks were already assembled in the lower crust. However, no addition of juvenile material has been detected and preservation of pre-Lapland-Kola metamorphic zircon indicates that some xenoliths represent an older lower crust. Granulites, pyroxenites and Phl-rich rocks have a common metamorphic history since at least c. 1•75 Ga. At about 1•64 Ga metasomatic introduction of phlogopite took place; however, this was only one of several phlogopite-forming events in the lower crust.
DS200712-1119
2007
Larionov, A.N.Vetrin, V.R., Lepekhina, E.N., Larionov, A.N., Presnyakov, S.L., Serov, P.A.Initial subalkaline magmatism of the Neoarchean alkaline province of the Kola Peninsula.Doklady Earth Sciences, Vol. 415, No. 5, June-July pp. 714-717.Russia, Kola PeninsulaAlkalic
DS200912-0410
2009
Larionov, A.N.Koreshkova, M.Y., Downes, H., Nikitina, L.P., Vladykin, N.V., Larionov, A.N., Sergeev, S.A.Trace element and age characteristics of zircons in granulite xenoliths from the Udachnaya pipe, Siberia.Precambrian Research, Vol. 168, 3-4, pp. 197-212.Russia, YakutiaGeochronology
DS201212-0620
2012
Larionov, A.N.Samsonov, A.V., Tretyachenko, W., Nosova, A.A., Larionova, Yu.O., Lepekhina, E.N., Larionov, A.N., Ipatieva, I.S.Sutures in the early Precambrian crust as a factor responsible for localization of Diamondiferous kimberlites in the northern east European platform.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractRussia, Kola PeninsulaStructure
DS201312-0751
2012
Larionov, A.N.Romanova, I.V., Vernikovskaya, A.E., Vernikovsky, V.A., Matushkin, N.Yu., Larionov, A.N.Neoproterozoic alkaline magmatism and associated igneous rocks in the western framing of the Siberian craton: petrography, geochemistry, and geochronology.Russian Geology and Geophysics, Vol. 53, 11, pp. 1176-1196.RussiaMagmatism
DS202006-0921
2020
Larionov, A.N.Gusev, N.I., Sergeeva, L. Yu., Larionov, A.N., Skublov, S.G.Relics of the Eoarchean continental crust of the Anabar shield, Siberian Craton.Petrology, Vol. 28, 2, pp. 118-140.Russiadeposit - Daldyn

Abstract: In the northern part of the Anabar Shield, orthopyroxene plagiogneisses of the granulite Daldyn Group host lenses of mafic rocks surrounded by melanocratic rims. According to their chemical composition, the mafic rocks correspond to subalkaline gabbro, the plagiogneisses correspond to granodiorites contaminated with mafic material, and the rims are diorites. The orthopyroxene plagiogneisses of granodiorite composition have 147Sm/144Nd = 0.1097, ?Nd(?) = 1.6, TNd(DM) = 3.47 Ga and are metamorphosed anatectic granitoids with an age of 3.34 Ga. The mafic rocks have high Zr, Th, and Pb contents, are enriched in REE (?REE = 636 ppm), with a high degree of fractionation [(La/Yb)N = 17.73] and a well-defined Eu minimum (Eu/Eu* = 0.51), and have 147Sm/144Nd = 0.099, ?Nd(?) = 1.4 and TNd(DM) = 3.65 Ga. It is assumed that these rocks crystallized from melt derived from an enriched mantle (plume) source. Based on U-Pb (SHRIMP-II) dating of 50 zircon grains from the mafic rocks, a group of grains with concordant ages from 3567 to 1939 Ma was distinguished, along with a large number of discordant values. Multiple measurements in zircon grains with discordant age values make it possible to identify seven grains of Eoarchean age, with upper intercepts of the discordia corresponding to 3987 ± 71 to 3599 ± 33 Ma. The Lu-Hf systematics of 14 zircon grains is characterized by ?Hf(T) = +3.7 and by close values of THf(DM) = 3.95 and TCHf = 3.93 Ga (3.99 Ga for the oldest zircon). The Paleoarchean (3.57 Ga) zircons are characterized by negative values of ?Hf(T) = -5.3 and -6.8, THf(DM) = 3.92-3.98 Ga, and TCHf = 4.14-4.24 Ga, which indicate recycling of the preexisting Eoarchean and Hadean continental crust. The younger zircon (3287-2410 Ma) was also formed when the preexisting crust was recycled.
DS202008-1414
2020
Larionova, Y.Lebedeva, N., Nosova, A., Kargin, A., Larionova, Y., Sazonova, L., Tikhomirova, Y.Grib kimberlite peridotitic xenoliths: isotopic evidence of variable source of mantle metasomatism.Goldschmidt 2020, 1p. AbstractRussia, Kola Peninsuladeposit - Grib

Abstract: We present petrography and mineral chemistry for both phlogopite, from mantle-derived xenoliths (garnet peridotite, eclogite and clinopyroxene-phlogopite rocks) and for megacryst, macrocryst and groundmass flakes from the Grib kimberlite in the Arkhangelsk diamond province of Russia to provide new insights into multi-stage metasomatism in the subcratonic lithospheric mantle (SCLM) and the origin of phlogopite in kimberlite. Based on the analysed xenoliths, phlogopite is characterized by several generations. The first generation (Phl1) occurs as coarse, discrete grains within garnet peridotite and eclogite xenoliths and as a rock-forming mineral within clinopyroxene-phlogopite xenoliths. The second phlogopite generation (Phl2) occurs as rims and outer zones that surround the Phl1 grains and as fine flakes within kimberlite-related veinlets filled with carbonate, serpentine, chlorite and spinel. In garnet peridotite xenoliths, phlogopite occurs as overgrowths surrounding garnet porphyroblasts, within which phlogopite is associated with Cr-spinel and minor carbonate. In eclogite xenoliths, phlogopite occasionally associates with carbonate bearing veinlet networks. Phlogopite, from the kimberlite, occurs as megacrysts, macrocrysts, microcrysts and fine flakes in the groundmass and matrix of kimberlitic pyroclasts. Most phlogopite grains within the kimberlite are characterised by signs of deformation and form partly fragmented grains, which indicates that they are the disintegrated fragments of previously larger grains. Phl1, within the garnet peridotite and clinopyroxene-phlogopite xenoliths, is characterised by low Ti and Cr contents (TiO2 < 1 wt.%, Cr2O3 < 1 wt.% and Mg# = 100 × Mg/(Mg + Fe) > 92) typical of primary peridotite phlogopite in mantle peridotite xenoliths from global kimberlite occurrences. They formed during SCLM metasomatism that led to a transformation from garnet peridotite to clinopyroxene-phlogopite rocks and the crystallisation of phlogopite and high-Cr clinopyroxene megacrysts before the generation of host-kimberlite magmas. One of the possible processes to generate low-Ti-Cr phlogopite is via the replacement of garnet during its interaction with a metasomatic agent enriched in K and H2O. Rb-Sr isotopic data indicates that the metasomatic agent had a contribution of more radiogenic source than the host-kimberlite magma. Compared with peridotite xenoliths, eclogite xenoliths feature low-Ti phlogopites that are depleted in Cr2O3 despite a wider range of TiO2 concentrations. The presence of phlogopite in eclogite xenoliths indicates that metasomatic processes affected peridotite as well as eclogite within the SCLM beneath the Grib kimberlite. Phl2 has high Ti and Cr concentrations (TiO2 > 2 wt.%, Cr2O3 > 1 wt.% and Mg# = 100 × Mg/(Mg + Fe) < 92) and compositionally overlaps with phlogopite from polymict breccia xenoliths that occur in global kimberlite formations. These phlogopites are the product of kimberlitic magma and mantle rock interaction at mantle depths where Phl2 overgrew Phl1 grains or crystallized directly from stalled batches of kimberlitic magmas. Megacrysts, most macrocrysts and microcrysts are disintegrated phlogopite fragments from metasomatised peridotite and eclogite xenoliths. Fine phlogopite flakes within kimberlite groundmass represent mixing of high-Ti-Cr phlogopite antecrysts and high-Ti and low-Cr kimberlitic phlogopite with high Al and Ba contents that may have formed individual grains or overgrown antecrysts. Based on the results of this study, we propose a schematic model of SCLM metasomatism involving phlogopite crystallization, megacryst formation, and genesis of kimberlite magmas as recorded by the Grib pipe.
DS200912-0660
2009
Larionova, Y.A.O.A.Samsonov, A.A.V.A., Nosova, A.A.A.A., Tretyachenko, V.A.V.A., Larchenko, V.A.A.A., Larionova, Y.A.O.A.Collisional sutures in the early Precambrian crust as a factor for localization of Diamondiferous kimberlites in the northern east European platform.Doklady Earth Sciences, Vol. 425, 2, pp. 226-230.RussiaTectonics
DS201312-0775
2013
Larionova, Y.O.Samsonov, A.V., Griban, J.G., Larionova, Y.O., Nosova, A.A., Tretyachenko, V.V.Evolution of deep crustal roots of the Arhangelsk Diamondiferous province: evidences from crustal xenoliths and xenocrysts from Devonian kimberlite pipes.Goldschmidt 2013, 1p. AbstractRussia, Kola PeninsulaDeposit - Arkangel
DS201707-1344
2016
Larionova, Y.O.Larionova, Y.O., Sazonova, L.V., Lebedeva, N.M., Nosova, A., Tretyachenko, V.V., Travin, A.V., Kargin, A.V., Yudin, D.S.Kimberlite age in the Arkhangelsk province, Russia: isotopic geochronologic Rb-Sr and 40Ar/39Ar and mineralogical dat a on phlogopite.Petrology, Vol. 24, 6, pp. 562-593.Russiageochronology

Abstract: The paper reports detailed data on phlogopite from kimberlite of three facies types in the Arkhangelsk Diamondiferous Province (ADP): (i) massive magmatic kimberlite (Ermakovskaya-7 Pipe), (ii) transitional type between massive volcaniclastic and magmatic kimberlite (Grib Pipe), and (iii) volcanic kimberlite (Karpinskii-1 and Karpinskii-2 pipes). Kimberlite from the Ermakovskaya-7 Pipe contains only groundmass phlogopite. Kimberlite from the Grib Pipe contains a number of phlogopite populations: megacrysts, macrocrysts, matrix phlogopite, and this mineral in xenoliths. Phlogopite macrocrysts and matrix phlogopite define a single compositional trend reflecting the evolution of the kimberlite melt. The composition points of phlogopite from the xenoliths lie on a single crystallization trend, i.e., the mineral also crystallized from kimberlite melt, which likely actively metasomatized the host rocks from which the xenoliths were captured. Phlogopite from volcaniclastic kimberlite from the Karpinskii-1 and Karpinskii-2 pipes does not show either any clearly distinct petrographic setting or compositional differentiation. The kimberlite was dated by the Rb–Sr technique on phlogopite and additionally by the 40Ar/39Ar method. Because it is highly probable that phlogopite from all pipes crystallized from kimberlite melt, the crystallization age of the kimberlite can be defined as 376 ± 3 Ma for the Grib Pipe, 380 ± 2 Ma for the Karpinskii-1 pipe, 375 ± 2 Ma for the Karpinskii-2 Pipe, and 377 ± 0.4 Ma for the Ermakovskaya-7 Pipe. The age of the pipes coincides within the error and suggests that the melts of the pipes were emplaced almost simultaneously. Our geochronologic data on kimberlite emplacement in ADP lie within the range of 380 ± 2 to 375 ± Ma and coincide with most age values for Devonian alkaline–ultramafic complexes in the Kola Province: 379 ± 5 Ma; Arzamastsev and Wu, 2014). These data indicate that the kimberlite was formed during the early evolution of the Kola Province, when alkaline–ultramafic complexes (including those with carbonatite) were emplaced.
DS202005-0754
2020
Larionova, Y.O.Nosova, A.A., Kargin, A.V., Sazonova, L.V., Dubinina, E.O., Chugaev, A.V., Lebedeva, N.M., Yudin, D.S., Larionova, Y.O., Abersteiner, A., Gareev, B.I., Batalin, G.A.Sr-Nd-Pb isotopic systematic and geochronology of ultramafic alkaline magmatism of the southwestern margin of the Siberian craton: metasomatism of the sub-continental lithospheric mantle related to subduction and plume events.Lithos, Vol. 364-365, 21p. PdfRussia, Siberiadeposit - Ilbokich, Chadobets

Abstract: To provide new insights into the origin and evolution of ultramafic lamprophyres (UMLs) and their mantle source, we examined two UML (aillikite and damtjernite) occurrences of different ages in the western portion of the Siberian Craton (Ilbokich and Chadobets). New age, mineral and rock geochemistry, along with Sr-Nd-Pb-C-O isotope data was obtained. Our new 206Pb/238U perovskite age (399 ± 4 Ma) confirms the previously published Early Devonian age of the Ilbokich aillikite. RbSr isochron and 40Ar/39Ar dating yielded a Middle Triassic age (243 ± 3 Ma and 241 ± 1 Ma, respectively) for the Chadobets aillikites, indicating post-Trap emplacement of these rocks. Both UMLs are characterized by incompatible elements, including light rare earth element (LREE) enrichments (La is up to ×200 chondrite concentration), and strong fractionation of REEs ((La/Yb)n: 33-84). Despite the close geochemical affinity of both UMLs, the Nd isotopic compositions of aillikites, as well as the Pb isotopic composition of Chadobets and Ilbokich UMLs, do not overlap and are distinctly different from each other. The initial Sr and Nd isotopic compositions of the Ilbokich UMLs fall in within a narrow 87Sr/86Sr0 range (0.7032-0.7042) and ?Nd(T) (4.03-3.97). Chadobets UMLs have a similar Sr isotopic signature (87Sr/86Sr0: 0.7031-0.7043) and a more depleted Nd isotopic signature (?Nd(T) 4.09-5.08). The initial Pb isotope compositions of the Chadobets UMLs are moderately radiogenic, ranging between 206Pb/204Pb = 18.4-19.0, 208Pb/204Pb = 38.3-38.8, and are characterized by a narrow 207Pb/204Pb ratio between 15.5 and 15.6. The Ilbokich Pb isotope compositions are less variable and range between 206Pb/204Pb = 18.0-18.4, 208Pb/204Pb = 37.8-38.4 and 207Pb/204Pb ratios between 15.5 and 15.6. The oxygen isotopic composition of carbonate from both UMLs is characterized by highly variable ?18O values from +12.1 and up to +20.5‰ (SMOW). The isotopic composition of ?13C values range from ?1.3‰ to ?7.1. Based on the minor impact of crustal contamination in both aillikites, it is inferred that their radiogenic isotope composition reflects a mantle source signature. The mantle source of the Chadobets aillikites is likely to include carbonatitic magma as a metasomatic agent. In contrast, phlogopite-rich metasomes within the lithospheric mantle could have contributed more significantly to the Ilbokich aillikites. These metasomes could be formed during the Caledonian orogeny, which did not only affect the southwestern boundary of the Siberian Craton, but also expanded to the craton interior. This study provides additional support for the evolution of the south-western portion of the Siberian SCLM, ranging from mantle containing phlogopite enrichment domains during the Early Devonian to hydrous-phase reduced mantle in the Triassic due to the thermal impact of the Siberian Traps.
DS202006-0943
2020
Larionova, Y.O.Novosa, A.A., Kargin, A.V., Sazonova, L.V., Dubinina, E.O., Chugaev, A.V., Lebedeva, N.M., Yudin, D.S., Larionova, Y.O., Abersteiner, A., Gareev, B.I., Batalin, G.A.Sr-N-Pb isotopic systematic and geochronology of ultramafic alkaline magmatism of the southwestern margin of the Siberian craton: metasomatism of the sub-continental lithospheric mantle related to subduction and plume events.Lithos, Vol. 364-365, 21p. PdfRussiaailikite, damjernite

Abstract: To provide new insights into the origin and evolution of ultramafic lamprophyres (UMLs) and their mantle source, we examined two UML (aillikite and damtjernite) occurrences of different ages in the western portion of the Siberian Craton (Ilbokich and Chadobets). New age, mineral and rock geochemistry, along with Sr-Nd-Pb-C-O isotope data was obtained. Our new 206Pb/238U perovskite age (399 ± 4 Ma) confirms the previously published Early Devonian age of the Ilbokich aillikite. RbSr isochron and 40Ar/39Ar dating yielded a Middle Triassic age (243 ± 3 Ma and 241 ± 1 Ma, respectively) for the Chadobets aillikites, indicating post-Trap emplacement of these rocks. Both UMLs are characterized by incompatible elements, including light rare earth element (LREE) enrichments (La is up to ×200 chondrite concentration), and strong fractionation of REEs ((La/Yb)n: 33-84). Despite the close geochemical affinity of both UMLs, the Nd isotopic compositions of aillikites, as well as the Pb isotopic composition of Chadobets and Ilbokich UMLs, do not overlap and are distinctly different from each other. The initial Sr and Nd isotopic compositions of the Ilbokich UMLs fall in within a narrow 87Sr/86Sr0 range (0.7032-0.7042) and ?Nd(T) (4.03-3.97). Chadobets UMLs have a similar Sr isotopic signature (87Sr/86Sr0: 0.7031-0.7043) and a more depleted Nd isotopic signature (?Nd(T) 4.09-5.08). The initial Pb isotope compositions of the Chadobets UMLs are moderately radiogenic, ranging between 206Pb/204Pb = 18.4-19.0, 208Pb/204Pb = 38.3-38.8, and are characterized by a narrow 207Pb/204Pb ratio between 15.5 and 15.6. The Ilbokich Pb isotope compositions are less variable and range between 206Pb/204Pb = 18.0-18.4, 208Pb/204Pb = 37.8-38.4 and 207Pb/204Pb ratios between 15.5 and 15.6. The oxygen isotopic composition of carbonate from both UMLs is characterized by highly variable ?18O values from +12.1 and up to +20.5‰ (SMOW). The isotopic composition of ?13C values range from ?1.3‰ to ?7.1. Based on the minor impact of crustal contamination in both aillikites, it is inferred that their radiogenic isotope composition reflects a mantle source signature. The mantle source of the Chadobets aillikites is likely to include carbonatitic magma as a metasomatic agent. In contrast, phlogopite-rich metasomes within the lithospheric mantle could have contributed more significantly to the Ilbokich aillikites. These metasomes could be formed during the Caledonian orogeny, which did not only affect the southwestern boundary of the Siberian Craton, but also expanded to the craton interior. This study provides additional support for the evolution of the south-western portion of the Siberian SCLM, ranging from mantle containing phlogopite enrichment domains during the Early Devonian to hydrous-phase reduced mantle in the Triassic due to the thermal impact of the Siberian Traps.
DS202010-1856
2020
Larionova, Y.O.Lebedeva, N.M., Nosova, A.A., Kargin, A.V., Larionova, Y.O., Sazonova, L.V., Tikhomirova, Y.S.S-Nd-O isotopic evidence of variable sources of mantle metasomatism in the subcratonic lithospheric mantle beneath the Grib kimberlite, northwestern Russia.Lithos, in press available, 54p. PdfRussia, Kola Peninsuladeposit - Grib

Abstract: To provide new insights into the type and extent of mantle metasomatism in the subcratonic lithospheric mantle, we examined the Sr-Nd-O isotopic compositions of orthopyroxene, clinopyroxene, garnet, ilmenite and phlogopite from sheared garnet lherzolite, granular garnet harzburgites and lherzolites and clinopyroxene-phlogopite rocks from the Grib kimberlite in the Arkhangelsk diamond province in northwestern Russia. Clinopyroxene and orthopyroxene from sheared garnet lherzolite initially have a close value of 87Sr/86Sr(t) (~0.7034) and close weak positive ?Nd. Orthopyroxene and clinopyroxene are in oxygen isotope equilibrium with coexisting olivine. Clinopyroxene from a garnet harzburgite has a low 87Sr/86Sr(t) isotope ratio of 0.70266. Clinopyroxene from granular garnet lherzolites has a relatively narrow variation in 87Sr/86Sr(t) (0.70456-0.70582) and considerably larger variations in ?Nd (?4.3???+1.0) isotope ratios. Garnet displays elevated initial 87Sr/86Sr(t) values (0.70540-0.70633). Ilmenite shows a narrow range in 87Sr/86Sr(t) (0.70497-0.70522) coupled with ?Nd values of +0.4 and +3.5. These isotopic data suggest granular garnet lherzolite of mantle metasomatism took place during the interaction of kimberlite melts with SCLM that contained mica-amphibole-rutile-ilmenite-diopside (MARID)-type metasomes. Clinopyroxenes from clinopyroxene-phlogopite (phlogopite wehrlite) xenoliths display a broader range in 87Sr/86Sr(t) (0.70486-0.70813) that is significantly higher than the kimberlite values and a circa-chondritic ?Nd (?0.1 ??+1.3) with a restricted ?18O range (5.11‰-5.33‰). More radiogenic Sr isotopic composition decoupled from Nd isotopes could have been induced by metasomatic melt/fluid related to a subducted material. The isotopic compositions of mantle minerals preserve Sr-Nd isotopic evidence of pre-kimberlite metasomatic events that were probably due to incomplete reequilibration with ultramafic carbonated melt. Based on mineral pairs Rb-Sr isochrons and a clinopyroxene-based Sm-Nd errochron, these mantle metasomatic events correspond to ~550-600?Ma and ~1200?Ma episodes of magmatic-thermal activity.
DS201412-0443
2014
Larionova, Yu.Kargin, A., Nosova, A., Larionova, Yu., Kononova, V., Borisovsky, S., Kovalchuk, E., Griboedova, I.Mesoproterozoic orangeites ( Kimberlites II) of west Karelia: mineralogy, geochemistry and Sr-Nd isotope composition.Petrology, Vol. 22, 2, pp. 151-183.RussiaOrangeites
DS201212-0620
2012
Larionova, Yu.O.Samsonov, A.V., Tretyachenko, W., Nosova, A.A., Larionova, Yu.O., Lepekhina, E.N., Larionov, A.N., Ipatieva, I.S.Sutures in the early Precambrian crust as a factor responsible for localization of Diamondiferous kimberlites in the northern east European platform.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractRussia, Kola PeninsulaStructure
DS201612-2315
2016
Larionova, Yu.O.Larionova, Yu.O., Sazonova, L.V., Lebedeva, N.M., Nosova, A.A., Tretyachenko, V.V., Travin, A.V., Kargin, A.V., Yudin, D.S.Kimberlite age in the Arkhangelsk province, Russia: isotopic geochronologic Rb-Sr and 40Ar/39Ar and mineralogical dat a on phlogopite.Petrology, Vol. 24, 6, pp. 562-593.Russia, Archangel, Kola PeninsulaDeposit - Ermakovskaya-7, Grib, Karpinski

Abstract: The paper reports detailed data on phlogopite from kimberlite of three facies types in the Arkhangelsk Diamondiferous Province (ADP): (i) massive magmatic kimberlite (Ermakovskaya-7 Pipe), (ii) transitional type between massive volcaniclastic and magmatic kimberlite (Grib Pipe), and (iii) volcanic kimberlite (Karpinskii-1 and Karpinskii-2 pipes). Kimberlite from the Ermakovskaya-7 Pipe contains only groundmass phlogopite. Kimberlite from the Grib Pipe contains a number of phlogopite populations: megacrysts, macrocrysts, matrix phlogopite, and this mineral in xenoliths. Phlogopite macrocrysts and matrix phlogopite define a single compositional trend reflecting the evolution of the kimberlite melt. The composition points of phlogopite from the xenoliths lie on a single crystallization trend, i.e., the mineral also crystallized from kimberlite melt, which likely actively metasomatized the host rocks from which the xenoliths were captured. Phlogopite from volcaniclastic kimberlite from the Karpinskii-1 and Karpinskii-2 pipes does not show either any clearly distinct petrographic setting or compositional differentiation. The kimberlite was dated by the Rb-Sr technique on phlogopite and additionally by the 40Ar/39Ar method. Because it is highly probable that phlogopite from all pipes crystallized from kimberlite melt, the crystallization age of the kimberlite can be defined as 376 ± 3 Ma for the Grib Pipe, 380 ± 2 Ma for the Karpinskii-1 pipe, 375 ± 2 Ma for the Karpinskii-2 Pipe, and 377 ± 0.4 Ma for the Ermakovskaya-7 Pipe. The age of the pipes coincides within the error and suggests that the melts of the pipes were emplaced almost simultaneously. Our geochronologic data on kimberlite emplacement in ADP lie within the range of 380 ± 2 to 375 ± Ma and coincide with most age values for Devonian alkaline-ultramafic complexes in the Kola Province: 379 ± 5 Ma; Arzamastsev and Wu, 2014). These data indicate that the kimberlite was formed during the early evolution of the Kola Province, when alkaline-ultramafic complexes (including those with carbonatite) were emplaced.
DS202010-1843
2020
Larionova, Yu.O.Erofeeva, K.G., Samsonov, A.V., Stepanova, A.V., Larionova, Yu.O., Dubinina, E.O., Egorova, S.V., Arzamastesev, A.A., Kovalchuk, E.V., Abramova, V.D.Olivine and clinopyroxene phenocrysts as a proxy for the origin and crustal evolution of primary mantle melts: a case study of 2.40 Ga mafic sills in the Kola-Norwegian Terrane, northern Fennoscandia.Petrology, Vol. 28, 4, pp. 338-356. pdfEurope, Norway, Kola Peninsulamelting

Abstract: New petrographic, geochemical, and isotopic (Sr, Nd, and ?18?) data on olivine and pyroxene phenocrysts provide constraints on the composition and crustal evolution of primary melts of Paleoproterozoic (2.40 Ga) picrodoleritic sills in the northwest Kola province, Fennoscandian Shield. The picrodolerites form differentiated sills with S-shaped compositional profiles. Their chilled margins comprise porphyritic picrodolerite (upper margin) and olivine gabbronorite (bottom) with olivine and clinopyroxene phenocrysts. Analysis of the available data allows us to recognize three main stages in the crystallization of mineral assemblages. The central parts of large (up to 2 mm) olivine phenocrysts (Ol-1-C) crystallized at the early stage. This olivine (Mg# 85-92) is enriched in Ni (from 2845 to 3419 ppm), has stable Ni/Mg ratio, low Ti, Mn and Co concentrations, and contains tiny (up to 10 ?m) diopside-spinel dendritic lamella that probably originated due to the exsolution from high Ca- and Cr- primary magmatic olivine. All these features of Ol-1-C are typical of olivine from primitive picritic and komatiitic magmas (De Hoog et al., 2010; Asafov et al., 2018). Ol-1-C contains large (up to 0.25 mm) crystalline inclusions of high-Al enstatite (Mg# 80-88) and clinopyroxene (Mg# 82-90), occasionally in association with Ti-pargasite and chromian spinel (60.4 wt.% Al2O3). These inclusions are regarded as microxenoliths of wall rock that were captured by primary melt at depths more than 30 km and preserved due to the conservation in magmatic olivine. The second stage was responsible for the crystallization of Ol-1 rim (Ol-1-R), small (up to 0.3 mm) olivine (Ol-2, Mg# 76-85) grains, and central parts of large (up to 1.5 mm) clinopyroxene (Cpx-C) phenocrysts in the mid-crustal transitional magma chamber (at a depth of 15-20 km) at 1160-1350°C. At the third stage, Cpx-C phenocrysts were overgrown by low-Mg rims (Mg# 70-72) similar in composition to the groundmass clinopyroxene from chilled picrodolerite and gabbro-dolerite in the central parts of the sills. This stage likely completed the evolution of picrodoleritic magma and occurred in the upper crust at a depth of about 5 km. All stages of picrodoleritic magma crystallization were accompanied by contamination. Primary melts were contaminated by upper mantle and/or lower crust as recognized from xenocrystic inclusions in Ol-1-C. The second contamination stage is supported by the negative values of ?Nd(2.40) = -1.1 in clinopyroxene phenocrysts. At the third stage, contamination likely occurred in the upper crust when ascending melts filled gentle fractures. This caused vertical whole-rock Nd heterogeneity in the sills (Erofeeva et al., 2019), and difference in Nd isotopic composition of clinopyroxene phenocrysts and doleritic groundmass. It was also recognized that residual evolved melts are enriched in radiogenic strontium but have neodymium isotopic composition similar to other samples. It could be explained by the interaction of the melts with fluid formed via decomposition of biotite from surrounding gneisses under the effect of high-temperature melts.
DS200612-0319
2006
Lariviere, J.M.Day, S.J.A., Lariviere, J.M., Friske, P.W.B., McNeil, R.J., McCurdy, M.W.National geochemical Reconnaissance: regional stream sediment and water data: Travaillant Lake area.. analytical, mineralogical kimberlite indicator dataGeological Survey of Canada Open File, 4951, 1 CD May 17, $ 9.10Canada, Northwest TerritoriesGeochemistry - NTS 106N part of 106O
DS1991-0953
1991
Larkin, B.J.Larkin, B.J.An ANSI C routine to determine if a point is within a specified convex polygon in logarithmic timeComputers and Geosciences, Vol. 17, No. 6, pp. 841-848GlobalComputers, Program -ANSI C -polygon
DS2002-0918
2002
Larkin, D.Larkin, D.The role of a professional institute in addressing the sustainability of human capital in minerals industry.Australian Institute of Mining and Metallurgy, No. 3/2002, pp.37-40.AustraliaEmployment trends, Sustainable development - trends
DS2001-0795
2001
Larkin, P.A.Moore, A.E., Larkin, P.A.Drainage evolution in south central Africa since the break up of GondwanaSouth African Journal of Geology, Vol. 104, pp. 47-68.South AfricaGeomorphology - Zambezi, Limpopo
DS1997-0650
1997
Larkin, S.P.Larkin, S.P., Levander, A. , Henstock, T.J.Is the MOHO flat? Seismic evidence for a rough crust-mantle interface beneath the north Basin -RangeGeology, Vol. 25, No. 5, May pp. 451-454United States, Basin and RangeGeophysics - seismics, Crust - mantle
DS2000-0656
2000
Larkina, V.I.Migulin, V.V., Larkina, V.I., Sergeeva, N.G., Senin, B.Reflection of geodynamic processes in characteristics of electromagnetic radiation above Baltic Shield...Doklady Academy of Sciences, Vol. 373, No. 5, June-July, pp.845-50.Russia, Baltic Shield, Barents-Kara regionTectonics, Geophysics
DS1989-1172
1989
Larochelle, A.Park, J.K., Norris, D.K., Larochelle, A.Paleomagnetism and the origin of the Mackenzie Arc of northwestern CanadaCanadian Journal of Earth Sciences, Vol. 26, pp. 2194-2203.British ColumbiaGeophysics - paleomagnetics
DS201607-1310
2016
LaRocque, A.Ou, C., Leblon, B., Zhang, Yu., LaRocque, A., Webster, K., McLaughlin, J.Modelling and mapping permafrost at high spatial resolution using Land sat and Radarsat images in northern Ontario: model calibration and regional mapping.International Journal of Remote Sensing, Vol. 37, 12, pp. 2727-2779.Canada, OntarioNews item - permafrost

Abstract: Permafrost is an important ground thermal condition that has significant biophysical and socio-economic impacts. In order to better understand the distribution and dynamics of permafrost, there is a need to map permafrost at high spatial resolution. This study is part of a research project that aims to model and map permafrost using remote sensing images and the Northern Ecosystem Soil Temperature (NEST) model in the central part of the Hudson Bay Lowland in northern Ontario, Canada. The study area is near the southern margin of permafrost region where permafrost exists only in isolated patches. In this study, we ran the NEST model from 1932 to 2012 using a climate data set compiled from station observations and grid data sources. The model outputs were then compared to field observations acquired during 2009 -2012 at seven peat monitoring stations and two flux towers, which represent three major types of peatland in the study area (bog, fen, and palsa). The simulated soil temperatures at various depths show good agreement with the observations, and the simulated latent and sensible heat fluxes and net radiation are similar to the observations at the two flux towers. The model accurately shows the existence of permafrost only at palsa sites. Based on the general range of climate and ground conditions in this area, sensitivity tests indicate that the modelled permafrost conditions are sensitive to leaf area index, air temperature, precipitation, and soil texture. Therefore, the NEST model is capable of simulating ground temperature and permafrost conditions in where permafrost occurs only sporadically. A companion paper (part 2) uses the model with Landsat and Radarsat imagery to map the distribution and dynamics of permafrost in this area.
DS1998-0829
1998
Larocque, A.C.L.Larocque, A.C.L., Rasmussen, P.E.An overview of trace metals in the environment, from mobilization toremediationEnviron. Geology, Vol. 33, No. 2-3, Feb. pp. 85-91GlobalGeochemistry - trace metals, Environment
DS2002-1094
2002
Larose, T.M.Morris, T.F., Pitre, S.A., Larose, T.M.Kimberlite and base metal exploration targets, derived from overburden heavy mineral dat a Schreiber area, northwestern Ontario.Ontario Geological Survey Open File, No. 6074, 113p.OntarioGeochemistry
DS200412-1371
2002
Larose, T.M.Morris, T.F., Pitre, S.A., Larose, T.M.Kimberlite and base metal exploration targets, derived from overburden heavy mineral dat a Schreiber area, northwestern Ontario.Ontario Geological Survey Open File, No. 6074, 113p.Canada, OntarioGeochemistry
DS201708-1701
2017
Laroulandie, C.Laroulandie, C.Barium and titanium enrichment of zoned phlogopite xenocrysts and phenocrysts in the Adamantin kimberlites, Quebec, Canada.11th. International Kimberlite Conference, PosterCanada, Quebecdeposit - Adamantin
DS202010-1862
2020
Larre, C.Morizet, Y., Larre, C., Di Carlo, I., Gaillard, F.High S and high CO2 contents in haplokimberlite: an experimental and Raman spectroscopic study.Mineralogy and Petrology, Vol. 114, pp. 363-373. pdfMantlemelting

Abstract: Sulfur is an important element present in natural kimberlites and along with CO2, S can play a role in the kimberlite degassing. We have investigated experimentally the change in S content and CO2 solubility in synthetic kimberlitic melts in response to a range of pressure (0.5 to 2.0 GPa) and temperature (1500 to 1525 °C). Several initial S concentrations were investigated ranging from 0 to 24000 ppm. The dissolved CO2 and S were determined by Raman spectroscopy and Electron Probe Micro-Analyses. Under the investigated oxidizing conditions (?FMQ?+?1), S is dissolved in the glass only as S6+ forming sulfate molecular groups (SO42?). The measured S concentration in the glasses increases from 2900 to 22000 ppm. These results suggest that the experimental conditions were below saturation with respect to S and that the S solubility is higher than 22000 ppm for kimberlitic melts; regardless of the experimental conditions considered here. CO2 is dissolved as CO32? molecular groups. The CO2 solubility ranges from 3.0 to 11.3 wt% between 0.5 and 2.0 GPa. CO2 solubility is not affected by the presence of S; which suggests that SO42? and CO32? clusters have two distinct molecular environments not interacting together. This result implies that both CO2 and S are efficiently transported by kimberlitic melt from the upper mantle towards the atmosphere.
DS1989-1053
1989
Larrere, M.Moretti, I., Larrere, M.LOCACE: computer aided construction of balanced geological crosssectionsGeobyte, Vol. 4, No. 5, pp. 16-24. Database #18196GlobalComputer, Program -LOCACE.
DS1995-0694
1995
Larroque, C.Guilhaumou, N., Larroque, C.Les circulations de fluides dans les prismes d'accretion: fluides fossile set fluides actuelsC.r. Academy Of Science Paris, Vol. 321, 11a, pp. 939-957GlobalGeodynamics, Paleomarkers
DS201801-0009
2017
Larrouturou, G.Coltice, N., Larrouturou, G., Debayle, E., Garnero, E.J.Interactions of scales of convection in the Earth's mantle.Tectonophysics, in press available, 9p.Mantleplate tectonics, geophysics - seismics

Abstract: The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
DS201901-0020
2018
Larrouturou, G.Coltice, N., Larrouturou, G., Debayle, E., Garnero, E.J.Interactions of scales of convection in the Earth's mantle.Tectonophysics, Vol. 746, pp. 669-677.Mantleconvection

Abstract: The existence of undulations of the geoid, gravity and bathymetry in ocean basins, as well as anomalies in heat flow, point to the existence of small scale convection beneath tectonic plates. The instabilities that could develop at the base of the lithosphere are sufficiently small scale (< 500 km) that they remain mostly elusive from seismic detection. We take advantage of 3D spherical numerical geodynamic models displaying plate-like behavior to study the interaction between large-scale flow and small-scale convection. We find that finger-shaped instabilities develop at seafloor ages > 60 Ma. They form networks that are shaped by the plate evolution, slabs, plumes and the geometry of continental boundaries. Plumes impacting the boundary layer from below have a particular influence through rejuvenating the thermal lithosphere. They create a wake in which new instabilities form downstream. These wakes form channels that are about 1000 km wide, and thus are possibly detectable by seismic tomography. Beneath fast plates, cold sinking instabilities are tilted in the direction opposite to plate motion, while they sink vertically for slow plates. These instabilities are too small to be detected by usual seismic methods, since they are about 200 km in lateral scale. However, this preferred orientation of instabilities below fast plates could produce a pattern of large-scale azimuthal anisotropy consistent with both plate motions and the large scale organisation of azimuthal anisotropy obtained from recent surface wave models.
DS201710-2257
2017
Larroza, F.A.Presser, J.L.B., Tondo, M.J., Dolsa, S.F., Rocca, M.C.L., Alonso, R.N., Benetiz, P., Larroza, F.A., Duarte, B.J.R., Cabral-Antunez, N.D.Brief comments on the impact metamorphism in Cerro Leon quartzites, western Paraguay. English abstract ** in PORTPyroclastic Flow, Vol. 7, 1,pp. 16-24.South America, Paraguayimpact diamonds

Abstract: The petrographic study of two samples (quartzite and impactite) of Cerro León, a mountain range located in the middle of very probable impact basins (Cerro Leon-1, 2, 3 and 4-department of Alto Paraguay, Western-Paraguay) indicated evidences of impact metamorphism: PDFs (Not decorated and decorated) and diaplectic glass. Associated with diaplectic glass, impact diamonds or diamond/lonsdaleite crystals (micro and small macros) were observed with a range of morphologies including isolated and mostly agglutinated crystal varieties. Impact diamonds estimated to have formed by carbonate impact metamorphism present in the sedimentary target-rock of the Silurian/Devonian age. The identification of elements that reveal the impact metamorphism, in the analyzed samples of the Cerro León, evidences that the area of occurrence that would have been indicated as Very Probable Impact Basin, would be more of an Impact Basin.
DS201802-0259
2017
Larroza, F.A.Presser, J.L.B., Alonso, R.N., Farina Dolsa, S., Larroza, F.A., Rocca, M.C.L., Hornes, K., Baller, L.Impact metamorphism evidence of Negla and Yasuka Renda large impact crater. ***PORT only abstract in eng Boletin Museum History Natural Paraguay ***IN PORT, Vol. 21, no. 2, pp. 69-82. pdfSouth America, Paraguayimpact craters
DS201702-0234
2016
Larroza-Cristaldo, F.A.Presser, J.L.B., Farina-Dolsa, S., Larroza-Cristaldo, F.A., Rocca, M., Alonso, R.N., Acededo, R.D., Cabral-Antunez, N.D., Baller, L., Zarza-Lima, P.R., Sekatcheff, J.M.Modeled mega impact structures in Paraguay: II the eastern region. **PortBoletin del Museo Nacional de Historia Narural del Paraguay, Vol. 20, 2, pp. 205-213. pdf available in * PortSouth America, ParaguayImpact Crater

Abstract: We report here the discovery and study of several new modeled large impact craters in Eastern Paraguay, South America. They were studied by geophysical information (gravimetry, magnetism), field geology and also by microscopic petrography. Clear evidences of shock metamorphic effects were found (e.g., diaplectic glasses, PF, PDF in quartz and feldspar) at 4 of the modeled craters: 1) Negla: diameter:~80-81 km., 2) Yasuka Renda D:~96 km., 3) Tapyta, D: ~80 km. and 4) San Miguel, D: 130-136 km. 5) Curuguaty, D: ~110 km. was detected and studied only by geophysical information. Target-rocks range goes from the crystalline Archaic basement to Permian sediments. The modeled craters were in some cases cut by tholeiitic/alkaline rocks of Mesozoic age and partially covered by lavas of the basaltic Mesozoic flows (Negla, Yasuka Renda, Tapyta and Curuguaty). One of them was covered in part by sediments of Grupo Caacupé (age: Silurian/Devonian). Some of these modeled craters show gold, diamonds, uranium and REE mineral deposits associated. All new modeled large impact craters are partially to markedly eroded.
DS2001-0488
2001
LarsenHopper, W.S., Larsen, Korenaga, DahlJensen, Reid etc.Mantle thermal structure and active upwelling during continental breakup in the North Atlantic.Earth and Planetary Science Letters, Vol. 190, No. 3-4, pp. 251-66.Baltica, Greenland, NorwayTectonics, Plume
DS200912-0143
2009
LarsenDale, C.W., Pearson, D.G., Starkey, N.A., Stuart, F.M., Ellam, Larsen, Fitton, MacPhersonOsmium isotope insights into high 3He4He mantle and convecting mantle in the North Atlantic.Goldschmidt Conference 2009, p. A260 Abstract.Canada, Nunavut, Baffin Island, Europe, GreenlandPicrite
DS201112-0280
2011
Larsen, B.T.Dominguez, A.R., Van der Voo, R., Torsvik, T.H., Hendriks, B.W.H, Abrajevitch, A., Domeier, M., Larsen, B.T., Rousse, S.The ~270 Ma paleolatitude of Baltica and its significance for Pangea models.Geophysical Journal International, In press availableEurope, Baltic ShieldGeochronology
DS2001-0216
2001
Larsen, D.Cox, R.T., Vn Arsdale, R.B., Harris, J.B., Larsen, D.Neotectonics of the southeastern Reelfoot rift zone margin, central United States And implications for regional strainGeology, Vol. 29, No. 5, May, pp. 419-22.Missouri, Mississippi, MidcontinentTectonics, paleoseismology
DS1930-0197
1935
Larsen, E.S.Larsen, E.S., Hurlburt, C.S. JR., Burgess, C.H., Griggs, D.T.The Igneous Rocks of the Highwood Mountains of Central Montana.American GEOPYS. UNION, Transactions 16TH. MEETING, PP. 288-292.United States, Montana, Rocky MountainsBlank
DS1930-0278
1938
Larsen, E.S.Larsen, E.S., Buie, B.F.Potash Analcime and Pseudoleucite from the Highwood Mountains of Montana.American Mineralogist., Vol. 23, PP.837-849.Montana, Rocky MountainsLeucite
DS1940-0029
1941
Larsen, E.S.Larsen, E.S.Igneous Rocks of the Highwood Mountains, Montana. Part Ii. The Extrusive Rocks.Geological Society of America (GSA) Bulletin., Vol. 52, PP. 1733-1752.Montana, Rocky MountainsBlank
DS1992-1678
1992
Larsen, G.Wilson, M., Rosenbaum, J.M., Dunsworth, E.A., Larsen, G.Are melillitites partial melts of the thermal boundary layer?Eos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.325Europe, GermanyUpper Rhinegraben Volcanic Province, Melillitite
DS2002-0207
2002
Larsen, H.C.Bromann Klausen, M., Larsen, H.C.East Greenland coast parallel dike swarm and its role in continental breakupGeological Society of America Special Paper, No. 192, pp. 133-158.GreenlandDike swarms, Tectonics
DS2002-1137
2002
Larsen, H.C.Nielsen, T.K., Larsen, H.C., Hopper, J.R.Contrasting rifted margin styles south of Greenland: implications for mantle plume dynamics.Earth and Planetary Science Letters, Vol.200,No. 3-4, pp. 271-86.GreenlandTectonics, Geodynamics
DS200412-0217
2002
Larsen, H.C.Bromann Klausen, M., Larsen, H.C.East Greenland coast parallel dike swarm and its role in continental breakup.Geological Society of America Special Paper, No. 192, pp. 133-158.Europe, GreenlandDike swarms Tectonics
DS200412-1932
2004
Larsen, H.C.Storey, M., Pedersen, A.K., Stecher, O., Bernstein, S., Larsen, H.C., Larsen, L.M., Baker, Duncan, R.A.Long lived post breakup magmatism along the East Greenland margin: evidence for shallow mantle metasomatism by the Iceland plumeGeology, Vol. 32, 2, Feb. pp. 173-176.Europe, Greenland, IcelandMagmatism
DS1982-0359
1982
Larsen, J.G.Larsen, J.G.Mantle Derived Dunite and Lherzolite Nodules from Ubekendt Ejland, West Greenland Tertiary Province.Mineralogical Magazine., Vol. 46, No. 340, PP. 329-336.GreenlandKimberlite
DS1992-0567
1992
Larsen, J.G.Gill, R.C.O., Pedersen, A.K., Larsen, J.G.Tertiary picrites in West Greenland: melting at the periphery of a plume?Geological Society Special Publication, Magmatism and the Causes of Continental, No. 68, pp. 335-348GreenlandPicrites, Plume
DS1992-0721
1992
Larsen, J.G.Holm, P.M., Gill, R.C.O., Pedersen, A.K., Larsen, J.G., Hald, N.The Icelandic mantle plume: compositional constraints from the West Greenland Tertiary picritesEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.336GreenlandPicrites, Mantle plume
DS1993-0694
1993
Larsen, J.G.Holm, P.M., Gill, R.C.O., Pedersen, A.K., Larsen, J.G., Hald, N.The Tertiary picrites of West Greenland: contributions from Icelandic and other sourcesEarth and Planetary Science Letters, Vol. 115, No. 1-4, March pp. 227-244GreenlandPicrites, Alkaline rocks
DS1975-1109
1979
Larsen, L.M.Larsen, L.M.Lamprophyric and Kimberlitic Dykes Associated with the Safartoq Carbonatite Complex Southern West Greenland.Greenland Geol. Unders. Rapp., No. 100, Report OF ACTIVITIES, PP. 65-69.GreenlandKimberlite
DS1975-1110
1979
Larsen, L.M.Larsen, L.M.Lampropyric and Kimberlitic Dykes Associated with the Safartoq Carbonatite Complex Southern West Greenland.Greenland Geol. Unders. Rapp., No. 100, PP. 65-69.GreenlandBlank
DS1980-0301
1980
Larsen, L.M.Secher, K., Larsen, L.M.Geology and Mineralogy of the Sarfartoq Carbonatite Complex southern West Greenland.Lithos, Vol. 13, PP. 199-212.GreenlandRelated Rocks
DS1982-0360
1982
Larsen, L.M.Larsen, L.M., Pederson, A.K.A Minor Carbonatite Occurrence in Southern West Greenland, ThetupertalikintrusionGeological Survey Greenland Report of activities, Vol. 110, pp. 38-43GreenlandCarbonatite, Qaqarssuk Complex
DS1983-0388
1983
Larsen, L.M.Larsen, L.M., Rex, D.C., Secher, K.The Age of Carbonatites, Kimberlites and Lamprophyres from Southern West Greenland: Recurrent Alkaline Magmatism During2500 Million Years.Lithos, Vol. 16, No. 3, PP. 215-221.GreenlandGeochronology, Related Rocks, Ivigtut, Fiskenaesset
DS1985-0312
1985
Larsen, L.M.Jones, A.P., Larsen, L.M.Geochemistry and rare earth elements (REE) minerals of nepheline syenites from theMotzfeldtCentre, South GreenlandAmerican Mineralogist, Vol. 70, pp. 1087-1100GreenlandRare Earth Elements (ree), Larvikite, Mineral Chemistry, Rare Earth
DS1985-0382
1985
Larsen, L.M.Larsen, L.M.The Ilimaussaq Intrusion Revisited: the Evolution of an Agpaitic Magma.Conference Report of The Meeting of The Volcanic Studies Gro, 1P. ABSTRACT.Scandinavia, DenmarkGeochemistry
DS1991-0954
1991
Larsen, L.M.Larsen, L.M.Registration of kimberlites and other potentially diamond-bearing rocks inGreenlandGronlands Geol. Unders. Rapp, No. 152, pp. 61-65GreenlandKimberlites, Known localities
DS1991-0955
1991
Larsen, L.M.Larsen, L.M.Occurrences of kimberlite, lamproite and ultramafic lamprophyre inGreenlandGronlands Geologiske Undersogelse, Report No. 91/2, 36p. 5 figs. appendix 9p. 5 maps $20.0GreenlandOccurrences, Kimberlite, lamproite, lamprophyres
DS1992-0909
1992
Larsen, L.M.Larsen, L.M., Rex, D.C.A review of the 2500 MA span of alkaline ultramafic potassic and carbonatitic magmatism in West Greenland (Review)Lithos, Vol. 28, No. 3-6. November pp. 367-402GreenlandAlkaline rocks, Potassic rocks
DS1993-0882
1993
Larsen, L.M.Larsen, L.M., Ronsbo, J.Conditions of origin of kimberlites in West Greenland: new evidence From the Sarfartoq and Sukkertoppen regions.Gronleands Geologiske Undersogelse, Current Research, No. 159, pp. 115-120.GreenlandKimberlite, Genesis
DS1994-1582
1994
Larsen, L.M.Shearer, C.K., Larsen, L.M.Sector zoned aegirine from the Ilmaussaq alkaline intrusion, SouthGreenland: implications for trace element behaviour in pyroxene.American Mineralogist, Vol. 79, No. 3, 4, March-April pp. 340-351.GreenlandAlkaline rocks
DS1998-1022
1998
Larsen, L.M.Mitchell, R.H., Scott Smith, B.H., Larsen, L.M.Mineralogy of ultramafic dikes from the Sarfartoq Sismut and Manitsoqareas, kimberlites or alnoites?7th International Kimberlite Conference Abstract, pp. 600-2.GreenlandClassification - ultramafic dikes, Petrology
DS1999-0484
1999
Larsen, L.M.Mitchell, R.H., Scott Smith, B.H., Larsen, L.M.Mineralogy of ultramafic dikes from the Sarfartoq, Sisimiut and Manitsoq areas, West Greenland.7th International Kimberlite Conference Nixon, Vol. 2, pp. 574-83.GreenlandPetrography - dikes, mica, spinel, ilmenite, Classificication
DS1999-0711
1999
Larsen, L.M.Steenfelt, A., Jensen, S.M., Larsen, L.M., Stendal, H.Diamond exploration in southern West GreenlandAssocation of Exploration Geologists (AEG) 19th. Diamond Exploration Methods Case Histories, pp. 76-84.GreenlandKimberlite - petrology, Sisimuit, Sarfartoq, Maniitsoq
DS2000-0551
2000
Larsen, L.M.Larsen, L.M., Pedersen, A.K.Processes in high magnesium, high 7 magmas: evidence from olivine, chromite and glass in Palaeogene picrites.Journal of Petrology, Vol. 41, No. 7, July pp.1071-98.GreenlandPicrites
DS2003-0774
2003
Larsen, L.M.Larsen, L.M., Pedersen, A.K., Sundvoll, B., Frei, R.Alkali picrites formed by melting of old metasomatized lithospheric mantle: ManitdlatJournal of Petrology, Vol. 44, 1, pp. 3-38.GreenlandPicrites
DS200412-1932
2004
Larsen, L.M.Storey, M., Pedersen, A.K., Stecher, O., Bernstein, S., Larsen, H.C., Larsen, L.M., Baker, Duncan, R.A.Long lived post breakup magmatism along the East Greenland margin: evidence for shallow mantle metasomatism by the Iceland plumeGeology, Vol. 32, 2, Feb. pp. 173-176.Europe, Greenland, IcelandMagmatism
DS200712-1034
2007
Larsen, L.M.Starkey, N., Stuart, F.M., Ellam, R.M., Fitton, J.G., Basu, S., Larsen, L.M.No role for discrete, depleted high 3 He/4He mantle.Plates, Plumes, and Paradigms, 1p. abstract p. A967.Canada, Nunavut, Baffin Island, Europe, GreenlandPicrite
DS200912-0144
2009
Larsen, L.M.Dale, C.W., Pearson, D.G., Starkey, N.A., Stuart, F.M., Ellam, R.M., Larsen, L.M., Fitton, J.G., Grousset, F.E.Osmium isotopes in Baffin Island and West Greenland picrites: implications for the 187 Os and 188 Os composition of the convection mantle and nature 3He/4heEarth and Planetary Interiors, Vol. 278, 3-4, pp. 267-277.MantleConvection
DS201012-0424
2009
Larsen, L.M.Larsen, L.M., Pedersen, A.K.Petrology of the Paleocene picrites and flood basalts on Disko and Nuussuaq, West GreenlandJournal of Petrology, Vol. 50,9, pp. 1667-1711.Europe, GreenlandPicrite
DS201212-0702
2012
Larsen, L.M.Starkey, N.A., Fitton, J.G., Stuart, F.M., Larsen, L.M.As commodity, is it diamond's time to shine?The New York Times Magazine, April 14, 1p.GlobalDiamond backed exchange traded fund
DS1998-0302
1998
Larsen, M.Dam, G., Larsen, M., Sonderholm, M.Sedimentary response to mantle plumes: implications from Paleocene onshoresuccessions, West and East.Geology, Vol. 26, No. 3, March pp. 207-210.GreenlandPlume model, volcanism.
DS1988-0158
1988
Larsen, O.Dawes, P.R., Larsen, O., Kalsbeek, F.Archean and Proterzoic crust in Northwest Greenland: evidence from Rubidium-Strontium whole rock age determinations.Canadian Journal of Earth Sciences, Vol. 25, pp. 1365-73.GreenlandGeochronology
DS1995-1059
1995
Larsen, R.Larsen, R., Burke, E.A.J., Dobrzhinetskaya, L.F., et al.N2 CO2 CH2 H2O metamorphic fluids in microdiamond bearing lithologies From the western gneiss region.Ngu (norges Geol. Undersoklse, Bulletin., No. 427, pp. 41-43.NorwayDiamonds
DS1998-0830
1998
Larsen, R.B.Larsen, R.B., Eide, E.A., Burke, E.A.J.Evolution of metamorphic volatiles during exhumation of microDiamond bearing granulites Western Gneiss Region.Contributions to Mineralogy and Petrology, Vol. 133, No. 1-2, pp. 106-27.NorwayMicrodiamond, metamorphism
DS1997-0651
1997
Larsen, T.B.Larsen, T.B., Yuen, D.A.Ultrafast upwelling bursting through the upper mantleEarth and Planetary Letters, Vol. 146, No. 3/4. Feb 1, pp. 393-400.MantlePlumes
DS1999-0394
1999
Larsen, T.B.Larsen, T.B., Yuen, D.A., Storey, M.Ultrafast mantle plumes and implications for flood basalt volcanism in the northern Atlantic region.Tectonophysics, Vol. 311, No. 1-4, Sept. 30, pp. 31-82.Baltic States, Quebec, Ungava, Finland, Sweden, NorwayMantle plumes, Flood basalts - review
DS200412-0406
2004
Larsen, T.B.Darbyshire, F.A., Larsen, T.B., Mosegaard, K., Dahl Jensen, T., Gudmundsson, O., Bach, T., Gregersen, S., PedeA first detailed look at the Greenland lithosphere and upper mantle; using Rayleigh wave tomography.Geophysical Journal International, Vol. 158, 1, pp. 267-286.Europe, GreenlandGeophysics - seismic
DS200712-0204
2007
LarsonCourtier, A.M., Jackson, Lawrence, Wang, Lee, Halama, Warren, Workman, Xu, Hirschmann, Larson, Hart, Lithgo-Bertelloni, Stixrude, ChenCorrelation of seismic and petrologic thermometers suggests deep thermal anomalies beneath hotspots.Earth and Planetary Science Letters, Vol. 264, 1-2, pp. 308-316.MantleGeothermometry
DS200612-0766
2006
Larson, A.M.Larson, A.M., Snoke, J.A., James, D.E.S-wave velocity structure, mantle xenoliths and the upper mantle beneath the Kaapvaal Craton.Geophysical Journal International, Vol. 167, 1, Oct., pp. 171-186.Africa, South AfricaGeophysics - seismics
DS201412-0938
2014
Larson, D.J.Valley, J.W., Cavosie, T., Ushikubo, T., Reinhard, D.A., Lawrence, D.F., Larson, D.J., Clifton, P.H., Kelly, T.F., Wilde, S.A., Moser, D.E., Spicuzza, M.J.Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography.Nature Geoscience, Vol. 7, pp.219-223.MantleGeochronology
DS201509-0434
2015
Larson, D.J.Valley, J.W., Reinhard, D.A., Cavosie, A.J., Ushikubo, T., Lawrence, D.F., Larson, D.J., Kelly, T.F., Snoeyenbos, D.R., Strickland, A.Nano- and micro-geochronology in Hadean and Archean zircons by atom-probe tomography and SIMS: new tools for old minerals.American Mineralogist, Vol. 100, pp. 1355-1377.AustraliaGeochronology

Abstract: Atom-probe tomography (APT) and secondary ion mass spectrometry (SIMS) provide complementary in situ element and isotope data in minerals such as zircon. SIMS measures isotope ratios and trace elements from 1–20 ?m spots with excellent accuracy and precision. APT identifies mass/charge and three-dimensional position of individual atoms (±0.3 nm) in 100 nm-scale samples, volumes up to one million times smaller than SIMS. APT data provide unique information for understanding element and isotope distribution; crystallization and thermal history; and mechanisms of mineral reaction and exchange. This atomistic view enables evaluation of the fidelity of geochemical data for zircon because it provides new understanding of radiation damage, and can test for intracrystalline element mobility. Nano-geochronology is one application of APT in which Pb isotope ratios from sub-micrometer domains of zircon provide model ages of crystallization and identify later magmatic and metamorphic reheating.
DS1960-1098
1969
Larson, E.Eggler, D.H., Larson, E., Bradley, W.E.Granites, Grusses and the Sherman Erosion Surface Southern Laramie Range, Colorado-wyoming.American Journal of Science, Vol. 267, No. 4, PP. 510-522.United States, Colorado, Wyoming, State Line, Rocky MountainsBlank
DS1970-0550
1972
Larson, E.E.Kridelbaugh, S.J., Hobbitt, R.P., Kellogg, K., Larson, E.E.Petrologic and Paleomagnetic Implication of the Green Mountain Diatreme.Geological Society of America (GSA), Vol. 4, No. 6, P. 386, (abstract.).United States, Colorado, Rocky Mountains, VermontRelated Rocks
DS1981-0259
1981
Larson, E.E.Larson, E.E., Amini, M.H.Fission Track Dating of the Green Mountain Kimberlite Diatreme Near Boulder Colorado.The Mountain Geologist., Vol. 18, No. 1, PP. 19-22.ColoradoKimberlite, Rocky Mountains
DS1985-0383
1985
Larson, E.E.Larson, E.E., Patterson, P.E., Curtis, G., Drake, R., Mutschler.Petrologic, Paleomagnetic, and Structural Evidence of a Paleozoic Rift System in Oklahoma, New Mexico, Colorado, and Utah.Geological Society of America (GSA) Bulletin., Vol. 96, No. 11, NOVEMBER PP. 1364-1372.United States, Gulf Coast, Colorado Plateau, Oklahoma, New Mexico, ColoradoGeotectonics
DS1992-0910
1992
Larson, G.P.Larson, G.P.Marketing value-added minerals to specialized marketsMining Engineering, Vol. 44, No. 2, February pp. 161-163GlobalEconomics, Markets-specialized
DS1990-0962
1990
Larson, J.E.Jr.Luza, K.V., Larson, J.E.Jr.Seismicity and neotectonics along the southern midcontinent -Texas cratontransectGeological Society of America (GSA) Abstracts with programs, South-Central, Vol. 22, No. 1, p. 14GlobalMidcontinent, Tectonics
DS202002-0201
2019
Larson, K.M.Larson, K.M.Unanticipated uses of the Global Positioning System.Annual Review of Earth and Planetary Sciences, Vol. 47, pp. 19-40.GlobalGPS system

Abstract: Global Positioning System (GPS) instruments are routinely used today to measure crustal deformation signals from tectonic plate motions, faulting, and glacial isostatic adjustment. In parallel with the expansion of GPS networks around the world, several new and unexpected applications of GPS have been developed. For example, GPS instruments are now being used routinely to measure ground motions during large earthquakes. Access to real-time GPS data streams has led to the development of better hazard warnings for tsunamis, flash floods, earthquakes, and volcanic eruptions. Terrestrial water storage changes can be derived from GPS vertical coordinate time series. Finally, GPS signals that reflect on the surfaces below a GPS antenna can be used to measure soil moisture, snow accumulation, vegetation water content, and water levels. In the future, combining GPS with the signals from the Russian, European, and Chinese navigation constellations will significantly enhance these applications.
DS202005-0745
2019
Larson, K.M.Larson, K.M.Unanticipated uses of the Global Positioning System. Just interesting not specific to diamonds.Annual Review of Earth and Planetary Sciences, Vol. 47, pp. 19-40. pdfGlobalGPS

Abstract: Global Positioning System (GPS) instruments are routinely used today to measure crustal deformation signals from tectonic plate motions, faulting, and glacial isostatic adjustment. In parallel with the expansion of GPS networks around the world, several new and unexpected applications of GPS have been developed. For example, GPS instruments are now being used routinely to measure ground motions during large earthquakes. Access to real-time GPS data streams has led to the development of better hazard warnings for tsunamis, flash floods, earthquakes, and volcanic eruptions. Terrestrial water storage changes can be derived from GPS vertical coordinate time series. Finally, GPS signals that reflect on the surfaces below a GPS antenna can be used to measure soil moisture, snow accumulation, vegetation water content, and water levels. In the future, combining GPS with the signals from the Russian, European, and Chinese navigation constellations will significantly enhance these applications. 1) GPS data are now routinely used to study the dynamics of earthquake rupture. 2) GPS instruments are an integral part of warning systems for earth- quakes, tsunamis, flash floods, and volcanic eruptions. 3) Reflected GPS signals provide a new source of soil moisture, snow depth, vegetation water content, and tide gauge data. 4)GPS networks can sense changes in soil moisture, groundwater, and snow depth and thus can contribute to water resource assessments.
DS1997-1112
1997
Larson, M.S.Stone, W.E., Deloule, E., Larson, M.S., Lesher, C.M.Evidence for hydrous high MgO melts in the PrecambrianGeology, Vol. 25, No. 2, Feb. pp. 143-146Ontario, QuebecKomatiites, Abitibi belt
DS200512-0598
2004
Larson, P.Larson, P., Doyle, B., Kivi, K.Utilization of drift exploration techniques to constrain kimberlite indicator dispersal, train sources, Credit Lake property, Nunavut.32nd Yellowknife Geoscience Forum, Nov. 16-18, p.44. (talk)Canada, NunavutGeomorphology - till
DS201608-1388
2016
Larson, P.B.Andersen, A.K., Clar, J.G., Larson, P.B., Neill, O.K.Mineral chemistry and petrogenesis of a HFSE(+HREE) occurrence, peripheral to carbonatites of the Bear Lodge alkaline complex, Wyoming.American Mineralogist, Vol. 101, pp. 1604-1623.United States, Wyoming, Colorado PlateauBear Lodge

Abstract: Rare earth mineralization in the Bear Lodge alkaline complex (BLAC) is mainly associated with an anastomosing network of carbonatite dikes and veins, and their oxidized equivalents. Bear Lodge carbonatites are LREE-dominant, with some peripheral zones enriched in HREEs. We describe the unique chemistry and mineralogy one such peripheral zone, the Cole HFSE(+HREE) Occurrence (CHO), located ~2 km from the main carbonatite intrusions. The CHO consists of anatase, xenotime-(Y), brockite, fluorite, zircon, and K-feldspar, and contains up to 44.88% TiO2, 3.12% Nb2O5, 6.52% Y2O3, 0.80% Dy2O3, 2.63% ThO2, 6.0% P2O5, and 3.73% F. Electron microprobe analyses of xenotime-(Y) overgrowths on zircon show that oscillatory zoning is a result of variable Th and Ca content. Cheralite-type substitution, whereby Th and Ca are incorporated at the expense of REEs, is predominant over the more commonly observed thorite-type substitution in xenotime-(Y). Th/Ca-rich domains are highly beam sensitive and accompanied by high-F concentrations and low-microprobe oxide totals, suggesting cheralite-type substitution is more easily accommodated in fluorinated and hydrated/hydroxylated xenotime-(Y). Analyses of xenotime-(Y) and brockite show evidence of Embedded Image substitution for Embedded Image with patches of an undefined Ca-Th-Y-Ln phosphovanadate solid-solution composition within brockite clusters. Fluorite from the CHO is HREE-enriched with an average Y/Ho ratio of 33.2, while other generations of fluorite throughout the BLAC are LREE-enriched with Y/Ho ratios of 58.6-102.5. HFSE(+HREE) mineralization occurs at the interface between alkaline silicate intrusions and the first outward occurrence of calcareous Paleozoic sedimentary rocks, which may be local sources of P, Ti, V, Zr, and Y. U-Pb zircon ages determined by LA-ICP-MS reveal two definitive 207Pb/206Pb populations at 2.60-2.75 and 1.83-1.88 Ga, consistent with derivation from adjacent sandstones and Archean granite. Therefore, Zr and Hf are concentrated by a physical process independent of the Ti/Nb-enriched fluid composition responsible for anatase crystallization. The CHO exemplifies the extreme fluid compositions possible after protracted LREE-rich crystal fractionation and subsequent fluid exsolution in carbonatite-fluid systems. We suggest that the anatase+xenotime-(Y)+brockite+fluorite assemblage precipitated from highly fractionated, low-temperature (<200 °C), F-rich fluids temporally related to carbonatite emplacement, but after significant fractionation of ancylite and Ca-REE fluorocarbonates. Low-temperature aqueous conditions are supported by the presence of fine-grained anatase as the sole Ti-oxide mineral, concentrically banded botryoidal fluorite textures, and presumed hydration of phosphate minerals. Fluid interaction with Ca-rich lithologies is known to initiate fluorite crystallization which may cause destabilization of (HREE,Ti,Nb)-fluoride complexes and precipitation of REE+Th phosphates and Nb-anatase, a model valuable to the exploration for economic concentrations of HREEs, Ti, and Nb.
DS201709-1951
2017
Larson, P.B.Andersen, A.K., Clark, J.G., Larson, P.B., Donovan, J.J.REE fractionation, mineral speciation, and supergene enrichment of the Bear Lodge carbonatites, Wyoming, USA.Ore Geology Reviews, Vol. 89, pp. 780-807.United States, Wyomingcarbonatite - Bear Lodge

Abstract: The Eocene (ca. 55–38 Ma) Bear Lodge alkaline complex in the northern Black Hills region of northeastern Wyoming (USA) is host to stockwork-style carbonatite dikes and veins with high concentrations of rare earth elements (e.g., La: 4140–21000 ppm, Ce: 9220–35800 ppm, Nd: 4800–13900 ppm). The central carbonatite dike swarm is characterized by zones of variable REE content, with peripheral zones enriched in HREE including yttrium. The principle REE-bearing phases in unoxidized carbonatite are ancylite and carbocernaite, with subordinate monazite, fluorapatite, burbankite, and Ca-REE fluorocarbonates. In oxidized carbonatite, REE are hosted primarily by Ca-REE fluorocarbonates (bastnäsite, parisite, synchysite, and mixed varieties), with lesser REE phosphates (rhabdophane and monazite), fluorapatite, and cerianite. REE abundances were substantially upgraded (e.g., La: 54500–66800 ppm, Ce: 11500–92100 ppm, Nd: 4740–31200 ppm) in carbonatite that was altered by oxidizing hydrothermal and supergene processes. Vertical, near surface increases in REE concentrations correlate with replacement of REE(±Sr,Ca,Na,Ba) carbonate minerals by Ca-REE fluorocarbonate minerals, dissolution of matrix calcite, development of Fe- and Mn-rich gossan, crystallization of cerianite and accompanying negative Ce anomalies in secondary fluorocarbonates and phosphates, and increasing ?18O values. These vertical changes demonstrate the importance of oxidizing meteoric water during the most recent modifications to the carbonatite stockwork. Scanning electron microscopy, energy dispersive spectroscopy, and electron probe microanalysis were used to investigate variations in mineral chemistry controlling the lateral complex-wide geochemical heterogeneity. HREE-enrichment in some peripheral zones can be attributed to an increase in the abundance of secondary REE phosphates (rhabdophane group, monazite, and fluorapatite), while HREE-enrichment in other zones is a result of HREE substitution in the otherwise LREE-selective fluorocarbonate minerals. Microprobe analyses show that HREE substitution is most pronounced in Ca-rich fluorocarbonates (parisite, synchysite, and mixed syntaxial varieties). Peripheral, late-stage HREE-enrichment is attributed to: 1) fractionation during early crystallization of LREE selective minerals, such as ancylite, carbocernaite, and Ca-REE fluorocarbonates in the central Bull Hill dike swarm, 2) REE liberated during breakdown of primary calcite and apatite with higher HREE/LREE ratios, and 3) differential transport of REE in fluids with higher PO43?/CO32? and F?/CO32? ratios, leading to phosphate and pseudomorphic fluorocarbonate mineralization. Supergene weathering processes were important at the stratigraphically highest peripheral REE occurrence, which consists of fine, acicular monazite, jarosite, rutile/pseudorutile, barite, and plumbopyrochlore, an assemblage mineralogically similar to carbonatite laterites in tropical regions.
DS1995-0955
1995
Larson, R.Kincaid, C., Larson, R.Slab penetration events through 670 and the evolution of plumes:implications for ocean crustal production.Eos, Vol. 76, No. 46, Nov. 7. p.F172. Abstract.MantlePlumes, Subduction
DS1991-0956
1991
Larson, R.L.Larson, R.L.Latest pulse of earth: evidence for a mid-Cretaceous superplumeGeology, Vol. 19, No. 6, June pp. 547-550GlobalEarth, Superplume
DS1991-0957
1991
Larson, R.L.Larson, R.L.Geological consequences of superplumesGeology, Vol. 19, No. 10, October pp. 963-966GlobalSuperplumes, Pulsation tectonics
DS1991-0958
1991
Larson, R.L.Larson, R.L., Olson, P.Mantle plumes control magnetic reversal frequencyEarth and Planetary Science Letters, Vol. 107, No. 3/4, December pp. 437-447MantlePlumes, Geophysics -magnetics
DS1993-0883
1993
Larson, R.L.Larson, R.L.Mantle plumes and magnetic reversals: a surprising linkEos, Transactions, American Geophysical Union, Vol. 74, No. 4, January 26, p. 46MantleGeophysics -magnetics, Plumes
DS1995-1060
1995
Larson, R.L.Larson, R.L.The Mid Cretaceous superplume episodeScientific American, Vol. 272, No. 2, Feb. pp. 82-86.MantlePlumes, Cretaceous
DS1996-0809
1996
Larson, R.L.Larson, R.L., Kincaid, C.Onset of mid-Cretaceous volcanism by elevation of the 670 km thermal boundary layerGeology, Vol. 24, No. 6, June pp. 551-554Mantle, crustSubduction, slab, Core-mantle boundary
DS2001-0090
2001
Larson, R.L.Bartolini, A., Larson, R.L.Pacific microplate and the Pangea supercontinent in the Early to Middle Jurassic.Geology, Vol. 29, No. 8, Aug. pp. 735-8.PangeaContinents
DS1998-0831
1998
Larson, S.A.Larson, S.A., Tullborg, E.L.Why Baltic shield zircons yield late Paleozoic lower intercept ages on uranium-lead (U-Pb)concordia.Geology, Vol. 26, No. 10, Oct. pp. 919-23.Sweden, Baltic ShieldGeochronology
DS2000-0010
2000
Larson, S.A.Ahall, K.I., Larson, S.A.Growth related 1.85-1.55 Ga magmatism in the Baltic Shield: a review addressing tectonics characteristics.Gff., Vol. 122, pp. 193-206.Finland, Norway, Sweden, Baltic States, FennoscandiaTransscandinavian Igneous Belt, Magmatism, Tectonics
DS201706-1095
2017
Larson, T.Marshak, S., Domrois, S., Abert, C., Larson, T., Pavlis, G., Hamburger, M., Yang, X., Gilbert, H., Chen, C.The basement revealed: tectonic insight from a digital elevation model of the Great Unconformity, USA cratonic platform.Geology, Vol. 45, 5, pp. 391-394.United Statestectonics - Mid continent

Abstract: Across much of North America, the contact between Precambrian basement and Paleozoic strata is the Great Unconformity, a surface that represents a >0.4 b.y.-long hiatus. A digital elevation model (DEM) of this surface visually highlights regional-scale variability in the character of basement topography across the United States cratonic platform. Specifically, it delineates Phanerozoic tectonic domains, each characterized by a distinct structural wavelength (horizontal distance between adjacent highs) and/or structural amplitude (vertical distance between adjacent lows and highs). The largest domain, the Midcontinent domain, includes long-wavelength epeirogenic basins and domes, as well as fault-controlled steps. The pronounced change in land-surface elevation at the Rocky Mountain Front coincides with the western edge of the Midcontinent domain on the basement DEM. In the Rocky Mountain and Colorado Plateau domains, west of the Rocky Mountain Front, structural wavelength is significantly shorter and structural amplitude significantly higher than in the Midcontinent domain. The Bordering Basins domain outlines the southern and eastern edges of the Midcontinent domain. As emphasized by the basement DEM, several kilometers of structural relief occur across the boundary between these two domains, even though this boundary does not stand out on ground-surface topography. A plot of epicenters on the basement DEM supports models associating intraplate seismicity with the Midcontinent domain edge. Notably, certain changes in crustal thickness also coincide with distinct changes in basement depth.
DS201712-2679
2018
Larson, T.Chen, C., Hersh, G., Fischer, K.M., Andronicos, C.L., Pavlis, G.L., Hamburger, M.W., Marshak, S., Larson, T., Yang, X.Lithospheric discontinuities beneath the U.S. Midcontinent - signatures of Proterozoic terrane accretion and failed rifting.Earth and Planetary Science Letters, Vol. 481, pp. 223-235.United States, Illinois, Indiana, Kentuckygeophysics - seismics Reelfoot Rift

Abstract: Seismic discontinuities between the Moho and the inferred lithosphere-asthenosphere boundary (LAB) are known as mid-lithospheric discontinuities (MLDs) and have been ascribed to a variety of phenomena that are critical to understanding lithospheric growth and evolution. In this study, we used S-to-P converted waves recorded by the USArray Transportable Array and the OIINK (Ozarks-Illinois-Indiana-Kentucky) Flexible Array to investigate lithospheric structure beneath the central U.S. This region, a portion of North America's cratonic platform, provides an opportunity to explore how terrane accretion, cratonization, and subsequent rifting may have influenced lithospheric structure. The 3D common conversion point (CCP) volume produced by stacking back-projected Sp receiver functions reveals a general absence of negative converted phases at the depths of the LAB across much of the central U.S. This observation suggests a gradual velocity decrease between the lithosphere and asthenosphere. Within the lithosphere, the CCP stacks display negative arrivals at depths between 65 km and 125 km. We interpret these as MLDs resulting from the top of a layer of crystallized melts (sill-like igneous intrusions) or otherwise chemically modified lithosphere that is enriched in water and/or hydrous minerals. Chemical modification in this manner would cause a weak layer in the lithosphere that marks the MLDs. The depth and amplitude of negative MLD phases vary significantly both within and between the physiographic provinces of the midcontinent. Double, or overlapping, MLDs can be seen along Precambrian terrane boundaries and appear to result from stacked or imbricated lithospheric blocks. A prominent negative Sp phase can be clearly identified at 80 km depth within the Reelfoot Rift. This arrival aligns with the top of a zone of low shear-wave velocities, which suggests that it marks an unusually shallow seismic LAB for the midcontinent. This boundary would correspond to the top of a region of mechanically and chemically rejuvenated mantle that was likely emplaced during late Precambrian/early Cambrian rifting. These observations suggest that the lithospheric structure beneath the Reelfoot Rift may be an example of a global phenomenon in which MLDs act as weak zones that facilitate the removal of cratonic lithosphere that lies beneath.
DS201811-2605
2018
Larson, T.Salminen, J., Hanson, R., Evans, D.A.D., Gong, Z., Larson, T., Walker, O., Gumsley, A., Soderlund, U., Ernst, T.Direct Mesoproterozoic connection of the Congo and Kalahari cratons in proto-Africa: strange attractors across supercontinental cycles.Geology, doi.org/10.1130/G45294.1 4p.Africacraton

Abstract: Mobilistic plate-tectonic interpretation of Precambrian orogens requires that two conjoined crustal blocks may derive from distant portions of the globe. Nonetheless, many proposed Precambrian cratonic juxtapositions are broadly similar to those of younger times (so-called “strange attractors”), raising the specter of bias in their construction. We evaluated the possibility that the Congo and Kalahari cratons (Africa) were joined together prior to their amalgamation along the Damara-Lufilian-Zambezi orogen in Cambrian time by studying diabase dikes of the Huila-Epembe swarm and sills in the southern part of the Congo craton in Angola and in Namibia. We present geologic, U-Pb geochronologic, and paleomagnetic evidence showing that these two cratons were directly juxtaposed at ca. 1.1 Ga, but in a slightly modified relative orientation compared to today. Recurring persistence in cratonic connections, with slight variations from one supercontinent to the next, may signify a style of supercontinental transition similar to the northward motion of Gondwana fragments across the Tethys-Indian oceanic tract, reuniting in Eurasia.
DS201902-0316
2019
Larson, T.Salminen, J., Hanson, R., Evans, D.A.D., Gong, Z., Larson, T., Walker, O., Gumsley, A., Soderlund, U., Ernst, R.Direct Mesoproterozoic connection of the Congo and Kalahari cratons in proto-Africa: strange attractors across supercontinental cycles.Geology, Vol. 46, pp. 1101-1104.Africa, Angola, Namibiacraton

Abstract: Mobilistic plate-tectonic interpretation of Precambrian orogens requires that two conjoined crustal blocks may derive from distant portions of the globe. Nonetheless, many proposed Precambrian cratonic juxtapositions are broadly similar to those of younger times (so-called “strange attractors”), raising the specter of bias in their construction. We evaluated the possibility that the Congo and Kalahari cratons (Africa) were joined together prior to their amalgamation along the Damara-Lufilian-Zambezi orogen in Cambrian time by studying diabase dikes of the Huila-Epembe swarm and sills in the southern part of the Congo craton in Angola and in Namibia. We present geologic, U-Pb geochronologic, and paleomagnetic evidence showing that these two cratons were directly juxtaposed at ca. 1.1 Ga, but in a slightly modified relative orientation compared to today. Recurring persistence in cratonic connections, with slight variations from one supercontinent to the next, may signify a style of supercontinental transition similar to the northward motion of Gondwana fragments across the Tethys-Indian oceanic tract, reuniting in Eurasia.
DS201412-0220
2014
larson, T.E.Eiler, J.M., Berquist, B., Bourg, I., Cartigny, P., Farquhar, J., Gagnon, A., Guo, W., Halevy, I., Hofman, A., larson, T.E., Levin, N., Schauble, E.A., Stolper, D.Frontiers of stable isotope geoscience.Chemical Geology, Vol. 372, pp. 119-143.TechnologyReview of isotopes
DS1999-0395
1999
Larsson, J.O.Larsson, J.O.Europe: a new diamond province?North Atlantic Mineral Symposium, Sept., abstracts pp. 172-74.Finland, Russia, Kola, Sweden, Ireland, Baltic States, EuropeExploration - brief review
DS1998-0832
1998
Larsson, J-O.Larsson, J-O.Recent developments in diamond exploration in Sweden... legal framework, licences, history, companies active.Raw Materials Report, Vol. 13, No. 1, pp. 17-26.SwedenHistory, legal, Current activities, companies
DS1986-0484
1986
Larsson, S.Y.Larsson, S.Y., Stearn, C.W.Silurian stratigraphy of the Hudson bay Lowland in QuebecCanadian Journal of Earth Sciences, Vol. 23, pp. 288-99.QuebecStratigraphy
DS200912-0203
2009
Larsson, V.Ericsson, M., Larsson, V.E & MJ's annual survey of global mining investment.Engineering and Mining Journal, Jan-Feb. pp. 24-28.GlobalEconomics
DS201212-0186
2012
Larsson, V.Ericsson, M., Larsson, V.E & MJ's annual survey of global mining investment.E & MJ, Jan. pp. 24-29.GlobalMentions diamonds
DS1940-0073
1943
Larsson, W.Larsson, W.Zur Kenntnis der Alkalinen Ultrabasisc hen Ganggesteine der Kalix Gebiets Nord Schweden.Sveriges Geol. Unders. Arsbok, SER. C, No. 456. ARSBOK 37, No. 5, PP. 3-41.Sweden, ScandinaviaAlnoite, Mineralogy, Petrology
DS1998-0833
1998
Larter, R.D.Larter, R.D., King, E.C., Leat, P.T., Reading, SmellieSouth Sandwich slices reveal much about arc structure, geodynamics andcomposition.Eos, Vol. 79, No. 24, June 16, p. 281, 284-5.GlobalGeodynamics - not specific to diamonds, Arc structure
DS1982-0361
1982
Larue, D.K.Larue, D.K., Ueng, W.L.Early Proterozoic Arc-continent Collision Orogen, Lake Superior Region: Tectono-stratigraphic Terranes.Geological Society of America (GSA), Vol. 14, No. 7, P. 542, (abstract.).GlobalMid-continent
DS1983-0389
1983
Larue, D.K.Larue, D.K.Early Proterozoic Tectonics of the Lake Superior Region: Tectonostratigraphic Terranes Near the Purported Collision Zone.Geological Society of America (GSA) MEMOIR., No. 160, PP. 33-48.GlobalMid-continent
DS1985-0134
1985
Lasag, A.C.Cygan, R.T., Lasag, A.C.Self Diffusion of Magnesium in Garnet at 750 to 900 CAmerican Journal of Science, Vol. 285, April pp. 328-350GlobalBlank
DS1982-0161
1982
Lasaga, A.C.Cygan, R.T., Lasaga, A.C.Crystal Growth and the Formation of Chemical Zoning in GarnetsContributions to Mineralogy and Petrology, Vol. 79, pp. 187-200.GlobalMineralogy - Garnets
DS1989-0116
1989
Lasaga, A.C.Berner, R.A., Lasaga, A.C.Modeling the geochemical carbon cycleScientific American, Vol. 260, No. 3, pp. 74-81. Database # 17584GlobalGreenhouse effect, Geochemistry
DS1992-1468
1992
Lasaga, A.C.Steefel, C.I, Lasaga, A.C.Transport into water-rock interaction modelsGeology, Vol. 20, No. 8, August pp. 680-684GlobalFluid flow paths, Water-rock interaction
DS2001-0654
2001
Lasaga, A.C.Lasaga, A.C., Rye, D.M., Bolton, E.W.Calculation of fluid fluxes in Earth's CrustGeochimica et Cosmochimica Acta, Vol. 65, No. 7, pp. 1161-85.MantleGeochemistry - fluid flux models
DS1993-0096
1993
LaSalle, P.Beaumier, M., Dion, D-J., LaSalle, P., Moorhead, J.Exploration du diamant au Temiscamingue. (in French)Quebec Department of Mines Promotional, PRO 93-08, 7p.Quebec, TimiskamingGeochemistry, Heavy minerals-brief overview
DS1994-0123
1994
Lasalle, P.Beaumier, M., Lasalle, P., Warren, B., Lasalle, Y.R.Mineraux indicateurs de kimberlite dans les eskers du nord ouest Quebecois.(in French)Quebec Department of Mines, MB 93-60 1 map 1: 250, 000 paper copy $ 3.50QuebecGeochemistry, Mineralogy
DS1994-0123
1994
Lasalle, Y.R.Beaumier, M., Lasalle, P., Warren, B., Lasalle, Y.R.Mineraux indicateurs de kimberlite dans les eskers du nord ouest Quebecois.(in French)Quebec Department of Mines, MB 93-60 1 map 1: 250, 000 paper copy $ 3.50QuebecGeochemistry, Mineralogy
DS1993-1417
1993
Laschen..VA.Sekerin, A.P., Mensgagin, Y.V., Laschen..VA.Dokembrian lamproites of the Prisayan. (Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 329, No. 3, March pp. 328-331. # LG762RussiaLamproites
DS1910-0199
1911
Laschinger, E.J.Laschinger, E.J.The Kimberley and Rand Systems of Mining Compared. Discussion of Williams's Paper Entitled the Kimberley System of Handling Large Quantities of Ground.South African Mining Journal, Vol. 9, PT. 1, MAY 27TH. PP. 553-554.South AfricaMining Methods
DS1988-0404
1988
Lash, G.G.Lash, G.G.Along strike variations in foreland basin evolution: possible evidence for continental collision along an irregular marginBasin Research, Vol. 1, No. 2, June pp. 71-84GlobalBasin, Tectonics
DS1988-0622
1988
Lashchenov, V.A.Sekerin, A.P., Menshagin, I.V., Lashchenov, V.A.Alkaline-ultrabasic rocks and carbonatites of the eastern Sayan. (Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 299, No. 3, pp. 711-714RussiaBlank
DS1989-1367
1989
Lashchenov, V.A.Sekerin, A.P., Menshagin, Yu.V., Lashchenov, V.A., Tverdokh, ebova, A.A.New occurrence of carbonatites and the structural control of alkaline Rocks in the eastern Sayan Province, USSR. (Russian)Izk. Iruktsk. USSR. Izv. Akad. Nauk SSSR, No. 8, pp. 34-41RussiaAlkaline rocks, Carbonatite
DS1991-1538
1991
Lashchenov, V.A.Sekerin, A.P., Menshagin, V., Vladimirov, B.M., Lashchenov, V.A.Precambrian diamond bearing veined bodies from southwest of the SiberianPlatformProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 543-544RussiaVeins, lamproite, Chrome spinellids, geochronology
DS1992-1363
1992
Lashchenov, V.A.Sekerin, A.P., Menshagin, Yu.V., Lashchenov, V.A.New dat a on Precambrian kimberlites from the near Sayan regionSoviet Geology and Geophysics, Vol. 32, No. 12, pp. 57-63.Russia, SayanKimberlites, Textures
DS1995-1697
1995
Lashchenov, V.A.Sekerin, A.P., Menshagin, Yu.V., Lashchenov, V.A.Sayan Precambrian lamproitesDoklady Academy of Sciences, Vol. 329A, No. 3, April, pp. 99-104.Russia, SayanLamproites
DS1996-1276
1996
Lashchenov, V.A.Sekerin, A.P., Menshagin, Yu.V., Lashchenov, V.A.Origin of ultrabasic rocks of the dunite harzburigite association occurring in the Main Sayan Fault zone.Doklady Academy of Sciences, Vol. 340, No. 2, March., pp. 89-95.RussiaSiberian Craton, Malyy Tagui
DS1995-1698
1995
Lashenov, V.A.Sekerin, A.P., Menshagin, Yu.V., Lashenov, V.A.high Pressureotassic mantle magmatism and the problems of diamond bearing in the Irkutsk Prisyanye area.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 492-493.Russia, Irkutsk, PrisyanyeLamproite, Deposit -Ingashinskoe
DS2001-0767
2001
LashkevichMedvedev, V.Ya., Ivanova, Egorov, Lashkevich, UshchapovKelyphitic rims around garnet in kimberlites: an experimental studyDoklady, Vol.381A, No.9, Nov-Dec. pp. 1096-98.RussiaKimberlite - garnet mineralogy
DS200412-1086
2004
Lashkevich, V.V.Lashkevich, V.V., Medvedev, V.Y., Egorov, K.N., Ivanova, L.A.Experimental and numerical modeling of the metasomatic replacement of picroilmenites from kimberlites.Geochemistry International, Vol. 42, 1, pp. 49-56.RussiaMetasomatism, Deposit - Jubileinaya
DS201810-2352
2018
Lasiter, J.C.Marshall, E.W., Lasiter, J.C., Barnes, J.D.On the (mis) behavior of water in the mantle: controls on nominally anhydrous mineral water content in mantle peridotites.Earth and Planetary Science Letters, Vol. 499, pp. 219-229.United States, Colorado Plateaumetasomatism

Abstract: In magmatic settings, water behaves as an incompatible species and should be depleted during melting and enriched during metasomatism. Previous studies have identified correlations between nominally anhydrous mineral (NAM) water content ([H2O]) and indices of metasomatism or melt extraction, seemingly confirming this behavior in the mantle. However in detail, these correlations are ambiguous and do not reflect robust controls on NAM [H2O]. We measured orthopyroxene (opx) and clinopyroxene (cpx) [H2O] in variably hydrated and metasomatized peridotite xenoliths from the Navajo volcanic field (NVF) that sample the Colorado Plateau subcontinental lithospheric mantle (SCLM), an endmember of SCLM hydration and metasomatism. These xenoliths span a wide range of pyroxene [H2O] (opx from 50 to 588 ppm wt. H2O; cpx from 38 to 581 ppm wt. H2O), but NAM [H2O] does not correlate with either indices of melt depletion or metasomatism. Growth of hydrous minerals suggests higher water activity than in anhydrous peridotites, and therefore hydrous-mineral-bearing xenoliths and anhydrous xenoliths should have different NAM [H2O] and water activities. However, when the two groups are compared no significant differences can be found in either NAM [H2O] or water activity. We propose that the high diffusivity of hydrogen in the mantle allows for equilibration of water activity in the mantle over sub-kilometer length scales over geologic time. Such diffusive equilibration reduces water activity variability and results in the blurring and destruction of correlations between NAM [H2O] and indices of metasomatism or melt extraction. As a result of diffusive equilibration of water, there is a large difference in the variability of concentration between NAM [H2O] (spanning ?2 orders of magnitude) and similarly incompatible elements such as Ce in the same peridotites (spanning ?4 orders of magnitude). This difference in behavior explains why H2O/Ce ratios in mantle peridotites are highly variable relative to those of basalts.
DS201112-0100
2011
Laskar, J.Boulila, S., Galbrun, B., Miller, K.G., Pekar, S.F., Browning, J.V., Laskar, J., Wright, J.D.On the origin of Cenozoic and Mesozoic 'third order' eustatic sequences.Earth Science Reviews, Vol. 109, 3-4, pp. 94-112.GlobalGeomorphology - sea levels
DS200612-1616
2006
Laske, G.Zhou, Y., Nolet, G., Dahlen, F.A., Laske, G.Global upper mantle structure from finite frequency surface wave tomography.Journal of Geophysical Research, Vol. 111, B4 B04304 2005JB003677MantleTomography
DS200612-1617
2006
Laske, G.Zhou, Y., Nolet, G., Dahlen, F.A., Laske, G.Global upper mantle structure from finite frequency surface wave tomography.Journal of Geophysical Research, Vol. 111, B4, B04304.MantleGeophysics - seismics
DS200512-0714
2005
Laskevich, V.V.Medvedev, V.Y., Ivanova, L.A., Egorov, K.N., Laskevich, V.V.Formation of kelphytic rims around garnet in kimberlites: experimental and physicochemical modeling.Geochemistry International, Vol. 43, 8, pp. 769-775.RussiaMineral chemistry
DS1991-0514
1991
Laskey, R.Friday, L., Laskey, R.The fragile environment: new approaches to global problemsCambridge University of Press, $ 15.95 approx, GlobalBook -ad, Fragile environment
DS1983-0390
1983
Lasko, YE.YE.Lasko, YE.YE., Koptil, V.I., et al.Fassaite Clinpoyroxenes from Diamond Bearing Kyanite Eclogite Xenoliths.Doklady Academy of Sciences ACAD. NAUK USSR EARTH SCI. SECTION., Vol. 258, No. 1-6, PP. 138-142.Russia, YakutiaMineral Chemistry, Sytykan, Pipe, Analyses
DS1985-0083
1985
Lasnier, B.Boyer, H., Smith, D.C., Chopin, C., Lasnier, B.Raman Microprobe (rmp) Determinations of Natural and Synthetic Coesite.Physics Chem. Minerals, Vol. 12, No. 1, PP. 45-48.South Africa, NorwayEclogite, Roberts Victor, Westen Gneiss, Dora Maira, Brytting
DS1991-0234
1991
Lasnier, B.M.Castelo Branco, R.M.G., Lasnier, B.M.Geology and geophysics of the Redondao kimberlite diatreme northeasternBrasilProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 35-37BrazilGeophysics -magnetics, Structure -Redondao
DS2003-1343
2003
Lass Evans, S.Stuart, F.M., Lass Evans, S., Fitton, J.G., Ellam, R.M.High 3 He 4 He ratios in picritic basalts from Baffin Island and the role of a mixedNature, No. 6944, July 3, pp. 57-59.Northwest Territories, Baffin Island, NunavutPicrites
DS200412-1942
2003
Lass Evans, S.Stuart, F.M., Lass Evans, S., Fitton, J.G., Ellam, R.M.High 3 He 4 He ratios in picritic basalts from Baffin Island and the role of a mixed reservoir in mantle plumes.Nature, No. 6944, July 3, pp. 57-59.Canada, Nunavut, Baffin IslandPicrite
DS200612-0767
2006
Lassak, T.M.Lassak, T.M., Fouch, M.J., Hall, C.E., Kaminski, E.Seismic characterization of mantle flow in subduction systems: can we resolve a hydrated mantle wedge?Earth and Planetary Science Letters, Vol. 243, 3-4, March 30, pp. 632-649.MantleSubduction, water
DS200712-0597
2007
Lassak, T.M.Lassak, T.M., McNamara, A.K., Zhong, S.Influence of thermochemical piles on topography at Earth's core-mantle boundary.Earth and Planetary Science Letters, Vol. 261, 3-4, pp. 443-455.MantleGeothermometry
DS201012-0425
2010
Lassak, T.M.Lassak, T.M., McNamara, A.K., Garnero, E.J., Zhong, S.Core mantle boundary topography as a possible constraint on lower mantle chemistry and dynamics.Earth and Planetary Science Letters, Vol. 289, pp. 232-241.MantleConvection, plumes
DS2002-0899
2002
Lassen, A.Krawczyk, C.M., Eilts, F., Lassen, A., Thybo, H.Seismic evidence of Caledonian deformed crust and uppermost mantle structures in the northern part of the Trans European Suture Zone, SW Baltic Sea.Tectonophysics, Vol. 360, 1-4, pp. 215-44.Europe, Baltic SeaTectonics
DS200712-0840
2006
Lassen, A.Pharaoh, T.C., Winchester, J.A., Verniers, J., Lassen, A., Seghedi, A.The Western accretionary margin of the East European Craton: an overview.Geological Society of London Memoir, No. 32, pp. 291-312.Russia, Europe, UralsCraton
DS1991-0971
1991
Lasserre, J-L.Ledru, P., Lasserre, J-L., Manier, E., Mercier, D.The lower Proterozoic of northern Guiana: a revision of the lithology, transcurrent tectonics and sedimentary basin dynamicsBulletin Societe Geologique France, Vol. 162, No. 4, pp. 627-636GlobalBasin, Tectonics
DS1991-1477
1991
Lassiter, J.Rutz, J., Rattray, G., Wendlandt, E., Lassiter, J.Evolution of Lower crust: granulite facies xenoliths from cratons andriftsEos Transactions, Vol. 72, No. 44, October 29, abstract p. 543MantleDiatremes, Xenoliths
DS1995-1061
1995
Lassiter, J.C.Lassiter, J.C., De Paolo, D.J., Mahoney, J.J.Geochemistry of Wrangellia flood basalt province: implications for the roleof continental lithosphere.Journal of Petrology, Vol. 96, No. 4, pp. 983-1009United States, Wrangellia TerraneBasalt, Flood basalt genesis
DS200512-0599
2004
Lassiter, J.C.Lassiter, J.C.Role of recycled oceanic crust in the potassium and argon budget of the Earth: toward a resolution of the 'missing argon' problem.Geochemistry, Geophysics, Geosystems: G3, Vol. 5, pp. Q11012 10.1029/2004 GC000711MantleGeochemistry, cycles
DS200612-0768
2006
Lassiter, J.C.Lassiter, J.C.Constraints on the coupled thermal evolution of the Earth's core and mantle, the age of the inner core, and origin of the 186Os /1880s core signal in plume lavasEarth and Planetary Science Letters, Vol. 250, 1-2, pp. 306-317.MantleGeochronology
DS200612-0769
2006
Lassiter, J.C.Lassiter, J.C.Constraints on the age of the Earth's inner core and the origin of the 186 Os 188 Os core signal in plume related lavas.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 343, abstract only.MantleGeochronology
DS200612-0770
2006
Lassiter, J.C.Lassiter, J.C.Constraints on the coupled thermal evolution of the Earth's core and mantle, the age of the inner core and the origin of the 186 Os 188 Os core signal in plume..Earth and Planetary Science Letters, In press - availableUnited States, HawaiiGeothermometry - potassium, not specific to diamonds
DS201610-1849
2016
Lassiter, J.C.Chatterjee, R., Lassiter, J.C.186Os/188Os variations in upper mantle peridotites: constraints on the Pt/Os ratio of primitive upper mantle, implications for late veneer accretion and mantle mixing timescales.Chemical Geology, Vol. 442, pp. 11-22.United States, Colorado PlateauPeridotite

Abstract: 186Os/188Os variations in mantle peridotites provide constraints on the long-term Pt/Os evolution of the depleted mantle and the Pt/Os ratio of the primitive upper mantle (PUM). We report new 186Os/188Os data for mantle peridotites from continental (Rio Grande Rift and Colorado Plateau) and oceanic (Lena Trough and Hawaiian Islands) settings that span a wide range in fertility (Al2O3 ? 0.67-4.42 wt.%) and 187Os/188Os ratios (0.1138-0.1305). Although peridotite 186Os/188Os values span only a narrow range (from 0.1198345 to 0.1198384), 186Os/188Os broadly correlates with indices of melt depletion including bulk rock Al2O3, spinel Cr#, and clinopyroxene Cr#, consistent with Pt depletion in residual peridotites. PUM 186Os/188Os is estimated to be 0.1198378 ± 23 (2 SD) based on extrapolation of 186Os/188Os-fertility trends, which is very slightly lower than H-chondrites [? 0.1198398 ± 16 (2 SD); Brandon et al., 2006]. This value is consistent with a PUM Pt/Os of 1.7 ± 0.2, similar to average Pt/Os ratios of fertile continental peridotites. The inferred PUM Pt/Os is slightly lower than but within error of Pt/Os values measured in several classes of chondrites [Carbonaceous ? 1.8 ± 0.2, Ordinary ? 1.9 ± 0.1, and Enstatite ? 1.9 ± 0.1 (Brandon et al., 2006)] indicating that PUM Pt/Os is broadly chondritic. In contrast, estimates for PUM Ru/Ir and Pd/Ir (cf. Becker et al., 2006) are suprachondritic. The addition of a chondritic late veneer alone cannot create a combination of chondritic and suprachondritic HSE ratios for the PUM. Instead, minor core segregation occurring concurrently with the addition of a late veneer may explain the observed mantle HSE abundances and ratios. Combined 186Os/188Os-187Os/188Os isotopic and Pt/Os and Re/Os variability in peridotites suggest an average mantle homogenization timescale of ~ 1.2 Ga. In contrast, combined Hf-Nd isotopic and Lu/Hf and Sm/Nd variability in peridotites indicate much shorter homogenization timescales (< 0.4 Ga), potentially reflecting enhanced homogenization by melt-rock interaction to which the Pt-Os and Re-Os systems are relatively immune. The mechanical mixing timescale inferred from Os isotopes is consistent with timescales predicted for whole mantle convection.
DS201707-1348
2017
Lassiter, J.C.Marshall, E.W., Lassiter, J.C., Barnes, J.D., Luguet, A., Lissner, M.Mantle melt production during the 1.4 Ga Laurentian magmatic event: isotopic constraints from Colorado Plateau mantle xenoliths.Geology, Vol. 45, 6, pp. 519-522.United States, Colorado Plateaumelting - Navajo Volcanics

Abstract: Plutons associated with a 1.4 Ga magmatic event intrude across southwestern Laurentia. The tectonic setting of this major magmatic province is poorly understood. Proposed melting models include anorogenic heating from the mantle, continental arc or transpressive orogeny, and anatexis from radiogenic heat buildup in thickened crust. Re-Os analyses of refractory mantle xenoliths from the Navajo volcanic field (NVF; central Colorado Plateau) yield Re depletion ages of 2.1–1.7 Ga, consistent with the age of the overlying Yavapai and Mazatzal crust. However, new Sm-Nd isotope data from clinopyroxene in peridotite xenoliths from NVF diatremes show a subset of xenoliths that plot on a ca. 1.4 Ga isochron, which likely reflects mantle melt production and isotopic resetting at 1.4 Ga. This suggests that Paleoproterozoic subcontinental lithospheric mantle was involved in the 1.4 Ga magmatic event. Our constraints support a subduction model for the generation of the 1.4 Ga granites but are inconsistent with rifting and anorogenic anatexis models, both of which would require removal of ancient lithosphere.
DS201803-0464
2017
Lassiter, J.C.Marshall, E.W., Barnes, J.D., Lassiter, J.C.The role of serpentinite derived fluids in metasomatism of the Colorado Plateau ( USA) lithospheric mantle.Geology, Vol. 45, 12, pp. 1103-1106.United States, Colorado Plateausubduction

Abstract: Subducting serpentinized lithosphere has distinct ?D and ?18O values compared to normal mantle. Slab-derived fluids that infiltrate the mantle wedge can alter its oxygen and hydrogen isotope composition, raising or lowering the ?18O and ?D values depending on the nature of the subducted components. Hydrous minerals in peridotite xenoliths from the Colorado Plateau (southwestern USA) have ?D values (up to ?33‰) much higher than average mantle (?80‰), but similar to ?D values of olivine-hosted melt inclusions within arc basalts, suggesting a slab-derived fluid source. Oxygen isotope ratios of olivine from these xenoliths are similar to average mantle, yet display a strong negative correlation with clinopyroxene Ce/Sm, a proxy of metasomatism. This correlation is most simply explained by metasomatism from fluids derived from the serpentinized portion of the Farallon slab. Although ?18O values of mantle minerals span a narrow range, integration of stable isotope data with other geochemical tracers can provide new constraints on modern and ancient subduction-related processes, potentially providing a method for probing Archean lithospheric mantle for evidence of early subduction.
DS201809-2053
2018
Lassiter, J.C.Lassiter, J.C.On the equilibration timescales of isolated trace phases in mantle peridotites: implications for the interpretation of grain scale isotope heterogeneity in peridotitic sulfides.Earth and Planetary Science Letters, Vol. 498, pp. 427-435.Mantleperidotites

Abstract: Geochemical studies of mid-ocean-ridge basalts (MORB) and mantle peridotites (e.g., abyssal peridotites) provide independent constraints on the composition and evolution of the convecting mantle. Recent studies have revealed systematic differences in the radiogenic isotope compositions of MORB and abyssal peridotites that call into question the complementary nature of these two windows to the upper mantle. The origin of these differences is fundamental to our understanding of MORB petrogenesis and the composition and depletion history of the upper mantle. The use of isotope variations in basalts to probe the composition and evolution of the mantle is predicated on the assumption of local (i.e., grain-scale) isotopic equilibrium during mantle melting. However, several studies have reported Os- and Pb-isotope disequilibrium in distinct populations of peridotite-derived sulfides, with sulfides included within silicate grains typically possessing more “depleted” isotopic compositions than interstitial sulfides. In principle, grain-scale isotopic heterogeneity could reflect variable radiogenic ingrowth in ancient sulfides with variable parent/daughter ratios, or partial re-equilibration of low-Re/Os and U/Pb sulfides with more radiogenic silicate phases along grain boundaries during mantle melting. This would require that sulfides fail to maintain isotopic equilibrium with neighboring phases over geologically long (? Ga) time scales. The preservation of Os-isotope disequilibrium in peridotites has been ascribed in several studies to the armoring effect of low-[Os] silicates, which limits diffusive exchange between isolated Os-rich sulfides. This raises the prospect that peridotite-derived melts may not inherit the Os- (or Pb-) isotope composition of their source, which could account for the recently documented systematic differences in the Os- and Pb-isotope compositions of MORB and mantle peridotites. Although the preservation of isotopic heterogeneity in mantle sulfides is commonly ascribed to the above “armoring effect”, the diffusive equilibration timescale of spatially separated sulfides in mantle peridotites has not previously been rigorously estimated. This study examines the parameters that control this equilibration timescale (average sulfide size and spacing, Os and Pb diffusivity in armoring silicate minerals, and element partitioning between silicate and sulfide phases). Equilibration timescale estimates using available constraints on these parameters reveal that most mantle sulfides are expected to isotopically re-equilibrate with neighboring sulfides in less than a few 10 s of Myr at convecting mantle temperatures. Maintenance of isotopic disequilibrium over the ? Ga timescales suggested by observed intra-sample Os- and Pb-isotope heterogeneity requires very large sulfides (>100 ?m) separated by several mm or diffusion rates (D <10?18 m2/s), slower than for most elements in olivine. Combined with the observation of intra-sample major element heterogeneity in sulfide Ni and Fe abundances (which should equilibrate quickly in the convecting mantle), these results suggest that the observed isotopic disequilibrium is unlikely to be an ancient feature in mantle peridotites. Instead, recent sulfide metasomatism linked to interaction with melts derived from isotopically enriched eclogite or pyroxenite (or fertile and/or metasomatized peridotite) components is a more likely explanation for observed intra-sample isotopic heterogeneity in peridotites. This interpretation is also consistent with systematic differences between the Nd- and Hf-isotope compositions of MORB and abyssal peridotites. These results further strengthen the proposal that MORB do not accurately reflect the average isotopic composition of the convecting upper mantle, and that upper mantle peridotite is, on average, significantly more depleted and refractory than suggested by MORB-based estimates. The effects of melt generation in a heterogeneous marble-cake mantle need to be explicitly considered when using basalt compositions to constrain mantle composition and evolution.
DS201809-2068
2018
Lassiter, J.C.Marshall, E.W., Lassiter, J.C., Banes. J.B.Understanding the (mis) behaviour of water contents in nominally anhydrous mantle minerals.Goldschmidt Conference, 1p. AbstractMantleperidotites

Abstract: The H/C ratio in earth’s exosphere is higher than it is in the source region of primitive basalts, suggesting an enriched carbon reservoir in the mantle[1]. A plausible explanation is that subduction of carbon may have enriched the mantle in recycled carbon over time. Average basaltic crust contains ~ 2 wt.% CO2 [2], and modeling of slab devolatilisation suggests that subducted carbonate may survive to be transported deeper into the mantle [3]. Carbonated oceanic crust should melt in the transition zone along most subduction geotherms due to a deep trough in the carbonated basalt solidus, and mineral inclusions in superdeep diamonds testify to carbonate melt in their formation [4]. Along cool subduction geotherms carbonate may subduct into the lower mantle, potentially enriching the deep mantle in carbon. Here we report on laser-heated diamond anvil cell experiments in the CaO-MgO-SiO2-CO2 and FeO-MgO-SiO2-CO2 systems at lower mantle pressures where we investigate the stability of carbonate in oceanic crust, and test for decarbonation and diamond forming reactions involving carbonate and coexisiting free silica. We find that carbonate reacts with silica to form bridgmanite ± Ca-perovskite + CO2 at pressures in the range of ~50 to 70 GPa. These decarbonation reactions form an impenetrable barrier to subduction of carbonate into the deeper lower mantle, however, slabs may carry solid CO2 (Phase V) into the deeper lower mantle. We also identify reactions where carbonate or CO2 dissociate to form diamond plus oxygen. We suggest that the deep lower mantle may become enriched in carbon in the form of diamond over time due to subduction of carbonate and solid CO2 and its eventual dissociation to form diamond plus oxygen. Release of oxygen during diamond formation may also provide a mechanism for locally oxidizing the deep mantle.
DS201012-0763
2010
Lassonde, J.Strand, P., Lassonde, J., Burgess, J.Transforming a diamond mine: the Jericho diamond mine update.38th. Geoscience Forum Northwest Territories, Abstract pp.87-88.Canada, NunavutJericho project
DS201112-1011
2011
Lassonde, J.Strand, P., Lassonde, J.Geological and project update: Jericho diamond mine, Nunavut.Yellowknife Geoscience Forum Abstracts for 2011, abstract p. 81-82.Canada, NunavutGeology - model
DS200412-1087
2003
Lassonde, P.Lassonde, P.How to earn your social licence.. without local community support, your project is going nowhere.Mining Review, Summer, pp. 7,9,10,11,13.GlobalLegal - social
DS1996-1045
1996
LastNyblade, A.A., Birt, C., Langston, C.A., Owens, T.J., LastSeismic experiment reveals rifting of Craton in TanzaniaEos, Vol. 77, No. 51, Dec. 17, p. 517, 521.TanzaniaGeophysics - seismics, Craton
DS201112-0867
2011
LastochkinRipp, G.S., Doboshkevich, A.G., Ripp, G.S., Lastochkin, Izbrodin, RampilovA way of carbonatite formation from alkaline gabbros, Oshurkovo massif.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.39-41.RussiaOshurkovo
DS201112-0868
2011
LastochkinRipp, G.S., Doboshkevich, A.G., Ripp, G.S., Lastochkin, Izbrodin, RampilovA way of carbonatite formation from alkaline gabbros, Oshurkovo massif.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.39-41.RussiaOshurkovo
DS200612-0771
2006
Lastochkin, E.I.Lastochkin, E.I., Ripp, G.S., Doroshkevich, A.G., Badmatsirenov, M.V.Metamorphism of the Vesloe carbonatites, north Transbaikalia, Russia.Vladykin: VI International Workshop, held Mirny, Deep seated magmatism, its sources and plumes, pp. 207-RussiaCarbonatite
DS1987-0397
1987
Lastovickova, M.Lastovickova, M., Ramana, Y.V., Gogte, B.S.Electrical conductivity of some rocks from the Indian subcontinentStudies Geophysics Geody, Vol.31, No. 1 pp. 60-72IndiaGeophysics, Kimberlite
DS2001-0655
2001
Lastowika, L.A.Lastowika, L.A., Sheehan, A.F., Schneider, J.M.Seismic evidence for partial lithospheric delamination model of Colorado Plateau Uplift.Geophysical Research Letters, Vol. 28, No. 7, April 1, pp.1319-22.Colorado PlateauTectonics, Geophysics - seismics
DS2000-0552
2000
Lastowka, L.A.Lastowka, L.A.Western United States upper mantle velocity structure from PN arrivals and Rayleigh wave dispersion data.Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-103.Colorado PlateauGeophysics - seismics, Tectonics
DS1860-0559
1887
Latchinoff, M.M.Latchinoff, M.M., Joefeif.Meteorite from Novy Urej Penza SiberiaNature., Dec. 1ST.RussiaMeteorite
DS201112-0569
2011
LatelineLatelineRio Tinto accused of threatening endangered tigers.... Bundar area.abc.net.au, Dec. 1, 2p.IndiaNews item - Rio Tinto
DS1988-0405
1988
Latham, L.R.Latham, L.R., Newill, R.J., Wallin, E.T.uranium-lead (U-Pb) (U-Pb) geochronology of southern MissouriGeological Society of America Abstracts with Program, Vol. 20, No. 2, January p. 122. Sth. Central, LawrenceMissouriMid continent
DS1986-0348
1986
Latham, T.Hauser, E.C., Barnes, A., Gephart, J., Latham, T., Lundy, J.Brown.COCORP deep reflection transect in Arizona: across the transition zone from Colorado Plateau to core complexesEos, Vol. 67, No. 44, Nov. 4th. p. 1096. (abstract.)Colorado Plateau, ArizonaGeophysics, Tectonics
DS1990-1064
1990
Latham, T.Morel-a-l'hussier, P., Green, A. G., Jones, A.G., Latham, T.The crust beneath the intracratonic Williston Basin from geophysical datain: Pinet, B., Bois, C. editors The potential of deep seismic profiling for, pp. 141-160SaskatchewanGeophysics, Williston Basin
DS1992-0319
1992
Latham, T.Culotta, R., Latham, T., Sydow, M., Oliver, J., Brown, L., KaufmanDeep structure of the Texas Gulf passive margin and its Ouachita Precambrian basement: results of the COCORP San Marcos Arch surveyAmerican Association of Petroleum Geologists Bulletin, Vol. 76, No. 2, February pp. 270-285GlobalTectonics, Geophysics -seismics COCORP
DS1988-0406
1988
Latham, T.S.Latham, T.S., Best, J., Chaimov, T., Oliver, J., Brown, L.COCORP profiles from the Montana plains: the Archean cratonic crust And a lower crustal anomaly beneath the Williston basinGeology, Vol. 16, No. 12, December pp. 1073-1076MontanaMantle, Geophysics
DS1860-0898
1895
Latimer, E.W.Latimer, E.W.Europe in Africa in the Nineteenth CenturyChicago: Mcclurg, 451P.Africa, South AfricaHistory
DS1990-0905
1990
Latin, D.Latin, D., White, N.Generating melt during lithospheric extension: pureshear vs. simpleshearGeology, Vol. 18, No. 4, April pp. 327-331GlobalMantle melt, Tectonics -shear
DS1993-0884
1993
Latin, D.Latin, D., Norry, M.J., Tarzey, R.J.E.Magmatism in the Gregory Rift, East Africa: evidence for melt generation bya plume.Journal of Petrology, Vol. 24, No. 5, October pp. 1007-1028.TanzaniaTectonics, Magmatism
DS1992-0911
1992
Latin American InstituteLatin American InstituteThe South American mining guideLatin American Institute, Subscription $ 995.00South AmericaBook -ad, Mining laws, legal
DS1982-0362
1982
Latou, A.Latou, A.Les Gisements de Diamant de la Republique Centraafricaine Dans Leur Contexte Geologique de l'afrique Centrale: Cas Particulier de N'zako.Ph.d. Thesis, University Paris, 114P.West Africa, Central African RepublicOrigin, Diamonds
DS201708-1571
2017
Latouche, C.Fritsch, E., Rondeau, B., Devouard, B., Pinsault, L., Latouche, C.Why are some crystals gem quality? Crystal growth considerations on the 'GEM FACTOR'.The Canadian Mineralogist, Vol. 55, 4, pp. 521-533.TechnologyDeposit - Renard 2

Abstract: The purpose of this work is to investigate the crystal growth parameters necessary or sufficient to obtain a crystal specifically of gem quality. We assume adequate chemistry is available. First, nucleation must occur with only a limited number of nuclei, otherwise too many crystals will be produced, and they will be too small to be faceted into a gem. Two growth mechanisms are readily documented for gems: Most commonly there is slow growth, driven by a spiral growth mechanism, leading to large single individuals. There are only a few examples of fast growth leading to gem-quality edifices: examples include “gota de aceite” Colombian emerald or the dendritic “pseudo cube” for gem diamonds. We have not documented the intermediate conditions between these two extremes in the Sunagawa diagram, which would correspond to 2D nucleation growth. The presence of inclusions is to be limited to desirable ones. Thus, in general, a good stability of the growth interface is the best guarantee of good clarity in the final gem. As for the interface, in general, growth conditions must be relatively stable over the period necessary to achieve growth. Perhaps surprisingly, it has become well documented that gem-quality near-colorless diamonds may have experienced quite a complex growth history. Therefore, the term stability has to be re-defined for each system producing a given gem. The length of time it takes to achieve crystallization of the gem has rarely been studied or estimated. Scientific evidence from experimental petrology and the growth of synthetic gems indicates that it does not take millions of years to grow a gem, but that this exercise may be achieved in a week to, arguably, a few years at the most. Available free space to grow does not appear always necessary, but it helps. Otherwise deformation, inclusions, and other negative effects may occur. Finally, no dramatic post-growth events, such as fracturing or etching, should affect the gem crystal.
DS1994-0988
1994
LaTourette, T.LaTourette, T., Holloway, J.R.Oxygen fugacity of the diamond + C-O fluid assemblage and CO2 fugacity at 8GPa.Earth Planetary Science Letters, Vol. 128, No. 3-4, Dec. pp. 439-452.GlobalDiamond genesis
DS1991-0588
1991
Lattanzi, C.R.Goode, J.R., Davie, M.J., Smith, L.D., Lattanzi, C.R.Back to basics: the feasibility studyThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 84, No. 953, September pp. 53-61GlobalEconomics, Valuation
DS1991-0959
1991
Lattanzi, P.Lattanzi, P.Applications of fluid inclusions in the study and exploration of mineraldepositsEur. Journal of Mineral, Vol. 3, No. 4, pp. 689-701GlobalOre deposits, Fluid inclusions
DS1989-0854
1989
Lattanzi, R.Lattanzi, R.Significant factors in mine valuationThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) 91st. Annual Meeting Preprint, No. 79, 20p. Database # 17962GlobalEconomics, Mine evaluation
DS1910-0069
1910
LatteuxLatteuxAu Pays de L'or et les DiamantParis: Ailland, Alves And Cie, Rio De Janeiro: Francisco, Alvi, 430P.BrazilKimberlite
DS1910-0070
1910
LatteuxLatteuxAu Pays de L'or et des Diamants. a Travers le BresilParis: Ailland, Alves And Cie., 430P.BrazilKimberlite
DS200612-0506
2006
Latti, D.Grutter, H., Latti, D., Menzies, A.Cr saturation arrays in concentrate garnet compositions from kimberlite and their use in mantle barometry.Journal of Petrology, Vol. 47, 4, April pp. 801-820.MantleGeobarometry, chromite, chromium
DS202004-0526
2020
Laturtrie. B.Laturtrie. B., Ross, P-S.Phreatomagmatic vs magmatic eruptive styles in maar-diatremes: a case study at Twin Peaks, Hopi Buttes volcanic field, Navajo Nation, Arizona.Bulletin of Volcanology, Vol. 82, 28.United States, Arizonamagmatism

Abstract: The Hopi Buttes volcanic field (HBVF) is located on the Colorado Plateau, Northern Arizona. In this Miocene volcanic field, the erosion level increases southward, allowing the study of maar-diatreme volcanoes from top (posteruptive crater infill and ejecta ring) to bottom (lower diatreme). The Twin Peaks volcanic complex consists mostly of two hills (North Peak and South Peak) with thick lavas at their summits and pyroclastic rocks underneath. In the HBVF, such volcanic remnants have received little scientific attention so far, despite their relative abundance. Our field observations allow us to interpret the North and South Peaks as remnants of two maar-diatreme volcanoes which evolved into lava lakes filling the craters. Within the complex, we distinguish four volcanic units (from unit 1 at the bottom to unit 4 at the top). On the basis of the field description of the deposits and the componentry measurements, we suggest that unit 1 is phreatomagmatic, unit 2 is phreato-strombolian (with mixed phreatomagmatic and strombolian characteristics), unit 3a is phreato-hawaiian (with mixed phreatomagmatic and hawaiian characteristics), unit 3b is hawaiian (formed by lava fountains) and unit 4 consists of lava lakes filling the maar craters. There is therefore a progressive evolution from a purely phreatomagmatic eruptive style, which excavated the craters and diatremes and partly filled them, to magmatic explosive to nonexplosive eruptive styles, which filled the maar craters up to the pre-eruptive surface. We discuss traditional criteria used to distinguish phreatomagmatic from magmatic eruptive styles in ultramafic to mafic maar-diatreme volcanoes.
DS202103-0392
2020
Latutrie, B.Latutrie, B., Ross, P-S.What lithic clasts and lithic-rich facies can tell us about diatreme processes: an example at Round Butte, Hopi Buttes volcanic field, Navajo Nation, Arizona.Journal of Volcanology and Geothermal Research ( researchgate), 34p. PdfUnited States, Arizonadiatremes

Abstract: Round Butte (Hopi Buttes volcanic field, Arizona) exposes a diatreme 170-190 m across, 190 m below the pre-eruptive surface. The central part of the massif is 130-150 m in diameter, displaying 20-30 m-high subvertical cliffs. The well-known layer-cake stratigraphy of the sedimentary rocks of the Colorado Plateau permits identification of the largest lithic fragments preserved in the Round Butte diatreme. We define three main groups of pyroclastic facies: undisturbed beds, disturbed beds and non-bedded rocks. Two other minor facies groups were mapped: megablocks (blocks over 2 m in long axis), and small-volume debris avalanche deposits. Pyroclastic megablocks are finer grained and richer in lithic clasts than most diatreme rocks surrounding them. These pyroclastic megablocks are interpreted as subsided portions of the maar ejecta ring. Sedimentary megablocks originate either from above, or from the same level, relative to their current location, i.e. no megablock has a net upward displacement. Small-volume debris avalanche deposits are poorly sorted deposits resulting from gravitational destabilization of the surrounding country rocks into the syn-eruptive crater. Small-volume debris avalanches and individual megablock collapse are the main ways in which the crater grew in size laterally during the eruption. We combine the componentry of the disturbed bedded pyroclastic facies, the non-bedded pyroclastic facies and the pyroclastic megablocks with a series of conceptual models for country rock fragmentation. This exercise further allows us to estimate diatreme wall slopes of 70° below the Bidahochi Formation to approximately the depth of the root zone around 440 m below the pre-eruptive surface. Lithic fragments at the current level of exposure come from elevations up to 190 m above (i.e., up to the pre-eruptive surface) and up to 250 m below (i.e., down to the root zone) their current locations. Pyroclastic units displaying the richest content of lithic clasts with a deep origin are typically the non-bedded facies interpreted to have formed from debris jets during the eruption.
DS201903-0526
2019
Latypov, R.Latypov, R., Chisryakova, S., Griev, R., Huhma, H.Evidence for igneous differentiation in Sudbury Igneous Complex and impact driven evolution of Terrestrial planet proto-crusts.Nature Communications, Vol. 10, # 508, pp. 1-13.Canada, Ontariometeorite

Abstract: Bolide impact is a ubiquitous geological process in the Solar System, which produced craters and basins filled with impact melt sheets on the terrestrial planets. However, it remains controversial whether these sheets were able to undergo large-scale igneous differentiation, or not. Here, we report on the discovery of large discrete bodies of melanorites that occur throughout almost the entire stratigraphy of the 1.85-billion-year-old Sudbury Igneous Complex (SIC) - the best exposed impact melt sheet on Earth - and use them to reaffirm that conspicuous norite-gabbro-granophyre stratigraphy of the SIC is produced by fractional crystallization of an originally homogeneous impact melt of granodioritic composition. This implies that more ancient and compositionally primitive Hadean impact melt sheets on the Earth and other terrestrial planets also underwent large-volume igneous differentiation. The near-surface differentiation of these giant impact melt sheets may therefore have contributed to the evolution and lithological diversity of the proto-crust on terrestrial planets.
DS1995-1062
1995
Latypov, R.M.Latypov, R.M.On origin of anorthosites in Pansky Tundra layered intrusion: field evidence (Kola Peninsula)Russian Geology and Geophysics, Vol. 36, No. 3, pp. 49-56Russia, Kola PeninsulaAnorthosites, Layered intrusion
DS1996-0810
1996
Latypov, R.M.Latypov, R.M.Mechanism of the rhythmic layering of the Pana Tundra intrusion, KolaPeninsulaDoklady Academy of Sciences USSR, Vol. 336, pp. 103-107Russia, Kola PeninsulaLayered intrusion
DS1999-0396
1999
Latypov, R.M.Latypov, R.M., Mitrofanov, Alapietti, HalkoahoPetrology of the lower layered horizon of the Western Pansky TundraIntrusion, Kola Peninsula.Petrology, Vol. 7, No. 5, pp. 482-508.Russia, Kola PeninsulaLayered intrusion - not specific to diamonds
DS1999-0397
1999
Latypov, R.M.Latypov, R.M., Mitrofanov, F.P., Alapieti, KaukkonenPetrology of the upper layered horizon of the West Pansky tundra intrusion( Kola Peninsula).Russian Geology and Geophysics, Vol. 40, No. 10, pp. 1413-36.Russia, Kola PeninsulaLayered intrusion
DS2001-0656
2001
Latypov, R.M.Latypov, R.M., Chistakova, S.Yu.Physiochemical aspects of magnetite gabbro formation in the layered intrusion of the Western Pansky Tundra.Petrology, Vol. 9, No. 1, pp. 25-45.Russia, Kola PeninsulaLayered intrusion
DS1999-0142
1999
Latysh, N.Condie, K.C., Latysh, N., Selverstone, J.Geochemistry, neodymium and Strontium isotopes and uranium-lead (U-Pb) zircon ages of granitoid metasedimentary xenoliths from Navajo...Chemical Geology, Vol. 156, No. 1-4, Apr. 1, pp. 95-134.Arizona, New Mexico, Colorado, WyomingFour Corners area, Navajo volcanic field, Xenoliths
DS201312-0869
2012
Latyshev, A.V.Sonin, V.M., Chepurov, A.A., Shcheglov, D.V., Kosolobov, S.S., Logvinova, A.M., Chepurov, A.I., Latyshev, A.V., Sobolev, N.V.Study of the surface of natural diamonds by the method of atomic force microscopy.Doklady Earth Sciences, Vol. 447, 2, pp. 1314-1316.TechnologyDiamond morphology
DS201709-1972
2017
Latyshev, A.V.Chepurov, A.A., Kosolobov, S.S., Shcheglov, D.V., Sonin, V.M., Chepurov, A.I., Latyshev, A.V.Nanosculptures on round surfaces of natural diamonds.Geology of Ore Deposits, Vol. 59, 3, pp. 256-264.Russiadeposit - Udachnaya -East

Abstract: The results of a study using scanning electron microscopy and atomic force microscopy comprising the micromorphology of the ditrigonal and trigonal layers on surfaces near the edges of octahedral diamond crystals from the Udachnaya-Eastern kimberlite pipe in Yakutia are presented. The studied surface sculptures are elongated parallel to the direction ?111? and have similar morphological features, characterized by a wavy profile across the lamination, the absence of flat areas at the micro- and nanolevel. It is proposed that both sculpture types were formed as a result of dissolution under natural conditions. This suggestion is corroborated by the revelation of negative trigons on the octahedral facets of the studied diamonds.
DS202107-1116
2020
Latyshev, A.V.Myshenkova, M.S., Zaitsev, V.A., Thomson, S., Latyshev, A.V., Zakharov, V.S., Bagdasaryan, T.E., Veselovsky, R.E.Thermal history of the Guli Pluton ( north of the Siberian platform) according to apatite fission-track dating and computer modeling. (carbonatite)Geodynamics & Tectonophysics, Vol. 11, pp. 75-87. pdfRussia, Siberiageothermometry

Abstract: We present the first results of fission-track dating of apatite monofractions from two rock samples taken from the Southern carbonatite massif of the world’s largest alkaline ultrabasic Guli pluton (~250 Ma), located within the Maymecha-Kotuy region of the Siberain Traps. Based on the apatite fission-track data and computer modeling, we propose two alternative model of the Guli pluton's tectonothermal history. The models suggest (1) rapid post-magmatic cooling of the studied rocks in hypabyssal conditions at depth about 1.5 km, or (2) their burial under a 2-3 km thick volcano-sedimentary cover and reheating above 110°C, followed by uplift and exhumation ca. 218 Ma.
DS202003-0348
2020
Lau, D.Lee, C.W.Y., Cheng, J., Yium Y.C., Chan, K., Lau, D., Tang, W.C., Cheng, K.W,m Kong, T., Hui, T.K.C., Jelezko, F.Correlation between EPR spectra and coloration of natural diamonds.Diamond & Related Materials, Vol. 103, 13p. PdfGlobaldiamond colour

Abstract: White diamonds color grading is one of the basic diamond evaluations. The color value based on a scale that ranges from D to Z, with D being the more colorless and more valuable, among other qualifications. As the diamond grade moves on this scale, its color appears more yellow progressively. This yellowish color, present only in Type I diamonds, is mainly due to the nitrogen related defects such as N3 center and C-center. The current color grading system is based on a visual method, where gemologist compares the sample with a Master Color set. However, this method is very subjective. Several defects responsible for light absorption in diamond are carrying electron spin and appear in Electron Paramagnetic Resonance (EPR) spectrum. In this study, we developed a new EPR based technique for a quantitative measurement of N3 center and C-center in diamond through quantitative EPR spectroscopy. The correlation between EPR spectra and color grades of diamond was established.
DS2001-0701
2001
Lau, H.Louden, K., Lau, H.Insights from scientific drilling on rifted continental marginsGeoscience Canada, Vol.28, 4, Dec. pp.187-95.GreenlandTectonics - rifting, breakup
DS202011-2049
2020
Lau, H.Lau, H., Holtzman, B., Havlin, C.Towards a self-consistent characterization of lithospheric plates using full-spectrum viscoelasticity.AGU Advances, dor.or/10.101029 /2020AV000205Mantletectonics

Abstract: On Earth, broken, rigid tectonic plates lie atop slowly flowing mantle rock (over millions to billions of years). A basic understanding of the global variation in thickness of this rigid lid provides the foundation to many geodynamical predictions. However, using different techniques to estimate its thickness, for example, seismic wave propagation (acting on timescales of seconds), to the warping of plates under the weight of volcanoes (acting on timescales of millions of years) reveals many inconsistencies. At the heart of these inconsistencies is the fact that rock deforms differently to forces acting on different timescales. At very fast timescales rock deforms like an elastic solid, but at much longer timescales, rock flows. To resolve these inconsistencies, we attempt to coherently tie these disparate observations together to reach a more holistic understanding of plate thickness, accounting for these timescale effects. By incorporating current understanding on rock deformation from laboratory experiments, we demonstrate that on fast timescales (of the seismic waves used to image the Earth's interior), tectonic plates appear significantly thicker than the true thickness at million? to billion?year timescales of plate tectonics. This demonstration involves a new theoretical and conceptual framework for interpreting distinct observations acting on vastly different timescales.
DS1989-1266
1989
LaubachReynolds, S.J., Spencer, J.E., Asmerom, Y., DeWitt, E., LaubachEarly Mesozoic uplift in west-central Arizona and southeastern CaliforniaGeology, Vol. 17, No. 3, March pp. 207-211Arizona, CaliforniaGreat Basin area, Proterozoic
DS1996-0811
1996
Laube, N.Laube, N., et al.MODUSCALC - a computer program to calculate a mode from a geochemical rockanalysisComputers and Geosciences, Vol. 22, No. 6, pp. 631-638GlobalComputers, Program -MODUSCALC.
DS200712-0598
2007
Lauenaudie Merelani, S.Lauenaudie Merelani, S.An ambitious jewelery upstart is dusting off the 20th century's greatest promotional coup in its bid to make tanzanite the next hot rock.Time Magazine, Spring pp. 43-45.Africa, TanzaniaNews item - tanzanite
DS1997-0419
1997
LauerGladwin, D., Konda, B., Lauer, Camilucci, D.A comparative analysis of income based taxes on miningThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 90, No. 1009, April pp. 33-35CanadaEconomics, Tax - mining
DS201112-0895
2011
Laufer, A.Saalmann, K., Gerdes, A., Lahaye, Y., Hartmann, L.A., Remus, M.V.D., Laufer, A.Multiple accretion at the eastern margin of the Rio de la Plat a craton: the prolonged Brasiliano orogeny in southernmost Brazil.International Journal of Earth Sciences, Vol. 100, 2, pp. 355-378.South America, BrazilCraton, not specific to diamonds
DS1910-0467
1915
Laufer, B.Laufer, B.The Diamond, a Study in Chinese and Hellenistic Folk-loreChicago: Field Museum of Natural History, Anthropological Series, No. 184, Vol. 15, No. 1, 75P.ChinaHistorical
DS1981-0003
1981
Laughlin, A.W.Aldrich, M.J., Ander, M.E., Laughlin, A.W.Geological and Geophysical Signatures of the Jemez Lineament: a Reactivated Precambrian Structure.National Technical Information Service LA-UR-82-561, Conference 8L0887-2, DE82011971, 35P.GlobalMid-continent, Tectonic
DS1984-0005
1984
Laughlin, A.W.Aldrich, M.J.JR., Laughlin, A.W.A Model for the Tectonic Development of the Southeastern Colorado Plateau Boundary.Journal of Geophysical Research, Vol. 89, No. B12, PP. 10, 207-10218.United States, Colorado PlateauTectonics
DS1985-0384
1985
Laughlin, A.W.Laughlin, A.W., Aldrich, M.J.JR., Shafiqullah, M., Husler, J.Tectonic implications of the age, composition and orientation of lamprophyric dikes, Navajo volcanic fieldEarth and Planetary Science Letters, Vol. 76, pp. 361-374Colorado Plateau, ArizonaKatungite, Minette Potassium Metasomatism, Tectonic
DS1985-0694
1985
Laughlin, A.W.Vaniman, D., Laughlin, A.W., Gladney, E.S.Navajo Minettes in the Cerros de la Mujeres, New MexicoEarth Plan. Sci. Letters, Vol. 74, PP. 69-80.United States, Colorado Plateau, New MexicoMicroprobe Analyses, Geochemistry, Age Dating, Geochronology
DS1986-0008
1986
Laughlin, A.W.Aldrich, M.J. Jr., Laughlin, A.W.Proceedings of the Sixth International Conference on Basement Tectonics, held Santa Fe Sept. 1985International Basement Tectonics Publ, 210pGlobalTectonics
DS1986-0485
1986
Laughlin, A.W.Laughlin, A.W., Aldrich, M.J.Jr., Shafiqulla, M., Husler, J.Comments on tectonic implications of the age, composition and orientation of lamprophyre dikes, Navajo Volcanic field,Arizona #1Earth and Planetary Science Letters, Vol. 80, No. 3-4, November pp. 415-417ArizonaTectonics, Dikes
DS1986-0486
1986
Laughlin, A.W.Laughlin, A.W., Charles, R.W., Aldrich, M.J.Heteromorphism and crystallization paths of katungites, Navajo volcanic field Arizona, USAProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 187-189ArizonaBlank
DS1989-0834
1989
Laughlin, J.R.Kuehner, S.M., Laughlin, J.R., Grossman, L., Johnson, M.L., BurnettDetermination of trace element mineral/liquid partition coefficients in melilite and diopside by ion and electron microprobe techniquesGeochimica et Cosmochimica Acta, Vol. 53, pp. 3115-3130GlobalMelilite, Experimental petrology
DS1970-0120
1970
Laughlin, W.A.Laughlin, W.A., Caussey, J.D.Phlogopite Kaesutite Bearing Ultramafic Inclusions from a New Locality, bandera Crater, Valencia County, New Mexico.Eos, Vol. 51, No. 4, P. 449. (abstract.).United States, New Mexico, Colorado PlateauBlank
DS1991-0960
1991
Laughren, J.Laughren, J.Diamonds :markets and merchandisingInternational Gemological Symposium, June 20-24, 1991 Los Angeles, Gems and Gemology, Vol. 27, Spring, Program p. 11GlobalDiamond markets
DS1987-0398
1987
Laukkanen, J.Laukkanen, J.The lamprophyres of central Finland. *FINTutkimusrap- Geol., *FIN., Vol. 76, pp. 91-98.VFinlandCamptonite, kersantite
DS1983-0595
1983
Laul, J.C.Taylor, L.A., Shervais, J.W., Hunter, R.H., Laul, J.C.Major and Trace Element Geochemistry of Garnets and Ilmenites from Eastern United States (us) Kimberlites.Geological Society of America (GSA), Vol. 15, No. 6, P. 704. (abstract.).United States, Appalachia, Tennessee, Virginia, Kentucky, PennsylvaniaGeochemistry
DS1987-0670
1987
Laul, J.C.Shervais, J.W., Taylor, L.A., Laul, J.C.Magma mixing and kimberlite genesis: mineralogic, petrologic and trace element evidence from eastern USA kimberlitesMantle metasomatism and alkaline magmatism, edited E. Mullen Morris and, No. 215, pp. 101-114GlobalPetrology, Analyses p. 106
DS201012-0880
2010
Laumonier, M.Yoshino, T., Laumonier, M., McIssac, E., Katsura, T.Electrical conductivity of basaltic and carbonatite melt bearing peridotites at high pressures: implications for melt distribution and melt fractionEarth and Planetary Science Letters, Vol. 295, 3-4, pp. 593-602.MantleMelting - upper
DS201412-0600
2014
Laumonier, M.Moussallam, Y., Morizet, Y., Massuyeau, M., Laumonier, M.COs solubility in kimberlite melts.Chemical Geology, 33p.MantleMelting
DS201603-0403
2015
Laumonier, M.Moussallam, Y., Morizet, Y., Massuyeau, M., Laumonier, M., Gaillard, F.CO ( sub 2) solubility in kimberlite melts.Chemical Geology, Vol. 418, pp. 198-205.MantleExperimental Petrology

Abstract: Carbon dioxide is the most abundant volatile in kimberlite melts and its solubility exerts a prime influence on the melt structure, buoyancy, transport rate and hence eruption dynamics. The actual primary composition of kimberlite magma is the matter of some debate but the solubility of CO2 in kimberlitic melts is also poorly constrained due to difficulties in quenching these compositions to a glass that retains the equilibrium CO2 content. In this study we used a range of synthetic, melt compositions with broadly kimberlitic to carbonatitic characteristics which can, under certain conditions, be quenched fast enough to produce a glass. These materials are used to determine the CO2 solubility as a function of chemical composition and pressure (0.05-1.5 GPa). Our results suggest that the solubility of CO2 decreases steadily with increasing amount of network forming cations from ~ 30 wt.% CO2 at 12 wt.% SiO2 down to ~ 3 wt.% CO2 at 40 wt.% SiO2. For low silica melts, CO2 solubility correlates non-linearly with pressure showing a sudden increase from 0.1 to 100 MPa and a smooth increase for pressure > 100 MPa. This peculiar pressure-solubility relationship in low silica melts implies that CO2 degassing must mostly occur within the last 3 km of ascent to the surface having potential links with the highly explosive nature of kimberlite magmas and some of the geo-morphological features of their root zone. We present an empirical CO2 solubility model covering a large range of melt composition from 11 to 55 wt.% SiO2 spanning the transition from carbonatitic to kimberlitic at pressures from 1500 to 50 MPa.
DS201912-2798
2019
Laumonier, M.Laumonier, M., Laporte, D., Faure, F., Provost, A., Schiano, P., Ito, K.An experimental study of dissolution and precipitation of forsterite in a thermal gradient: implications for cellular growth of olivine phenocrysts in basalt and melt inclusion formation.Contributions to Mineralogy and Petrology, Vol. 174, 21p. PdfMantlebasanite

Abstract: The morphology of crystals in magmas strongly depends on the temperature regime of the system, in particular the degree of undercooling and the cooling rate. To simulate low degrees of undercooling, we developed a new experimental setup based on thermal migration, in which large cylinders of forsterite (single crystals) immersed in haplobasaltic melt were subjected to a temperature gradient. As forsterite solubility is sensitive to temperature, the forsterite on the high-temperature side undergoes dissolution and the dissolved components are transported toward the low-temperature side where a layer of newly grown forsterite forms (up to 340 ?m thick after 101 h). A striking feature is that the precipitation process does not produce a planar front of forsterite advancing at the expense of liquid: the growth front shows a fingered outline in planar section, with solid lobes separated by glass tubes that are perpendicular to the growth front. We ascribe this texture to cellular growth, a type of growth that had not been experimentally produced so far in silicate systems. We find that the development of cellular growth requires low degrees of undercooling (a few °C) and large crystal-liquid interfaces (~?1 mm across or more), and that it occurs at a growth rate of the order of 10?9 m/s. We found natural occurrences of cellular growth on the rims of olivines from basanites, but otherwise cellular textures are poorly documented in natural volcanic rocks. Melt inclusions were produced in our experiments, showing that they can form in olivine at relatively slow rates of growth (10?9 m/s or lower).
DS1900-0202
1903
Launay, L. DE.Launay, L. DE.Richesses Minerales de L'afriqueParis: Beranger., ( DIAMONDS PP. 193-205 ). XEROX.GlobalKimberley, Geology, Janlib, Kimberlite
DS1910-0200
1911
Launay, L. DE.Launay, L. DE.Diamants D'indeParis: Librarie Polytechnique Beranger., PP. 705-709.IndiaHistory
DS1910-0360
1913
Launay, L. DE.Launay, L. DE.Gites Mineraux et MetalliferesParis And Liege: Beranger., ( DIAMONDS PP. 398-439 ). XEROX.GlobalKimberley, Geology, Janlib, Kimberlite
DS201012-0695
2010
Laur, B.M.Shigley, J.E., Laur, B.M., Janse, A.J.A., Elen, S., Dirlam, D.M.2010 gem localities of the 2000's.Gems & Gemology, Vol. 46, 3, pp. 188-216.GlobalDiamond included in profile
DS201810-2372
2018
Laure, A.Rielli A., Tomkins, A.G., Nebel, O., Raveggi, M., Jeon, H., Martin, L., Laure, A., Janaina, N.Sulfur isotope and PGE systematics of metasomatised mantle wedge.Earth and Planetary Science Letters, Vol. 497, 1, pp. 181-192.Mantlemetasomatism

Abstract: At convergent margins fluids liberated from subducting slabs metasomatise the overlying mantle wedge, enriching it in volatiles, incompatible elements and possibly ore-forming metals. Despite the genetic link between this process, the genesis of arc magmas, and formation of porphyry Cu-Au deposits, there is currently little understanding of the behaviour of chalcophile and siderophile elements during subduction-related mantle metasomatism. In this study, we report sulfur isotopic compositions and PGE concentrations of sulfides in a suite of garnet peridotites from the Western Gneiss Region of Norway, sampling mantle wedge from ?100 to ?250 km depth. Sulfides hosted in metasomatised samples have deviated from typical mantle values, ranging between ?10.0 and +5.4‰, indicating derivation of sulfur from subducted crust. Sulfides in pervasively metasomatised samples have atypical PGE signatures, with strong enrichment in Os and Ru relative to Ir, whereas channelised fluid flow produced sulfides extremely enriched in Pd, up to 700 times the concentration found in non-metasomatised samples. These signatures are reconcilable with a high oxidation state of the metasomatising agents and demonstrate that subduction can recycle chalcophile and siderophile elements into and within the mantle, along with sulfur. We further show that because the solubility of Os and Ru in fluids is redox sensitive, and Pd is more soluble than the I-PGE, ratios such as Os/Ir, Ru/Ir plotted against Pd/Ir can be used to trace the metasomatic oxidation of mantle samples, mantle-derived magmas and porphyry Cu±Au deposits. This geochemical insight is used to show that Au-rich porphyry Cu deposits are derived from more oxidised mantle wedge than Au-poor porphyry deposits.
DS2002-0919
2002
Laurence, D.C.Laurence, D.C.Optimizing mine closure outcomes for the community - lessons learntMinerals and Energy, Vol. 17,1,March pp.27-34.GlobalMining - mine closure, Socio-environmental
DS1860-0516
1886
Laurence, P.M. Sir.Laurence, P.M. Sir.Diamonds and Diamond FieldsCape Town: The Cape Argus, 474p. In: Cowen's South African , PP. 255-283.Africa, South AfricaHistory
DS1900-0203
1903
Laurence, P.M. Sir.Laurence, P.M. Sir.On Circuit in Kaffirland, and other Sketches and StudiesLondon And Cape Town: Macmillan, And Juta., 335P.Africa, South AfricaBiography, Kimberley
DS1900-0338
1905
Laurence, P.M. SIR.Laurence, P.M. SIR.CollectaneaLondon: Macmillan., 2ND. EDITION 437P.Africa, South AfricaHistory, Biography, Kimberley
DS201412-0652
2014
Laurent, G.J.Paczkowski, K., Laurent, G.J., Long, M.D., Thissen, C.J.Three dimensional flow in the subslab mantle.Geochemistry, Geophysics, Geosystems: G3, Vol. 15, pp. 3989-4008.MantleSubduction
DS201412-0653
2014
Laurent, G.j.Paczkowski, K., Thissen, C.J., Montesi, M.D., Laurent, G.j.Deflection of mantle flow beneath subducting slabs and the origin of subslab anisotropy.Geophysical Research Letters, Vol. 41, 19, pp. 6734-42.MantleSubduction
DS201602-0223
2015
Laurent, O.Masse, P., Laurent, O.Geological exploration of Angola from Sumbe to Namibe: a review at the frontier between geology, natural resources and the history of geology.Comptes Rendus Geoscience, in press available 9p.Africa, AngolaCoast - Angola

Abstract: This paper provides a review of the Geological exploration of the Angola Coast (from Sumbe to Namibe) from pioneer's first geological descriptions and mining inventory to the most recent publications supported by the oil industry. We focus our attention on the following periods: 1875-1890 (Paul Choffat's work, mainly), 1910-1949 (first maps at country scale), 1949-1974 (detailed mapping of the Kwanza-Namibe coastal series), 1975-2000, with the editing of the last version of the Angola geological map at 1:1 million scale and the progressive completion of previous works. Since 2000, there is a renewal in geological fieldwork publications on the area mainly due to the work of university teams. This review paper thus stands at the frontier between geology, natural resources and the history of geology. It shows how geological knowledge has progressed in time, fueled by economic and scientific reasons.
DS201801-0075
2018
Laurent, O.Vezinet, A., Moyen, J-F., Stevens, G., Nicoli, G., Laurent, O., Couzinie, S., Frei, D.A record of 0.5 Ga of evolution of the continental crust along the northern edge of the Kaapvaal Craton, South Africa: consequences for the understanding of Archean geodynamic processes.Precambrian Research, Vol. 305, pp. 310-326.Africa, South Africacraton - Kaapvaal

Abstract: Geodynamics of crustal growth and evolution consist in one of the thorniest questions of the early Earth. In order to solve it, Archean cratons are intensively studied through geophysical, geochemical and geochronological investigations. However, timing and mechanisms leading to accretion and stabilization of crustal blocks are still under question. In this study, new information on the evolution of Archean cratons is provided through complementary approaches applied to the northern margin of the Archean Kaapvaal craton (KC). The study area comprises the Pietersburg Block (PB) and the terrane immediately adjacent to the North: the Southern Marginal Zone of the Limpopo Complex (SMZ). We present a comprehensive petro-metamorphic study coupled with LA-ICP-MS U-Pb isotope examination of both Na- and K-rich granitoids from the two areas. This dataset points toward a new interpretation of the northern KC (PB?+?SMZ). Two significant magmatic events are newly recognized: (i) a ca. 3.2?Ga event, and (ii) a protracted magmatic event between ca. 2.95–2.75?Ga. These events affected in both investigated areas and are unrelated to the ca. 2.7?Ga-old event usually attributed to the SMZ. More importantly, phase equilibrium modelling of several lithologies from the SMZ basement points to middle-amphibolite facies conditions of equilibration instead of granulite-facies conditions historically assumed. This study has both important regional and global implications. Firstly, the presence of a continuous basement from the Thabazimbi-Murchison Lineament to the Palala Shear Zone, different than Central Zone of the Limpopo Complex basement, implies a complete reviewing of the whole Limpopo Complex concept. Secondly, the geometry observed in the northern Kaapvaal craton is assumed to testify for a complete accretionary orogenic sequence with formation of both mafic and TTG lithologies through arc-back arc geodynamic. This was followed by a long-lived lateral compression triggering partial melting of the lower continental crust and emplacement of Bt-granitoids bodies that stabilizes the continental crust. Lastly, partial melting of the underlying enriched mantle stabilized the entire lithosphere allowing long-term preservation of the crustal block.
DS201802-0254
2018
Laurent, O.Moyen, J-F., Laurent, O.Archean tectonic systems: a view from igneous rocks.Lithos, Vol. 302-303, pp. 99-125.Globalgeochemistry

Abstract: This work examines the global distribution of Archaean and modern igneous rock's compositions, without relying on preconceptions about the link between rock compositions and tectonic sites (in contrast with “geotectonic” diagrams). Rather, Archaean and modern geochemical patterns are interpreted and compared in terms of source and melting conditions. Mafic rocks on the modern Earth show a clear chemical separation between arc and non-arc rocks. This points to the first order difference between wet (arc) and dry (mid-ocean ridges and hotspots) mantle melting. Dry melts are further separated in depleted (MORB) and enriched (OIB) sources. This three-fold pattern is a clear image of the ridge/subduction/plume system that dominates modern tectonics. In contrast, Archaean mafic and ultramafic rocks are clustered in an intermediate position, between the three main modern types. This suggests that the Archaean mantle had lesser amounts of clearly depleted or enriched portions; that true subductions were rare; and that the distinction between oceanic plateaus and ridges may have been less significant. Modern granitic rocks dominantly belong to two groups: arc-related granitoids, petrologically connected to arc basalts; and collision granitoids, related to felsic sources. In contrast, the Archaean record is dominated by the TTG suite that derives from an alkali-rich mafic source (i.e. altered basalt). The geochemical diversity of the TTG suite points to a great range of melting depths, from ca. 5 to > 20 kbar. This reveals the absence of large sedimentary accumulations, again the paucity of modern-like arc situations, and the importance played by reworking of an earlier basaltic shell, in a range of settings (including some proto-subduction mechanisms). Nonetheless, granitoids in each individual region show a progressive transition towards more modern-looking associations of arc-like and peraluminous granites. Collectively, the geochemical evidence suggests an Archaean Earth with somewhat different tectonic systems. In particular, the familiar distinction between collision, arcs, ridges and hotspots seems to blur in the Archaean. Rather, the large-scale geochemical pattern reveals a long-lived, altered and periodically resurfaced basaltic crust. This protocrust is reworked, through a range of processes occurring at various depths that correspond to a progressive stabilization of burial systems and the establishment of true subductions. A punctuated onset of global plate tectonics is unlikely to have occurred, but rather short-term episodes of proto-subduction in the late Archaean evolved over time into longer-term, more stable style of plate tectonics as mantle temperature decayed.
DS1975-1111
1979
Laurent, R.Laurent, R., Herbert, Y.Paragenesis of Serpentine Assemblages in Harzburgite Tectonite and Dunite Cumulate from the Quebec Appalachians.Canadian Mineralogist., Vol. 17, No. 4, PP. 857-870.Canada, QuebecRelated Rocks
DS1996-0812
1996
Laurentian UniversityLaurentian UniversityMining environment databaseCentre in Mining and Mineral Exploration Research., GlobalEnvironmental database, Ad
DS1994-0989
1994
Laurentian University Centre in Mining and Mineral Exploration ResearchLaurentian University Centre in Mining and Mineral Exploration ResearchCentre in Mining and Mineral Exploration Research database now on disketteLaurentian University Centre in Mining and Mineral Exploration Research, 8000 citations, approx. $ 275.00CanadaEnvironmental, Database -Centre in Mining and Mineral Exploration Research.
DS201112-0053
2011
Laurenz, V.Ballhaus, C., Laurenz, V., Fonseca, R., Munker, C., Albarede, Rohrbach, Schmidt, Jochum, Stoll, Weis, HelmyLate volatile addition to Earth.Goldschmidt Conference 2011, abstract p.475.MantleW and Cr elements
DS201312-0053
2013
Laurenz, V.Ballhaus, C., Laurenz, V., Munker, C., Fonseca, R.O.C., Albarede, F., Rohrbach, A., Lagos, M., Schmidt, M.W., Jochum, K-P., Stoll, B., Weis, U., Helmy, H.M.The U /Pb ratio of the Earth's mantle - a signature of late volatile addition.Earth and Planetary Interiors, Vol. 362, pp. 237-245.MantleMelting
DS201910-2240
2019
Laurenz, V.Abeykoon, S., Frost, D.J., Laurenz, V., Miyajima, N.A new geothermometer based on the oxygen content of sulphide inclusions in diamonds.Goldschmidt2019, 1p. AbstractMantlegeothermometry

Abstract: Sulphides are the most common type of inclusions found in diamonds and are widely used to determine the timing and lithology of diamond formation. Typical inclusions are monosulfide solid solutions (MSS) in the Fe-Ni-S system with minor amounts of Cu, Co and Mo. Previous experimental studies show that oxygen partitions into sulphide melts but most importantly measurements of natural sulphide inclusions indeed show measureable oxygen concentrations. If the parameters that control sulphide oxygen concentration can be determined then they could be potentially used to understand formation conditions of diamonds. We performed a series of high pressure (3-11 GPa) and high temperature (1573-1973 K) experiments in order to parameterize the oxygen content in sulphides in equilibrium with a mantle peridotite assemblage relevant to diamond formation. Multi-anvil experiments were carried out in graphite capsules and a peridotite silicate composition was equilibrated with molten FeS for at least 5 hrs. Run products that contained mantle silicate minerals and quenched sulphide melts were analysed using the electron microprobe. In some cases Ir was added in sufficient quantities to saturate the sulphides and form an Fe-Ir alloy from which the oxygen fugacity could be accurately determined. We measured up to 16 weight % of FeO in our experimental sulphide melts at mantle conditions. Moreover, the content of oxygen in the sulphide is found to be not controlled by fO2 or fS2, which is in disagreement with previous experimental studies conducted at ambient pressure conditions. The experiments indicate that the oxygen concentration is mainly controlled by the FeO activity in coexisting silicate phases and the temperature. In order to fit the data and to account for the observed FeO dependence, we developed a thermodynamic model using an end-member equilibrium between olivine, pyroxene and FeO in the sulphide melt. Using this relationship with measurements of oxygen in natural sulphide inclusions in diamonds reveals temperatures for lithospheric diamond formation in the range of 1140 – 1410 ºC.
DS1989-0192
1989
Laurenzi, M.Burgess, R., Turner, G., Laurenzi, M., Harris, J.W.40Ar 39Ar laser probe dating of individual clinopyroxene inclusions in Premier eclogitic diamondsEarth and Planetary Science Letters, Vol. 94, No.l 1/2, August pp. 22-28South AfricaGeochronology, Diamond Inclusions
DS200912-0057
2009
Laurenzi, M.A.Boari, E., Tommasini, S., Laurenzi, M.A., Conticelli, S.Transition from ultrapotassic kamafugitic to sub-alkaline magmas: Sr Nd and Pb isotope, trace element and 40Ar 39Ar age dat a from the Middle LatinJournal of Petrology, Vol. 50,no. 7,. pp. 1327-1357.Europe, ItalyKamafugite
DS201212-0397
2012
Laurie, A.Laurie, A., Stevens, G., Van Hunen, J.The end of continental growth by TTG magmatism.Terra Nova, In press availableMantleSubduction
DS1970-0693
1973
Laurin, A.F.Gittins, J., Hewins, R.H., Laurin, A.F.Kimberlitic Carbonatitic Dikes of the Saguenay River ValleyProceedings of First International Kimberlite Conference, EXTENDED ABSTRACT PP. 127-130.Canada, QuebecOccurrences
DS1975-0085
1975
Laurin, A.F.Gittins, J., Hewins, R.H., Laurin, A.F.Kimberlitic and Carbonatitic Dykes of the Saguenay River Valley, Quebec, Canada.Physics and Chemistry of the Earth., Vol. 9, PP. 137-148.Canada, QuebecRelated Rocks, Carbonatite, Kimberlite, Arvida
DS1993-0571
1993
Lauriol, B.Gray, J., Lauriol, B., Bruneau, D., Ricard, J.Post glacial emergence of Ungava Peninsula, and its relationship to glacialhistory.Canadian Journal of Earth Sciences, Vol. 30, No. 8, August pp. 1676-1696.QuebecGeomorphology
DS2001-0657
2001
Laurora, A.Laurora, A., Mazzucchelli, M et al.Metasomatism and melting in carbonated peridotite xenoliths from the mantle wedge: Gobernador GregoresJournal of Petrology, Vol. 42, No. 1, Jan. pp. 69-88.GlobalMetasomatism - xenoliths
DS200512-0907
2004
Laurora, A.Rivalenti, G., Mazzucchelli, M., Laurora, A., Ciuffi, S.I.A., Zanetti, A., Vannucci, R., Cingolani, C.A.The backarc mantle lithosphere in Patagonia, South America.Journal of South American Earth Sciences, Vol. 17, 2, Oct. 30, pp. 121-152.South America, PatagoniaXenoliths, geothermometry, melting, slab, subduction
DS201805-0956
2018
Laurs, B.Laurs, B.Diamond mining at Namdeb's southern coastal mines, Namibia. Site visitJournal of Gemmology, Vol. 36, 1, pp. 16-18.Africa, Namibiadeposit - namdeb
DS200912-0270
2009
Laurs, B.M.Groat, L.A., Laurs, B.M.Gem formation, production,and exploration: why gem deposits are rare and what is being done to find them.Elements, Vol. 5, 3, June pp. 153-158.Canada, GlobalOverview
DS201707-1345
2017
Laurs, B.M.Laurs, B.M.Recent alluvial diamond mining in South Africa. Fieldtrip leader M. De Wit 35th. IGC CongressJournal of Gemmology, Vol. 35, 6, pp. 484-485.Africa, South Africadeposit - Tirisano
DS1970-0335
1971
Lautel, R.F.Lautel, R.F.Report on Five Exploration Licences in New South WalesIn: Prospectus For Audimco Ltd., PP. 10-20.Australia, New South WalesDiamond Prospecting, Inverell, Copeton, Bingara
DS2002-1023
2002
Lauterbach, S.McCammon, C., Lauterbach, S., Van Akern, P., Langenhorst, F., Seifert, F.EELS studies of lower mantle mineral assemblages: a window to redox conditions18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.77.MantleUHP mineralogy - perovskite
DS2002-1025
2002
Lauterbach, S.McCammon, C.A., Beccero, A.I., Lauterbach, S., Blass, U., Marion, S.Oxygen vacancies in perovskite and related structures: implications for the lower mantle.Materials Research Society Symposium Proceedings, Vol. 718, pp. 109-114. Ingenta 1025440383MantlePerovskite
DS200412-1258
2004
Lauterbach, S.McCammon, C.A., Lauterbach, S., Seifert, F., Langenhorst, F., Van Aken, P.A.Iron oxidation state in lower mantle mineral assemblages. Part 2.Earth and Planetary Science Letters, Vol. 222, 2, pp. 435-449.MantleMineral chemistry
DS201312-0722
2013
Lauterbach, S.Purwin, H., Lauterbach, S., Brey, G.P., Woodland, A.B., Kleebe, H-J.An experimental study of Fe oxidation states in garnet and clinopyroxene as a function of temperature in the system CaO FeO Fe2O3 MgO Al2O3 SiO2: implications for garnet-clinopyroxene geothermometry.Contributions to Mineralogy and Petrology, Vol. 164, 4, pp. 623-639.TechnologyGeobarometry
DS2002-1108
2002
Lauterjung, J.Muller, H.J., Schilling, F.R., Lauterjung, J.In situ investigation of physical properties of rocks and minerals at lower crustal and mantle conditions - methods, measurements, challenges.Zeitschrift fur Geologische Wissenschaften, Vol.30,1-2,pp.49-76.MantleMetasomatism
DS1988-0407
1988
Laval, M.Laval, M., Johan, V., Tourliere, B.Mabounie carbonatite: example of the formation of a residual deposit withpyrochlore. (in French)Chron. Recher. Min., (in French), Vol. 56, No. 491, June pp. 125-136GlobalCarbonatite, Phosphate
DS1992-0912
1992
Laval, M.Laval, M.Les terres rares: gisements et apercu economique.(in French)Chronique de la Recherche Miniere, (in French), June No. 507, pp. 27-42GlobalRare earths, Economics
DS1992-0913
1992
Laval, M.Laval, M., Hottin, A.M.The Mlindi ring structure - an example of an ultrapotassic pyroxenite to syenite differentiated complexGeologische Rundschau, Vol. 81, No. 3, pp. 737-757GlobalRing structure, Ultrapotassic rocks
DS1992-0914
1992
Laval, M.Laval, M., Hottin, A.M.The Mlindi ring structure. an example of an ultrapotassic pyroxenite to syenite differentiated complexGeologische Rundschau, Vol. 81, No. 3, pp. 737-757MalawiUltrapotassic rocks, Structure
DS1993-0885
1993
Laval, M.Laval, M., Kosakevitch, A., Fontan, F.Behaviour of rare earth elements (REE) in lateritic profile, example of Mabounie GabonRare earth Minerals: chemistry, origin and ore deposits, International Geological Correlation Programme (IGCP) Project, p. 66. abstractGlobalCarbonatite, Weathering
DS1993-0886
1993
Laval, M.Laval, M., Piantone, P., Freyssinet, Ph., Kosakevitch, A.Role of florencite and pyrochlore in the behaviour of rare earth elements (REE) duringlaterisation: example of Mabounie carbonatite (Gabon)Terra Abstracts, IAGOD International Symposium on mineralization related to mafic, Vol. 5, No. 3, abstract supplement p. 25GlobalCarbonatite
DS201212-0610
2012
Lavallee, Y.Russell, J.K., Porritt, L.A., Lavallee, Y., Dingwell, D.Kimberlite ascent by assimilation fueld bouyancy.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractGlobalDiamond genesis
DS201412-0451
2014
Lavallee, Y.Kendrick, J.E., Lavallee, Y., Hirose, T., Di Toro,G., Hornby, A.J., De Angelis, S., Dingwell, D.B.Volcanic drumbeat seismicity caused by stick-slip motion and magmatic fictional melting.Nature Geoscience, Vol. 7, pp. 438-442.MantleMagmatism
DS1994-0990
1994
Lavandaio, E.Lavandaio, E., Fusari, C.Nuevas areas con oro diseminado en el distrito polimetalico Mendoza NorteActas del Encuentro International de Mineria, Vol. 1, pp. 52-58ArgentinaPrecordillera de Mendoza, Metallogeny
DS201905-1056
2019
Lavayssiere, A.Lavayssiere, A., Drooff, C., Ebinger, C., Gallacher, R., Illsley-Kemp, F., Finnigan, Oliva, S.J., Keir, D.Deep extent and kinematics of faulting in the southern Tanganyika Rift, Africa.Tectonics, Vol. 38, 3, pp. 842-862.Africarifting

Abstract: Unusually deep earthquakes occur beneath rift segments with and without surface expressions of magmatism in the East African Rift system. The Tanganyika rift is part of the Western rift and has no surface evidence of magmatism. The TANG14 array was deployed in the southern Tanganyika rift, where earthquakes of magnitude up to 7.4 have occurred, to probe crust and upper mantle structure and evaluate fault kinematics. Four hundred seventy?four earthquakes detected between June 2014 and September 2015 are located using a new regional velocity model. The precise locations, magnitudes, and source mechanisms of local and teleseismic earthquakes are used to determine seismogenic layer thickness, delineate active faults, evaluate regional extension direction, and evaluate kinematics of border faults. The active faults span more than 350 km with deep normal faults transecting the thick Bangweulu craton, indicating a wide plate boundary zone. The seismogenic layer thickness is 42 km, spanning the entire crust beneath the rift basins and their uplifted flanks. Earthquakes in the upper mantle are also detected. Deep earthquakes with steep nodal planes occur along subsurface projections of Tanganyika and Rukwa border faults, indicating that large offset (?5 km) faults penetrate to the base of the crust, and are the current locus of strain. The focal mechanisms, continuous depth distribution, and correlation with mapped structures indicate that steep, deep border faults maintain a half?graben morphology over at least 12 Myr of basin evolution. Fault scaling based on our results suggests that M > 7 earthquakes along Tanganyika border faults are possible.
DS1996-0813
1996
Lave, J.Lave, J., Avouac, J.P., Montagner, J.P.Seismic anisotropy beneath Tibet: evidence for eastward extrusion of the Tibetan lithosphere.Earth and Planetary Science Letters, Vol. 140, No. 1-4, May 1, pp. 83-96.China, TibetGeophysics -seismics, Lithosphere
DS201606-1103
2016
Lavecchia, A.Lavecchia, A., Clark, S.A., Beekman, F., Cloetingh, S.A.P.L., Burov, E.Thermal perturbation, mineral assemblages and rheology variations by dyke emplacement in the crust.Tectonics, in press availableMantleBasaltic dykes, two layered continental crust

Abstract: We constructed a thermomechanical model to examine the changes in rheology caused by the periodic intrusion of basaltic dykes in a two-layered continental crust. Dyke intrusion can locally change the mineralogical composition of the crust in space and time as a result of temperature-induced metamorphism. In our models we paid particular attention to determine how different mineral assemblages and reaction kinetics during metamorphism impact on the thermomechanical behavior of the crust, in terms of differential stress values. We investigated several lithologies characteristic for intracontinental crust: (1) a quartz-feldspathic crust (QF), (2) a crust with a mineralogical assemblage resembling the average chemical composition occurring in literature (CC), and (3) a micaschist crust (MS). Our model shows that temperature profiles are weakly influenced by metamorphism, with negligible variations in the T-t paths. The results indicate that intrusion-induced changes in the crustal rheology are strongly dependent on mineralogical assemblage variation. The strength of a dyke aureole in the upper crust increases during dyke emplacement, which may cause migration of later dykes and influence the dyke spacing. In contrast, in the lower crust the strength of a dyke aureole decreases during dyke emplacement. Fast kinetics results in a ductile lower crust in proximity of the dykes, whereas slower kinetics leads to the formation of partial melts and subsequent switch from ductile to brittle behavior. Lithology exerts a dominant role on the quantity of melt produced, with higher volume percentages occurring in the MS case study. Produced melts may migrate and support acidic volcanic activity.
DS201706-1089
2017
Lavecchia, A.Lavecchia, A., Thieulot, C., Beekman, F., Cloetingh, S., Clark, S.Lithosphere erosion and continental breakup: interaction of extension, plume upwelling and melting.Earth and Planetary Science Letters, Vol. 467, pp. 89-98.Mantlemelting

Abstract: We present the results of thermo-mechanical modelling of extension and breakup of a heterogeneous continental lithosphere, subjected to plume impingement in presence of intraplate stress field. We incorporate partial melting of the extending lithosphere, underlying upper mantle and plume, caused by pressure-temperature variations during the thermo-mechanical evolution of the conjugate passive margin system. Effects of melting included in the model account for thermal effects, causing viscosity reduction due to host rock heating, and mechanical effects, due to cohesion loss. Our study provides better understanding on how presence of melts can influence the evolution of rifting. Here we focus particularly on the role of melting for the temporal and spatial evolution of passive margin geometry and rift migration. Depending on the lithospheric structure, melt presence may have a significant impact on the characteristics of areas affected by lithospheric extension. Pre-existing lithosphere heterogeneities determine the location of initial breakup, but in presence of plumes the subsequent evolution is more difficult to predict. For small distances between plume and area of initial rifting, the development of symmetric passive margins is favored, whereas increasing the distance promotes asymmetry. For a plume-rifting distance large enough to prevent interaction, the effect of plumes on the overlying lithosphere is negligible and the rift persists at the location of the initial lithospheric weakness. When the melt effect is included, the development of asymmetric passive continental margins is fostered. In this case, melt-induced lithospheric weakening may be strong enough to cause rift jumps toward the plume location.
DS2000-0553
2000
Lavecchia, G.Lavecchia, G., Boncio, P.Tectonic setting of the carbonatite melitilite association of ItalyMineralogical Magazine, Vol. 64, No. 4, Aug. 1, pp. 583-92.ItalyMelilite
DS200512-0600
2003
Lavechhia, G.Lavechhia, G., Creati, N.Lithosphere tectonic context of the carbonatite melilitite rocks of Italy.Periodico di Mineralogia, Vol. LXX11, 1. April, pp. 33-40.Europe, ItalyMetasomatism
DS2000-0219
2000
Lavelle, M.De Villiers, S., Compton, J.S., Lavelle, M.The strontium isotope systematics of the Orange River, Southern AfricaSouth African Journal of Geology, Vol. 103, pp. 237-48.South Africa, southern AfricaWeathering - chemical, geochemistry
DS2000-0236
2000
Lavelle, M.Dingle, R.V., Lavelle, M.Antarctic Peninsula Late Cretaceous Early Cenozoic paleoenvironments and Gondwana paleogeographies.Journal of African Earth Sciences, Vol.31, No.1, July, pp.91-105.AntarcticaGondwana, Paleogeorgraphy
DS1988-0619
1988
Lavenu, A.Sebrier, M., Lavenu, A., Fornari, SoulasTectonics and uplift in Central Andes from Eocene to presentGeodynamique, Eng., Vol. 3, No. 1-2, pp. 85-106.Peru, Bolivia, ChileTectonics
DS1995-1063
1995
Lavenu, A.Lavenu, A., Winter, T., Davila, F.A Pliocene Quaternary compressional basin in the Interandean Depression, central EcuadorGeophys. Journal, Vol. 121, pp. 279-300GlobalNeotectonics, Basin stratigraphy
DS1996-1040
1996
Lavenu, A.Noblet, C., Lavenu, A., Marocco, R.Concept of continuum as opposed to periodic tectonism in the AndesTectonophysics, Vol. 255, No. 1-2, April 20, pp. 65-78Andes, PeruTectonics
DS2001-0658
2001
Laverne, C.Laverne, C., Agriniet, P., Hermitte, D., Bohn, M.Chemical fluxes during hydrothermal alteration of 1200 m long section of dikes in the oceanic crust Hole 504B.Chemical Geology, Vol. 181,No. 1-4, pp. 73-98.GlobalDike - sheeted, ophiolite, dolerite, Geochemistry
DS1990-0521
1990
Laverova, T.N.Garanin, V.K., Zhukov, G.D., Kudrjavtseva, G.P., Laverova, T.N.Mineralogy of garnets with inclusions from Sitikanskaja kimberlite pipeInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 2, extended abstract p. 799-801RussiaMineralogy -garnets, Sitikanskaja
DS1991-0533
1991
Laverova, T.N.Garanin, V.K., Kudrjavtseva, G.P., Laverova, T.N.The comparative characteristics of ilmenite from the kimberlite Provinces of the USSRProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 508-509RussiaIlmenite, Mineral chemistry
DS1993-0138
1993
Laverova, T.N.Borshchecskiy, Yu.A., Laverova, T.N.Oxygen isotopes of ilmenite from diamond-bearing kimberlite pipesDoklady Academy of Sciences USSR, Earth Science Section, Vol. 321, No. 8, August 1993, pp. 188-191.Russia, Commonwealth of Independent States (CIS)Geochronology, Ilmenites
DS1991-0151
1991
Laverova, Y.N.Borshchevskii, Y.A., Laverova, Y.N.Oxygen isotopic pecularities of ilmenite from diamond bearing kimberlitepipes.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 320, No. 1, pp. 174-176RussiaGeochronology, Ilmenite
DS202106-0933
2021
Lavhale, P.Dongre, A., Lavhale, P.,Li, Q-L.Perovskite U-Pb age and petrogenesis of the P-12 kimberlite from the Eastern Dharwar craton, southern India: impilcations for a possible linkage at the 1110 Ma large igneous province.Journal of Asian Earth Sciences, Vol.213, 104750, 12p.pdfIndiadeposit -P12

Abstract: Petrology, bulk-rock geochemistry, and perovskite U-Pb age for the P-12 kimberlite pipe from the Wajrakarur kimberlite field, Eastern Dharwar craton (EDC) of southern India is reported. Perovskites yielded a high-precision U-Pb age of 1122 ± 7.7 Ma, taken to be an emplacement age of the host P-12 kimberlite pipe. The groundmass of coherent facies P-12 kimberlite contains monticellite, clinopyroxene, andradite, atoll spinel with titanomagnetite trend, and perovskite with an elevated REE contents. Phlogopite shows restricted Al2O3 and TiO2 contents. Furthermore, olivines with a wider and higher range of core compositions (i.e. Mg# = 84-94) and multi-granular nodules are the hallmark features of the P-12 pipe. This assorted primary mineral content and its composition indicates the transitional nature of the P-12 towards the Kaapvaal lamproites. However, concentrations of bulk-rock major and trace elements in the P-12 and other Wajrakarur kimberlites are similar to the global hypabyssal magmatic kimberlites. Large ion lithophile and high field strength elements (e.g. Ba and Nb) and their ratios (e.g. La/Nb and Th/Nb) suggest the presence of a heterogeneous and lithosphere influenced mantle source region which have been severely overprinted by metasomatizing fluids/melts emanating from the deep sourced upwelling mantle. The presence of such mixed and metasomatized mantle source regions likely to be an important factor for the transitional nature of the P-12 and other Mesoproterozoic kimberlites. Based on the availability of the newest emplacement ages, we propose a geodynamic model for the origin of kimberlites in the Indian subcontinent. The U-Pb age of 1122 ± 7.7 Ma for the P-12 pipe shows its close temporal association to the emplacement of the recently proposed 1110 Ma Large Igneous Province (LIP), with plume center beneath the NW part of the Kalahari craton. Emplacement of the P-12 and other contemporaneous Indian kimberlites, therefore, marks the impingement of mantle plume which contributed heat and triggered partial melting of metasomatized lithospheric mantle without melt input. The eruption phase of ~ 100 million years (i.e. 1050-1153 Ma), for the kimberlites and related rocks in the Indian shield, does not appear to be continuous and can be separated into several short-durational magmatic events. For this reason, small-volume, volatile-rich magmatism during the Mesoproterozoic time in India is linked to the presence of a number of LIPs and associated mantle plumes during Columbia to Rodinia supercontinent transition and assembly of cratonic blocks of the latter.
DS1995-1064
1995
Lavier, L.Lavier, L.Reconstruction of the Cenozoic development of the Angolan continentalmargin.Eos, Abstracts, Vol. 76, No. 17, Apr 25, p. S 284.AngolaStructure, Congo River
DS2003-0532
2003
Lavier, L.Hall, C.E., Gurnis, M., Sdrolias, M., Lavier, L., Muller, R.D.Catastrophic initiation of subduction following forced convergence across fractureEarth and Planetary Science Letters, Vol. 212, 1-2, pp. 15-30.MantleBlank
DS200412-0762
2003
Lavier, L.Hall, C.E., Gurnis, M., Sdrolias, M., Lavier, L., Muller, R.D.Catastrophic initiation of subduction following forced convergence across fracture zones.Earth and Planetary Science Letters, Vol. 212, 1-2, pp. 15-30.MantleTectonics
DS201906-1275
2019
Lavier, L.Biemiller, J., Ellis, S., Mizera, M., Little, T., Wallace, L., Lavier, L.Tectonic inheritance following failed continental subduction: a model for core complex formation in cold, strong lithosphere.Tectonics, in press available, 22p.Mantlesubduction

Abstract: Inherited structural, compositional, thermal, and mechanical properties from previous tectonic phases can affect the deformation style of lithosphere entering a new stage of the Wilson cycle. When continental crust jams a subduction zone, the transition from subduction to extension can occur rapidly, as is the case following slab breakoff of the leading subducted oceanic slab. This study explores the extent to which geometric and physical properties of the subduction phase affect the subsequent deformation style and surface morphology of post subduction extensional systems. We focus on regions that transition rapidly from subduction to extension, retaining lithospheric heterogeneities and cold thermal structure inherited from subduction. We present numerical models suggesting that following failed subduction of continental crust (with or without slab breakoff), the extensional deformation style depends on the strength and dip of the preexisting subduction thrust. Our models predict three distinct extensional modes based on these inherited properties: (1) reactivation of the subduction thrust and development of a rolling?hinge detachment that exhumes deep crustal material in a domal structure prior to onset of an asymmetric rift; (2) partial reactivation of a low?angle subduction thrust, which is eventually abandoned as high?angle, “domino”?style normal faults cut and extend the crust above the inherited thrust; and (3) no reactivation of the subduction fault but instead localized rifting above the previous subduction margin as new rift?bounding, high?angle normal faults form. We propose that the first mode is well exemplified by the young, rapidly exhumed Dayman?Suckling metamorphic core complex that is exhuming today in Papua New Guinea.
DS1990-0503
1990
Lavigne, M.Fytas, K., Chaouai, N-E., Lavigne, M.Gold deposits estimation using indicator kriging.Sub-heading ..indicator kriging ideal for estimating the reserves of irregular mineralizations ie.diamondsThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 83, No. 934, February pp. 77-83GlobalGeostatistics, Application general for p
DS1975-1173
1979
Lavin, B.M.Parrish, J.B., Lavin, B.M.The Relationship of Geophysical and Remote Sensing Lineaments to Regional Structure and Kimberlite Intrusions in the Appalachian Plateau of Pennsylvania.Geological Society of America (GSA), Vol. 11, No. 1, P. 48, (abstract.).GlobalKimberlite, Geophysics
DS1992-1028
1992
Lavin, O.P.McClenaghan, M.B., Lavin, O.P., Nichol. I., Shaw, J.Geochemistry and clast lithology as an aid to till classification, Matheson, Ontario, CanadaJournal of Geochemical Exploration, Vol. 42, No. 2-3, February pp. 237-260OntarioGeochemistry, Till classification, -Not specific to kimberlite mineralogy -mentions
DS1999-0645
1999
Lavina, B.Secco, L., Lavina, B.Crystal chemistry of natural magmatic norsethites, Ba Mg Co3 2 from magnesium carbonatite of alkaline carbonatitic .Neues Jahrbuch Mineralogische Abhandlung, No. 2, pp. 87-96.BrazilCarbonatite, Tapira Complex
DS201312-0708
2013
Lavoie, D.Pinet, N., Lavoie, D., Dietrich, J., Hu, K., Keating, P.Architecture and subsidence history of the intracratonic Hudson Bay Basin, northern Canada.Earth Science Reviews, Vol. 125, pp. 1-23.CanadaTectonics
DS1989-0855
1989
Lavreau, J.Lavreau, J., Buyagu, S., Liegeois, J.P., Navez, J.Geochemical evidence for a non-alkalic origin for the carbonatitic bodies of Kibuye, RwandaJournal of African Earth Sciences, Vol. 9, No. 2, pp. 335-340GlobalCarbonatite, Geochemistry
DS1990-0906
1990
Lavreau, J.Lavreau, J., Poidebin, J.L., Lendent, D., Liegeois, J.P., Weis, D.Contribution to the geochronology of the basement of the Central AfricanRepublicJournal of African Earth Sciences, Vol. 11, No. 1/2, pp. 69-82Central African RepublicGeochronology, Tectonics
DS201012-0719
2009
Lavrenchuk, A.V.Sklyarov, E.V., Fedorovsky, V.S., Kotov, A.B., Lavrenchuk, A.V., Mazukebzov, A.M., Levitsky, V.I., et al.Carbonatites in collisional settings and pseudo-carbonatites of the Early Paleozoic Olkhon collisional system.Russian Geology and Geophysics, Vol. 50, 12, pp. 1091-1106.RussiaTectonics
DS1970-0829
1973
Lavrentev, Y.G.Sobolev, N.V., Lavrentev, Y.G., Pokhilenko, N.P. USOVA.Chrome Rich Garnets from Kimberlites of Yakutia and their ParagenesesContributions to Mineralogy and Petrology, Vol. 40, pp. 39-52.Russia, YakutiaMineralogy - Garnets
DS200512-0601
2005
Lavrentev, Y.G.Lavrentev, Y.G., Usova, L.V., Korolyuk, V.N., Logvinova, A.M.Electron probe microanalysis of Cr spinel for zinc and nickel traces as applied to study of the geothermometry of peridotites.Russian Geology and Geophysics, Vol. 46, 7, pp. 725-730.TechnologyPeridotite
DS1987-0399
1987
Lavrentev, Yu.G.Lavrentev, Yu.G., Usova, L.V., Kuznetsova, A.I., Letov, S.V.Quantiometric x-ray spectral microanalysis of the major minerals ofkimberlites.(Russian)Geologii i Geofiziki, (Russian), No. 5, pp. 75-81RussiaBlank
DS200612-0772
2006
Lavrentev, Yu.G.Lavrentev, Yu.G., Korolyuk, V.N., Usova, L.V., Logvinova, A.M.Electron probe microanalysis of pyrope for nickel traces as applied to study of the geothermometry of peridotites.Russian Geology and Geophysics, Vol. 47, 10, pp. 1075-1078.TechnologyPeridotite
DS200612-0773
2005
Lavrentev, Yu.G.Lavrentev, Yu.G., Usova, L.V., Korolyuk, V.N., Logvinova, A.M.Electron probe microanalysis of Cr spinel for zinc and nickel traces as applied to study of the geothermometry of peridotites.Russian Geology and Geophysics, Vol. 46, 7 pp. 725-730.TechnologyPeridotite - chrome spinel
DS201510-1782
2015
Lavrentev, Yu.G.Lavrentev, Yu.G., Karmanov, N.S., Usova, L.V.Electron probe microanalysis of minerals: micranalyzer or scanning electron microscope?Russian Geology and Geophysics, Vol. 56, pp. 1154-1161.TechnologySpectrometry

Abstract: The results of electron probe microanalysis of several rock-forming minerals by wavelength-dispersive spectrometry (WDS) and energy-dispersive spectrometry (EDS) are compared, and the metrological characteristics of both methods are studied. The measurements were made with the use of a JXA-8100 (JEOL) microanalyzer with five wavelength-dispersive spectrometers and a MIRA 3 LMU (Tescan) scanning electron microscope equipped with an INCA Energy 450 XMax 80 (Oxford Instruments) microanalysis system. Specimens with olivine, garnet, pyroxene, ilmenite, and Cr-spinel grains were analyzed. The variation coefficients that characterize the repeatability of a single determination are found to be ~ 0.5% for WDS and ~ 0.9% for EDS in the compositional range of the main components (C > 10%). For minor components (1% < C < 10%), the variation coefficients are 1.4% and 3.0%, respectively, and for impurities (0.3% < C < 1%), 2.7% and 13%, respectively. For lower contents EDS is almost inapplicable. The ratio of the results obtained by the two methods is reproduced with high precision: For major components, the variation coefficient is 0.56%; for minor components, 1.7%; and even for impurities, it is ~ 8%. The magnitude of the bias is between 0.2 and 3.2 rel.%, which is acceptable. The results show that the accuracies of WDS and EDS are similar for measuring major and minor components of rock-forming minerals. Energy-dispersive spectrometry is inferior to wavelength-dispersive spectrometry for impurities and is completely inapplicable for still lower contents. This method is easier to implement, and the results are available soon after switching on the instrument. Wavelength-dispersive spectrometry needs more time for preparation, but it ensures a precise high-efficiency large-scale analysis of samples of similar compositions, even when the element contents are lower than 1%.
DS200812-1095
2008
lavrentew, Y.G.Soloveva, L.V., lavrentew, Y.G., Egorov, K.N., Kostrovitskii, S.I., Korolyuk, V.N., Suvorova, L.F.The genetic relationship of the deformed peridotites and garnet megacrysts from kimberlites with asthenospheric melts.Russian Geology and Geophysics, Vol. 49, 4, pp. 207-224.RussiaPetrology - Udachnaya
DS1984-0692
1984
Lavrentiev, I.G.Sobolev, N.V., Efimova, E.S., Lavrentiev, I.G., Sobolev, V.S.Predominating Calc-silicate Association of Crystalline Inclusions in Diamonds from the South Australia Placers.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 274, No. 1, PP. 172-179.Australia, South AustraliaAlluvial Diamond Deposits, Mineralogy
DS1960-1212
1969
Lavrentyev, YU. G.Sobolev, N.V., Lavrentyev, YU. G.Chrome Pyropes from Yakutian DiamondsDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 189, PP. 162-165.RussiaInclusions, Diamond Morphology
DS1970-0603
1972
Lavrentyev, YU.G.Sobolev, V.S., Sobolev, N.V., Lavrentyev, YU.G.Inclusions in Diamond from a Diamond Bearing EclogiteDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 207, PP. 164-167.RussiaDiamond Morphology
DS1975-0306
1976
Lavrentyev, YU.G.Kepezhinskas, V.V., Lavrentyev, YU.G., Usova, L.V.Eclogites of Subcrustal Zones of Fold SystemsDoklady Academy of Science USSR, Earth Science Section., Vol. 231, No. 1, PP. 131-134.RussiaXenolith, Pyrope, Kimberlite
DS1985-0636
1985
Lavrentyev, YU.G.Sobolev, N.V., Yefimova, E.S., Lavrentyev, YU.G., Sobolev, V.S.Dominant calc-silicate association of crystalline inclusions in placer diamonds from southeastern AustraliaDoklady Academy of Science USSR, Earth Science Section, Vol. 275, April pp. 148-152AustraliaNew South Wales, Diamond Morphology
DS200412-0078
2004
Lavrik, S.N.Avchenko, O.V., Lavrik, S.N., Aleksandrov, I.A., Velivetskaya, T.A.Isotopic heterogeneity of carbon in metamorphic fluid.Doklady Earth Sciences, Vol. 394, 1, pp. 81-84.Russia, Aldan ShieldMetamorphism, petrology
DS1975-0773
1978
Lavrova, L.D.Kaminskiy, F.V., Lavrova, L.D., Shepeleva, K.A.Garnets in Alpine Type Ultramafic Rocks of the UralsDoklady Academy of Science USSR, Earth Science Section., Vol. 241, No. 1-6, PP. 193-195.RussiaKimberlite
DS1991-0961
1991
Lavrova, L.D.Lavrova, L.D.New type of diamond deposits. (Russian)Tsentr. Nauch. Issled. Geol. Institute Tsvetn, i Blagorodn. Met. (Russian), Vol. 1991 No. 12, pp. 62-68Russia, Kazakhstan, AsiaMetamorphic rocks
DS1992-1721
1992
Lavrova, L.D.Yekimova, T.V., Lavrova, L.D., Petrova, M.A.Diamond inclusions in rock-forming minerals of metamorphic rocks.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 322, No. 2, pp. 366-368RussiaDiamond inclusions, Metamorphic rocks
DS1993-1460
1993
Lavrova, L.D.Shukolyukov, Yu.A., Pleshakov, A.M., Lavrova, L.D.The unprecendentedly high 3He/4He ratio in diamonds from metamorphic rock of the Kokchetav Massif.Petrology, Vol. 1, No. 1, pp. 95-Russia, KazakhstanDiamond inclusions, helium, Metamorphic rocks
DS1994-0489
1994
Lavrova, L.D.Ekimova, T.E., Lavrova, L.D., Nadezhdina, E.D., Petrova, M.Conditions of the formation of the Kumdykol diamond deposit, NorthernKazakhstan.Geology of Ore Deposits, Vol. 36, No. 5, pp. 410-419.Russia, KazakhstanDiamond genesis, Deposit -Kumdykol
DS1994-1965
1994
Lavrova, L.D.Yekimova, T.Ye., Lavrova, L.D., Petrova, M.A.Diamond inclusions in the rock forming minerals of metamorphic rocksDoklady Academy of Sciences Acad. Science USSR, Vol. 323, No. 2, June pp. 101-103.RussiaDiamond inclusions, Metamorphic rocks
DS1995-1065
1995
Lavrova, L.D.Lavrova, L.D., Pechniko, V.A., Petrova, M.A., Ekimova, T.E.Minerals - indicators of diamond in the metamorphic rocks. (Russian)Doklady Academy of Sciences Nauk, (Russian), Vol. 343, No. 2, July pp. 220-224.Russiametamorphism
DS1995-1066
1995
Lavrova, L.D.Lavrova, L.D., Petchnikov, V.A., Petrova, M.A., EkimovaNew genetic type of diamond deposits: geological pecularities and originProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 311-313.Russia, KazakhstanMetamorphic, Deposit -Kumdykolskoye
DS1996-0814
1996
Lavrova, L.D.Lavrova, L.D., et al.Accessory minerals of diamond in metamorphic rocksDoklady Academy of Sciences, Vol. 345 No. 8, August pp. 120-125.Russia, KazakhstanMetamorphic rocks, Deposit - Kumdykol
DS1997-0652
1997
Lavrova, L.D.Lavrova, L.D., Karpenko, S.F., Shukoloukov, Yu.A.Diamond formation in the age succession of geological events on the Kokchetav Massif: evidence geochronologyGeochemistry International, Vol. 35, No. 7, July, pp. 589-595.RussiaGeochronology, Kokchetav Massif, metamorphic
DS1995-1067
1995
Lavrukhina, A.K.Lavrukhina, A.K., Fisenko, A.V.Origin of interstellar diamonds, silicon carbode and graphite inchondrites.Geochemistry International, Vol. 32, No. 6, pp. 114-121.GlobalSiC., Chondrites
DS1995-1068
1995
Lavrukhina, A.K.Lavrukhina, A.K., Fisenko, A.V.Properties and isotopic composition of interstellar diamonds, silicon carbide and graphite in chrondites.Geochemistry International, Vol. 32, No. 6, pp. 87-98.GlobalSiC., Chondrites
DS200512-0602
2004
Law, E.Law, E., Bear, S., Van Horn, S.Petrographic evidence of an instant freeze of kimberlite diatreme.Geological Society of America Northeastern Meeting ABSTRACTS, Vol. 36, 2, p. 71.United States, PennsylvaniaTanoma kimberlite dykes, phreatomagmatism
DS2000-0554
2000
Law, K.M.Law, K.M., Blundy, J.D., Wood, B.J., Ragnarsdottir, K.Trace element partioning between wollastonite and silicate carbonate meltMineralogical Magazine, Vol. 64, No. 4, Aug. pp. 651-62.GlobalGeochemistry, Carbonatite
DS1994-0799
1994
Law, L.K.Hyndman, R.D., Vanyan, L.L., Marquis, G., Law, L.K.The origin of electrically conductive lower continental crust: saline wateror graphite?Physics of the Earth and Planetary Interiors, Vol. 81, pp. 325-344.MantleGeophysics -magnetotellurics, Graphite, carbon
DS2001-0847
2001
Law, R.O'Brien, P.J., Zotov, N., Law, R., Khan, M.A., Jan. M.Coesite in Himalayan eclogite and implications for models of India Asia collision.Geology, Vol. 29, No. 5, May, pp. 435-8.GlobalEclogite, coesite, metamorphism
DS1990-0846
1990
Law, R.D.Knipe, R.J., Ritter, E.H., Agar, S.M., Prior, D.J., Law, R.D.Deformation mechanisms, rheology and tectonicsGeological Society of London Special Publication, No. 54, 520pGlobalRock deformation, fracture, faulting, flow mechanisms, Flow laws, rock fabrics, tectonics
DS1992-1131
1992
Law, R.D.Nyman, M.W., Law, R.D., Smelik, E.A.Cataclastic deformation mechanism for the development of core mantle structures in amphiboleGeology, Vol. 20, No. 5, May pp. 455-458WyomingMedicine Bow Mountains, Core-mantle
DS200712-0599
2006
Law, R.D.Law, R.D., Searle, M.P., Godin, L.Channel flow, ductile extrusion and exhumation in continental collision zones.Geological Society of London , SP 268, Nov. 632p. $ 225. www.geolsoc.org.uk/bookshopCanadaGeodynamics
DS200812-1113
2008
Lawie, D.Stanley, C.R., Lawie, D.Thompson-Howarth error analysis: unbiased alternatives to the large sample method for assessing non-normally distributed measurement error in geochemical samples.Geochemistry, Exploration, Environment Analysis, Vol. 8, pp. 173-182.TechnologySampling - Not specific to diamonds
DS1860-0711
1891
Lawler, E.J.Lawler, E.J.On Diamond Digging in South AfricaCosmopolitan Magazine, JULY, PP. 285-293.Africa, South Africa, Cape ProvinceTravelogue
DS1995-1808
1995
Lawler, T.L.Spector, A., Lawler, T.L.Application of aeromagnetic dat a to mineral potential evaluation inMinnesotaGeophysics, Vol. 60, No. 6, Nov. Dec. pp. 1704-1714MinnesotaGeophysics, Metallogeny
DS1960-0766
1966
Lawless, J.M.Wilson, A.N., Lawless, J.M.One Hundred Years of Diamonds in South AfricaJohannesburg: S.a.b.c., UNPUBL.South AfricaHistory, Kimberley
DS200612-0369
2006
Lawless, P.Ekkerd, J., Stiefenhofer, J., Field, M., Lawless, P.The geology of Finsch mine, northern Cape Province, South Africa.Emplacement Workshop held September, 5p. extended abstractAfrica, South AfricaDeposit - Finsch geology
DS1970-0952
1974
Lawless, P.J.Lawless, P.J.Some Aspects of the Geochemistry of Kimberlite XenocrystsCape Town: Msc. Thesis, University Cape Town., 121P.South Africa, LesothoKimberlite, Xenoliths
DS1975-0059
1975
Lawless, P.J.Dawson, J.B., Gurney, J.J., Lawless, P.J.Paleothermal Gradients Derived from Xenoliths in KimberliteNature., Vol. 257, No. 5524, PP. 299-300.South AfricaGeothermometry
DS1975-0794
1978
Lawless, P.J.Lawless, P.J.Some Aspects of the Mineral Chemistry of the Peridotite Xenolith Suite from the Bultfontein Diamond Mine, South Africa.Cape Town: Ph.d. Thesis, University Cape Town., 194P.South AfricaMineral Chemistry, Kimberley
DS1975-1112
1979
Lawless, P.J.Lawless, P.J., Gurney, J.J., Dawson, J.B.Polymict Peridotites from the Bultfontein and de Beers Mines,kimberley South Africa.Proceedings of Second International Kimberlite Conference, Proceedings Vol. 2, PP. 145-155.South AfricaPetrography
DS1982-0363
1982
Lawless, P.J.Lawless, P.J., Wyatt, B.A.Ilmenite in Upper Mantle Polymict Xenoliths from BultfonteinProceedings of Third International Kimberlite Conference, TERRA COGNITA, ABSTRACT VOLUME., Vol. 2, No. 3, P. 222, (abstract.).South AfricaKimberlite, Lhzerolite
DS1984-0776
1984
Lawless, P.J.Wyatt, B.A., Lawless, P.J.Ilmenite in Polymict Xenoliths from the Bultfontein and de Beers Mines, South Africa.Proceedings of Third International Kimberlite Conference, Vol. 2, PP. 43-56.South AfricaPetrography, Mineral Chemistry, Analyses
DS1988-0734
1988
Lawless, P.J.Viljoen, K.S., Lawless, P.J.Finsch mine-the largest diamond producer in South AfricaGeoBulletin, Vol. 31, No. 1, pp. 48-49South AfricaBlank
DS1995-1996
1995
Lawless, P.J.Viljoen, K.S., Lawless, P.J.Finsch mine - the largest diamond producer in South AfricaMdd/seg Guidebook Nov., 18p.South AfricaBrief overview, Deposit -Finsch
DS201708-1702
2017
Lawless, P.J.Lawless, P.J.Relationships between the Diamond Trading Company ( DTC) round aperture diamond sieve ( DS) plates.11th. International Kimberlite Conference, PosterTechnologyDTC
DS201810-2342
2018
Lawley, C.Lawley, C., Kjarsgaard, B., Jackson, S., Yang, Z., Petts, D., Roots, E.Trace metal and isotopic depth profiles through the Abitibi. Kirkland Lake kimberlite field.Lithos, Vol. 314-315, pp. 520-533.Canada, Ontariodeposit - Kirkland Lake

Abstract: Geophysical imaging of trans-lithospheric structures provide a spatial link between ore deposits in the crust and the underlying cratonic mantle. However, the deep lithosphere's role in ore deposit genesis remains poorly understood because remotely acquired datasets do not provide any direct constraints on the behaviour of ore elements within these mantle-roots. The abundance and behaviour of ore elements governs the metallic endowment of the cratonic mantle and the economic potential of mantle-derived magmas. Herein we present in situ electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) geochemical datasets for clinopyroxene and olivine mantle xenocrysts from the Jurassic Kirkland Lake kimberlite field, Abitibi greenstone belt, Canada. We specifically focus on unconventional trace elements, including ore elements with chalcophile and/or siderophile affinities (Ag-As-Au-Bi-Cu-Mo-Pb-Pt-Pd-Sb-Se-Sn-Te-W-Zn). Robust principal component analysis suggests that low-T, large-ion lithophile element alteration (Ba-Sr), which likely occurred during kimberlite emplacement, represents the largest source of variance for the xenocryst dataset. PT-dependent element partitioning during sub-solidus equilibration represents the second most important control on olivine and clinopyroxene chemistry. We demonstrate that least-altered, high-PT mantle silicates are, in fact, a significant mineral host for a range of ore elements (Cu-Zn ± Ag ± As ± Se ± Sn ± Mo) within equilibrated, garnet peridotite at depth (70-190 km). Statistical analysis of the raw, individual mass sweeps for each LA-ICP-MS signal suggest that the most abundant ore elements (Cu-Zn) occur predominantly as PT-dependent substitution reactions with the dominant mineral-forming elements, rather than as inclusions. A subset of high-PT olivine (160-180 km) yields Fe-Ni-S-poor and Na (Au ± Pt ± Pd)-rich compositions, which may reflect metasomatism, sulphide segregation and trapping of precious metal-bearing fluids at the base of the lithosphere. These anomalous mantle fragments possibly represent the first, direct sampling of precious metal-modified mantle peridotite beneath the Abitibi. Mid-PT olivine xenocrysts (70-120 km), which yield Mg-rich and high field-strength element-poor compositions, document a highly melt-depleted segment of mantle peridotite coincident with and below a shallow-dipping, low-seismic-velocity anomaly and conductive feature of the Kirkland Lake mid-lithosphere at 70-100 km. We speculate that the trace element signature of mid-PT xenocrysts documents the re-distribution of high-charge and incompatible elements from refractory garnet peridotite to phlogopite- and/or amphibole-bearing peridotite with conductive metasomatic up-flow zones. The rapid, sub-solidus diffusion of elements at high-T suggest that these processes likely occurred during, and/or immediately preceding, kimberlite volcanism. New in situ Pb isotope analyses of clinopyroxene xenocrysts sampled from metasomatized, low-Al garnet peridotite, however, also document ancient metasomatic events that likely pre-date Jurassic kimberlitic volcanism by at least one billion years.
DS201906-1358
2019
Lawley, C.Veglio, C., Lawley, C., Kjarsgaard, B., Pearson, D.G.Behaviour of ore forming elements in the subcontinental lithospheric mantle below the Slave craton.GAC/MAC annual Meeting, 1p. Abstract p. 187.Canada, Northwest Territoriesdeposit - Jericho, Muskox

Abstract: The fertility of the subcontinental lithospheric mantle as source for metal-rich magmas remains poorly understood. We report new major (EPMA), minor and trace element (LA-ICP-MS) results for olivine mantle xenocrysts sourced from the Jurassic age Jericho, Muskox and Voyageur kimberlites, western Nunavut in the Slave Craton, approximately 30 km north of the Lupin gold mine. Target elements include a suite of ore-forming elements that are unconventional for mantle petrology studies, but may represent important geochemical tracers for metal metasomatism. Using single-grain aluminum-in-olivine thermometry, formation temperatures for the olivine grains were calculated and projected on to a mantle geotherm to estimate PT conditions. The suite of xenocrysts corresponds to mantle sampling between 100-190 km depth. Their range in Mg# indicates that all 3 kimberlites sampled variably depleted mantle peridotite. The patterns of trace element enrichments found are consistent with those documented previously for mantle olivine xenocryst samples from the lithosphere below the Superior Craton in Kirkland Lake, Ontario. In both studies, some ore-forming elements were found to partition into mantle silicates more at the higher temperatures and pressure prevalent at the base of the lithospheric mantle, notably copper, with concentrations varying from ~ 1 ppm in shallow samples up to 11 ppm at the maximum depth sampled. Because the concentration of metals in melt-depleted lithospheric peridotite is expected to be low (< 20 ppm Cu), mantle silicates likely become a significant host for some ore elements at depth. Highly incompatible high field strength elements yield decreasing concentrations with depth, possibly the result of mantle metasomatic processes. Fluid metasomatized mantle peridotite domains are also inferred from olivine xenocrysts that yield unexpected trace element concentrations (ppb to ppm) for other highly incompatible ore-elements (e.g. As, Mo). We expect that some of these fluid-mobile and highly incompatible ore-elements represent trapped fluid and/or melt inclusions.
DS201809-2054
2018
Lawley, C.J.M.Lawley, C.J.M., Kjarsgaard, B.A., Jackson, S.E., Yang, Z., Petts, D.C.Olivine and clinopyroxene mantle xenocryst geochemistry from the Kirkland Lake kimberlite field, Ontario.Geological Survey of Canada, Open File 8376, 9p.Canada, Ontariogeochemistry
DS202002-0202
2020
Lawley, C.J.M.Lawley, C.J.M., Pearson, G., Waterton, P., Zagorevski, A., Bedard, J.H., Jackson, S.E., Petts, D.C., Kjarsgaard, B.A., Zhang, S., Wright, D.Element and isotopic signature of re-fertilized mantle peridotite as determined by nanopower and olivine LA-ICPMS analyses.Chemical Geology, DOI:101016/ j.chemgeo.2020.119464Mantleperidotite

Abstract: The lithospheric mantle should be depleted in base- and precious-metals as these elements are transferred to the crust during partial melting. However, some melt-depleted mantle peridotites are enriched in these ore-forming elements. This may reflect re-fertilization of the mantle lithosphere and/or sequestering of these elements by residual mantle phase(s). Both processes remain poorly understood because of the low abundances of incompatible elements in peridotite and the nugget-like distribution of digestion-resistant mantle phases that pose analytical challenges for conventional geochemical methods. Herein we report new major and trace element concentrations for a suite of mantle peridotite and pyroxenite samples from the Late Permian to Middle Triassic Nahlin ophiolite (Cache Creek terrane, British Columbia, Canada) using Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS) analysis of nanoparticulate powders and olivine. Compatible to moderately incompatible element concentrations suggest that Nahlin ophiolite peridotites represent residues after ?20% melt extraction. Pyroxenite dykes and replacive dunite bands are folded and closely intercalated with residual harzburgite. These field relationships, coupled with the presence of intergranular base metal sulphide, clinopyroxene and Cr-spinel at the microscale, point to percolating melts that variably re-fertilized melt-depleted mantle peridotite. Radiogenic Pb (206Pb/204Pb?=?15.402-19.050; 207Pb/204Pb?=?15.127-15.633; 208Pb/204Pb?=?34.980-38.434; n?=?45) and Os (187Os/188Os 0.1143-0.5745; n?=?58) isotope compositions for a subset of melt-depleted peridotite samples further support metasomatic re-fertilization of these elements. Other ore-forming elements are also implicated in these metasomatic reactions because some melt-depleted peridotite samples are enriched relative to the primitive mantle, opposite to their expected behaviour during partial melting. New LA-ICPMS analysis of fresh olivine further demonstrates that a significant proportion of the highly incompatible element budget for the most melt-depleted rocks is either hosted by, and/or occurs as trapped inclusions within, the olivine-rich residues. Trapped phases from past melting and/or re-fertilization events are the preferred explanation for unradiogenic Pb isotope compositions and Paleozoic to Paleoproterozoic Re-depletion model ages, which predate the Nahlin ophiolite by over one billion years.
DS202106-0949
2021
Lawley, C.J.M.Lawley, C.J.M., Somers, A.M., Kjarsgaard, B.A.Rapid geochemical imaging of rocks and minerals with handheld laser induced breakdown spectroscopy. ( LIBS)Journal of Geochemical Exploration, Vol. 222, 106694, 16p. PdfCanada, Nunavutdeposit - Jericho, Muskox

Abstract: Geochemical imaging is a powerful tool for unravelling the complex geological histories of rocks and minerals. However, its applications have until recently been restricted to geological research in a lab environment due to the cost and size of conventional instrumentation, long analysis times, and extensive sample preparation for some methods. Herein we present a rapid, qualitative geochemical imaging method for rocks and minerals using handheld LIBS. Analyses were completed directly on sawed drill core surfaces for a suite of kimberlite-hosted mantle xenoliths (Jericho and Muskox kimberlites, Nunavut, Canada). Semi-automated LIBS spectral processing following a new open-source workflow allows stitching of multiple small-area maps (each approximately 3 × 3 mm that take 2-3 min to complete) to produce cm-scale geochemical images of variably altered mantle xenolith samples (total data acquisition in 1-2 h). Replicate analyses of a Znsingle bondAl alloy reference material (NZA-1; CANMET) that were undertaken during standard-sample bracketing suggests that the relative standard deviation (RSD) is typically 15-20% for sum-normalized emission intensities above the estimated background. We demonstrate with open-source machine learning tools how qualitative LIBS spectral data can be converted to Feature-Of-Interest (FOI) maps to distinguish a variety of metasomatic and alteration features (e.g., Cr-diopside, kelyphite rims on pyrope garnet, and calcite veinlets) from the primary mantle mineralogy (e.g., olivine and orthopyroxene). Our results further demonstrate that the resolution of handheld LIBS-based geochemical imaging is sufficient to map veinlets and grain boundaries lined with metasomatic minerals. The LIBS approach is particularly sensitive for mapping the microscale distribution of elements with low atomic number (e.g., Li and Na). These light elements are difficult to detect at low concentrations with other handheld and field-portable technologies, but represent important geochemical tracers of hydrothermal and magmatic processes. Rapid LIBS mapping thus represents an emerging geochemical imaging tool for unravelling the complex geological history of rocks and minerals in the field with minimal to no sample preparation.
DS202205-0726
2022
Lawley, C.J.M.Veglio, C., Lawley, C.J.M., Kjarsgaard, B., Petts, D., Pearson, G., Jackson, S.E.Olivine xenocrysts reveal carbonated mid-lithosphere in the northern Slave craton.Lithos, 10.1016/j.lithos.2022.106633, 14p. PdfCanada, Northwest Territoriesolivine

Abstract: The cold, rigid, and melt-depleted mantle underlying Archean cratons plays an important role in the preservation of the overlying continental crust and is one of the main sources of diamonds. However, with the possible exception of rare earth elements (REE) and platinum group-elements (PGE), the concentrations and host mineral phases for many other critical trace elements within lithospheric mantle remain very poorly understood. Here we address that knowledge gap, presenting new electron microprobe and laser-ablation inductively-coupled-plasma mass-spectrometry results for a suite of mantle xenoliths (n = 12) and olivine xenocrysts (n = 376) from the Jericho, Muskox, and Voyageur kimberlites (northern Slave craton, Canada). Low-temperature (<1000 °C) harzburgite xenoliths and olivine xenocrysts suggest that the shallowest portions of the garnet-bearing mantle (?160 km) underlying the northern Slave craton is chemically depleted and becomes increasing re-fertilized from 160 to 200 km. High-temperature (>1000 °C) garnet and clinopyroxene crystals with Ti/Eu ratios > > 1000, and olivine xenocrysts suggest that interaction with ultramafic silicate melts is the most likely mechanism to re-fertilize melt-depleted peridotite with incompatible elements toward the base of the lithosphere (~200 km). In contrast, lower temperature garnet and clinopyroxene with Ti/Eu ratios <1000 are more likely related to metasomatism by carbonatitic melts and/or fluids. Carbonatitic metasomatism is also interpreted as the preferred explanation for the trend of Nb (4 ppm)- and Ta (185 ppb)-rich concentrations of olivine xenocrysts sampled from mid-lithosphere depths (~140 km). With the exception of a few elements that substitute into the olivine crystal structure during sub-solidus re-equilibration (e.g., Ca, Cr, Cu, Na, Sc, V, Zn), most other olivine-hosted trace elements do not systematically vary with depth. Instead, we interpret olivine-hosted trace element concentrations that are significantly above the analytical detection and/or quantification limits to reflect trapped fluid (e.g., As, Mo, Sb, Sn), base-metal sulphide (e.g., Ag, Au, Bi, Pd, Pt, Se, Te), and other mineral inclusions (e.g., U, Th) rather than enrichments of these elements due to substitution reactions or analytical artefacts. We interpret that these inclusions occur in olivine throughout the garnet stability field, but are relatively rare. As a result, these trapped carbonatitic, proto-kimberlite, and/or other ultramafic silicate melts do not represent a significant source for the suite of trace elements that become enriched to economic levels in the crust.
DS1860-1038
1898
Lawn, J.G.Lawn, J.G.The Story of the Diamond MinesDiamond Fields Advertiser (kimberley), CHRISTMAS NUMBER.South Africa, Cape Province, Kimberley AreaHistory
DS1900-0780
1909
Lawn, J.G.Lawn, J.G.Discussion on Paper by Harger " the Occurrence of Diamond In the Dwyka Conglomerate".Geological Society of South Africa Proceedings, Vol. 12, P. XLIX.Africa, South AfricaGeology, Diamond Genesis
DS1910-0201
1911
Lawn, J.G.Lawn, J.G.Les Mines de L'afrique du Sud (1911) - the Mines of South AfricaRevue Econ. International, Vol. 4, PP. 466-489.South AfricaGeology
DS1994-0991
1994
LawrenceLawrence, Qu, Qi, Taylor, A., Sobolev, N.V.Eclogites from the Obnazhennaya kimberlite pipe, Yakutia, RussiaInternational Geology Review, Vol. 36, No. 10, Oct. 1, pp. 911-924.RussiaEclogites, petrology, Deposit - Obnazhennaya
DS200712-0204
2007
LawrenceCourtier, A.M., Jackson, Lawrence, Wang, Lee, Halama, Warren, Workman, Xu, Hirschmann, Larson, Hart, Lithgo-Bertelloni, Stixrude, ChenCorrelation of seismic and petrologic thermometers suggests deep thermal anomalies beneath hotspots.Earth and Planetary Science Letters, Vol. 264, 1-2, pp. 308-316.MantleGeothermometry
DS200512-0112
2005
Lawrence, A.Bremen, J., Lawrence, A.Taking it to the bank - making your mining project bankable.Engineering and Mining Journal, Sept. pp. 80-83.GlobalEconomics - feasibility studies
DS1960-0857
1967
Lawrence, A.L.Lawrence, A.L.Field Prospecting for Diamonds in Isolated AreasLiberia Geol. Min. Met. Soc. Bulletin., Vol. 2, PP. 1-3.GlobalGeology
DS1960-0979
1968
Lawrence, D.E.Lee, H.A., Lawrence, D.E.A New Occurrence of Kimberlite in Gauthier TownshipGeological Survey of Canada (GSC) PAPER., No. 68-22, 16P.Canada, OntarioGeology
DS201412-0938
2014
Lawrence, D.F.Valley, J.W., Cavosie, T., Ushikubo, T., Reinhard, D.A., Lawrence, D.F., Larson, D.J., Clifton, P.H., Kelly, T.F., Wilde, S.A., Moser, D.E., Spicuzza, M.J.Hadean age for a post-magma-ocean zircon confirmed by atom-probe tomography.Nature Geoscience, Vol. 7, pp.219-223.MantleGeochronology
DS201509-0434
2015
Lawrence, D.F.Valley, J.W., Reinhard, D.A., Cavosie, A.J., Ushikubo, T., Lawrence, D.F., Larson, D.J., Kelly, T.F., Snoeyenbos, D.R., Strickland, A.Nano- and micro-geochronology in Hadean and Archean zircons by atom-probe tomography and SIMS: new tools for old minerals.American Mineralogist, Vol. 100, pp. 1355-1377.AustraliaGeochronology

Abstract: Atom-probe tomography (APT) and secondary ion mass spectrometry (SIMS) provide complementary in situ element and isotope data in minerals such as zircon. SIMS measures isotope ratios and trace elements from 1–20 ?m spots with excellent accuracy and precision. APT identifies mass/charge and three-dimensional position of individual atoms (±0.3 nm) in 100 nm-scale samples, volumes up to one million times smaller than SIMS. APT data provide unique information for understanding element and isotope distribution; crystallization and thermal history; and mechanisms of mineral reaction and exchange. This atomistic view enables evaluation of the fidelity of geochemical data for zircon because it provides new understanding of radiation damage, and can test for intracrystalline element mobility. Nano-geochronology is one application of APT in which Pb isotope ratios from sub-micrometer domains of zircon provide model ages of crystallization and identify later magmatic and metamorphic reheating.
DS1989-0294
1989
Lawrence, D.H.Corr, D.G., Tailor, A.M., Cross, A., Hogg, D.C., Lawrence, D.H.Progress in automatic analysis of multi-temporal remotely sensed dataInternational Journal of Remote Sensing, Vol. 10, No. 6, June pp. 1175-1196GlobalRemote sensing, Computer Program
DS201312-0126
2012
Lawrence, D.M.Carmody, L., Jones, A.P., Mikhail, S., Bower, D.M., Steele, A., Lawrence, D.M., Verchovsky, A.B., Buikin, A., Taylor, L.A.Is the World's only carbonatite volcano a dry anhydrous system?Geological Society of America Annual Meeting abstract, Paper 157-2, 1/2p. AbstractAfrica, TanzaniaDeposit - Oldoinyo Lengai
DS202003-0367
2020
Lawrence, D.M.Turetsky, M.R., Abbott, B.W., Jones, M.C., Walter Anthony, K.. Olefeldt, D., Schuur, E.A.G., Grosse, G., Kuhry, P., Higelius, G., Koven, C., Lawrence, D.M., Gibson, C., Sannel, A.B.K., McGuire, A.D.Carbon release through abrupt permafrost thaw. ( not specific to diamonds but interest)Nature Geoscience, Vol. 13, pp. 138-143.Mantlecarbon

Abstract: The permafrost zone is expected to be a substantial carbon source to the atmosphere, yet large-scale models currently only simulate gradual changes in seasonally thawed soil. Abrupt thaw will probably occur in <20% of the permafrost zone but could affect half of permafrost carbon through collapsing ground, rapid erosion and landslides. Here, we synthesize the best available information and develop inventory models to simulate abrupt thaw impacts on permafrost carbon balance. Emissions across 2.5?million?km2 of abrupt thaw could provide a similar climate feedback as gradual thaw emissions from the entire 18?million?km2 permafrost region under the warming projection of Representative Concentration Pathway 8.5. While models forecast that gradual thaw may lead to net ecosystem carbon uptake under projections of Representative Concentration Pathway 4.5, abrupt thaw emissions are likely to offset this potential carbon sink. Active hillslope erosional features will occupy 3% of abrupt thaw terrain by 2300 but emit one-third of abrupt thaw carbon losses. Thaw lakes and wetlands are methane hot spots but their carbon release is partially offset by slowly regrowing vegetation. After considering abrupt thaw stabilization, lake drainage and soil carbon uptake by vegetation regrowth, we conclude that models considering only gradual permafrost thaw are substantially underestimating carbon emissions from thawing permafrost.
DS1999-0398
1999
Lawrence, E.M.Lawrence, E.M.Diamond exploration for the May Lake areaAlberta Geological Survey, MIN 199900016AlbertaExploration - assessment
DS2000-0555
2000
Lawrence, J.Lawrence, J.Proving provenance of a diamondThe Basel, July p. 35, 36.GlobalDiamond - technology, techniques
DS1960-0261
1962
Lawrence, J.C.Lawrence, J.C.Wasatch and Green River Formations of the Cumberland Gap Area, Lincoln and Uinta Counties Wyoming.M.a. Thesis, University Wyoming At Laramie., 72P.United States, Wyoming, UtahRegionlal Studies
DS200612-0774
2006
Lawrence, J.F.Lawrence, J.F., Shearer, P.M., Masters, G.Mapping attenuation beneath North America using waveform cross correlation and cluster analysis.Geophysical Research Letters, Vol. 33, 7, April 16, L07315Canada, United StatesGeophysics - seismics
DS200612-0775
2006
Lawrence, J.F.Lawrence, J.F., Wysession, M.E.QLM9: a new radial quality factor (Q) model for the lower mantle.Earth and Planetary Science Letters, Vol. 241, 3-4, pp. 962-971.MantleTectonics
DS200712-0600
2006
Lawrence, J.F.Lawrence, J.F., Wysession, M.E.Seismic evidence for subduction transported water in the lower mantle.American Geophysical Union, Geophysical Monograph, No. 168, pp. 251-262.MantleSubduction
DS201112-0570
2011
Lawrence, J.F.Lawrence, J.F., Prieto, G.A.Attenuation tomography of the western United States from ambient seismic noise.Journal of Geophysical Research, Vol. 116, B6, B06302.United StatesGeophysics - seismic
DS1970-0336
1971
Lawrence, M.J.Lawrence, M.J.The Diamond Search in Australia: Specifications of a Mobile prospection Unit and the Concept of Mineral Geochemistry.Australasian Institute of Mining And Metallurgy., Paper Preprint No. 24., No. 24, PP. 24-2-24-44.AustraliaKimberlite, Prospecting
DS1970-0746
1973
Lawrence, M.J.Lawrence, M.J.Diamond ProspectingAustralian Gemologist., Vol. 11, No. 11, PP. 22-29.AustraliaKimberlite
DS1992-0915
1992
Lawrence, M.J.Lawrence, M.J., Hancock, R.G., Dewar, G.J.A.New due diligence requirements affecting technical experts contributing to prospectuses involving resource assetsAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 4, July pp. 34-35, 37-38AustraliaGeostatistics, Ore reserves, due diligence
DS1997-0653
1997
Lawrence, M.J.Lawrence, M.J.A comparison of Australian accreditation initiatives for geologists, engineers, metallurgist and environ..Australian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 2, March pp. 73-82AustraliaAccreditation
DS1998-0834
1998
Lawrence, M.J.Lawrence, M.J.The revised VALMIN code and guidelines ( 1998): an aide memoire to assistits interpretationAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 3, May, pp. 80-83AustraliaLegal, Economics, success, ore reserves, geostatistics
DS1998-0835
1998
Lawrence, M.J.Lawrence, M.J.Australian project valuation lessons for Canadian developersPros. Developers Assoc, Short course pp. 69-85Australia, CanadaReserves, Valuation
DS2001-0584
2001
Lawrence, M.J.Kelly, J.J., Lawrence, M.J., Stitt, P.2001 independent review of the VALMIN code (1998) - panel discussion issues paper.Valmin 01, Mineral Asset Valuation Oct. 25-6th., pp.209-15.AustraliaEconomics - legal code, Mineral reserves, resources, valuation, exploration
DS2001-0659
2001
Lawrence, M.J.Lawrence, M.J.An outline of market based approaches for mineral asset valuation best practiceValmin 01, Mineral Asset Valuation Oct. 25-6th., pp.115-37.AustraliaEconomics - legal code, Mineral reserves, resources, valuation, exploration
DS2001-0660
2001
Lawrence, M.J.Lawrence, M.J.History and relevance of Australian Institute of Mining and Metallurgy (AusIMM)'s VALMIN code 1981-2000Valmin 01, Mineral Asset Valuation Oct. 25-6th., pp.201-5.AustraliaEconomics - legal code, Mineral reserves, resources, valuation, exploration
DS2002-0920
2002
Lawrence, M.J.Lawrence, M.J.The VALMIN code - the Australian experienceC.i.m. Bulletin, Vol.95,1058,Feb.pp.76-81.GlobalEconomics - ore reserves, exploration, discoveries
DS1981-0260
1981
Lawrence, P.D.Lawrence, P.D.The Glory of DiamondsMainliner( American Airlines), NOVEMBER PP. 37-40.GlobalPopular Account For Investing
DS1900-0428
1906
Lawrence, P.M. SIR.Lawrence, P.M. SIR.A Quarter of a Century in the Diamond FieldsDiamond Field Advertiser Christmas Issue., DECEMBER, PP. 1-3.Africa, South AfricaHistory
DS1989-0856
1989
Lawrence, R.D.Lawrence, R.D.Valuation of mineral assets: accountancy or alchemy?The Canadian Institute of Mining, Metallurgy and Petroleum (CIM) 91st. Annual Meeting Preprint, No. 78, 20p. Database # 17963GlobalEconomics, Mine evaluation
DS1992-0916
1992
Lawrence, R.D.Lawrence, R.D.Some thoughts on ore reserves- a presentation to the association of mining financial professionalsPreprint Talk given April 2, 1992 Denver Colorado, 22pGlobalGeostatistics, Ore reserves
DS1994-0992
1994
Lawrence, R.D.Lawrence, R.D.Structuring mining ventures in a newly competitive global environmentCanadian Institute 1994 Canadian Mining Symposium, Preprint, 39pCanadaEconomics, Mining industry -mining ventures
DS1998-1565
1998
Lawrence, R.D.Ward, M-C, Lawrence, R.D.Comparable transaction analysis: the market is always rightPros. Developers Assoc, Short course pp. 53-68GlobalReserves, discoveries, success, economics, Valuation
DS2001-0661
2001
Lawrence, R.D.Lawrence, R.D.Income approaches to valuation. DCF, Monte Carlo, real option pricing, tree analysis weighted average cost...Valmin 01, Mineral Asset Valuation Oct. 25-6th., pp.147-59.GlobalEconomics - costs, Mineral reserves, resources, valuation, exploration
DS2002-0921
2002
Lawrence, R.D.Lawrence, R.D.Valuation of mineral properties without mineral resources: a review of market based approaches.C.i.m. Bulletin, Vol. 95,1060, April Pp. 103-6., Vol. 95,1060, April pp. 103-6.GlobalEconomics - reserves, resources, market approach
DS2002-0922
2002
Lawrence, R.D.Lawrence, R.D.Valuation of mineral properties without mineral resources: a review of market based approaches.C.i.m. Bulletin, Vol. 95,1060, April Pp. 103-6., Vol. 95,1060, April pp. 103-6.GlobalEconomics - reserves, resources, market approach
DS200612-1150
2006
Lawrence, S.Reilinger, R., McClusky, S., Vernant, P., Lawrence, S., Ergintav, Cakmak, Ozener, Kadirov, Guliev, StepanyanGPS constraints on continental deformation in the Africa Arabia Eurasia continental collision zone and implications for the dynamics of plate interactions.Journal of Geophysical Research, Vol. 111,B5 B05411.AfricaGeodynamics
DS200612-1155
2006
Lawrence, S.Relinger, R., McClusky, S., Vernant, P., Lawrence, S.GPS constraints on continental deformation in the Africa-Arabia-Eurasia continental collision zone and implications for the dynamics of plate interactions.Journal of Geophysical Research, Vol. 111, B5, May 31, B05411AfricaTectonics
DS200812-1189
2008
Lawrence, S.R.Turner, J.P., Green, P.F., Hoford, S.P., Lawrence, S.R.Thermal history of the Rio Muni (West Africa) - NE Brazil margins during continental breakup.Earth and Planetary Science Letters, Vol. 270, 3-4, pp. 354-367.Africa, West Africa, South America, BrazilGeothermometry
DS201012-0279
2010
Lawrence Livermore National LaboratoryHigh Pressure Physics Group, Lawrence Livermore National LaboratoryOhmic heating - laser heating - brief backgrounder - heating experiments at high pressure valuable in understanding behavior of materials.adg.gov, 2p.TechnologyOverview - brief using diamond anvil cells
DS1860-0852
1894
Lawson, A.C.Lawson, A.C., Coleman, A.P.Diamonds Might Be Found in the Rainy Lakes RegionCanadian Naturalist., N.S. Vol. IV, PP. 61-63.Canada, OntarioDiamond Occurrence
DS1900-0339
1905
Lawson, C.Lawson, C.Memories of MadrasLondon: Swan Sonnenschein And Co., 302P. CHAPTER II, PP. 17-53.IndiaPurchase Of Koh-i-noor, Diamonds Notable
DS202110-1621
2021
Lawson, C.Lawson, C., Simmiss, M.Provenance proof - new technologies to track and trace gems in the supply chain.Australian Gemmologist, Vol. 27, 5, pp. 262-271.Australiamarkets
DS1982-0381
1982
Lawson, J.E.JR.Luza, K.V., Lawson, J.E.JR.Seismicity and Tectonic Relationships of the Nemaha Uplift In Oklahoma- Part V.Nureg Cr 3109, Oklahoma Geological Survey, 128P.OklahomaMid-continent, Geophysics
DS1982-0382
1982
Lawson, J.E.JR.Luza, K.V., Lawson, J.E.JR.Seismicity and Tectonic Relationships of the Nemaha Uplift In Oklahoma, Pt. Iv.Oklahoma Geological Survey Special Publishing, No. 82-1, 52P.OklahomaMid-continent, Geophysics
DS1993-0887
1993
Lawson, S.C.Lawson, S.C., Kanda, H.Nickel in diamond - an annealing studyDiamond Relat, Vol. 2, No. 2-4, March 31, pp. 130-135GlobalDiamond inclusions
DS200412-1233
2004
Lawson, S.C.Martineau, P.M., Lawson, S.C., Taylor, A.I., Quinn, S.J., Evans, D.J.F., Crowder, M.J.Identification of synthetic diamond grown using chemical vapor deposition (CVD).Gems & Gemology, Vol. 40, 1, Spring, pp. 2-25.TechnologyDiamond synthesis - review
DS1994-0993
1994
Lawton, D.C.Lawton, D.C., Spratt, D.A., Hopkins, J.C.Tectonic wedging beneath the Rocky Mountain foreland basin, Alberta, Canada.Geology, Vol. 22, No. 6, June pp. 519-522.AlbertaStructure, Tectonics
DS1992-1261
1992
Lawton, S.E.Rayner, N.W., Tays, R.H., Lawton, S.E.New mining legislation in CanadaPda Seminar, Held April 2, 1992, 160p. $ 45.00CanadaLegal, Mining legislation seminar notes
DS1994-0994
1994
Lawton, T.F.Lawton, T.F., Boyer, S.E., Schmitt, J.G.Influence of inherited taper on structural variability and conglomeratedistribution, Cordilleran fold and thrust belt, western United StatesGeology, Vol. 22, No. 4, April pp. 339-342Nevada, CordilleraStructure, Foreland basin
DS1999-0045
1999
Lawton, T.F.Bartolini, C., Wilson, J.L., Lawton, T.F.Mesozoic sedimentary and tectonic history of north central MexicoGeological Society of America Special paper, No. 340, 380p.MexicoBook - table of contents
DS1994-0995
1994
Lawver, L.A.Lawver, L.A., Muller, R.D.Iceland hotspot trackGeology, Vol. 22, No. 4, April pp. 311-314GlobalTectonics, Plate model
DS1995-0380
1995
Lawver, L.A.Dalziel, I.W.D., Lawver, L.A.Plumes and dynamics of supercontinental fragmentationEos, Vol. 76, No. 46, Nov. 7. p.F172. Abstract.MantlePlumes, Gondwana
DS2000-0200
2000
Lawver, L.A.Dalziel, I.W.D., Lawver, L.A., Murphy, J.B.Plumes, orogenesis, and supercontinental fragmentationEarth and Planetary Science Letters, Vol. 178, No. 1-2, May 15, pp. 1-12.MantleMantle plumes, Genesis - Tectonics, plate
DS2000-0556
2000
Law-West, D.Law-West, D.Diamonds. Summary of 1999Canadian Minerals Yearbook, 12p.CanadaDiamond - overview, Economics, exploration, mining, evaluation
DS1993-0888
1993
Lawyer, L.A.Lawyer, L.A., Dulziel, I.W.D.Antarctic plate: tectonics from a gravity anomly and infrared satelliteimageGsa Today, Vol. 3, No. 6, May pp. 117, 118, 119, 122AntarcticaTectonics, Geophysics -gravity, ice
DS201805-0955
2018
Laxman, B. M.Kokandakar, G.J., Ghodke, S.S., Rathna, K., Laxman, B. M., Nagaraju, B., Bhosle, M.V., Kumar, K.V.Density, viscosity and velocity ( ascent rate) of alkaline magmas.Journal of the Geological Society of India, Vol. 91, pp. 135-146.IndiaAlkaline - Prakasam

Abstract: Three distinct alkaline magmas, represented by shonkinite, lamprophyre and alkali basalt dykes, characterize a significant magmatic expression of rift-related mantle-derived igneous activity in the Mesoproterozoic Prakasam Alkaline Province, SE India. In the present study we have estimated emplacement velocities (ascent rates) for these three varied alkaline magmas and compared with other silicate magmas to explore composition control on the ascent rates. The alkaline dykes have variable widths and lengths with none of the dykes wider than 1 m. The shonkinites are fine- to medium-grained rocks with clinopyroxene, phologopite, amphibole, K-feldspar perthite and nepheline as essential minerals. They exhibit equigranular hypidiomorphic to foliated textures. Lamprophyres and alkali basalts characteristically show porphyritic textures. Olivine, clinopyroxene, amphibole and biotite are distinct phenocrysts in lamprophyres whereas olivine, clinopyroxene and plagioclase form the phenocrystic mineralogy in the alkali basalts. The calculated densities [2.54-2.71 g/cc for shonkinite; 2.61-2.78 g/cc for lamprophyre; 2.66-2.74 g/cc for alkali basalt] and viscosities [3.11-3.39 Pa s for shonkinite; 3.01-3.28 Pa s for lamprophyre; 2.72-3.09 Pa s for alkali basalt] are utilized to compute velocities (ascent rates) of the three alkaline magmas. Since the lamprophyres and alkali basalts are crystal-laden, we have also calculated effective viscosities to infer crystal control on the velocities. Twenty percent of crystals in the magma increase the viscosity by 2.7 times consequently decrease ascent rate by 2.7 times compared to the crystal-free magmas. The computed ascent rates range from 0.11-2.13 m/sec, 0.23-2.77 m/sec and 1.16-2.89 m/sec for shonkinite, lamprophyre and alkali basalt magmas respectively. Ascent rates increase with the width of the dykes and density difference, and decrease with magma viscosity and proportion of crystals. If a constant width of 1 m is assumed in the magma-filled dyke propagation model, then the sequence of emplacement velocities in the decreasing order is alkaline magmas (4.68-15.31 m/sec) > ultramafic-mafic magmas (3.81-4.30 m/sec) > intermediate-felsic magmas (1.76-2.56 m/sec). We propose that SiO2 content in the terrestrial magmas can be modeled as a semi-quantitative "geospeedometer" of the magma ascent rates.
DS1988-0408
1988
Lay, T.Lay, T.The deep roots of continentsNature, Vol. 333, May 19, pp. 209-210GlobalBlank
DS1990-0907
1990
Lay, T.Lay, T., Ahrens, T.J., Olson, P., Smyth, J., Loper, D.Studies of the earth's deep interior: goals and trendsPhysics Today, Vol. 43, No. 10, October pp. 44-52GlobalDynamic earth system, Mantle
DS1991-0962
1991
Lay, T.Lay, T.Mantle structure - a matter for resolutionNature, Vol. 352, No. 6331, July 11, pp. 105-107GlobalMantle, Structure
DS1991-1528
1991
Lay, T.Schwartz, S.Y., Lay, T., Grand, S.P.Seismic imaging of subducted slabs: trade offs with deep path and near receiver effectsGeophysical Research Letters, Vol. 18, No. 7, July pp. 1265-1268GlobalMantle, Tectonis, subduction, geophysics, seismics
DS1993-0742
1993
Lay, T.Jeanloz, R., Lay, T.The core-mantle boundaryScientific American, May pp. 48-55MantleOverview of structure of earth, Tectonics, Core
DS1993-0834
1993
Lay, T.Knittle, E., Lay, T.Properties of silicate perovskite and seismic structures in the LowerMantle.American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 571.MantleGeophysics -seismics, Perovskite
DS1994-0996
1994
Lay, T.Lay, T.Deep earth seismology.. brief overviewGeotimes, Vol. 39, No. 6, June pp. 12-15.MantleGeophysics -seismics
DS1994-0997
1994
Lay, T.Lay, T.The fate of descending slabsAnnual Review of Earth and Planet. Sciences, Vol. 22, pp. 33-62.MantleSubduction, Tectonics, plates
DS1995-1069
1995
Lay, T.Lay, T.Slab burial groundsNature, Vol. 374, No. 6518, March 9, pp. 115.MantleGeophysics -seismics, Subduction -slab
DS1995-1106
1995
Lay, T.Loper, D.E., Lay, T.The core mantle boundary regionJournal of Geophysical Research, Vol. 100, No. B4, April 10, pp. 6397-6420MantleBoundary -review, CMB transition zone, geophysics
DS1995-1107
1995
Lay, T.Loper, D.E., Lay, T.The core-mantle boundary region #1Journal of Geophysical Research, Vol. 100, No. B4, April 10, pp. 6397-6420.MantleReview -overview CMB., Geodynamics
DS1996-0815
1996
Lay, T.Lay, T., Young, C.J.Imaging scattering structures in the lower mantle by migration of long period S waves.Journal of Geophysical Research, Vol. 101, No. B9, Sept. 10, pp. 20, 023-40.MantleStructure, Geophysics -seismic
DS1997-0654
1997
Lay, T.Lay, T., Williams, Q., Garnero, E.J.The core mantle boundaryNature, Vol. 392, No. 6675, Apr. 2, pp. 461-468.MantleBoundary
DS1998-0836
1998
Lay, T.Lay, T., Williams, Q.Dynamics of Earth's interior.... upper mantle, core-mantle boundary.Geotimes, Vol. 43, No. 11, Nov. pp. 26-30.MantleBoundary - core, General - brief history ( not specific to diamonds)
DS1999-0829
1999
Lay, T.Zhang, Y.S., Lay, T.Evolution of the oceanic upper mantle structurePhys. Earth. Plan. International, Vol. 114, No. 1-2, July 6, pp. 71-80.MantleTectonics, Oceanic structure
DS2000-0546
2000
Lay, T.Kuo, B.Y., Garnero, E.J., Lay, T.Tomographic inversion of S SKS times for shear velocity heterogeneity in D" degree 12 and hybrid models.Journal of Geophysical Research, Vol. 105, No.12, Dec.10, pp.218139-58.MantleTomography
DS2002-1211
2002
Lay, T.Pankow, K.L., Williams, Q., Lay, T.Using shear wave amplitude patterns to detect metastable olivine in subducted slabsJournal of Geophysical Research, June 7, 10.1029/2001JB000608MantleGeophysics - seismics, Subduction
DS200412-1088
2004
Lay, T.Lay, T., Garnero, E.J., Williams, Q.Partial melting in a thermo-chemical boundary layer at the base of the mantle.Physics of the Earth and Planetary Interiors, Vol. 146, 3-4, pp. 441-467.MantleGeothermometry, geochemistry
DS200412-1360
2004
Lay, T.Moore, M.M., Garnero, E.J., Lay, T., Williams, Q.Shear wave splitting and waveform complexity for lowermost mantle structures with low velocity lamellae and transverse isottropyJournal of Geophysical Research, Vol. 109, B2, 10.1029/2003 JB002546MantleGeophysics - seismics
DS200512-0310
2004
Lay, T.Ganero, E.J., Maupin, V., Lay, T., Founch, M.J.Variable azimuthal anisotropy in Earth's lowermost mantle.Science, No. 5694, Oct. 8, p. 259-260.MantleGeophysics
DS200512-0603
2005
Lay, T.Lay, T.The deep mantle thermo-chemical boundary layer: the putative mantle plume source.Plates, plumes and Planetary Processes, pp. 193-206. ( total book 861p. $ 144.00)MantleGeothermometry
DS200512-0604
2005
Lay, T.Lay, T.Is the D' region the source of mantle plumes?Chapman Conference held in Scotland August 28-Sept. 1 2005, 1p. abstractMantleMantle plume, core-mantle boundary
DS200512-0605
2004
Lay, T.Lay, T., Garnero, E.J.Core mantle boundary structures and processes.Geophysical Monograph, AGU, No. 150, pp. 25-42.MantleGeophysics - seismics
DS200612-0563
2005
Lay, T.Helmberger, D., Lay, T., Ni, S., Gurnis, M.Deep mantle structure and the postperovskite phase transition.Proceedings of National Academy of Science USA, Vol. 102, no. 48, pp. 17257-283,MantleTectonics
DS200612-0612
2006
Lay, T.Hutko, A.R., Lay, T., Garnero, E.J., Revenaugh, J.Seismic detection of folded, subducted lithosphere at the core mantle boundary.Nature, Vol. 441, 7091, May 18, pp. 333-336.MantleGeophysics - seismics
DS200712-0349
2007
Lay, T.Garnero, E.J., Lay, T., McNamara, A.Implications of lower mantle structural heterogeneity for the existence and nature of whole mantle plumes.Plates, plumes and Planetary Processes, pp. 79-102.MantleStructure
DS200812-0472
2007
Lay, T.Hirose, K., Brodholt, J., Lay, T., Yuen, D.A.An introduction to post-perovskite: the last mantle phase transition.AGU American Geophysical Union Monograph, No. 174, pp. 1-8.MantlePerovskite
DS200812-0473
2008
Lay, T.Hirose, K., Lay, T.Discovery of post perovskite and new views on the core mantle boundary region.Elements, Vol. 4, 3, June pp. 183-189.MantleBoundary
DS200812-0497
2008
Lay, T.Hutko, A.R., Lay, T., Revenaugh, J., Garnero, E.J.Anticorrelated seismic velocity anomalies from post perovskite in the lowermost mantle.Science, No. 5879, May 23, pp. 1070-1973.MantleGeophysics - seismics
DS200812-0633
2008
Lay, T.Lay, T., Hernlund, J., Buffett, B.A.Core mantle boundary heat flow.Nature Geoscience, Vol. 1, 1, pp. 25-32.MantleGeothermometry
DS200812-0817
2008
Lay, T.Ohta, K., Hirose, K., Lay, T., Sata, N., Ohishi, Y.Phase transitions in pyrolite and MORB at lowermost mantle conditions: implications for a MORB rich pile above the core-mantle boundary.Earth and Planetary Science Letters, Vol. 267, 1-2, pp.107-117.MantlePetrology
DS201112-0571
2011
Lay, T.Lay, T., Gamero, E.J.Deep mantle seismic modeling and imaging.Annual Review of Earth and Planetary Sciences, Vol. 39, pp. 91-123.MantleGeophysics - seismics
DS201412-0809
2014
Lay, T.Shim, S-H., Lay, T.Deep Earth: post-perovskite at ten.Nature Geoscience, Vol. 7, pp. 621-623.MantleGeophysics - seismics
DS1989-0857
1989
Layer, P.W.Layer, P.W., Kroner, A., Mcwilliams, M., York, D.Elements of the Archean thermal history and apparent polar wander of the eastern Kaapvaal craton, Swaziland, from single grain dating andPaleomagnetismEarth and Planetary Science Letters, Vol. 93, No. 1, May pp. 23-34GlobalGeochronology
DS1992-0917
1992
Layer, P.W.Layer, P.W., Kroner, A., York, D.Pre-3000 Ma thermal history of the Archean Kaap Valley pluton, SouthAfricaGeology, Vol. 20, No. 8, August pp. 717-720South AfricaGeochronology, Barberton greenstone belt
DS1997-0362
1997
Layer, P.W.Fuijita, K., Stone, D.M., Layer, P.W., Parfenov, KozminCooperative program helps decipher tectonics of northeastern RussiaEos, Vol. 78, No. 24, June 17, p. 245, 252-54.RussiaTectonics, Siberian Platform
DS2001-0662
2001
Layer, P.W.Layer, P.W., Newberry, Fujita, Parfenov, TrunlinaTectonic setting of the plutonic belts of Yakutia, northeast Russia based on 40 Ar 39 Ar geochronology..Geology, Vol. 29, No. 2, Feb. pp. 167-70.Russia, YakutiaGeochemistry - trace element, Subduction - not specific to diamonds
DS2002-1341
2002
Layer, P.W.Ring, U., Kroner, A., Buchwaldt, R., Toulkeridis, T., Layer, P.W.Shear zone patterns and eclogite facies metamorphism in the Mozambique belt ofPrecambrian Research, Vol. 116, No.1-2, pp. 19-56.Malawi, East AfricaMetamorphism, Tectonics
DS2003-0426
2003
Layer, P.W.Friese, A.E.W., Reimold, W.U., Layer, P.W.40 Ar/39 Ar dating of and structural information on tectonite bearing faults in theSouth Africa Journal of Geology, Vol. 106, No. 1, pp. 41-70.South AfricaGeochronology, Geothermometry, tectonics
DS200412-0583
2003
Layer, P.W.Friese, A.E.W., Reimold, W.U., Layer, P.W.40 Ar 39 Ar dating of and structural information on tectonite bearing faults in the Witwatersrand Basin: evidence for multi-stagSouth African Journal of Geology, Vol. 106, no. 1, pp. 41-70.Africa, South AfricaGeochronology Geothermometry, tectonics
DS1992-0918
1992
Layman, C.A.Layman, C.A.Glacial geology of western Hudson Strait, Canada, with reference to Laurentide Ice Sheet dynamicsGeological Society of America (GSA) Bulletin, Vol. 104, No. 9, September pp. 1169-1177OntarioGeomorphology, Laurentide Ice Sheet
DS1991-0963
1991
Laymon, C.A.Laymon, C.A.Marine episodes in Hudson Strait and Hudson Bay, Canada, during the Wisconsin glaciationQuaternary Research, Vol. 35, No. 1, January pp. 53-62OntarioGeomorphology, Glaciation
DS2002-0404
2002
Layne, G.Draut, A.E., Clift, P.D., Hannigan, R.E., Layne, G., Shimizu, N.A model for continental crust genesis by arc accretion: rare earth element evidence from the Irish Caledonides.Earth and Planetary Science Letters, Vol. 203, 3-4, pp. 861-877.Ireland, ScandinaviaOrogenesis - REE
DS1996-1298
1996
Layne, G.D.Shearer, C.K., Papike, J.J., Layne, G.D.The role of ilmenite in the source region for mare basalts: evidence fromniobium, zirconium, ceriuM.Geochimica et Cosmochimica Acta, Vol. 60, No. 18, pp. 3521-30.MoonGeochemistry - picrites, glass
DS1998-1339
1998
Layne, G.D.Shimizu, N., Layne, G.D.In situ lead isotope analysis of Mid Ocean Ridge Basalt (MORB) melt inclusions and the origin of garnet signatures.Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1393.MantleMid Ocean Ridge Basalt (MORB)., Olivine
DS2002-1650
2002
Layne, G.D.Van Orman, J.A., Grove, T.L., Shimizu, N., Layne, G.D.Rare earth element diffusion in a natural pyrope single crystal at 2.8 GPaContributions to Mineralogy and Petrology, Vol. 142, No. 4, pp. 416-25.GlobalPetrology - garnet not specific to diamond
DS201012-0788
2010
Layne, G.D.Timm, J., Layne, G.D., Haase, K.M., Barnes, J.D.Chlorine isotope evidence for crustal recycling into the Earth's mantle.Earth and Planetary Science Letters, Vol. 298, 1-2, Sept. 15, pp. 175-182.MantleSubduction
DS1960-1150
1969
Layton And Association Pty. LtdLayton And Association Pty. LtdReport on a to P 578m Silver Hills, Rubyvale QldQueensland Open File., No. GSQ CR 2801, 9P. UNPUBL.Australia, QueenslandGeology, Stratigraphy, Geochemistry, Prospecting, Stream Sediments
DS1980-0210
1980
Layton and association pty. ltd., JINGELLIC MINERALS NL.Layton and association pty. ltd., JINGELLIC MINERALS NL.El 468- Jamestown Area, South Australia, Progress ReportsSouth Australia Open File., No. E3555, 27P. UNPUBL.Australia, South AustraliaGeochemistry, Geophysics, Stream Sediment Sampling, Soil Sampling
DS1980-0211
1980
Layton and association pty. ltd., SAVATA PTY. LTD.Layton and association pty. ltd., SAVATA PTY. LTD.El 462- Algebuckin a Area, South Australia, Progress and Fin al Reports.South Australia Open File., No. E3579, 37P. UNPUBL.Australia, South AustraliaPhotogeology, Geochemistry, Stream Sediment Sampling, Geophysics
DS1980-0212
1980
Layton and association pty. ltd., SAVATA PTY. LTD.Layton and association pty. ltd., SAVATA PTY. LTD.El 459- Yongala Area, South Australia, Progress and Final Reports.South Australia Open File., No. E3578, 45P. UNPUBL.Australia, South AustraliaPhotogeology, Prospecting, Geochemistry, Stream Sediment Sampling
DS201412-0918
2014
Layton-Matthews, D.Tappert, M.C., Rivard, B., Layton-Matthews, D., Tappert, R.High-spatial resolution hyper spectral imagery: a new analytical technique for obtaining compositional information from kimberlites ( Snap Lake, NT) and kimberlite indicator minerals.2014 Yellowknife Geoscience Forum, p. 75, abstractCanada, Northwest TerritoriesDeposit - Snap Lake
DS202001-0027
2019
Layton-Matthews, D.Lougheed, H.D., McClenaghan, M.B., Layton-Matthews, D., Leybourne, M.I.Evaluation of single use nylon screened sieves for use with fine grained sediment samples.Geological Survey of Canada, Open File 8613, 13p. PdfGlobalsieves
DS202204-0528
2022
Layton-Matthews, D.Layton-Matthews, D.Current techniques and applications of mineral chemistry to mineral exploration; examples from glaciated terrain.MDPI, Vol. 12, 1, 21p.Globalgeochemistry

Abstract: This paper provides a summary of traditional, current, and developing exploration techniques using indicator minerals derived from glacial sediments, with a focus on Canadian case studies. The 0.25 to 2.0 mm fraction of heavy mineral concentrates (HMC) from surficial sediments is typically used for indicator mineral surveys, with the finer (0.25-0.50 mm) fraction used as the default grain size for heavy mineral concentrate studies due to the ease of concentration and separation and subsequent mineralogical identification. Similarly, commonly used indicator minerals (e.g., Kimberlite Indicator Minerals—KIMs) are well known because of ease of optical identification and their ability to survive glacial transport. Herein, we review the last 15 years of the rapidly growing application of Automated Mineralogy (e.g., MLA, QEMSCAN, TIMA, etc) to indicator mineral studies of several ore deposit types, including Ni-Cu-PGE, Volcanogenic Massive Sulfides, and a variety of porphyry systems and glacial sediments down ice of these deposits. These studies have expanded the indicator mineral species that can be applied to mineral exploration and decreased the size of the grains examined down to ~10 microns. Chemical and isotopic fertility indexes developed for bedrock can now be applied to indicator mineral grains in glacial sediments and these methods will influence the next generation of indicator mineral studies.
DS200612-0912
2005
Lazanskii, A.Yu.Metelkin, D.V., Vernikovksy, V.A., Lazanskii, A.Yu., Belonos, I.V.The Siberian Craton in the structure of the supercontinent Rodinia: analysis of paleomagnetic data.Doklady Earth Sciences, Vol. 404, 7, pp. 1021-1026.RussiaTectonics, geophysics - paleomagnetism
DS1994-0998
1994
Lazarenko, V.G.Lazarenko, V.G., Malich, K.N.Platinum group element distribution in meymechites of the Maymecha-Kotuyprovince.Doklady Academy of Sciences Acad. Science USSR, Vol. 323, No. 2, June pp. 185-188.RussiaMeimechitites
DS1970-0747
1973
Lazarenkov, V.G.Lazarenkov, V.G., Ignatov, A.V., Loginova, T.I.Structure of the Feldspathoidal Syenitic Massif of the Area of the Los Pluton.Zap. Vses. Min. Obshch., Vol. 102, No. 1, PP. 43-53.Russia, West Africa, GuineaPetrology, Texture, Mineralogy
DS1975-0123
1975
Lazarenkov, V.G.Lazarenkov, V.G., Loginova, T.I.Dynamic Petrochemistry of Feldspathoidal Syenites in the Los Pluton.Zap. Vses. Min. Obshch., Vol. 104, No. 6, PP. 678-686.Russia, West Africa, GuineaMineral Chemistry, Cretaceous
DS1975-0323
1976
Lazarenkov, V.G.Lazarenkov, V.G.Alkalic Lamprophyres of the Los Pluton GuineaSoviet Geology And Geophysics, Vol. 17, No. 5, PP. 101-107.Guinea, West AfricaRelated Rocks
DS1981-0261
1981
Lazarenkov, V.G.Lazarenkov, V.G.Distribution of Alkalic Rocks in TimeDoklady Academy of Science USSR, Earth Science Section., Vol. 256, PP. 78-79.RussiaBlank
DS1984-0444
1984
Lazarenkov, V.G.Lazarenkov, V.G.Tectonic Setting and Petrology of Young Alkaline Provinces Of Continents and Oceans.International Geology Review, Vol. 26, No. 6, JUNE PP. 626-634.RussiaTectonics
DS1984-0445
1984
Lazarenkov, V.G.Lazarenkov, V.G.Tectonic Position and Formation Series of Young Alkaline Provinces of Continents and Oceans.Izvest. Sssr Geol., No. 7, JULY PP. 84-92.RussiaBlank
DS1995-1070
1995
Lazarenkov, V.G.Lazarenkov, V.G., Lutkov, V.S.Distribution of platinum group elements in green and black clinopyroxenites from mantle inclusions-Tien ShanDoklady Academy of Sciences Acad. Science Russia, Vol. 331, No. 5, May pp. 198-202.ChinaMantle xenoliths, Deposit -Tien Shan basaltoid pipes
DS1996-0816
1996
Lazarenkov, V.G.Lazarenkov, V.G., Lutkov, V.S.Distribution of noble metals in spinel lherzolites from mantle xenoliths South Tian Shan alkali basaltoid pipesDoklady Academy of Sciences, Vol. 341A No. 3, April, pp. 167-170.ChinaXenoliths, Deposit - Kaloch
DS200612-1009
2006
Lazarenkov, V.G.Okrugin, A.V., Kostoyanov, A.I., Shevchenko, S.S., Lazarenkov, V.G.The model of Re-Os age of platinum group minerals from Vilyui placers in the eastern Siberian Craton.Doklady Earth Sciences, Vol. 410, 7, pp. 1044-1047.Russia, SiberiaGeochronology - not specific to diamonds
DS200912-0427
2009
Lazarenkov, V.G.Lazarenkov, V.G.Alkaline plume magmatism of continents and oceans and roots of alkaline plumes.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractMantleHeat flow
DS202006-0946
2020
Lazareva, E.V.Ponomarchuk, V.A., Dobretsov, N.L. , Lazareva, E.V., Zhmodik, S.M., Karmanov, N.S., Tolstov, A,V., Pyryaev, A.N.Evidence of microbial-induced mineralization in rocks of the Tomtor carbonatite complex ( Arctic Siberia).Doklady Earth Science, Vol. 490, 2, pp. 76-80.Russia, Siberiacarbonatite

Abstract: Carbonates of the Tomtor complex of ultramafic alkaline rocks and carbonatites (the northern part of the Republic of Sakha Yakutia) are distinguished by a wide range of carbon isotopic composition ?13C from +2 to -59.9‰. The geological position, localization patterns, mineral and chemical compositions and the relationship with REE mineralization of samples with values of ?13C carbonates from -25 to -59‰ are characterized. The formation of abnormally low ?13C in carbonates is determined by the biogenic oxidation of methane from ?13Cmet to -70‰.
DS202104-0571
2021
Lazareva, E.V.Dobretsov, N.L., Zhmodik, S.M., Lazareva, E.V., Bryanskaya, A.V., Ponomarchuk, V.A., Saryg-ool, B. Yu., Kirichenko, I.S., Tolstov, A.V., Karmanov, N.S.Structural and morphological features of the participation of microorganisms in the formation of Nb-REE-rich ores of the Tomtor field, Russia.Doklady Earth Sciences, Vol. 496, pp. 135-138. Russiadeposit - Tomtor

Abstract: Data indicating the important role of microorganisms in the redistribution of REEs in the weathering crust and the decisive role in the concentration of REEs during the formation of ores in the upper ore horizon of the Tomtor field are obtained. The uptake of REEs was carried out by the community of microorganisms, such as phototrophs, methanogens, methanotrophs, and proteobacteria, which form the basis of the microbiocenosis for this paleoecosystem. The isotopic composition of C carbonates in all samples studied with fossilized microorganisms corresponds to the biogenic one, and the isotopic composition ?18?SMOW (from 7 to 20‰) indicates the endogenous (hydrothermal) and, to a lesser extent, exogenous nature of the solutions. The low (87Sr/86Sr)I values of carbonates (~0.7036-0.7042) exclude the participation of seawater.
DS200612-0349
2006
Lazarov, M.Downes, H., Cvetkovic, V., Hock, V., Prelevic, D., Lazarov, M.Refertilization of highly depleted lithospheric mantle ( Balkan Peninsula, SE Europe): evidence from peridotite xenoliths.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.EuropeGeochemistry
DS200612-0776
2006
Lazarov, M.Lazarov, M., Brey, G., Lahaye, Y.Mapping of the Kaapvaal craton lithosphere with garnets from a polymict peridotite.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 345. abstract only.Africa, South AfricaGeochemistry - garnets
DS200712-0211
2007
Lazarov, M.Cvetkovi, V., Lazarov, M., Downes, H., Prevelvi, D.Modification of the subcontinental mantle beneath East Serbia: evidence from orthopyroxene rich xenoliths.Lithos, Vol. 92, 1-4, pp. 90-110.EuropeXenoliths - not specific to diamonds
DS200712-0601
2007
Lazarov, M.Lazarov, M., Brey, G.P., HHHarris, J.W., Weyer, S.Timing of mantle depletion and enrichment from single subcalcic garnet grains (Finsch mine, SA).Plates, Plumes, and Paradigms, 1p. abstract p. A551.Africa, South AfricaFinsch
DS200912-0307
2009
Lazarov, M.Hofer, H.E., Lazarov, M., Brey, G.P., Woodland, A.B.Oxygen fugacity of the metasomatizing melt in a polymict peridotite from Kimberley.Lithos, In press - available 25p.Africa, South AfricaDeposit - Kimberley
DS200912-0428
2009
Lazarov, M.Lazarov, M., Brey, G.P., Weyer, S.Time steps of depletion and enrichment in the Kaapvaal Craton as recorded by subcalcic garnets from Finsch (SA).Earth and Planetary Science Letters, Vol. 279, 1-2, pp. 1-10.Africa, South AfricaGeochronology deposit - Finsch
DS201012-0426
2009
Lazarov, M.Lazarov, M., Woodland, A.B., Brey, G.P.Thermal state and redox conditions of the Kaapvaal mantle: a study of the Finsch mine, South Africa.Lithos, Vol. 112 S pp. 913-923.Africa, South AfricaGeothermometry
DS201012-0577
2010
Lazarov, M.Peslier, A.H., Woodland, A.B., Bell, D.R., Lazarov, M.Olivine water contents in the continental lithosphere and the longevity of cratons.Nature, Vol. 467, Sept. 2, pp. 78-81.MantleGeodynamics - cratons
DS201212-0088
2012
Lazarov, M.Brey, G.P., Luchs, T., Shu, Q., Lazarov, M., Becker, H.Combined trace element, SM-ND, Luf-Hf and Re-Os studies constrain the age, origin and the development of the Kaapvaal subcratonic mantle.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South AfricaGeochemistry
DS201212-0398
2012
Lazarov, M.Lazarov, M., Brey, G.P., Weyer, S.Evolution of the South Africa mantle - a case study of garnet peridotites from the Finsch diamond mine ( Kaapvaal craton) part 1: inter-mineral trace element and isotopic equilibrium.Lithos, in press available 55p.Africa, South AfricaDeposit - Finsch
DS201212-0550
2012
Lazarov, M.Peslier, A.H., Woodland, A.B., Bell, D.R., Lazarov, M., Lapen, T.J.Metasomatic control of water contents in the Kaapvaal cratonic mantle.Geochimica et Cosmochimica Acta, Vol. 97, pp. 213-246.Africa, South Africa, LesothoDeposit - Finsch, Kimberley, Jagersfontein, Letseng, Liqhobong
DS1995-1071
1995
Lazebik, K.A.Lazebik, K.A., Zayakina, N.V., Makhotko, V.F.A new thorium silicate from carbonatites at the Sirenevyy Kaman charoititedeposit.Doklady Academy of Sciences, Vol. 336, No. 4, Nov., pp. 97-101.Russia, YakutiaAlkaline rocks, Carbonatite -charoite
DS1983-0391
1983
Lazebnik, K.A.Lazebnik, K.A.Remarks on the Article by Yu. A. Alekseev Entitled Carbonatites of the Murun Ultrapotassic Alkaline Complex.Soviet Geology And Geophysics, Vol. 24, No. 12, PP. 117-119.RussiaBlank
DS1983-0392
1983
Lazebnik, K.A.Lazebnik, K.A.Remarks on the Article by Yu.a. Alekseev Entitled Carbonatites of the Murun Ultrapostassic Alkaline Complex.Soviet Geology And Geophysics, Vol. 24, No. 2, PP. 117-118.RussiaBlank
DS1985-0363
1985
Lazebnik, K.A.Kovalskiy, V.V., Kochetkov, A.YA., Lazebnik, K.A.Petrologic and geochemical features of the plutonic evolution of substances in kimberlite and mafic magmatic systems.(Russian)Akad. Nauk SSSR Sib. Otd. Yakutsk Fil. (Russian), 200pRussiaBlank
DS1985-0385
1985
Lazebnik, K.A.Lazebnik, K.A., Makhoto, V.F., Lazebnik, Y.D.The First Finding of Priderite in Eastern Siberia.(russian)Mineral. Zhurn., (Russian), Vol. 7, No. 4, pp. 81-83RussiaLamproite
DS1994-0999
1994
Lazebnik, K.A.Lazebnik, K.A., Nikishova, L.V.First find of manganese bearing silicate in charoititesDoklady Academy of Sciences Acad. Science USSR, Vol. 323A, No. 3, June pp. 164-169.RussiaCharoite
DS1998-0837
1998
Lazebnik, K.A.Lazebnik, K.A., Zyakina, N.V., Patskevich, G.P.Strontium free lamprophyllite - a new member of the lamprophyllite groupDoklady Academy of Sciences, Vol. 361A, No. 6, pp. 817-20.Russia, Aldan, YakutiaLamprophyres, Inagli Massif
DS1985-0385
1985
Lazebnik, Y.D.Lazebnik, K.A., Makhoto, V.F., Lazebnik, Y.D.The First Finding of Priderite in Eastern Siberia.(russian)Mineral. Zhurn., (Russian), Vol. 7, No. 4, pp. 81-83RussiaLamproite
DS2002-0228
2002
Lazelle, E.Burgess, R., Lazelle, E., Turner, G., Harris, J.W.Constraints on the age and halogen composition of mantle fluids in Siberian coated diamonds.Earth and Planetary Science Letters, Vol.197,3-4,pp. 193-203.RussiaGeochronology, Deposit - Aikhal
DS201507-0320
2015
Lazereva, E.V.Lazereva, E.V., Zhmodik, S.M., Dobretsov, N.L., Tolstov, A.V., Shcherbov, B.L., Karmanov, N.S., Gerasimov, E.Yu., Bryanskaya, A.V.Main minerals of abnormally high grade ores of the Tomtor deposit ( Arctic Siberia).Russian Geology and Geophysics, Vol. 56, pp. 844-873.RussiaDeposit - Tomtor
DS200712-0773
2007
LazkiNasir, S., Al-Khirbashi, S., Al-Sayigh, Alharthy, Mubarek, Rollinson, Lazki, Belouova, Griffin, KaminskyThe first record of allochthonous kimberlite within the Batain Nappes, eastern Oman.Plates, Plumes, and Paradigms, 1p. abstract p. A706.Africa, OmanBatain melange
DS1995-1715
1995
LazkoSharkov, E.V., Sarelainen, B.V., Quick, J.E., Lazko, BoginaArbanksy Massif in the eastern Siberia -the largest in Russia block of the Early Precambrian upper mantle.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 506-8.Russia, SiberiaArbansky Massif, Eclogites
DS200912-0781
2009
LazkoUstinov, V.N., Zagainyi, A.K., Smith, C.B., Ushkov, Lazko, Lukyanova, LobkovaEarly Proterozoic diamond bearing kimberlites of Karelia and their formation pecularities.Russian Geology and Geophysics, Vol. 50, 9, pp. 739-750.RussiaPetrology, Kimozero
DS2003-1175
2003
Lazko, E.Roden, M., Patino-Douce, A., Lazko, E., Jagoutz, E.Exsolution textures in high pressure garnets, Mir kimberlite, Sibveria8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractRussia, SiberiaDeposit - Mir
DS200412-1680
2003
Lazko, E.Roden, M., Patino-Douce, A., Lazko, E., Jagoutz, E.Exsolution textures in high pressure garnets, Mir kimberlite, Sibveria.8 IKC Program, Session 6, POSTER abstractRussia, SiberiaMantle petrology Deposit - Mir
DS1982-0364
1982
Lazko, E.E.Lazko, E.E., Serenko, V.P., et al.Disthen Diamond Bearing Eclogites of Sytykanskaya Kimberlite Pipe ( Yakutia ).Academy of Science SSSR, GEOL. SER. Bulletin., No. 7, JULY, PP. 55-69.RussiaKimberlite
DS1982-0365
1982
Lazko, E.E.Lazko, E.E., Serenko, V.P., Muravickaja. g.n.Zoned Garnets in a Xenolith of Cataclastic Peridotite from The Udchanaya Kimberlite Pipe in Yakutia.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 268, No. 5, PP. 1204-1208.RussiaBlank
DS1982-0557
1982
Lazko, E.E.Serenko, V.P., Nikinov, K.N., Lazko, E.E.Zoned Garnets in Porphyroblast Lherzolites from the Mir Kimberlite Pipe.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 267, No. 2, PP. 438-441.RussiaBlank
DS1982-0558
1982
Lazko, E.E.Serenko, V.P., Nikishov, K.N., Lazko, E.E.Zonal Garnets in the Porphyroblastic Lherzolites from the Kimberlite Pipe Mir.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 267, No. 2, PP. 438-441.RussiaBlank
DS1983-0393
1983
Lazko, E.E.Lazko, E.E., et al.Cataclazed Peridotite with a Garnet of Varying Composition from the kimberlite Pipe Udachnaia, Yakutia.Doklady Academy of Sciences AKAD NAUK SSSR., Vol. 268, No. 6, PP. 1458-1462.Russia, YakutiaPetrography
DS1983-0394
1983
Lazko, E.E.Lazko, E.E., Serenko, V.P.Peridotites Containing Zonal Garnets from Kimberlites in Yakutia an Evidence for High Temperature Deep Metasomatism And intermantle Diapirism.Soviet Geology, No. 12, PP. 41-53.Russia, YakutiaGenesis
DS1983-0395
1983
Lazko, E.E.Lazko, E.E., Serenko, V.P., Muravitskaia, G.N.Zonal Granites in Xenolite of Cataclazed Peridotite from The Kimberlite Pipe Udachnaia (yakutia).Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 268, No. 5, PP. 1204-1207.Russia, YakutiaMineralogy, Petrography
DS1991-0964
1991
Lazko, E.E.Lazko, E.E., Serenko, V.P.Unequilibrated ultramafic xenoliths from Udachnaya kimberlite pipe, westernYakutiaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 228-230RussiaPeridotites, garnets, Geochemistry
DS1991-1935
1991
Lazko, E.E.Zhuravlev, A.Z., Lazko, E.E., Ponomarenko, A.I.Ancient depleted subcontinental lithosphere under Siberian platform: neodymium-SrProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 581-583RussiaXenoliths, Petrology, geochemistry
DS1992-0919
1992
Lazko, E.E.Lazko, E.E., Serenko, V.P.Unequilibriated ultramafic xenoliths from Udachnaya kimberlite pipe, YakutiaProceedings of the 29th International Geological Congress. Held Japan August 1992, Vol. 1, abstract p. 179Russia, YakutiaXenoliths, Peridotites, zoned garnets
DS1992-1743
1992
Lazko, E.E.Zhuravlev, A.Z., Lazko, E.E., Ponamarenko, A.I.Ancient depleted subcontinental lithosphere under Siberian platform:Proceedings of the 29th International Geological Congress. Held Japan, Vol. 1, abstract p. 179Russia, YakutiaGeochronology, Mir pipe
DS1993-0889
1993
Lazko, E.E.Lazko, E.E., Roden, M.F.Mineralogy of garnet peridotite xenoliths from the Mir kimberlite pipe, Siberia.American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 637.Russia, SiberiaMineralogy, Deposit -Mir
DS1993-0890
1993
Lazko, E.E.Lazko, E.E., Sharkov, E.V., Boatikov, D.A.Mantle substrates, their geochemical typization and role in the subcrust magma formation. (Russian)Geochemistry International (Geokhimiya), (Russian), No. 2, February pp. 165-188Russia, Commonwealth of Independent States (CIS)Geochemistry, Mantle, crust
DS1995-1584
1995
Lazko, E.E.Roden, M.F., Lazko, E.E., Ponomarenko, A.I., Serenko, V.P.Mineralogy of peridotite xenoliths from the Mir kimberlite Yakutia, Russia.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 462-464.Russia, YakutiaXenoliths, Deposit -Mir
DS1998-1246
1998
Lazko, E.E.Roden, M.F., Lazko, E.E., Jagoutz, E.Petrology and geochemistry of peridotite inclusions from the Mirkimberlite, Siberia.7th. Kimberlite Conference abstract, pp. 741-2.Russia, Siberia, YakutiaXenoliths - inclusions, Deposit - Mir
DS1999-0606
1999
Lazko, E.E.Roden, M.F., Lazko, E.E., Jagoutz, E.The role of garnet pyroxenites in the Siberian lithosphere: evidence from the Mir kimberlite.7th International Kimberlite Conference Nixon, Vol. 2, pp. 714-20.Russia, Siberia, YakutiaMineralogy, thermobarometry, mineral chemistry, analyse, Deposit - Mir
DS200512-0908
2004
Lazko, E.E.Roden, M., Patino-Douce, A., Lazko, E.E.Evidence for high pressure garnet pyroxenites in the continental lithosphere.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 17-4, Vol. 36, 5, p. 46.RussiaMir, mineral chemistry
DS200612-1165
2006
Lazko, E.E.Roden, M.F., Paino-Douce, A.E., Jagoutz, E., Lazko, E.E.High pressure petrogenesis of Mg rich garnet pyroxenites from Mir kimberlite, Russia.Lithos, Vol. 90, 1-2, pp. 77-91.Russia, SiberiaMajorite
DS200612-1166
2006
Lazko, E.E.Roden, M.F., PatinoDouce, A.E., Jagoutz, E., Lazko, E.E.High pressure petrogenesis of Mg rich garnet pyroxenites from Mir kimberlite, Russia.Lithos, Vol.90, 1-2, August pp. 77-91.Russia, YakutiaDeposit - Mir, petrology
DS1989-1376
1989
Lazko, Ye.YeSharkov, Ye.V., Lazko, Ye.Ye, Fedodosova, S.P., Khanna, S., AliPegmatoid hornblende clinopyroxene xenoliths with barium zeolite from diatremes of northwestern SyriaInternational Geology Review, Vol. 31, No. 4, April pp. 380-386SyriaXenoliths, Diatremes
DS1982-0366
1982
Lazko, YE.YE.Lazko, YE.YE., Serenko, V.P., et al.Diamond rich eclogites with kyanite in the Sitykanskaya kimberlite @Yakutia.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 268, No. 6, pp. 55-69RussiaEclogite
DS1983-0396
1983
Lazko, YE.YE.Lazko, YE.YE., Serenko, V.P.Zoned garnet peridotites in Yakutia kimberlites: indicators of deep metasomatism at high temperature and intramantlediapirisim? (Russian)Izv. Akad. Nauk SSSR Ser. Geol. (Russian), No. 12, pp. 41-53RussiaMantle
DS1983-0397
1983
Lazko, YE.YE.Lazko, YE.YE., Serenko, V.P., et al.Zoned garnets in a xenolith of cataclastic peridotite in the Udachnaya kimberlite pipe, Yakutia. (Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 268, No. 5, pp. 1204-1208RussiaPetrology
DS1983-0398
1983
Lazko, YE.YE.Lazko, YE.YE., Serenko, V.P., et al.Cataclase peridotite with garnet of variable composition in the Udachnaya kimberlitic pipe, Yakutia.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 268, No. 6, pp. 1458-1462RussiaPetrology
DS1983-0399
1983
Lazko, YE.YE.Lazko, YE.YE., Serenko, V.P., Koptil, V.I., Rudnitskaya, YE.S.The Diamond Bearing Kyanite Eclogites from the Sytykanskaya kimberlite Pipe Yakutia.International Geology Review, Vol. 25, No. 4, APRIL, PP. 381-394.RussiaGenesis, Mineralogy, Petrography
DS1984-0446
1984
Lazko, YE.YE.Lazko, YE.YE., Serenko, V.P.Peridotites with Zoned Garnets from Yakutian Kimberlites: Evidence for Deep High Temperature Metasomatism and Mantle Diapirism?International Geology Review, Vol. 26, No. 3, MARCH PP. 318-331.Russia, South Africa, United States, Colorado PlateauGenesis, Mineralogy
DS1984-0649
1984
Lazko, YE.YE.Serenko, V.P., Nikishov, K.N., Lazko, YE.YE.Zoned Garnets in Porphyroblastic Lherzolite Xenoliths from The Mir Kimberlite Pipe.Doklady Academy of Science USSR, Earth Science Section., Vol. 267, No. 1-6, JUNE PP. 116-118.RussiaMineralogy
DS1988-0409
1988
Lazko, Ye.Ye.Lazko, Ye.Ye.Kimberlites.(Russian)Ultrabasic rocks, Magmaticheskiye Gornyye Porody, Izd. Nauka, Moscow, Vol. 5, pp. 196-217RussiaKimberlites, Geochemistry
DS1988-0410
1988
Lazko, Ye.Ye.Lazko, Ye.Ye.Deep ultramafic inclusions in kimberlites (Russian)Ultrabasic rocks, Magmaticheskiye Gornyye Porody, Izd. Nauka, Moscow, Vol. 5, pp. 346-379RussiaKimberlites, Geochemistry-xenoliths
DS1991-0139
1991
Lazko, Ye.Ye.Bogatikov, O.A., Lazko, Ye.Ye., Sharkov, Ye.V.Potential sources of subcrustal magmasDoklady Academy of Sciences USSR Earth Sci. Section, Vol. 313, No. 1, pp. 175-178RussiaMantle, Kimberlite
DS1992-1744
1992
Lazko, Ye.Ye.Zhuravlev, A.Z., Lazko, Ye.Ye., Ponomarenko, A.I.Radiogenic isotopes and rare earth elements (REE) in garnet peridotite xenoliths from the Mirkimberlite pipe, YakutiaGeochemistry International, Vol. 29, No. 2, pp. 45-55RussiaGeochemistry, Deposit -Mir pipe
DS1993-0891
1993
Lazko, Ye.Ye.Lazko, Ye.Ye., Sharkov, Ye.V., Bogatikov, O.A.Mantle substrates: their geochemical classification and role in subcrustal magma formation.Geochemistry International, Vol. 30, No. 9, pp. 1-24.MantleGeochemistry, Xenoliths in basalts and kimberlites
DS1993-1437
1993
Lazko, Ye.Ye.Sharkov, Ye.V., Lazko, Ye.Ye., Hanna, S.Plutonic xenoliths from the Nabi Matta explosive centre northwest SyriaGeochemistry International, Vol. 30, No. 4, pp. 23-44.SyriaEclogites, Xenoliths
DS1970-0337
1971
Laz'ko, YE.Y.Laz'ko, YE.Y.The Problem of the Origin of Garnet in Kimberlites of the Udachnaya Pipe.Zap. Vses. Miner. Obshch., PT. 100, No. 6, PP. 703-712.RussiaBlank
DS1989-0858
1989
Laznicka, P.Laznicka, P.Breccias and ores. Part 1. History, organization and petrography ofbrecciasOre Geology Reviews, Vol. 4, pp. 315-344. Database # 18097GlobalBreccia ores, Classification
DS1989-1547
1989
Laznicka, P.Veizer, J., Laznicka, P., Jansen, S.L.Mineralization through geologic time: recycling perspectiveAmerican Journal of Science, Vol. 289, April pp. 484-524. Database # 17843GlobalMetallogeny, Review -Recycling
DS1993-0892
1993
Laznicka, P.Laznicka, P.Precambrian empirical metallogenyElsevier, est. cost $ 280. 00 United States due out May 1993GlobalBook -ad, Metallogeny
DS1994-1533
1994
Lazor, P.Saxena, S.K., Shen, G., Lazor, P.Temperatures in earth's core based on melting and phase transformation experiments on iron.Science, Vol. 264, April 15, pp. 405-407.MantleCore, Temperature -iron melt
DS1998-1288
1998
Lazor, P.Saxena, S.K., Dubrovinsky, L.S, Lazor, P.Mineralogy of the core and lower mantleIma 17th. Abstract Vol., p. A 42, abstractMantleMineralogy
DS2000-0861
2000
Lazor, P.Saxena, S.K., Lazor, P., Dubrovinsky, L.S.A model of Earth's deep interior based on mineralogical dataMin. Petrol., Vol. 69, No. 1-2, pp. 1-10.MantleMineralogy, Model - mineralogy
DS201902-0322
2019
Lazzarin, M.Spiga, R., Barberi, C., Bertini, I., Lazzarin, M., Nestola, F.The origin of water on Earth: stars or diamonds?Rendiconti Lincei. Scienze Fisische e Naturali *** In Eng, 8p. PdfMantlewater

Abstract: This contribution deals with two different hypotheses on the origin of superficial water on the Earth: the Endogenous hypothesis and the Exogenous one. They proposed that water either was brought to the surface of the Earth from the deep interior of the Earth or would have come to the Earth from celestial bodies that bombarded the planet billions of years ago. The evidence from recent astronomical and geological findings supporting the two alternative hypotheses will be discussed.
DS201112-0572
2011
Le, C.T.A.Le Roux, V., Dasgupta, R., Le, C.T.A.Mineralogical heterogeneities in the Earth's mantle: constraints from Mn, Co, Ni and Zn partitioning during partial melting.Earth and Planetary Science Letters, Vol. 307, 3-4, pp. 395-408.MantleMineralogy
DS2002-0353
2002
Le Bars, M.Davaille, A., Girard, F., Le Bars, M.How to anchor hotspots in a convecting mantle?Earth and Planetary Science Letters, Vol. 203, 3, pp. 621-34.MantleHot spots, Convection - model
DS2003-0311
2003
Le Bars, M.Davaille, A., Le Bars, M., Carbonne, C.Thermal convection in a heterogeneous mantleComptes Rendus Geoscience, Vol. 335, 1, pp. 141-156.MantleGeothermometry
DS200412-1089
2004
Le Bars, M.Le Bars, M., Davaille, A.Whole layer convection in a heterogeneous planetary mantle.Journal of Geophysical Research, Vol. 109, 3, DOI 10.1029/2003 JB002617MantleStratigraphy
DS2002-0729
2002
Le BasHoernle, K., Tilton, Le Bas, Duggen, Garbe-SchonbergGeochemistry of oceanic carbonatites compared with continental carbonatites: mantle recycling of oceanic..Contributions to Mineralogy and Petrology, Vol. 142, No. 5, Feb. pp. 520-42.MantleGeochemistry, Carbonatite - crustal carbonate
DS1997-1287
1997
Le Bas, M.Zaitsev, A., Wall, F., Bell, K., Le Bas, M.Minerals from the Khibin a carbonatites, Kola Peninsula, their paragenesis and evolution.Geological Association of Canada (GAC) Abstracts, POSTER.Russia, Kola PeninsulaCarbonatite, Deposit - Khibina
DS1996-1559
1996
Le Bas, M. et.Woolley, A.R., Bergman, S.C., Edgar, A.D., Le Bas, M. et.Classification of lamprophyres, lamproites, kimberlites and the melilitic and leucitic rocks.Canadian Mineralogist, Vol. 34, pt. 2, April pp. 175-186.GlobalClassification, Kimberlites, lamproites
DS1975-0552
1977
Le bas, M.J.Le bas, M.J.Carbonatite- Nephelinite VolcanismLondon: J. Wiley And Sons, 347P.South Africa, Southwest Africa, GlobalKimberlite
DS1975-0795
1978
Le bas, M.J.Le bas, M.J.Crbonatite-nephelinite VolcanismJ. Wiley And Sons, 350P.South Africa, Africa, KenyaRelated Rocks, Kimberley
DS1981-0262
1981
Le bas, M.J.Le bas, M.J., Aspden, J.A.The Comparability of Carbonatitic Fluid Inclusions in Ijolites with Natrocarbonatite Lavas.Bulletin VOLCANOLOGIQUE., Vol. 44, No. 3, PP. 429-438.GlobalBlank
DS1984-0447
1984
Le bas, M.J.Le bas, M.J.Oceanic CarbonatitesProceedings of Third International Kimberlite Conference, Vol. 1, PP. 169-178.GlobalRelated Rocks, Petrology, Ijolite
DS1985-0386
1985
Le bas, M.J.Le bas, M.J.Nephelinites and CarbonatitesConference Report of A Meeting of The Volcanic Studies Group, 1P. ABSTRACT.GlobalPetrography, Geochemistry
DS1986-0568
1986
Le Bas, M.J.Mian, I., Le Bas, M.J.Sodic amphiboles in fenites from the Loe Shilman carbonatite complex, northwestPakistanMineralogical Magazine, Vol. 50, No. 356, pt. 2, June pp. 187-198PakistanCarbonatite
DS1987-0400
1987
Le Bas, M.J.Le Bas, M.J.Nephelinites and carbonatitesin: Fitton and Upton, Alkaline igneous rocks, Blackwell publ, pp. 53-84GlobalCarbonatite
DS1987-0472
1987
Le Bas, M.J.Mian, I., Le Bas, M.J.The biotite phlogopite series in fenites from the Low Shilmancarbonatitecomplex, northwest PakistanMineralogical Magazine, No. 361, September pp. 397-408PakistanCarbonatite
DS1989-0648
1989
Le Bas, M.J.Hoernie, K.A., Tilton, G., Le Bas, M.J., Staudigel, H.A plume origin for Fuerteventura (Canary Islands) carbonatitesEos, Vol. 70, No. 15, April 11, p. 503. (abstract.)GlobalCarbonatite
DS1989-0859
1989
Le Bas, M.J.Le Bas, M.J.Petrogenesis of carbonatites and fenites: some recent developmentsGeological Society of India, Memoir, Editor C. LeelanandaM., No. 15, pp. 137-144GlobalAlkaline rocks, Fenites review carbonatit
DS1989-0860
1989
Le Bas, M.J.Le Bas, M.J.Nephelinite and basanitic rocksJournal of Petrology, Vol. 30, No. 5, October pp. 1299-1312GlobalBasanite, Nephelinite
DS1989-0861
1989
Le Bas, M.J.Le Bas, M.J.Diversification of carbonatite #2Carbonatites -Genesis and Evolution, Ed. K. Bell Unwin Hyman Publ, pp. 428-447GlobalPetrology, Carbonatite classificatio
DS1989-0862
1989
Le Bas, M.J.Le Bas, M.J., Srivastava, R.K.The mineralogy and geochemistry of the Mundwara carbonatite dykes, SirohiDistrict, Rajasthan, IndiaNeues Jahrb. F. Mineralogie, Abh, Vol. 160, No. 2, March, pp. 202-227IndiaGeochemistry, Carbonatite
DS1990-0337
1990
Le Bas, M.J.Clarke, L.B., Le Bas, M.J.Magma mixing and metasomatic reaction in silicate-carbonate liquids atthe Krudfontein carbonatitic volcanic complex, TransvaalMineralogical Magazine, Vol 54, No. 374, pt.1, March pp. 45-56South AfricaCarbonatite, Krudfontein
DS1990-0908
1990
Le Bas, M.J.Le Bas, M.J., Keller, J., Kejie, T., Wall, F., Williams, C.T., Zhang Pei-shanCarbonatite dikes at Bayan-Obo, Inner Mongolia, ChinaInternational Mineralogical Association Meeting Held June, 1990 Beijing China, Vol. 2, extended abstract p. 940-941ChinaCarbonatite, Baiyan Obo -dikes
DS1991-0273
1991
Le Bas, M.J.Clarke, L.B., Le Bas, M.J., Spiro, B.Rare earth, trace element and stable isotope fractionation of carbonatites at Kruidfontein, TransvaalProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 49-51South AfricaCarbonatite, Sovite, Alvikite
DS1991-0965
1991
Le Bas, M.J.Le Bas, M.J., Streckeisen, A.L.The IUGS systematics of igneous rocksJournal of the Geological Society of London, Vol. 148, No. 5, September pp. 825-834GlobalClassification, Igneous rocks
DS1992-0920
1992
Le Bas, M.J.Le Bas, M.J., Le Maitrem R.W., Woolley, A.R.The construction of the total alkali silica chemical classification of volcanic rocks.Min. Pet., Vol. 46, pp. 1-22.GlobalClassification - volcanics
DS1993-0893
1993
Le Bas, M.J.Le Bas, M.J.Sovites and alvikitesTerra Abstracts, IAGOD International Symposium on mineralization related to mafic, Vol. 5, No. 3, abstract supplement p. 26, 27GlobalCarbonatite
DS1994-0314
1994
Le Bas, M.J.Clarke, L.B., Le Bas, M.J., Spiro, B.Rare earth, trace element and stabe isotope fractionation of carbonatites at Kruidfontein, Transvaal.Proceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 236-251.South AfricaRare earths, Carbonatite
DS1994-1141
1994
Le Bas, M.J.McCormick, G.R., Le Bas, M.J.Biotite-phlogopite crystallization in carbonatite magmasGeological Association of Canada (GAC) Abstract Volume, Vol. 19, p. PosterGlobalCarbonatite, Mineralogy
DS1994-1951
1994
Le Bas, M.J.Woolley, A.R., Bergman, S., Edgar, A.D., Le Bas, M.J., MitchellClassification of the lamprophyres, lamproites, kimberlites and thekalsilite, melilite and leucite bearing rocks.Submitted to Journal of Petrology, 32p.GlobalSystematics of Igneous rocks, Classification
DS1995-1072
1995
Le Bas, M.J.Le Bas, M.J., Rao, B.B.Are the Vinjamur rocks carbonatites or meta-limestones?Journal of Geological Society India, Vol. 46, No. 2, August pp. 125-138.IndiaCarbonatite
DS1995-2016
1995
Le Bas, M.J.Wall, F., Le Bas, M.J., Srivastava, R.K.Carbonatite dykes at Sarnu -Dandali, Rajasthan, IndiaGeological Society Africa 10th. Conference Oct. Nairobi, p. 126-7. Abstract.IndiaCarbonatite, Deposit -Sarnu Dandali
DS1996-0817
1996
Le Bas, M.J.Le Bas, M.J., et al.Geochemical characteristics of the iron-rare earth elements (REE) carbonatitic complex at BayanObo, Inner Mongolia.International Geological Congress 30th Session Beijing, Abstracts, Vol. 2, p. 390.China, MongoliaCarbonatite, Deposit -Bayan Obo
DS1996-0920
1996
Le Bas, M.J.McCormick, G.R., Le Bas, M.J.Phlogopite crystallization in carbonatitic magmas from UgandaCanadian Mineralogist, Vol. 34, pt. 2, April pp. 469-478.UgandaCarbonatite, Mineralogy, petrology
DS1997-0141
1997
Le Bas, M.J.Bulakh, A.G., Zaitsev, A.N., Le Bas, M.J., Wall, F.Ancylite bearing carbonatites of the Sevlyavr Massif, Kola PeninsulaGeological Association of Canada (GAC) Abstracts, POSTER.Russia, Kola PeninsulaCarbonatite, Deposit - Sevlyavr
DS1997-0655
1997
Le Bas, M.J.Le Bas, M.J., Spiro, B., Xueming, Y.Oxygen, carbon and strontium isotope study of the carbonatitic dolomitehost of the Bayan Obo rare earth elements (REE) depositMineralogical Magazine, No. 407, August pp. 531-542.ChinaCarbonatite, Deposit - Bayan Obo
DS1997-1288
1997
Le Bas, M.J.Zaitsev, A.N., Bell, K., Wall, F., Le Bas, M.J.Alkaline rare earth element carbonates from carbonatites of the KhibinyMassif: mineralogy, genesisDoklady Academy of Sciences, Vol. 355, No. 5, Jun-July pp. 786-90.RussiaCarbonatite
DS1998-1622
1998
Le Bas, M.J.Zaitsev, A.N., Wall, F., Le Bas, M.J.rare earth elements (REE) Strontium, Barium minerals from the Khibin a carbonatites, Kola Pen. Russia: their mineralogy, paragenesis, evolution.Mineralogical Magazine, Vol. 62, No. 2, Apr. pp. 225-250.Russia, Kola PeninsulaMineralogy, rare earths, Carbonatite
DS1999-0399
1999
Le Bas, M.J.Le Bas, M.J.Sovite and alvikite: two chemically distinct calciocarbonatites C1 and C2South African Journal of Geology, Vol. 102, No. 2, June, pp. 109-22.GlobalCarbonatite, Petrology
DS2000-0557
2000
Le Bas, M.J.Le Bas, M.J.IUGS reclassification of the high magnesium and picritic volcanic rocksJournal of Petrology, Vol 41, No. 10, Oct. pp. 1467-70.GlobalClassification - picrites, Petrology
DS2002-0923
2002
Le Bas, M.J.Le Bas, M.J., Subbarao, K.V., Walsh, J.N.Meta carbonatite or marble? the case of the carbonate pyroxenite calcite apatite rock complex at Borra.Journal Asian Earth Science, Vol. 20, No. 2, pp. 127-40.India, GhatsCarbonatite, metacarbonatite, trace elements, Review
DS2003-1186
2003
Le Bas, M.J.Rosatelli, G., Wall, F., Le Bas, M.J.Potassic glass and calcite carbonatite in lapilli from extrusive carbonatites at RangwaMineralogical Magazine, Vol. 67, 5, pp. 931-56.KenyaCarbonatite
DS2003-1522
2003
Le Bas, M.J.Yang, X.M., Yang, X.Y., Zheng, Y.F., Le Bas, M.J.A rare earth element rich carbonatite dyke at Bayan Obo, Inner Mongolia, NorthMineralogy and Petrology, Vol. 78, 1-2, pp. 93-110.ChinaREE, Deposit - Bayan Obo
DS2003-1523
2003
Le Bas, M.J.Yang, X-M., Yang, X-Y., Zheng, Y.F., Le Bas, M.J.A rare earth carbonatite dyke at Bayan Obo, Inner Mongolia, north ChinaMineralogy and Petrology, Vol. 78, 1-2, pp. 93-110.ChinaCarbonatite, Deposit - Bayan Obo
DS200412-1090
2004
Le Bas, M.J.Le Bas, M.J., Oa-bttat, M.A.O., Taylor, R.N., Milton, J.A., Windley, B.F., Evins, P.M.The carbonatite marble dykes of Abyan Province, Yemen Republic: the mixing of mantle and crustal carbonate materials revealed byMineralogy and Petrology, Vol. 82, 1-2, pp. 105- DOI 10.1007/ s00710-004-0056-2YemenCarbonatite, geochronology
DS200412-1691
2003
Le Bas, M.J.Rosatelli, G., Wall, F., Le Bas, M.J.Potassic glass and calcite carbonatite in lapilli from extrusive carbonatites at Rangwa Caldera Complex, Kenya.Mineralogical Magazine, Vol. 67, 5, pp. 931-55.Africa, KenyaCarbonatite
DS200412-2173
2003
Le Bas, M.J.Yang, X.M., Yang, X.Y., Zheng, Y.F., Le Bas, M.J.A rare earth element rich carbonatite dyke at Bayan Obo, Inner Mongolia, North China.Mineralogy and Petrology, Vol. 78, 1-2, pp. 93-110.ChinaREE Deposit - Bayan Obo
DS200512-1057
2003
Le Bas, M.J.Stoppa, F., Rosatelli, G., Wall, F., Le Bas, M.J.Texture and mineralogy of tuffs and tuffsites at Ruri volcano in western Kenya: a carbonatite, melilite mantle debris trio.Periodico di Mineralogia, (in english), Vol. LXX11, 1. April, pp. 181-204.Africa, KenyaPetrology, Homa
DS200812-0634
2008
Le Bas, M.J.Le Bas, M.J.Fenites associated with carbonatites.Canadian Mineralogist, Vol. 46, 4, August pp.Carbonatite
DS200812-0635
2008
Le Bas, M.J.Le Bas, M.J., Xueming, Y., Taylor, R.N., Spiro, B., Milton, J.A., Peishan, Z.New evidence from a calcite dolomite carbonatite dyke for the magmatic origin of the massive Bayan Obo ore bearing dolomite marble, Inner Mongolia, China.Mineralogy and Petrology, Vol. 90, 3-4, pp. 223-248.China, MongoliaCarbonatite
DS1997-0656
1997
Le Basm M.J.Le Basm M.J.Unwholesome carbonatite magmasGeological Association of Canada (GAC) Abstracts, GlobalCarbonatite, Magma
DS1993-0227
1993
Le Bei, G.Cavender, B., Le Bei, G.Determination of the optimum life time of a mining project using discounted cash flow and option pricing techniquesMining Engineering, Vol. 45, No. 11, November pp. 1409-1412GlobalEconomics, Mining projects
DS202107-1110
2021
Le Bras, L.Y.Le Bras, L.Y., Bolhar, R., Bam, L., Guy, B.M., Bybee, G.M., Nex, P.A.M.Three dimensional tectural investigation of sulfide mineralisation from the Loolekop carbonatite-phoscorite polyphase intrusion in the Phalaborwa Igneous Complex ( South Africa), with implications for ore-forming processes.Mineralogical Magazine, 19p. Pdf doi:10.1180/mgm.2021.32Africa, South Africadeposit - Phalaborwa
DS202109-1477
2021
Le Bras, L.Y.Le Bras, L.Y., Bolhar, R., Bam, L., Guy, B.M., Bybee, G.M., Nex, P.A.M.Three-dimensional textural investigation of sulfide mineralization from the Loolekop carbonatite-phoscorite polyphase intrusion in the Phalaborwa Igneous Complex ( South Africa), with implications for ore forming processes.Mineralogical Magazine, Vol. 85, 4, pp. 514-531.Africa, South Africadeposit - Phalaborwa

Abstract: Copper-sulfides within carbonatites and phoscorites of the Phalaborwa Igneous Complex, South Africa, have been investigated since the middle of the 20th Century. However, aspects of ore formation have remained unclear. This study examines the mechanisms involved in Cu-sulfide mineralisation by micro-focus X-ray computed tomography as applied to sulfide-rich drill core samples. Several texturally distinct assemblages of magmatic sulfides can be identified, including: (1) <500 ?m rounded bornite and chalcopyrite grains disseminated within the gangue; (2) elongated mm-scale assemblages of chalcopyrite and bornite; and (3) mm-to-cm thick chalcopyrite cumulates. Chalcopyrite veins were also observed, as well as late-stage valleriite, documenting late-stage fluid circulation within the pipe, and alteration of magmatic and hydrothermal sulfides along fractures within the gangue, respectively. The results of micro-focus X-ray computed tomography indicate that magmatic sulfides are sub-vertically aligned. Spatial variability of the sulfide assemblages suggests that textural changes within sulfide layers reflect fluctuating magma flow rate during emplacement of carbonatite-phoscorite magmas, through coalescence or breakup of sulfide liquid droplets during ascent. Modal sulfide abundances, especially for disseminated assemblages, differ from one carbonatite-phoscorite layer to another, suggesting a strong control of the mechanical sorting in the formation of Cu-sulfide textures within the Loolekop carbonatite. The alternation of carbonatite and phoscorite within the intrusion suggest that the Loolekop Pipe was emplaced through a series of successive magma pulses, which differentiated into carbonatite and phoscorite by melt immiscibility/progressive fractional crystallisation and pressure drop. Three-dimensional textural analysis represents an effective tool for the characterisation of magma flow and is useful for the understanding of magmatic processes controlling sulfide liquid-bearing phoscorite-carbonatite magmas.
DS201906-1327
2019
Le Breton, E.Muller, R.D., Zahirovic, S., Williams, S.E., Cannon, J., Seton, M., Bower, D.J., Tetley, M., Heine, C., Le Breton, E., Liu, S., Russell, S.H.J., Yang, T., Leonard, J., Gurnis, M.A global plate model including lithospheric deformation along major rifts and orogens since the Triassic.Tectonics, May 5, 36p. Mantleplate tectonics

Abstract: Global deep?time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic?Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hotspot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 million km2 in the Late Jurassic (~160?155 Ma), driven by a vast network of rift systems. After a mid?Cretaceous drop in deformation it reaches a high of 48 million km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate?mantle system.
DS201907-1562
2019
Le Breton, E.Muller, D., Zahirovic, S., Williams, S.E., Cannon, J., Seton, M., Bower, D.J., Tetley, M., Heine, C., Le Breton, E., Liu, S., Russell, S.H.J., Yang, T., Leonard, J., Gurnis, M.A global plate model including lithospheric deformation along major rifts and orogens since the Triassic.Tectonics, in press available, 37p.Africa, globalplate tectonics, rotation

Abstract: Global deep?time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic-Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hot spot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model, net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 × 106 km2 in the Late Jurassic (~160-155 Ma), driven by a vast network of rift systems. After a mid?Cretaceous drop in deformation, it reaches a high of 48 x 106 km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate?mantle system.
DS2001-0314
2001
Le Breton, N.Faure, M., Lin, W., Le Breton, N.Where is the North Chin a - South Chin a block boundary in eastern Chin a?Geology, Vol. 29, No. 2, Feb. pp. 119-22.ChinaTectonics, ultra high pressure (UHP), Qinling Dabie Shan belt
DS2003-0394
2003
Le Breton, N.Faure, M., Lin, W., Monie, P., Le Breton, N., Pouissineau, S., Panis, D., Deloule, E.Exhumation tectonics of the ultrahigh pressure metamorphic rocks in the Qinling orogenTectonics, Vol. 22, 3, 10.1029/2002TC001450ChinaTectonics - subduction
DS2003-0395
2003
Le Breton, N.Faure, M., Lin, W., Monie, P., Le Breton, N., Pouissineau, S., Panis, D., Deloule, E.Exhumation tectonics of the ultrahigh pressure metamorphic rocks in the Qinling orogenTectonics, Vol. 22, 3, 10.1029/2002TC001450China, ShandongUHP
DS200412-0537
2003
Le Breton, N.Faure, M., Lin, W., Monie, P., Le Breton, N., Pouissineau, S., Panis, D., Deloule, E.Exhumation tectonics of the ultrahigh pressure metamorphic rocks in the Qinling orogen in east China: new petrological structuraTectonics, Vol. 22, 3, 10.1029/2002TC001450China, ShandongUHP
DS1910-0361
1913
Le chatelier, H.L.Le chatelier, H.L.Vom Kohlenstoff Vorlesungen Ueber die Grundlagen der Reinenund Angewandten Chemie.Halle ( Saale): Wilhelm Knapp, 324P.GlobalKimberlite
DS2001-1238
2001
Le Cheminant, A.Wilkinson, L., Kjarsgaard, B., Le Cheminant, A., HarrisDiabase dyke swarms in the Lac de Gras area, and their significance to kimberlite exploration: initial resultsGeological Survey of Canada Current Research, C8, 24p.Northwest TerritoriesProterozoic dike, tectonics, emplacement, age, patterns, Geochemistry
DS1994-1000
1994
Le Cheminant, A.N.Le Cheminant, A.N.Proterozoic diabase dyke swarms, Lac de Gras and Aylmer Lake areaGeological Survey of Canada (GSC) Open File, No. 2975Northwest TerritoriesDike swarms
DS1997-1147
1997
Le Cheminant, A.N.Tella, S., Le Cheminant, A.N., Sanborn-Barrie et al.Geology and structure of parts of MacQuoid Lake map areaGeological Survey of Canada (GSC) Paper, No. 1997-C, pp. 123-32.Northwest TerritoriesGeology
DS2002-1229
2002
Le Cheminant, A.N.Paul, D., Hamner, S., Tella, S., Peterson, T.D., Le Cheminant, A.N.Compilation bedrock geology of part of Western Churchill Province, Nunuvut-Northwest Territories.Geological Survey of Canada Open File, No. 4236, Map 1: 1,000,000 $19.50Northwest Territories, NunavutGeology - not specific to diamonds
DS2003-1123
2003
Le Cheminant, A.N.Rainbird, R.H., Hadlari, T., Aspler, L.B., Donaldson, J.A., Le Cheminant, A.N.Sequence stratigraphy and evolution of the Paleoproterozoic intracontinental BakerPrecambrian Research, Vol. 125, 1-2, pp. 21-53.NunavutBlank
DS200412-1609
2003
Le Cheminant, A.N.Rainbird, R.H., Hadlari, T., Aspler, L.B., Donaldson, J.A., Le Cheminant, A.N., Peterson, T.D.Sequence stratigraphy and evolution of the Paleoproterozoic intracontinental Baker Lake and The lon Basins, western Churchill ProPrecambrian Research, Vol. 125, 1-2, pp. 21-53.Canada, NunavutGeology
DS201012-0387
2010
Le Cheminant, A.N.Kilian, T.M., Mitchell, R.N., Bleeker, W., Le Cheminant, A.N., Chamberlain, K.R., Evans, D.A.D.Paleomagnetism of mafic dykes from the Wyoming craton, USA.International Dyke Conference Held Feb. 6, India, 1p. AbstractUnited StatesCraton, connections
DS1992-0079
1992
Le Cheminant, G.M.Baragar, W.R.A., Mader, U., Le Cheminant, G.M.Lac Leclair carbonatitic ultramafic center, Cape Smith BeltGeological Survey of Canada (GSC) Paper, No. 92-1C, pp. 103-9.Quebec, Ungava, LabradorCarbonatite
DS1996-0818
1996
Le Cheminant, N.A.Le Cheminant, N.A.Lamprophyre dykes in the Awry plutonic suite, North Arm, Great Slave LakeGeological Survey of Canada (GSC) Paper, No. 1996-B, pp. 11-18.Northwest TerritoriesLamprophyre
DS201012-0511
2010
Le Cheminant, T.N.Mitchell, R.N., Van Breeman, O., Buchan, K.L., Le Cheminant, T.N., Bleeker, W., Evans, D.A.D.Supercratons at the ends of Early Proterozoic Earth: reconstruction of Slave, Superior, and Kaapvaal cratons at 2200-2000 Ma.International Dyke Conference Held Feb. 6, India, 1p. AbstractCanada, Africa, South AfricaKenorland
DS1994-1001
1994
Le Corre, C.A.Le Corre, C.A., Rossello, E.A.Kinematics of early Paleozoic ductile deformation in the basement of northwestArgentinaJournal of South American Earth Sciences, Vol. 7, No. 3-4. pp. 301-308ArgentinaTectonics, metamorphism
DS201510-1790
2015
Le Corvec, N.Muirhead, J.D., Kattenhorn, S.A., Le Corvec, N.Unravelling the complexity of upper crustal dike networks in continental rifts: examples from East Africa.Geochemistry, Geophysics, Geosystems: G3, Vol. 16, in press availableAfrica, East AfricaDyke swarms

Abstract: The role of dike intrusion in driving continental breakup is fundamental to our understanding of plate tectonics. Buck (2004) showed that the breakup of thick continental lithosphere requires more than far-field tectonic forces, illustrating the important role of dike opening in driving extension during the earliest stages of rifting. Upper crustal diking in rift environments is often depicted to occur through long (up to 80 km), sub-parallel swarms intruding along the full length of rift basins. These assertions are supported by recent dike-driven rifting events in Iceland and Ethiopia (Wright et al., 2012), and inform numerical modelling studies addressing the mechanical effects of dike intrusion to rift processes (e.g., Buck et al., 2005). Our current view of dike networks, however, may be biased to evolved (>20 Ma), oceanic (e.g., Krafla) or nascent (e.g., Dabbahu-Manda-Hararo) spreading centers. This is largely because magmatic rifting occurs in these regions with a high enough frequency that it can be persistently captured using modern-day monitoring techniques (e.g., InSAR and seismicity). Dike networks throughout other sectors of the East African Rift may instead exhibit greater complexity, particularly in early-stage rifts (<10 Ma) undergoing infrequent diking episodes (Calais et al., 2008). By unravelling the contributions of dikes in these basins we can further refine our understanding of the role of magmatism during continental rift initiation. Current geophysical techniques (e.g., seismic reflection) lack the capacity to resolve thin, sub-vertical structures in the sub-surface, and thus reconstructing the geometries of cooled, upper crustal dike swarms poses a significant challenge. Recent structural and volcanological studies in both active and eroded monogenetic volcanic fields have illustrated the utility of volcanic vent alignments and cone morphometrics for inferring the distributions and orientations of upper crustal dikes (Kiyosugi et al., 2012; Le Corvec et al., 2013; Keir et al., 2015). The East African Rift exhibits numerous monogenetic cone fields that may help us understand the distribution and geometry of shallow dike-feeders emplaced in the last few million years (Korme et al., 1997; Mazzarini et al., 2013). Building on these studies and methods, we performed a comparative analysis of upper crustal diking in various rift basins throughout East Africa, based on the distributions, alignments and morphologies of monogenetic cones (Muirhead et al., 2015).
DS200512-0804
2004
Le Fevre, B.Ohtani, L., Le Fevre, B., Vannucci, R.Direct assessment of mantle boron and lithium contents and distribution by SIMS analyses of peridotite minerals.Earth and Planetary Science Letters, Vol. 228, 1-2, Nov. 30, pp. 19-36.MantlePeridotite, pyrolitic mantle
DS1988-0164
1988
Le Fort, P.Debon, F., Le Fort, P.A cationic classification of common plutonic rocks and theirmagmaticassociations: principles, method, applicationsBulletin de Mineralogie, No. 5, pp. 493-510. english Database # 17339GlobalRock Classification, Plutonic rocks
DS1989-0143
1989
Le Fort, P.Bonin, B., Didier, J., Le Fort, P., et al.Magma -crust interaction and evolutionAugustithis Publishing, (Greece), 362p. $ 38.00GlobalGeophysical aspects, Magma/crust
DS200412-0934
2004
Le GallJourdan, F., Feraud, Bertrand, Kampunzu, Watkeys, Le Gall, TshosoNew age constraints on the Karoo Large Igneous Province: triple junction and brevity questioned.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A575.Africa, South AfricaGondwana, Karoo magmatism
DS2000-0558
2000
Le Gall, B.Le Gall, B., Tiercelin, J.J., Richert, Gente, SturchioA morphotectonics study of an extensional fault zone in a magma rich rift:the Baringo trachyte fault systemTectonophysics, Vol. 320, No. 2, May 15, pp. 87-106.KenyaTectonics - central Kenya Rift
DS2002-0924
2002
Le Gall, B.Le Gall, B., Tshoso, G., Jourdan, F., Feraud, G., Bertrand, H., Tiercelin, J.J.40 Ar/39 Ar geochronology and structural dat a from the giant Okavango and relatedEarth and Planetary Science Letters, Vol. 202, 3-4, pp. 595-606.BotswanaMagmatism - not specific to diamonds
DS200412-0935
2004
Le Gall, B.Jourdan, F., Feraud, G., Betrand, H., Kampunzu, A.B., Tshoso, G., Le Gall, B., Tiercelin, J.J., Capiz, P.The Karoo triple junction questioned: evidence from Jurassic and Proterzoic 40 Ar 39 Ar ages and geochemistry of the giant OkavaEarth and Planetary Science Letters, Vol. 222, 3-4, June 15, pp. 989-1006.Africa, BotswanaGeochronology, mantle plume
DS200512-0489
2005
Le Gall, B.Jourdan, F., Feraud, G., Kampunzu, A.B., Tshoso, G., Watkeys, M.K., Le Gall, B.Karoo large igneous province: brevity, origin and relation to mass extinction questioned by new 40 Ar 39 Ar age data.Geology, Vol. 33, 9, Sept. pp. 745-748.Africa, South AfricaGeochronology
DS200612-0647
2005
Le Gall, B.Jourdan, F., Feraud, G., Bertrand, H., Watkeys, M.K., Kampunzu, A.B., Le Gall, B.Basement control on dyke distribution in Large Igneous Provinces: case study of the Karoo triple junction.Earth and Planetary Science Letters, mantleplumes.orgAfrica, South AfricaGeochronology, mantle plume, structure, tectonics
DS200812-0636
2008
Le Gall, B.Le Gall, B., Nonnotte, P., Rolet, J., Benoit, M., Guillou, H., Mousseau Nonnotte, M., Albaric, DeverchreRift propogation at craton margin: distribution of faulting and volcanism in the north Tanzanian divergence ( East Africa) during Neogene times.Tectonophysics, Vol. 448, 1-4, pp. 1-19.Africa, TanzaniaMagmatism
DS2003-0858
2003
Le Goff, M.Macouin, M., Valet, J.P., Besse, J., Buchan, K., Ernst, R., Le Goff, M., ScharerLow paleointensities recorded in 1 to 2.4. Ga Proterozoic dykes, Superior ProvinceEarth and Planetary Science Letters, Vol. 213, 1-2, pp. 79-95.Ontario, ManitobaGeochronology
DS200412-1193
2003
Le Goff, M.Macouin, M., Valet, J.P., Besse, J., Buchan, K., Ernst, R., Le Goff, M., Scharer, U.Low paleointensities recorded in 1 to 2.4. Ga Proterozoic dykes, Superior Province, Canada.Earth and Planetary Science Letters, Vol. 213, 1-2, pp. 79-95.Canada, Ontario, ManitobaGeochronology
DS201112-0669
2011
Le Goff, M.Michael, W.R., Le Goff, M., De Wit, M.Anatomy of a pressure induced, ferromagnetic to paramagnetic transition in pyrrhotite: implications for formation pressure of diamonds.Journal of Geophysical Research, Vol. 116, B 10, B10101,MantleDiamond genesis
DS2002-0925
2002
Le Grand, H.E.Le Grand, H.E.Plate tectonics, terranes and continental geologyGeological Society of London, Special Publication, 192, pp. 199-214.GlobalPlate tectonics - history
DS200412-1091
2002
Le Grand, H.E.Le Grand, H.E.Plate tectonics, terranes and continental geology.Geological Society of London, Special Publication, 192, pp. 199-214.GlobalPlate tectonics - history
DS2002-0926
2002
Le Grand, P.Le Grand, P.Plate tectonics, terranes and continental geologyGeological Society of London Special Paper, No. 192, pp. 199-214.GlobalTectonics
DS200612-0777
2006
Le Guillou, C.Le Guillou, C., Brunet, F., Rouzand, J.N., Irifune, T., Ohfuji, H.New experimental constraints on nanodiamond formation mechanisms from carbon nanoparticles at high pressure.International Mineralogical Association 19th. General Meeting, held Kobe, Japan July 23-28 2006, Abstract p.161.TechnologyNanodiamonds
DS200812-0637
2008
Le Guillou, C.Le Guillou, C., Rouzaud, J.N., Bourot-Denise, M., Remusat, L., Jambion, A.Laboratory shock synthesized diamond vs carbons from a differentiated meteorite.Goldschmidt Conference 2008, Abstract p.A532.Urelilite
DS200812-0638
2008
Le Hir, G.Le Hir, G., Ramstein, G., Donnadieu, Y., Godderis, Y.Scenario for the evolution of atmospheric pCO2 during a snowball Earth.Geology, Vol. 36, 1, pp. 47-50.MantleCarbon cycle
DS201201-0845
2011
Le Hir, G.Godderis, Y., Le Hir, G., Donnadieu, Y.Modelling the Snowball Earth.The Geological Record of Neoproterozoic glaciations, Memoirs 2011; Vol. 36, pp. 151-161.GlobalSnowball - model
DS201509-0412
2015
Le Losq, C.Le Losq, C., Mysen, B.O., Cody, G.D.Water and magmas: insights about the water solution mechanisms in alkali silicate melts from infrared, Raman, and 29 Si solid-state NMR spectroscopies.Progress in Earth and Planetary Science, Vol. 2, 22p.MantleMagmatism

Abstract: Degassing of water during the ascent of hydrous magma in a volcanic edifice produces dramatic changes in the magma density and viscosity. This can profoundly affect the dynamics of volcanic eruptions. The water exsolution history, in turn, is driven by the water solubility and solution mechanisms in the silicate melt. Previous studies pointed to dissolved water in silicate glasses and melts existing as molecules (H 2 O mol species) and hydroxyl groups, OH. These latter OH groups commonly are considered bonded to Si 4+ but may form other bonds, such as with alkali or alkaline-earth cations, for instance. Those forms of bonding influence the structure of hydrous melts in different ways and, therefore, their properties. As a result, exsolution of water from magmas may have different eruptive consequences depending on the initial bonding mechanisms of the dissolved water. However, despite their importance, the solution mechanisms of water in silicate melts are not clear. In particular, how chemical composition of melts affects water solubility and solution mechanism is not well understood. In the present experimental study, components of such information are reported via determination of how water interacts with the cationic network of alkali (Li, Na, and K) silicate quenched melts. Results from 29 Si single-pulse magic-angle spinning nuclear magnetic resonance ( 29 Si SP MAS NMR), infrared, and Raman spectroscopies show that decreasing the ionic radius of alkali metal cation in silicate melts results in decreasing fraction of water dissolved as OH groups. The nature of OH bonding also changes as the alkali ionic radius changes. Therefore, as the speciation and bonding of water controls the degree of polymerization of melts, water will have different effects on the transport properties of silicate melts depending on their chemical composition. This conclusion, in turn, may affect volcanic phenomena related to the viscous relaxation of hydrous magmas, such as for instance the fragmentation process that occurs during explosive eruptions.
DS201909-2098
2019
Le Losq, C.Timmerman, S., Honda, M., Burnham, A.D., Amelin, Y., Woodland, S., Pearson, D.G., Jaques, A.L., Le Losq, C., Bennett, V.C., Bulanova, G.P., Smith, C.B., Harris, J.W., Tohver, E.Primordial and recycled helium isotope signatures in the mantle transition zone. Science, Vol. 365, 6454, pp. 692-694.Mantlediamond genesis

Abstract: Isotope compositions of basalts provide information about the chemical reservoirs in Earth’s interior and play a critical role in defining models of Earth’s structure. However, the helium isotope signature of the mantle below depths of a few hundred kilometers has been difficult to measure directly. This information is a vital baseline for understanding helium isotopes in erupted basalts. We measured He-Sr-Pb isotope ratios in superdeep diamond fluid inclusions from the transition zone (depth of 410 to 660 kilometers) unaffected by degassing and shallow crustal contamination. We found extreme He-C-Pb-Sr isotope variability, with high 3He/4He ratios related to higher helium concentrations. This indicates that a less degassed, high-3He/4He deep mantle source infiltrates the transition zone, where it interacts with recycled material, creating the diverse compositions recorded in ocean island basalts.
DS1987-0791
1987
Le Maitre, R.W.Wilkinson, J.F.G., Le Maitre, R.W.Upper mantle amphiboles and micas and TiO2, K2O and P2O5 abundances and 100 Mg (Mg+Fe2) ratios of common basalts and andesites: implications for modal mantle metalsoJournal of Petrology, Vol. 28, No.1, pp. 37-74GlobalPetrology, Mantle genesis
DS1992-0925
1992
Le Maitre, R.W.LeBas, M.J., Le Maitre, R.W., Wooley, A.R.The construction of the total alkali-silica chemical classification of volcanic rocksMineralogy and Petrology, Vol. 46, No. 1, pp. 1-22GlobalClassification, alkaline, silicates, Volcanics -Alkali-silica
DS2002-0927
2002
Le Maitre, R.W. editor.Le Maitre, R.W. editor.Igneous rocks: a classification and glossary of termsCambridge University Press, www.cambridge.org, 240p. revisedGlobalBook - Igneous rocks classification, glossary
DS1992-0920
1992
Le Maitrem R.W.Le Bas, M.J., Le Maitrem R.W., Woolley, A.R.The construction of the total alkali silica chemical classification of volcanic rocks.Min. Pet., Vol. 46, pp. 1-22.GlobalClassification - volcanics
DS1994-1002
1994
Le Messurier, P.Le Messurier, P.Exploration in the Northern TerritoryAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin., No. 3, May, pp. 37-39.AustraliaNews item, Exploration activity
DS2001-0663
2001
Le Meur, E.Le Meur, E.Effects of a viscoelastic lithosphere on the isostatic bedrock responseEarth and Planetary Science Letters, Vol. 188, No. 1, May 30, pp.221-7.MantleLithosphere
DS2001-0824
2001
Le MouelNarteau, C., Le Mouel, Poirier, Sepulveda, ShnirmanOn a small scale roughness of the core mantle boundaryEarth and Planetary Science Letters, Vol. 191, No. 1-2, Aug. 30, pp. 49-60.MantleCore - boundary
DS1992-0921
1992
Le Mouel, J.L.Le Mouel, J.L., Courtillot, V., Jault, D.Changes in earth rotation rateNature, Vol. 355, January 2, pGlobalMantle, Geophysics -electromagnetics
DS200612-0778
2006
Le Mouel, J.L.Le Mouel, J.L., Narteau, C., Greff-Lefftz, M., Holschneider, M.Dissipation at the core mantle boundary on a small scale topography.Journal of Geophysical Research, Vol. 111, 10p. B04413MantleCMB - friction
DS1992-0306
1992
Le Mouel, J-L.Courtillot, V., Valet, J-P., Hulot, G., Le Mouel, J-L.The earth's magnetic field: which geometry?Eos, Vol. 73, No. 32, August 11, p. 337, 340, 342GlobalGeophysics, Magnetic field
DS2000-0610
2000
Le Mouel, J-L.Mandea, M., Bellanger, E., Le Mouel, J-L.A geomagnetic jerk for the end of the 20th. century?Earth and Planetary Science Letters, Vol.183, No.3-4, pp.369-73.GlobalGeophysics - magnetics
DS200712-0670
2007
Le Page, Y.Mainprice, D., Le Page, Y., Rodgers, J., Jouanna, P.Predicted elastic properties of hydrous D phase at mantle pressures: implications for the anisotropy of subducted slabs near 670 km discontinuity and in the lower mantle.Earth and Planetary Science Letters, Vol. 259, 3-4, pp. 283-296.MantleSubduction
DS200712-0671
2007
Le Page, Y.Mainprice, D., Le Page, Y., Rodgers, J., Jouanna, P.Predicted elastic properties of hydrous D phase at mantle pressures: implications for the anisotropy of subducted slabs near 670 km discontinuity and in the lower mantle.Earth and Planetary Science Letters, Vol. 259, 3-4, pp. 283-296.MantleSubduction
DS202106-0950
2021
Le Pape, F.Le Pape, F., Jones, A.G., Jessell, M.W., Hogg, C., Siebenaller, L., Perrouty, S., Tour, A., Oiuya, P., Boren, G.The nature pf the southern West Africa craton lithosphere inferred from its electrical resistivity.Precambrian Research, Vol. 358, 106190, 15p. Pdf Africageophysics

Abstract: The West-African craton is defined by a combination of Archean and Palaeoproterozoic rocks that stabilised at ~2 Ga towards the end of the Paleoproterozoic Eburnean Orogeny, and therefore may reflect the transition from Archean to modern tectonic processes. Exploring its present lithospheric architecture aids further understanding of not only the craton’s stability through its history but also its formation. We investigate the lithospheric structure of the craton through analysing and modelling magnetotelluric (MT) data from a 500-km-long east-west profile in northern Ghana and southern Burkina Faso crossing part of the Baoulé-Mossi Domain and reaching the Volta Basin in the south-eastern part of the craton. Although the MT stations are along a 2D profile, due to the complexity of the structures characterising the area, 3D resistivity modelling of the data is performed to obtain insights on the thermal signature and composition of the subcontinental lithosphere beneath the area. The thermal structure and water content estimates from different resistivity models highlight a strong dependence on the starting model in the 3D inversions, but still enable us to put constraints on the deep structure of the craton. The present?day thermal lithosphere?asthenosphere boundary (LAB) depth is estimated to be at least 250 km beneath the Baoulé-Mossi domain. The area likely transitions from a cold and thick lithosphere with relatively low water content into thinner, more fertile lithosphere below the Volta Basin. Although the inferred amount of water could be explained by Paleoproterozoic subduction processes involved in the formation of the Baoulé-Mossi domain, later enrichment of the lithosphere cannot be excluded.
DS1990-0261
1990
Le Pichon, X.Cadet, J.P., Le Pichon, X.Fluids in subduction zonesInternational Conference held Nov. 5-6, 110p. abstracts onlyGlobalSubduction zones, Fluids
DS1993-0894
1993
Le Pichon, X.Le Pichon, X., et al.Magmatic underplating during extension, eclogitization during mountain building and the composition of the lower continental crust.American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 613.MantleEclogites
DS1993-0895
1993
Le Pichon, X.Le Pichon, X., Henry, P., Lallemant, S.Accretion and erosion in subduction zones: the role of fluidsAnnual Review of Earth and Planetary Sciences, Vol. 21, pp. 307-332MantleTectonics
DS1994-0788
1994
Le Pichon, X.Huchon, P., Le Pichon, X., Rangin, C.Indochin a Peninsula and the collision of India and EurasiaGeology, Vol. 22, No. 1, January pp. 27-30China, IndiaTectonics, Deformation
DS1994-0789
1994
Le Pichon, X.Huchon, P., Le Pichon, X., Rangin, C.Indochin a Peninsula and the collision of India and EurasiaGeology, Vol. 22, No. 1, January pp. 27-30.China, IndiaTectonics, Deformation
DS201908-1785
2019
Le Pichon, X.Le Pichon, X.Fifty years of plate tectonics afterthoughts of a witness.Tectonics, doi.org/10.1029 / 2018TC005350 27p. PdfGlobalplate tectonics

Abstract: I suggest that the Earth Sciences in the mid?1950's entered a state of supercooling where the smallest input could lead to the simultaneous crystallization of new ideas. I joined in 1959 the Lamont Geological Observatory, one of the hotbeds where the Plate Tectonic revolution germinated. This paper is not an exhaustive history from an unbiased outside observer. It is a report of one of the participants who interacted with quite a few of the main actors of this revolution and who, fifty years later, revisits these extraordinary times. I emphasize the state of confusion and contradiction but also of extraordinary excitement in which we, earth scientists, lived at this time. I will identify several cases of what I consider to be simultaneous appearances of new ideas and will describe what now appear to be incomprehensible failures to jump on apparently obvious conclusions, based on my own experience.
DS201910-2278
2019
Le Pichon, X.Le Pichon, X., Ceal Sengor. A.M., Imrem, C.Pangea and the lower mantle.Tectonics, in press available Mantlesubduction, hot spots

Abstract: We show that the peripheral Pangea subduction zone closely followed a polar great circle. We relate it to the band of faster?than?average velocities in lowermost mantle. Both structures have an axis of symmetry in the equatorial plane. Assuming geologically long term stationarity of the deep mantle structure, we propose to use the axis of symmetry of Pangea to define an absolute reference frame. This reference frame is close to the slab remnants and NNR frames of reference but disagrees with hot spots based frames. We apply this model to the last 400 Myr. We show that a hemispheric supercontinent appeared as early as 400 Ma. However, at 400 Ma, the axis of symmetry was situated quite far south and progressively migrated within the equatorial plane that it reached at 300 Ma. From 300 to 110?100 Ma, it maintained its position within the equatorial plane. We propose that the stationarity of Pangea within a single hemisphere surrounded by subduction zones led to thermal isolation of the underlying asthenosphere and consequent heating as well as a large accumulation of hot plume material. We discuss some important implications of our analysis concerning the proposition that the succession of supercontinents and dispersed continents is controlled by an alternation from a degree one to a degree two planform.
DS201911-2539
2019
Le Pichon, X.Le Pichon, X., Sengor, A.M.C., Imren, C.Pangea and lower mantle tectonics.Researchgate, doi.org/10.1029/2018TC005445Mantletectonics

Abstract: We show that the peripheral Pangea subduction zone closely followed a polar great circle. We relate it to the band of faster?than?average velocities in lowermost mantle. Both structures have an axis of symmetry in the equatorial plane. Assuming geologically long?term stationarity of the deep mantle structure, we propose to use the axis of symmetry of Pangea to define an absolute reference frame. This reference frame is close to the slab remnants and NNR frames of reference but disagrees with hot spot?based frames. We apply this model to the last 400 Myr. We show that a hemispheric supercontinent appeared as early as 400 Ma. However, at 400 Ma, the axis of symmetry was situated quite far south and progressively migrated within the equatorial plane that it reached at 300 Ma. From 300 to 110-100 Ma, it maintained its position within the equatorial plane. We propose that the stationarity of Pangea within a single hemisphere surrounded by subduction zones led to thermal isolation of the underlying asthenosphere and consequent heating as well as a large accumulation of hot plume material. We discuss some important implications of our analysis concerning the proposition that the succession of supercontinents and dispersed continents is controlled by an alternation from a degree 1 to a degree 2 planform.
DS202106-0951
2021
Le Pichon, X.Le Pichon, X., Jellinek, M., Lenardic, A., Sengor, A.M.C., Imren, C.Pangea migration.Tectonics, e2020TC006585 42p. PdfMantleplate tectonics

Abstract: We confirm the proposition of Le Pichon et al. (2019) that Pangea was ringed by a hemispheric subduction girdle from its formation 400 Ma to its dispersal 100 Ma. We quantify the northward migration, that we attribute to True Polar Wander (TPW), of its axis of symmetry, between 400 Ma and 150 Ma, from southern latitudes to the equatorial zone. The spatial stabilizing within the equatorial zone of the axis of symmetry in a fixed position with respect to lower mantle, was marked by alternating CW and CCW oscillations between 250 Ma and 100 Ma that we relate to tectonic events. A subduction girdle is predicted to set up lateral temperature gradients from relatively warm sub-Pangean mantle to cooler sub-oceanic mantle. Over time, this effect acts to destabilize the Pangea landmass and its associated subduction girdle. Quantitatively, a scaling theory for the stability of the subduction girdle against mantle overturn constrains the maximum magnitude of sub-Pangean warming before breakup to be order 100 oC, consistent with constraints on Pacific-Atlantic oceanic crustal thickness differences. Our predictions are in line with recent analyses of Jurassic-Cretaceous climate change and with existing models for potential driving forces for a TPW oscillation of Pangea across the equator. The timing and intensity of predicted sub-Pangean warming potentially contributed to the enigmatically large Siberian Traps and CAMP flood basalts at 250 Ma and 201 Ma, respectively.
DS201212-0399
2012
Le Pioffle, A.Le Pioffle, A., Canil, D.Iron in monticellite as an oxygen barometer for kimberlite magmas.Contributions to Mineralogy and Petrology, Vol. 163, 6, pp. 1033-1046. 1047 erratumTechnologyGeobarometry
DS200712-0125
2007
Le Pourthier, L.Burov, E.,Guillou Frottier, L., Acremont, E., Le Pourthier, L., Cloetingh, S.Plume head lithosphere interactions near intra continental plate boundaries.Tectonophysics, Vol. 434, 1-4, pp. 15-38.MantleHotspots
DS2003-0292
2003
Le RoexCoussaert, N., Gregoire, M., Mercier, J.C.C., Bell, D.R., Demaiffe, D., Le RoexThe origin of clinopyroxene in cratonic mantle8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractSouth AfricaMantle geochemistry, Deposit - Bultfontein, Jagersfontein, Monastery, Premie
DS201412-0500
2014
Le RoexLe Roex, Class, C.Metasomatism of the Pan-African lithospheric mantle beneath the Damara Belt, Namibia, by the Tristan mantle plume: geochemical evidence from mantle xenoliths.Contributions to Mineralogy and Petrology, Vol. 168, pp. 1046-Africa, NamibiaPlume
DS1998-0598
1998
Le Roex, A.Hawkesworth, C., Kelley, S., Turner, S., Le Roex, A.Mantle processes during Gondwana break up and dispersalJournal of African Earth Sciences, Vol. 27, 1A, p. 108. AbstractGondwanaTectonics
DS2002-1707
2002
Le Roex, A.Whitehead, K., Le Roex, A., Class, C., Bell, D.Composition and Cretaceous thermal structure of the upper mantle beneath the Damara Mobile Belt: evidenceJournal of Geological Society of London, Vol.159,pp.307-21., Vol.159,pp.307-21.NamibiaNepheline hosted peridotite xenoliths, Gibeon compariso, Deposit - Swakopmund area
DS2002-1708
2002
Le Roex, A.Whitehead, K., Le Roex, A., Class, C., Bell, D.Composition and Cretaceous thermal structure of the upper mantle beneath the Damara Mobile Belt: evidenceJournal of Geological Society of London, Vol.159,pp.307-21., Vol.159,pp.307-21.NamibiaNepheline hosted peridotite xenoliths, Gibeon compariso, Deposit - Swakopmund area
DS2003-0350
2003
Le Roex, A.Doyle, P.M., Gurney, J.J., Le Roex, A.Xenoliths from the Arnie, Misery and Pigeon kimberlites8ikc, Www.venuewest.com/8ikc/program.htm, Session 4, POSTER abstractNorthwest TerritoriesMantle geochemistry, Deposit - Arnie, Misery, Pigeon
DS200412-0799
2004
Le Roex, A.Harris, M., Le Roex, A., Class, C.Geochemistry of the Uintjiesberg kimberlite, South Africa: petrogenesis of an off-craton, group I, kimberlite.Lithos, Vol. 74, pp. 149-165.Africa, South AfricaGeochemistry - Namaqua-Natal Proterozoic belt
DS200712-0602
2007
Le Roex, A.Le Roex, A.Kimberlite magmatism in southern Africa: what was the cause, and where is the source?Diamonds in Kimberley Symposium & Trade Show, Bristow and De Wit held August 23-24, Kimberley, South Africa, GSSA Diamond Workshop CD slides 22Africa, southern AfricaClassification, distribution, Group I,II magmas,plumes
DS200812-0225
2008
Le Roex, A.Coe, N., Le Roex, A., Gurney, J., Pearson, D.G., Nowell, G.Petrogenesis of the Swartruggens and Star Group II kimberlite dyke swarms, South Africa: constraints from whole rock geochemistry.Contributions to Mineralogy and Petrology, Vol. 156, pp. 627-652.Africa, South AfricaKaapvaal Craton, petrogenesis
DS200812-0639
2008
Le Roex, A.Le Roex, A., Coe, N., Gurney, J., Pearson, D.G., Nowell, G.Petrogenesis of Group II kimberlites: a case study from southern Africa.9IKC.com, 3p. extended abstractAfrica, South Africa, BotswanaDeposit - Swartruggens, Star
DS200812-0741
2007
Le Roex, A.Merry, M., Le Roex, A.Megacryst suites from the Lekkerfontein and Uintjiesberg kimberlites, southern Africa: evidence for a non-cognate origin.South African Journal of Geology, Vol. 110, 4, pp. 597-610.Africa, South AfricaGeochemistry - trace elements
DS200812-0828
2008
Le Roex, A.Opperman, A., Le Roex, A.Dutoitspan kimberlite, South Africa: petrogenesis of the northwest corner intrusive phases.9IKC.com, 2p. extended abstractAfrica, South AfricaDeposit - Dutoitspan Group I
DS201012-0012
2010
Le Roex, A.Arndt, N.T., Guitreau, M., Boullier, A-M., Le Roex, A., Tommasi, A.M., Cordier, P., Sobolev, A.Olivine, and the origin of kimberlite.Journal of Petrology, Vol. 51, 3, pp. 573-602.TechnologyKimberlite genesis
DS201012-0243
2010
Le Roex, A.Gonzaga, R.G., Lowry, D., Jacob, D.E., Le Roex, A., Schulze, D., Menzies, M.A.Eclogites and garnet pyroxenes: similarities and differences.Journal of Volcanology and Geothermal Research, Vol. 190, 1-2 pp. 235-247.TechnologyEclogite
DS201012-0244
2010
Le Roex, A.Gonzaga, R.G., Menzies, M.A., Thirwala, M.F., Jacob, D.E., Le Roex, A.Eclogites and garnet pyroxenites: problems resolving provenance using Lu-Hf, Sm-Nd and Rb-Sr isotope systems.Journal of Petrology, Vol. 51, 1-2, pp. 513-535.MantleGeochronology
DS201012-0322
2010
Le Roex, A.Janney, P.E., Shirey, S.B., Carlson, R.W., Pearson, D.G., Bell, D.R., Le Roex, A., Ishikawa, Nixon, BoydAge, composition and thermal characteristics of South African off craton mantle lithosphere: evidence for a multi stage history.Journal of Petrology, Vol. 51, 9, pp. 1849-1890,Africa, South AfricaGeochronology, geothermometry
DS201412-0499
2014
Le Roex, A.Le Roex, A., Class, C.Trace element enrichment of off-craton peridotites: comparison of off-craton Proterozoic and Pan-African mantle beneath southern Africa.Economic Geology Research Institute 2014, No. 12485 1p. abstractAfrica, Southern AfricaPeridotite
DS201602-0218
2016
Le Roex, A.Le Roex, A., Class, C.Metasomatic enrichment of Proterozoic mantle south of the Kaapvaal craton, South Africa: origin of sinusoidal REE patterns in clinopyroxene and garnet.Contributions to Mineralogy and Petrology, Vol. 171, 24p.Africa, South AfricaDeposit - Melton Wold, Hebron, Uintjiesberg, Markt

Abstract: Xenoliths of mantle peridotite have been sampled from four kimberlite intrusions, Melton Wold, Hebron, Uintjiesberg and Markt, emplaced through the Mesoproterozoic Namaqua-Natal Belt, along the southern border of the Kaapvaal Craton. Although many of the xenoliths are heavily altered, constituent clinopyroxene, garnet and phlogopite are fresh and have been analysed by electron microprobe for major elements and by laser ablation ICP-MS for trace elements. Primitive mantle-normalised REE abundances in clinopyroxene are all strongly LREE enriched and show a range of patterns including uniformly MREE-HREE sloped (referred to here as ‘normal’), sinusoidal and humped sinusoidal patterns. HREE abundances are extremely low (Yb = 0.3-0.06 × PM). REEN patterns in coexisting garnets show a similar range of patterns. When normalised to primitive mantle values, trace element patterns in some clinopyroxenes show strong relative depletion in Rb-Ba, Ta-Nb and Ti, with some samples also being relatively depleted in Zr-Hf. These trace element characteristics are indistinguishable from those found in clinopyroxene and garnet from peridotites from the adjacent cratonic mantle. Numerical modelling of reactive porous flow of an enriched metasomatic melt through a geochemically depleted peridotite matrix can account for the full range in observed REEN patterns. The relative depletion in Rb-Ba, Ta-Nb and Ti can be accounted for by an early crystallisation of phlogopite from the percolating melt. The relative depletion in Zr-Hf in some clinopyroxenes requires either zircon to crystallise in the proximal metasomatic assemblage, or metasomatism by a carbonatitic melt. Modelling results, together with the absence of clinopyroxene with depleted or even partially enriched REEN patterns, suggest that all clinopyroxene has been modally introduced through metasomatism into an initially highly depleted harzburgitic protolith. The range in Sr and Pb isotopic composition of the clinopyroxenes indicates regional metasomatism by melts of various compositions. The strong HREEN depletion is interpreted to reflect the effect of initial melt depletion in the early Proterozoic, with melting extending into the spinel stability field requiring an oceanic realm, and again later in the Mesoproterozoic (Namaqua Orogeny). The superimposed incompatible element enrichment indicates subsequent multiple enrichment events by rising alkaline melts similar in composition to kimberlite or ultramafic alkaline lamprophyre, possibly related to Mesozoic plume upwelling beneath the region, that reintroduced clinopyroxene into the depleted Proterozoic harzburgite protolith.
DS202008-1413
2020
Le Roex, A.Le Roex, A., Tinguely, C., Gregoire, M.Eclogite and garnet pyroxenite xenoliths from kimberlites emplaced along the southern margin of the Kaapvaal craton, southern Africa: mantle or lower crustal fragments?Journal of Petrology, https://doi.org/ 10.1093/petrology /egaa040 50p. PdfAfrica, South Africakimberlites

Abstract: Eclogite xenoliths, together with garnet pyroxenites and some mafic garnet granulites, found in kimberlites located along the southern margin of the Kaapvaal craton in southern Africa have been analysed by electron microprobe and mass spectrometry techniques to determine their geochemical characteristics. The majority of eclogites are bimineralic with garnet and omphacitic clinopyroxene in subequal proportions, with rutile as the main accessory phase; a few contain kyanite. Based on K2O in clinopyroxene and Na2O in garnet, the eclogites can be classified as Group II eclogites, and the majority are high-Ca in character. Garnet pyroxenites comprise garnet clinopyroxenites and garnet websterites. Major and trace element concentrations and isotope ratios of reconstituted bulk rock compositions of the eclogites and garnet pyroxenites allow constraints to be placed on depth of origin and likely protolith history. Calculated Fe–Mg exchange equilibration temperatures for the eclogites range from 815 to 1000?°C, at pressures of 1·7?±?0·4?GPa as determined by REE partitioning, indicating that they were sampled from depths of 50–55?km; i.e. within the lower crust of the Namaqua–Natal Belt. The garnet pyroxenites show slightly lower temperatures (686–835?°C) at similar pressures of equilibration. Initial 143Nd/144Nd and 87Sr/86Sr ratios (calculated to time of kimberlite emplacement) of both lithologies overlap the field for lower crustal samples from the Namaqua–Natal Belt. Further evidence for a crustal origin is found in the similar REE patterns shown by many of the associated garnet granulite xenoliths. Garnet pyroxenites are interpreted to have a similar origin as the associated eclogites but with the mafic protolith having insufficient Na (i.e. low modal plagioclase) to allow for development of omphacitic pyroxene. Metamorphism of the mafic protoliths to these eclogites and garnet pyroxenites is inferred to have occurred during crustal shortening and thickening associated with the collision of the Namaqua–Natal Belt with the Kaapvaal craton at 1–1·2?Ga.
DS202009-1639
2020
Le Roex, A.Le Roex, A., Tinguely, C., Gregoire, M.Eclogite and garnet pyroxenite xenoliths from kimberlites emplaced along the southern margin of the Kaapvaal Craton, southern Africa: mantle or lower crustal fragments?Journal of Petrology, pp. 1-32. pdf.Africa, South Africaeclogite, pyroxenite

Abstract: Eclogite xenoliths, together with garnet pyroxenites and some mafic garnet granulites, found in kimberlites located along the southern margin of the Kaapvaal craton in southern Africa have been analysed by electron microprobe and mass spectrometry techniques to determine their geochemical characteristics. The majority of eclogites are bimineralic with garnet and omphacitic clinopyroxene in subequal proportions, with rutile as the main accessory phase; a few contain kyanite. Based on K2O in clinopyroxene and Na2O in garnet, the eclogites can be classified as Group II eclogites, and the majority are high-Ca in character. Garnet pyroxenites comprise garnet clinopyroxenites and garnet websterites. Major and trace element concentrations and isotope ratios of reconstituted bulk rock compositions of the eclogites and garnet pyroxenites allow constraints to be placed on depth of origin and likely protolith history. Calculated Fe-Mg exchange equilibration temperatures for the eclogites range from 815 to 1000?°C, at pressures of 1•7?±?0•4?GPa as determined by REE partitioning, indicating that they were sampled from depths of 50-55?km; i.e. within the lower crust of the Namaqua-Natal Belt. The garnet pyroxenites show slightly lower temperatures (686-835?°C) at similar pressures of equilibration. Initial 143Nd/144Nd and 87Sr/86Sr ratios (calculated to time of kimberlite emplacement) of both lithologies overlap the field for lower crustal samples from the Namaqua-Natal Belt. Further evidence for a crustal origin is found in the similar REE patterns shown by many of the associated garnet granulite xenoliths. Garnet pyroxenites are interpreted to have a similar origin as the associated eclogites but with the mafic protolith having insufficient Na (i.e. low modal plagioclase) to allow for development of omphacitic pyroxene. Metamorphism of the mafic protoliths to these eclogites and garnet pyroxenites is inferred to have occurred during crustal shortening and thickening associated with the collision of the Namaqua-Natal Belt with the Kaapvaal craton at 1-1•2?Ga.
DS202104-0602
2021
Le Roex, A.Ramokgaba, L., Le Roex, A., Robey, J.Phlogopite-rich and phlogopite-poor kimberlite intrusions within the Du Toitspan kimberlite pipe, South Africa: petrogenetic relationships and localised source heterogeneity.Lithos, in press available, 35p. PdfAfrica, South Africadeposit - Du Toitspan

Abstract: Samples from three petrographically distinct, intrusive kimberlite bodies and associated kimberlite dykes from the eastern lobe of the Du Toitspan kimberlite pipe, Kimberley, South Africa, have been analysed for their bulk rock major and trace element compositions and their olivine and phlogopite compositions. The two dominant intrusive bodies (D13, D14) are distinguished by the one (D13) being phlogopite-rich and best classified as a macrocrystic hypabyssal phlogopite kimberlite, and the other (D14) being phlogopite-poor and best classified as a macrocrystic hypabyssal monticellite kimberlite. The minor D17 intrusive body is classified as a macrocrystic transitional hypabyssal serpentinized phlogopite kimberlite. The associated kimberlite dykes range texturally from aphanitic to macrocrystic and are classified as calcite kimberlites. The major kimberlite intrusions and their associated dykes show no evidence of crustal contamination and are characterised by broadly overlapping geochemistry except for distinctly higher K2O (> 2?wt%) and Al2O3 (>3?wt%) and flattening HREE patterns (Gd/YbN?=?6.5-7.0) in the D13 - phlogopite kimberlite compared to the D14 - monticellite kimberlite and the calcite kimberlite dykes (Gd/YbN?=?9.6-12.1). These distinguishing geochemical features of the D13 - phlogopite kimberlite are comparable to typical Group II kimberlites in southern Africa. However, their diagnostic incompatible trace element ratios (for example, Th/Nb, La/Nb, Ce/Pb, and Ba/Nb) are instead comparable to other kimberlite intrusions analysed in this study and to southern African Group I kimberlites in general. Semi-quantitative modelling suggests that these kimberlite intrusions could have derived by low (<1%) degrees of partial melting of a source region that is enriched in LREE (Lan?=?~6.1; Ybn?~?1.47) comparable to metasomatised peridotites from the underlying lithospheric mantle. The composition of the D13 phlogopite kimberlite is consistent with a partial melt of a modally metasomatised source containing a higher proportion of residual clinopyroxene relative to garnet (compared to that giving rise to the D14 monticellite kimberlite and calcite kimberlite dykes), as well as accessory amounts of phlogopite, i.e. a garnet phlogopite peridotite (GPP). The absence of K-anomalies on primitive mantle normalized diagrams for the D13 phlogopite kimberlite requires that phlogopite was not a residual phase during partial melting and was exhausted shortly before or at the moment of melt segregation. The higher Gd/Yb ratios and lower K2O in the D14 monticellite kimberlite and calcite kimberlite dykes can be explained by partial melting of a cryptically metasomatized, phlogopite - free, garnet peridotite (GP) source, containing a higher proportion of garnet relative to clinopyroxene. The low absolute K and strong negative K-anomaly on primitive mantle normalized diagrams for the D14 monticellite kimberlite were inherited from a source region that previously experienced cryptic metasomatism by a differentiated fluid already carrying a negative K-anomaly.
DS1980-0213
1980
Le roex, A.P.Le roex, A.P.Geochemistry and Mineralogy of Selected Atlantic Ocean Basalts.Ph. D. Thesis, University of Cape Town., 281P.South AfricaBasaltic Rocks
DS1986-0487
1986
Le Roex, A.P.Le Roex, A.P.Geochemical correlation between southern African kimberlites and South Atlantic HotspotsNature, Vol. 324, Nov. 20, pp. 243-245South AfricaGeochemistry
DS1987-0401
1987
Le Roex, A.P.Le Roex, A.P.Source regions of mid-Ocean Ridge basalts: evidence forenrichmentprocessesIn: Mantle Metasomatism, edited M.A. Menzies, C.J. Hawkesworth, Academic, pp. 389-422GlobalBlank
DS1994-1888
1994
Le Roex, A.P.Watkins, R.T., McDougall, I., Le Roex, A.P.K-Ar ages of the Brandberg and Okenyenya igneous complexes, northwesternNamibiaGeologische Rundschau, Vol. 83, No. 2, July pp. 348-356NamibiaIgneous complexes, Geochronology
DS1995-0133
1995
Le Roex, A.P.Bell, D.R., Gurney, J.J., Le Roex, A.P., Moore, R.O, et al.Compositional evolution of the Monastery megacrysts and parent magmaProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 50-51.South AfricaPetrology, Deposit -Monastery
DS1995-1055
1995
Le Roex, A.P.Lanyon, R., Le Roex, A.P.Petrology of the alkaline and ultramafic lamprophyre associated with Okenyenya igneous complex, northeastSouth. African Journal of Geology, Vol. 98, No. 2, June pp. 140-156.NamibiaAlkaline rocks, Deposit -Okenyenya complex
DS1995-1056
1995
Le Roex, A.P.Lanyon, R., Le Roex, A.P.Petrogenesis of the lamprophyric intrusions associated with Damaral and igneous complexes, liquid immiscibilityEos, Vol. 76, No. 46, Nov. 7. p.F642-3. Abstract.NamibiaCarbonatite, lamprophyric diatremes, dikes, Damaraland
DS1995-1259
1995
Le Roex, A.P.Milner, S.C., Le Roex, A.P., O'Connor, J.M.Age of Mesozoic igneous rocks in northwestern Namibia and their relationship to continental breakupJournal of the Geological Society of London, Vol. 152, No. 1, Jan. pp. 97-104NamibiaTectonics, Geochronology
DS1996-0819
1996
Le Roex, A.P.Le Roex, A.P., Watkins, R.T., Reid, A.M.Geochemical evolution of the Okenyenya sub-volcanic ring complex, northwestern Namibia.Geology Magazine, Vol. 133, No. 6, pp. 645-670.NamibiaGeochemistry, Alkaline rocks
DS1996-0968
1996
Le Roex, A.P.Milner, S.C., Le Roex, A.P.Isotope characteristics of the Okenyenya igneous complex, northwest Namibia:constraints on composition....Earth and Planetary Science Letters, Vol. 141, No. 1-4, June 1, pp. 277-NamibiaTristan Plume, Mantle hotspots
DS1998-0683
1998
Le Roex, A.P.Janney, P.E., Le Roex, A.P.Causes of compositional diversity in the olivine melilitites of Namaqualand- Bushmanland.7th International Kimberlite Conference Abstract, pp. 371-3.South AfricaMelilitites, Alkaline diatremes
DS1998-0684
1998
Le Roex, A.P.Janney, P.E., Le Roex, A.P., Viljoen, K.S.Trace element and isotopic characteristics of olivine melilitites from The western Cape: source for Group I.7th International Kimberlite Conference Abstract, pp. 374-6.South Africa, NamaqualandCape Fold Belt, Melilitites, Group I kimberlites
DS1998-0838
1998
Le Roex, A.P.Le Roex, A.P., Lanyon, R.Isotope and trace element geochemistry of Cretaceous Damaral and lamprophyres and carbonatites...Journal of Petrology, Vol. 39, No. 6, June 1, pp. 1117-46.NamibiaPlume - lithosphere interactions, Carbonatite, lamprophyres
DS2001-0664
2001
Le Roex, A.P.Le Roex, A.P., Spath, A., Zartman, R.E.Lithospheric thickness beneath the southern Kenya Rift: implications from basalt geochemistry.Contributions to Mineralogy and Petrology, Vol. 142, No. 1, Oct. pp.89-106.Kenya, southern AfricaGeochemistry - basalt
DS2001-1108
2001
Le Roex, A.P.Spath, A., Le Roex, A.P., Opiyo-Akech, N.Plume lithosphere interaction and the origin of continental rift related alkaline volcanism - ChyluluJournal of Petrology, Vol. 42, No. 4, Apr. pp. 765-88.Kenyavolcanism, hot spots, alkaline rocks, Chylulu Hills Volcanic Province
DS2002-0613
2002
Le Roex, A.P.Gregoire, M., Bell, D.R., Le Roex, A.P.Trace element geochemistry of phlogopite rich mafic mantle xenoliths: their classification and relationshipContributions to Mineralogy and Petrology, Vol. 142, No. 5, Feb. pp. 603-25.MantlePeridotites, kimberlites - phlogopite bearing, Kimberlites
DS2002-0928
2002
Le Roex, A.P.Le Roux, P.J., Le Roex, A.P., Schilling, J.G., Shimizu, N., Perkins, W.W., PearceMantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidenceEarth and Planetary Science Letters, Vol. 203, 1, pp. 479-98.MantleGeochemistry
DS2003-0023
2003
Le Roex, A.P.Appleyard, C.M., Le Roex, A.P., Bell, D.R.The geochemistry of a suite of eclogite xenoliths from the Rietfontein kimberlite, South8ikc, Www.venuewest.com/8ikc/program.htm, Session 2, POSTER abstractSouth AfricaEclogites and Diamonds, Deposit - Rietfontein
DS2003-0263
2003
Le Roex, A.P.Coe, N.I.J., Le Roex, A.P., Gurney, J.J.The geochemistry of the Swartruggens and Star kimberlite dyke swarms, South Africa8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractSouth AfricaDeposit - Swartruggens, Star
DS2003-0646
2003
Le Roex, A.P.Janney, P.E., Le Roex, A.P., Carlson, R.W., Bell, D.R.Os and Hf isotope constraints on the sources of olivine melilitites from western South8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractSouth AfricaGeochronology
DS2003-0775
2003
Le Roex, A.P.Le Roex, A.P., et al.Petrogenesis of Group I Kimberlites from Kimberley, South Africa: Evidence fromJournal of Petrology, Vol. 44, No. 12, pp. 2261-2286South AfricaGroup 1 kimberlites - petrogenesis, geochemistry, trace elements
DS2003-0776
2003
Le Roex, A.P.Le Roex, A.P., Bell, B.R., Davis, P.Petrogenesis of Kimberley group 1 hypabyssal kimberlites: evidence from bulk rock8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, AbstractSouth AfricaKimberlite petrogenesis, Deposit - Kimberley pipes
DS2003-0777
2003
Le Roex, A.P.Le Roex, A.P., Bell, D.R., Davis, P.Petrogenesis of Group I kimberlites from Kimberley, South Africa: evidence from bulkJournal of Petrology, Vol. 44, 12, pp. 2261-86.South AfricaPetrology - Kimberley deposit
DS200412-0340
2003
Le Roex, A.P.Coe, N.I.J., Le Roex, A.P., Gurney, J.J.The geochemistry of the Swartruggens and Star kimberlite dyke swarms, South Africa.8 IKC Program, Session 7, POSTER abstractAfrica, South AfricaKimberlite petrogenesis
DS200412-0480
2004
Le Roex, A.P.Doyle, P.M., Bell, B.R., Le Roex, A.P.Fine grained pyroxenites from the Gansfontein kimberlite, South Africa: evidence for megacryst magma - mantle interaction.South African Journal of Geology, Vol. 107, 1/2, pp. 285-300.Africa, South AfricaDeposit - Gansfontein, petrology
DS200412-0903
2003
Le Roex, A.P.Janney, P.E., Le Roex, A.P., Carlson, R.W., Bell, D.R.Os and Hf isotope constraints on the sources of olivine melilitites from western South Africa.8 IKC Program, Session 7, POSTER abstractAfrica, South AfricaKimberlite petrogenesis Geochronology
DS200412-1092
2003
Le Roex, A.P.Le Roex, A.P., Bell, B.R., Davis, P.Petrogenesis of Kimberley group 1 hypabyssal kimberlites: evidence from bulk rock geochemistry.8 IKC Program, Session 7, AbstractAfrica, South AfricaKimberlite petrogenesis Deposit - Kimberley pipes
DS200412-1093
2003
Le Roex, A.P.Le Roex, A.P., Bell, D.R., Davis, P.Petrogenesis of Group I kimberlites from Kimberley, South Africa: evidence from bulk rock geochemistry.Journal of Petrology, Vol. 44, 12, pp. 2261-86.Africa, South AfricaPetrology - Kimberley deposit
DS200512-0367
2005
Le Roex, A.P.Gregoire, M., Tinguely, C., Bell, D.R., Le Roex, A.P.Spinel lherzolite xenoliths from the Premier kimberlite ( Kaapvaal craton) South Africa: nature and evolution of the shallow upper mantle beneath Bushveld Complex.Lithos, Vol. 84, 3-4, Oct. pp. 185-205.Africa, South AfricaPetrology - Premier, melting, metasomatism
DS200612-0107
2006
Le Roex, A.P.Becker, M., Le Roex, A.P.Geochemistry of South African On and Off craton, Group I and Group II kimberlites: petrogenesis and source region evolution.Journal of Petrology, Vol. 47, 4, April pp. 673-703.Africa, South AfricaGenesis - craton
DS200612-0259
2006
Le Roex, A.P.Class, C., Le Roex, A.P.Continental material in the shallow oceanic mantle - how does it get there?Geology, Vol. 34, 3, March pp. 129-132.MantleStratigraphy
DS200812-0094
2007
Le Roex, A.P.Becker, M., Le Roex, A.P.Geochemistry and petrogenesis of South African transitional kimberlites located on and off the Kaapvaal Craton.South African Journal of Geology, Vol. 110, 4, pp. 631-646.Africa, South AfricaPetrogenesis of Group I and II
DS201012-0725
2010
Le Roex, A.P.Smit, K.V., Shirey, S.B., Richardson, S.H., Le Roex, A.P., Gurney, J.J.Re-Os isotopic composition of peridotitic sulphide inclusions in diamonds from Ellendale, Australia: age constraints on Kimberley cratonic lithosphere.Geochimica et Cosmochimica Acta, Vol. 74, 11, pp. 3292-3306.AustraliaDeposit - Ellendale
DS201112-0663
2011
Le Roex, A.P.Melluso, L., Le Roex, A.P., Morra, V.Petrogenesis and Nd Pb Sr isotope geochemistry of the Cenozoic olivine melilitites and the olivine nephelinites ( ankaratrites) in Madagascar.Lithos, in press available 40p.Africa, MadagascarMelilitite
DS201112-0192
2011
Le Roux, A.Class, C., Le Roux, A.South Atlantic DUPAL anomaly - dynamic and compositional evidence against a recent shallow origin.Earth and Planetary Science Letters, Vol. 305, 1-2, pp. 92-102.AfricaGeochemistry of plumes
DS1992-0922
1992
Le Roux, J.P.Le Roux, J.P.Paleocurrent analysis using LOTUS 1-2-3Computers and Geosciences, Vol. 17, No. 10, pp. 1465-1468GlobalComputer, Program -LOTUS paleocurrents
DS1992-0923
1992
Le Roux, J.P.Le Roux, J.P.A spreadsheet model for integrating stratigraphic and lithofacies mapsComputers and Geosciences, Vol. 17, No. 10, pp. 1469-1472GlobalComputer, Program -spreadsheet stratigraphy
DS1994-1003
1994
Le Roux, J.P.Le Roux, J.P.Impacts, tillites and the breakup of Gondwanaland: a second discussion and reply by OberbeckJournal of Geology, Vol. 102, No. 4, July pp. 483-490Sedimentology, Tillites
DS1994-1004
1994
Le Roux, J.P.Le Roux, J.P.Impacts, tillites, and the break up of Gondwanaland: a second discussionJournal of Geology, Vol. 102, No. 4, July pp. 483-485.South AfricaSedimentalogy, Dwyka Formation
DS201904-0747
2019
Le Roux, P.Howarth, G.H., Moore, A.E., Harris, C., van der Meer, Q.H.A., Le Roux , P.Crustal versus mantle origin of carbonate xenoliths from Kimberley region kimberlites using C-O-Sr-Nd-Pb isotopes and trace element abundances.Geochimica et Cosmochimica Acta, in press available 42p.Africa, South Africageochronology
DS201905-1043
2019
Le Roux, P.Howarth, G.H., Moore, A.E., Harris, C., van der Meer, Q.H.A., Le Roux, P.Crustal versus mantle origin of carbonate xenoliths from Kimberly region kimberlites using C-O-Sr-Nd-Pb isotopes and trace element abundances.Geochimica et Cosmochimica Acta, in press available, 16p.Africa, South Africadeposit - Kimberly region

Abstract: Carbonate-bearing assemblages in the mantle have been interpreted to be the source for Si-undersaturated, CO2-rich magmas, including kimberlites. However, direct evidence for carbonate in the mantle is rare in the contemporary literature. Here we present petrography, trace element, and C-O-Sr-Nd-Pb isotope composition for a suite of carbonate xenoliths from the Kimberley region kimberlites to ascertain their mantle or crustal origin and gain insight to the potential for the occurrence of carbonate in the mantle. Carbonate xenoliths were found in large kimberlite blocks from the Bultfontein kimberlite and Big Hole region. The xenoliths are characterised by pale green alteration margins made of fine-grained microlites of an unknown mineral as well as spherules surrounded by glassy material. They are generally 1–4?cm in size, coarse-grained (1–2?mm), and comprised entirely of calcite. Carbonate xenoliths from the Bultfontein kimberlite have low total REE concentrations (0.2–4.9?ppm), constant 87Sr/86Sri (0.7047–0.7049) combined with variable ?Ndi (?0.1 to ?26.2) and 206Pb/204Pbi, 207Pb/204Pbi, and 208Pb/204Pbi of 16.7–18.8, 15.3–15.6, 36.5–38.4, respectively. Xenoliths from the Big Hole sample have higher 87Sr/86Sri (0.7088–0.7095), lower ?Ndi (?24.5 to ?3.8), and 206Pb/204Pbi, 207Pb/204Pbi, and 208Pb/204Pbi of 18.9–19.9, 15.7–15.8, 38.4–38.8, respectively. The ?13C values for both Bultfontein (?5.7 to ?6.6‰) and Big Hole (?4.7 to ?5.4‰) carbonates are within the typical range expected for mantle-derived carbonate. The ?18O values (15.5–17.5‰) are higher than those of mantle silicate rocks, indicative of late-stage low-temperature interaction with fluids; a common feature of groundmass calcite in the Kimberley kimberlites. The Sr- and C- isotope composition of the Bultfontein xenoliths indicates a mantle origin whereas the Big Hole xenolith Sr- and C-isotopes are more ambiguous. Isotope mixing models are inconsistent with interaction between the host kimberlite and carbonate xenoliths. Correlation between ?Ndi and ?18O values for the Bultfontein xenoliths indicates late-stage interaction with low-temperature fluids, which may also be responsible for the large range in ?Ndi. This in turn indicates that the highest ?Ndi of ?0.1 represents the primary carbonate xenolith signature, and this value overlaps typical Group I kimberlites. We discuss two possible origins for the carbonate xenoliths. (1) Carbonate xenoliths from the sub-continental lithospheric mantle (SCLM), where quenched margins and the large range of ?Ndi are related to formation in the mantle. (2) Carbonate xenoliths from an earlier phase of carbonatite magmatism. The similarity of isotope signatures of the Bultfontein carbonates to Group I kimberlite may further suggest a link between kimberlite and carbonatite volcanism such as observed elsewhere in the world.
DS201910-2272
2019
Le Roux, P.Khan, S., Dongre, A., Viljoen, F., Li, Q., Le Roux, P.Petrogenesis of lamprophyres synchronous to kimberlites from the Wajrakarur kimberlite field: implications for contrasting lithospheric mantle sources and geodynamic evolution of the eastern Dharwar craton of southern India.Geological Journal, Vol. 54, 5, pp. 2994-3016.Indiadeposit - Wajrakarur

Abstract: Kimberlite field is an example of widespread Mesoproterozoic intracontinental magmatism. Recent studies have identified deep subcontinental lithospheric mantle as a source region of the kimberlite magmatism while timing, origin, and processes responsible for the generation of coeval lamprophyres remain poorly constrained. Here, we present and discuss new petrological and geochemical data for two lamprophyre dykes from the Wajrakarur kimberlite field and assess their petrogenetic relation to the kimberlite occurrences. Based on mineral compositional and whole?rock geochemical characters, it is suggested that lamprophyres are formed through low degrees of partial melting of “enriched” lithospheric mantle that was modified and metasomatized by melts derived from recycled crust. This differs from geochemical imprints found in coeval kimberlites, where a crustal source component appears to be absent and is more consistent with rock derivation from “depleted” lithosphere which has experienced interaction with asthenosphere?derived melts. An apparent lack of garnet in the mantle sources of lamprophyres is suggestive of melting at comparatively shallow depth (~100 km) relative to the kimberlites. Hence, these geochemically contrasting rocks, although have formed at the same time, are derived from vertically heterogeneous lithospheric mantle sources and can be explained through and linked with a thermal anomaly in the underlying convective asthenosphere. We suggest that the deeper mantle source region of the kimberlites was more pristine and devoid of subduction?related signatures, whereas the shallower mantle source region of the lamprophyres seems to have preserved imprints of plate convergence and subduction associated with the evolution of the Dharwar Craton.
DS2002-0928
2002
Le Roux, P.J.Le Roux, P.J., Le Roex, A.P., Schilling, J.G., Shimizu, N., Perkins, W.W., PearceMantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidenceEarth and Planetary Science Letters, Vol. 203, 1, pp. 479-98.MantleGeochemistry
DS201905-1082
2019
Le Roux, P.J.van der Meer, Q.H.A., Scott, J.M., Serre, S.H., Whitehouse, M.J., Kristoffersen, M., Le Roux, P.J., Pope, E.C.Low delta 18 O zircon xenocrysts in alkaline basalts; a window into the complex carbonatite-metasomatic history of the Zealandia lithospheric mantle.Geochimica et Cosmochimica Acta, Vol. 254, pp. 21-39.New Zealandmetasomatism

Abstract: Megacrystic zircon grains from alkaline basaltic fields are rare but can provide fundamental insights into mantle metasomatic processes. Here, we report in-situ U-Pb ages, trace element concentrations and hafnium and oxygen isotopes for fourteen zircon megacrysts from two intraplate alkaline basalt locations in New Zealand. U-Pb ages indicate the zircons crystallised between 12.1 and 19.8 Ma. Zircon oxygen isotopic compositions range from low to mantle-like compositions (grain average ? ¹? O = 3.8-5.1‰). Hafnium isotopes (?Hf (t) = +3.3 to +10.4) mostly overlap with intraplate mafic rocks and clinopyroxene in metasomatized peridotitic mantle xenoliths but show no correlation with most trace element parameters or oxygen isotopes. The zircons are interpreted to have formed by the reaction between low-degree melts derived from pre-existing mantle metasomes and the depleted mantle lithosphere prior to eruption and transport to the surface. The low Hf concentration, an absence of Eu anomalies, and elevated U/Yb compared to Nb/Yb in the megacrystic zircons are interpreted to show that the source metasomes comprised subduction- and carbonatite-metasomatised lithospheric mantle. As these trace element characteristics are common for megacrystic zircon in intra-plate basaltic fields globally, they suggest the prevalence of subduction- and carbonatite-metsasomatised mantle under these intraplate volcanic regions. The unusually low ? ¹? O was likely present prior to metasomatic enrichment and may have resulted from high-temperature hydrothermal alteration during initial mantle lithosphere formation at a mid ocean ridge or, possibly, during subduction-related processes associated with continent formation. The combination of proportionally varied contributions from carbonatite- and subduction-metasomatised lithospheric melts with asthenospheric melts may explain the variety of primitive intraplate basalt compositions, including low ? ¹? O reported for some local intraplate lavas.
DS202004-0544
2020
Le Roux, P.J.Will, T.M., Hohn, S., Frimmel, H.E., Gaucher, C., Le Roux, P.J., Macey, P.H.Petrological, geochemical and isotopic data of Neoproterozoic rock units from Uruguay and South Africa: correlation of basement terranes across the South Atlantic.Gondwana Research, Vol. 80, pp. 12-32.South America, Uruguay, Brazil, Africa, Namibiacraton

Abstract: Felsic to intermediate igneous rocks from the Cuchilla Dionisio (or Punta del Este) Terrane (CDT) in Uruguay and the Várzea do Capivarita Complex (VCC) in southern Brazil were emplaced in the Tonian and experienced high-grade metamorphism towards the end of the Cryogenian. Geological and geochemical data indicate an S-type origin and formation in a continental within-plate setting by recycling of lower crustal material that was initially extracted from the mantle in the Palaeoproterozoic. Similar felsic igneous rocks of Tonian age occur in the Richtersveld Igneous Complex and the Vredefontein and Rosh Pinah formations in westernmost South Africa and southern Namibia and have been correlated with their supposed equivalents in Uruguay and Brazil. Geochemical and isotope data of the largely unmetamorphosed felsic igneous rocks in southwestern Africa imply a within-plate origin and formation by partial melting or fractional crystallization of mafic rocks that were extracted from the mantle in the Proterozoic. The parental melts of all of these Tonian igneous rocks from South America and southwestern Africa formed in an anorogenic continental setting at the western margin of the Kalahari Craton and were emplaced in, and/or contaminated by, Namaqua Province-type basement after separation from their source region. However, the source regions and the time of extractions thereof are different and, moreover, occurred at different palaeogeographical latitudes. New petrological data of CDT high-grade gneiss indicate a geothermal gradient of c. 20-25 °C/km, implying continental collisional tectonics following subduction and ocean basin closure at an active continental margin at the eastern edge of present-day South America in the late Cryogenian to early Ediacaran. The associated suture may be traced by the high-grade gneiss and amphibolite-facies mafic rocks in the CDT and probably continues northwards to the Arroio Grande Complex and the VCC in southern Brazil.
DS201012-0172
2010
Le Roux, T.Dransfield, M., Le Roux, T., Burrows, D.Airborne gravimetry and gravity gradiometry at Fugro airborne surveys.Australian Airborne Gravity Conference Extended Abstracts 2010, pp. 49-52.Canada, Northwest TerritoriesGeophysics - gravity, Ekati
DS201412-0501
2014
Le Roux, T.Le Roux, T., Steenkamp, B.Airborne geophysical characteristics of a few Angolan kimberlites.GSSA Kimberley Diamond Symposium and Trade Show provisional programme, Sept. 12, title onlyAfrica, AngolaGeophysics
DS200712-0603
2007
Le Roux, V.Le Roux, V., Bodinier, J-L., Alard, O., Wieland, P., O'Reilly, S.Y.Insights into refertilization processes in lithospheric mantle from integrated isotopic studies in the Lherz Massif.Plates, Plumes, and Paradigms, 1p. abstract p. A563.Europe, FranceMelting
DS200712-0604
2007
Le Roux, V.Le Roux, V., Bodinier, J-L., Tommasi, A., Alard, O., Dautria, J-M., Vauchez, A., Riches, A.J.V.The lherz spinel lherzolite: refertilized rather than pristine mantle.Earth and Planetary Science Letters, Vol. 259, 3-4, pp. 599-612.MantleLherzolite chemistry
DS200712-0605
2007
Le Roux, V.Le Roux, V., Bodinier, J-L., Tommasi, A., Alard, O., Dautria, J-M., Vauchez, A., Riches, A.J.V.The lherz spinel lherzolite: refertilized rather than pristine mantle.Earth and Planetary Science Letters, Vol. 259, 3-4, pp. 599-612.MantleLherzolite chemistry
DS200812-0011
2008
Le Roux, V.Alard, O., Le Roux, V., Bodinier, J.L., Lorand, J.P., Griffin, W.L., O'Reilly, S.Y.How primitive is the 'primitive' mantle?Goldschmidt Conference 2008, Abstract p.A13.MantleGeochemistry, structure
DS200812-0640
2008
Le Roux, V.Le Roux, V., Tommasi, A., Vauchez, A.Feedback between melt percolation and deformation in an exhumed lithosphere asthenosphere boundary.Earth and Planetary Science Letters, Vol. 274, pp. 410-413.MantleMelting
DS200912-0429
2009
Le Roux, V.Le Roux, V., Bodinier, J-L., Allard, O., O'Reilly, S.Y., Griffin, W.L.Isotopic decoupling during porous melt flow: a case study in the Lherz peridotite.Earth and Planetary Science Letters, Vol. 279, 1-2, pp.76-85.Europe, FranceGeochronology
DS201112-0572
2011
Le Roux, V.Le Roux, V., Dasgupta, R., Le, C.T.A.Mineralogical heterogeneities in the Earth's mantle: constraints from Mn, Co, Ni and Zn partitioning during partial melting.Earth and Planetary Science Letters, Vol. 307, 3-4, pp. 395-408.MantleMineralogy
DS201312-0919
2013
Le Roux, V.Tommasi, A., Baptiste, V., Soustelle, V., Le Roux, V., Mainprice, D., Vauchez, A.Heterogeneity and anisotropy in the lithospheric mantle.Goldschmidt 2013, AbstractMantleGeophysics
DS201610-1882
2016
Le Roux, V.Le Roux, V., Nielsen, S.G., Sun, C., Yao, L.Dating layered websterite formation in the lithospheric mantle.Earth and Planetary Science Letters, Vol. 454, pp. 103-112.Mantle, Africa, MoroccoMelting

Abstract: Pyroxenites are often documented among exhumed mantle rocks, and can be found in most tectonic environments, from supra-subduction to sub-continental and sub-oceanic mantle. In particular, websterites, i.e. orthopyroxene-clinopyroxene bearing pyroxenites, are found in parallel layers in most orogenic and ophiolitic peridotites. Their formation is often ascribed to melt infiltration and melt-rock reaction processes accompanied by variable amount of deformation. One outstanding question is whether the ubiquitous occurrence of layered websterites in exhumed rocks is generally linked to the exhumation process or truly represents large-scale melt infiltration processes at depth prior to exhumation. These two hypotheses can be distinguished by comparing the exhumation and formation ages of the websterites. However, determination of the layered websterite formation age is challenging. Here we present a novel approach to constrain the formation age of websterite layers using samples from the Lherz massif (France), where layered websterites and lherzolites have formed through melt-rock reaction. By combining high-resolution REE variations, isotope model ages, and diffusive re-equilibration timescales using REE closure temperatures across the websterite layers, we constrain a minimum age and a maximum age for the formation of layered websterites. We show that layered websterites in Lherz formed 1,500-1,800 Ma ago, and are thus clearly disconnected from the process of exhumation at 104 Ma. Multiple generations of layered websterites commonly found in ultramafic massifs, along with the evidence for ancient melt-rock reaction in Lherz, indicate that melt-rock reactions can happen episodically or continuously in the mantle and that layered websterites found in exhumed mantle rocks record ubiquitous melt infiltration processes in the mantle.
DS201805-0942
2018
Le Roux, V.Cruz-Uribe, A.M., Marschall, H.R., Gaetani, G.A., Le Roux, V.Generation of alkaline magmas in subduction zones by partial melting of melange diapirs - an experimental study.Geology, Vol. 48, 4, pp. 343-346.Technologysubduction

Abstract: Alkaline lavas occur globally in subduction-related volcanic arcs. Conventional models for the origin of these lavas typically invoke a multi-stage process in which mantle wedge peridotite, enriched in phlogopite and/or amphibole due to prior metasomatism, partially melts during infiltration by fluids and melts derived from subducted oceanic lithosphere. However, geochemical systematics in the majority of subduction-related alkaline lavas require physical mixing of subducted components and peridotite prior to partial melting. This can be explained by the mélange diapir model, which predicts the generation of arc magmas during advection of buoyant material from the slab-wedge interface into the mantle wedge below arcs. Here we report results from experiments in which natural mélange materials were partially melted at upper mantle conditions to produce alkaline magmas. Partial melts produced in our experiments have trace-element abundance patterns that are typical of alkaline arc lavas, such as enrichment in large ion lithophile elements (LILEs) and depletion in Nb and Ta. These results favor generation of alkaline magmas in the arc and backarc regions of subduction zones by partial melting of mélange materials rather than previously metasomatized peridotite.
DS201709-1990
2017
Le Sage, D.Glenn, D.R., Fu, R.R., Kehayias, P., Le Sage, D., Lima, E.A., Weiss, B.P., Walsworth, R.L.Micrometer-scale magnetic imaging of geological samples using a quantum diamond microscope. ( remnant magnetism meteorites)Geochemistry, Geophysics, Geosystems: G3, in press availableTechnologygeophsyics - magnetics

Abstract: Remanent magnetization in geological samples may record the past intensity and direction of planetary magnetic fields. Traditionally, this magnetization is analyzed through measurements of the net magnetic moment of bulk millimeter to centimeter sized samples. However, geological samples are often mineralogically and texturally heterogeneous at submillimeter scales, with only a fraction of the ferromagnetic grains carrying the remanent magnetization of interest. Therefore, characterizing this magnetization in such cases requires a technique capable of imaging magnetic fields at fine spatial scales and with high sensitivity. To address this challenge, we developed a new instrument, based on nitrogenvacancy centers in diamond, which enables direct imaging of magnetic fields due to both remanent and induced magnetization, as well as optical imaging, of room-temperature geological samples with spatial resolution approaching the optical diffraction limit. We describe the operating principles of this device, which we call the quantum diamond microscope (QDM), and report its optimized image-area-normalized magnetic field sensitivity (20 µT?µm/Hz½), spatial resolution (5 µm), and field of view (4 mm), as well as trade-offs between these parameters. We also perform an absolute magnetic field calibration for the device in different modes of operation, including three-axis (vector) and single-axis (projective) magnetic field imaging. Finally, we use the QDM to obtain magnetic images of several terrestrial and meteoritic rock samples, demonstrating its ability to resolve spatially distinct populations of ferromagnetic carriers.
DS1993-1303
1993
Le Stunff, Y.Ricard, Y., Richards, M., Lithgow-Bertelloni, C., Le Stunff, Y.A geodynamic model of mantle density heterogeneityJournal of Geophysical Research, Vol. 98, No. B 12, December 10, pp. 21-895-21, 909.MantleGeodynamics
DS1989-0152
1989
Le Sueur, E.Boudier, F., Le Sueur, E., Nicolas, A.Structure of an atypical ophiolite: the Trinity Complex, easternKlamathMountains, CaliforniaGeological Society of America (GSA) Bulletin, Vol. 101, No. 6, June pp. 820-833CaliforniaOphiolite, Trinity Complex
DS2003-0961
2003
Le Tendre, J.Mitchell, R.H., Le Tendre, J.Mineralogy and petrology of kimberlite from Wemindji, Quebec8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractQuebecBlank
DS200412-1338
2003
Le Tendre, J.Mitchell, R.H., Le Tendre, J.Mineralogy and petrology of kimberlite from Wemindji, Quebec.8 IKC Program, Session 7, POSTER abstractCanada, QuebecKimberlite petrogenesis
DS1996-0085
1996
Le Traon, P.-Y.Barlier, F., Le Traon, P.-Y., Gazenave, A.Point sur les missions d'altimetrie spatiale TOPX/POSEIDON et ERS-1C.r. Academy Of Science Paris, Vol. 323, 11a pp. 737-753.GlobalMarine oceanography, Coastal areas - general not specific to diamonds
DS201909-2065
2019
Le Trong, E.Nabyl, Z., Massuyeau, M., Gaillard, F., Tuduri, J., Iacono-Marziano, G., Rogerie, G., Le Trong, E., Di Carlo, I., Melleton, J., Bailly, L.REE-rich carbonatites immiscible with phonolitic magma.Goldschmidt2019, 1p. AbstractGlobalcarbonatite - REE

Abstract: uncommon type of magmatic rocks dominates by carbonate, are broadly enriched in rare earth elements (REE) relative to the majority of igneous silicate rocks. While more than 500 carbonatites are referenced worldwide [1], only a few contain economic REE concentrations that are widely considered as resulting from late magmatic-hydrothermal or supergene processes. Magmatic pre-enrichment, linked to the igneous processes at the origin of carbonatites, are, however, likely to contribute to the REE fertilisation. Field observations [1] and experimental surveys [2, 3] suggest that a large part of the carbonatite melts can be produced as immiscible liquids with silicate magmas. Experimental constraints reveals that such immiscibility processes can lead to both REE enrichments and depletions in carbonatites [2, 3], making the magmatic processes controlling REE enrichments unclear. Here we present results of high-pressure and hightemperature experiments, simultaneously addressing crystal fractionation of alkaline magmas and immiscibility between carbonate and silicate melts. The experimental data reveal that the degree of differentiation, controlling the chemical composition of alkaline melts is a key factor ruling the REE concentration of the coexisting immiscible carbonatites. The parameterization of the experimental data together with the compilation of geochemical data from various alkaline provinces show that REE concentrations similar to those of highly REE enriched carbonatites (?REE > 30000 ppm) can be produced by immiscibility with phono-trachytic melt compositions, while more primitive alkaline magma can only be immiscible with carbonatites that are not significantly enriched in REE.
DS202006-0940
2020
Le Trong, E.Nabyl, Z., Massuyeau, M., Gaillard, F., Tuduri, J., Iacono-Marziano, G., Rogerie, G., Le Trong, E., Di Carlo, I., Melleton, J., Bailly, L.A window in the course of alkaline magma differentiation conducive to immiscible REE-rich carbonatites.Geochimica et Cosmochimica Acta, in press available 57p. PdfMantlecarbonatite

Abstract: Rare earth element (REE) enrichments in carbonatites are often described as resulting from late magmatic-hydrothermal or supergene processes. However, magmatic pre-enrichment linked to the igneous processes at the origin of carbonatites are likely to contribute to the REE fertilisation. Experimental constraints reveals that immiscibility processes between carbonate and silicate melts can lead to both REE enrichments and depletions in carbonatites making the magmatic processes controlling REE enrichments unclear. We link REE contents of carbonatites to the magmatic stage at which carbonatites are separated from silicate magma in their course of differentiation. We present results of experiments made at pressure and temperature conditions of alkaline magmas and associated carbonatites differentiation (0.2-1.5 GPa; 725-975?°C; FMQ to FMQ?+?2.5), simultaneously addressing crystal fractionation of alkaline magmas and immiscibility between carbonate (calcio-carbonate type) and silicate melts (nephelinite to phonolite type). The experimental data shows that the degree of differentiation, controlling the chemical composition of alkaline melts, is a key factor ruling the REE concentration of the coexisting immiscible carbonate melts. In order to predict carbonate melt REE enrichments during alkaline magma differentiation, we performed a parameterisation of experimental data on immiscible silicate and carbonate melts, based exclusively on the silica content, the alumina saturation index and the alkali/alkaline-earth elements ratio of silicate melts. This parameterisation is applied to more than 1600 geochemical data of silicate magmas from various alkaline provinces (East African Rift, Canary and Cape Verde Islands) and show that REE concentrations of their potential coeval carbonatite melts can reach concentration ranges similar to those of highly REE enriched carbonatites (?REE?>?30 000?ppm) by immiscibility with phonolitic/phono-trachytic melt compositions, while more primitive alkaline magmas can only be immiscible with carbonatites that are not significantly enriched in REE.
DS202102-0207
2021
Le Trong, E.Massuyeau, M., Gardes, E., Rogerie, G., Aulbach, S., Tappe, S., Le Trong, E., Sifre, D., Gaillard, F.MAGLAB: A computing platform connecting geophysical signatures to melting processes in Earth's mantle.Physics of the Earth and Planetary Interiors, doi.org/10.1016/ j.pepi.2020.106638 51p. PdfMantlegeophysics - magnetics

Abstract: Decompression melting of the upper mantle produces magmas and volcanism at the Earth's surface. Experimental petrology demonstrates that the presence of CO2 and H2O enhances peridotite melting anywhere within the upper mantle down to approximately 200-300?km depth. The presence of mantle melts with compositions ranging from carbonate-rich to silicate-rich unavoidably affects the geophysical signals retrieved from Earth's mantle. Geochemical investigations of erupted intraplate magmas along with geophysical surveys allow for constraining the nature and volume of primary melts, and a sound formalism is required to integrate these diverse datasets into a realistic model for the upper mantle including melting processes. Here, we introduce MAGLAB, a model developed to calculate the composition and volume fraction of melts in the upper mantle, together with the corresponding electrical conductivity of partially molten mantle peridotites at realistic pressure-temperature conditions and volatile contents. We use MAGLAB to show how the compositions of intraplate magmas relate to variations in lithosphere thickness. Progressive partial melting of a homogeneous peridotitic mantle source can in theory create the diversity of compositions observed among the spectrum of intraplate magma types, with kimberlite melts beneath thick continental shields, alkaline magmas such as melilitite, nephelinite and basanite beneath thinner continents and relatively old plus thick oceanic lithospheres, and ‘regular’ basalts beneath the youngest and thinnest oceanic lithospheres as well as beneath significantly thinned continental lithospheres. MAGLAB calculations support recent experimental findings about the role of H2O in the upper mantle on producing primary kimberlitic melts in addition to CO2. We demonstrate the robustness of MAGLAB calculations by reproducing the compositions of erupted melts as well as associated mantle electrical conductivities beneath the Society hotspot in the Pacific Ocean. A comparison of our simulations with magnetotelluric surveys at various oceanic settings shows that the heterogeneities in electrical conductivity of Earth's upper mantle are related to variations in volatile content via the presence of small (generally <<1?wt%) and heterogeneously distributed fractions of CO2-H2O-bearing melts.
DS2000-0393
2000
Le Turdu, C.Hautot, S., tarits, P., Le Turdu, C.Deep structure of the Baringo Rift Basin from three dimensional magnetotelluric imaging: rift evolution.Journal of Geophysical Research, Vol. 105, No.B 10, Oct.10, pp.23493-518.KenyaGeophysics - magnetotellurics, Tectonics - rifting
DS201702-0223
2017
Le Voyer, M.Le Voyer, M.Deep mantle chemistry surprise: carbon content not uniform.Nature Communications, Jan. 13, 1p.MantleDiamond inclusions
DS201912-2788
2020
Le Voyer, M.Hauri, E.H., Cottrell, E., Kelley, K.A., Tucker, J.M., Shimizu, K., Le Voyer, M., Marske, J., Sall, A.E.Carbon in the convecting mantle. IN: Deep carbon: past to present, Orcutt, Daniel, Dasgupta eds., pp. 237-275.Mantlecarbon

Abstract: This chapter provides a summary of the flux of carbon through various oceanic volcanic centers such as mid-ocean ridges and intraplate settings, as well as what these fluxes indicate about the carbon content of the mantle. By reviewing methods used to measure the carbon geochemistry of basalts and then to estimate fluxes, the chapter provides insight into how mantle melting and melt extraction processes are estimated. The chapter discusses how the flux of carbon compares with other incompatible trace elements and gases. From there, the chapter discusses whether the budget of carbon in the ocean mantle can be explained by primordial carbon or whether carbon recycling is required to balance the budget.
DS1992-0262
1992
Lea, P.D.Clark, P.U., Lea, P.D.The last interglacial transition in North AmericaGeological Society of America Special Paper, No. 270, 320pUnited States, CanadaGeomorphology, glacial, Table of contents
DS1991-0966
1991
Leach, D.Leach, D.Application of fluid inclusions to minerals explorationExplore, No. 72, July pp. 12, 14, 15GlobalGeochemistry, Fluid inclusion -application
DS1970-0338
1971
Leadbeater, P.W.Leadbeater, P.W.Diamonds from SeawaterAustralian Gemologist., Vol. 11, No. 3, PP. 8-10.GlobalDiamond Genesis
DS1988-0411
1988
Leader-Williams, N.Leader-Williams, N., Albon, S.D.Allocation of resources for conservationNature, Vol. 336, Dec. 8, pp. 533-535. Database # 17545GlobalEnvironmental issue, Economics
DS1998-0839
1998
Leading EdgeLeading EdgeSpecial section on Gravity and MagneticsThe Leading Edge, Vol. 17, No. 1, Jan. pp. 41-117GlobalBook - table of contents, Geophysics - gravity and magnetics
DS1997-0657
1997
Leadville Herald DemocratLeadville Herald DemocratDiamond exhibit debuts at National Mining Hall of Fame. a new exhibit features Kelsey Lake diamonds.Leadville Herald Democrat, May 8, 1p.ColoradoNews item, Redaurum Limited
DS2001-0980
2001
LeahyRitzwoller, M.H., Shapiro, N.M., Levshin, LeahyCrustal and upper mantle structure beneath Antarctica and surrounding oceansJournal of Geophysical Research, Vol. 106, No. 12, pp. 30,645-70.AntarcticaTectonics
DS1960-0791
1967
Leahy, E.J.Bennett, G., Brown, D.D., George, P.T., Leahy, E.J.Operation KapuskasingOntario Department of Mines M.P., No. 10, 72P.Canada, Ontario, James Bay LowlandsTectonics, Rift Structure, Geomorphology
DS200512-0606
2005
Leahy, G.M.Leahy, G.M., Bercovici, D.The influence of the transition zone water filter on convective circulation in the mantle.Geophysical Research Letters, Vol. 31, 23, Dec. 16, DOI 10.1029/2004 GLO21206MantleConvection, water
DS200712-0606
2007
Leahy, G.M.Leahy, G.M., Bercovici, D.On the dynamics of a hydrous melt layer above the transition zone.Journal of Geophysical Research, Vol. 112, B7, B07401.MantleMelting
DS200912-0430
2009
Leahy, G.M.Leahy, G.M.Local variability in the 410 km mantle discontinuity under a hotspot.Earth and Planetary Science Letters, Vol. 288, 1-2, pp. 158-163.MantlePlume
DS201012-0427
2010
Leahy, G.M.Leahy, G.M., Bercovici, D.Reactive infiltration of hydrous melt above the mantle transition zone.Journal of Geophysical Research, Vol. 115, B8, B08406.MantleMelting
DS1993-1138
1993
Leahy, K.Nixon, P.H., Gummer, P.K., Halabura, S., Leahy, K., Finlay, S.Kimberlites of volcanic facies in the Sturgeon Lake areaRussian Geology and Geophysics, Vol. 34, No. 12, pp. 66-76.SaskatchewanVolcanic facies
DS1994-1282
1994
Leahy, K.Nixon, P.H., Leahy, K.Preserved diamond bearing volcanic superstructures of kimberlite pipes inSaskatchewan.Preprint from author, 8p.SaskatchewanKimberlite, Diamond genesis
DS1995-1073
1995
Leahy, K.Leahy, K., Taylor, W.R.The influence of the deep structure of the Glennie Domain on the Diamonds in Saskatchewan kimberlites.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 314-316.Saskatchewan, ColoradoTectonics, Deposit -Falc, Sloan
DS1996-0820
1996
Leahy, K.Leahy, K.The geology of kimberlites from the Fort a la Corne area, SaskatchewanPh. D., University of Leeds, 468p.SaskatchewanGeology, Deposit - Fort a la Corne area
DS1997-0658
1997
Leahy, K.Leahy, K.Discrimination of reworked pyroclastics from primary tephra fall tuffs: acase study using kimberlites....Bulletin. Volcanology, Vol. 59, pp. 65-71.SaskatchewanVolcanics, pyroclastics, Deposit - Fort a la Corne
DS1997-0659
1997
Leahy, K.Leahy, K., Taylor, W.R.The influence of the Glennie Domain deep structure on the diamonds inSaskatchewan.Russian Geology and Geophysics, Vol. 38, No. 2, pp. 481-491.SaskatchewanTeconics, structure, Glennie Domain
DS1998-1188
1998
Leahy, K.Pretorius, W., Leahy, K.Implications for diamond prospectivity from comparisons of diamond bearing lithosphere in two Proterozoic belts7th. Kimberlite Conference abstract, pp. 713-15.South Africa, Manitoba, northwest Territories, WyomingOrogeny - Limpopo, Glennie, Trans Hudson, Lithospheric composition, comparison
DS2001-0665
2001
Leahy, K.Leahy, K.Equatorial GuineaMining Annual Review, 3p.GuineaCountry - overview, economics, mining, Overview - brief
DS2001-0666
2001
Leahy, K.Leahy, K.Post eruptive processes in kimberlites - implications for diamond exploration.Transactions of the Institute of Mining and Metallurgy (IMM)., Vol. 110, pp. B1-4.SaskatchewanDiamond genesis, Exploration, discoveries, Fort a la Corne
DS2002-0929
2002
Leahy, M.Leahy, M.James Bay Lowlands; natures everchanging frontiersNorthern Impressions, Winter, pp. 20-23.Ontario, James Bay LowlandsHistory - pictoral
DS1990-0909
1990
Leake, B.E.Leake, B.E.Granite magmas: their sources, initiation and consequences of SOURCE[ Journal of the Geological Society of LondonJournal of the Geological Society of London, Vol. 147, pt. 4, July pp. 579-589GlobalGranite magmas, Review
DS1995-1074
1995
Leake, B.E.Leake, B.E., Farrow, C.M., Townend, R.Potassium poor titanium fluor richterite from near Nullagine Western Australia.American Mineralogist, Vol. 80, pp. 162-4.AustraliaBasalt
DS2001-0785
2001
Leake, B.E.Mogessie, A., Ettinger, K., Leake, B.E., Tessardi, R.AMPH-IMA97: a hypercard program to determine the name of an amphibole from electron microprobe...Comp. and Geosci., Vol. 27, No. 10, Dec. pp. 1169-78.GlobalMineralogy - amphiboles. wet chemical analyses, Computer - AMPH-IMA97
DS1995-1075
1995
Leake, R.C.Leake, R.C., Cornwell, J.D., Rollin, K.E., Styles, M.T.The potential for diamonds in BritainBritish Geological Survey Tech. Report, MRP No. 135, WF/95/1, 37p.GlobalGeology, Diamond potential
DS1994-1005
1994
Leal, C.Leal, C.Multivariate tool in process controlAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, Meeting held Albuquerque Feb. 14-17th, No. 94-86, 8pGlobalGeostatistics, Multivariate
DS201809-2055
2018
Leal, R.E.Leal, R.E., Lafon, J.M., da Ros Costa, L.T., Dantas, E.L.Orosirian magmatic episodes in the erepercuru-trombetas domain ( southeastern Guyana shield: implications for the crustal evolution of the Amazonian craton.South American Earth Sciences, Vol. 85, pp. 278-297.South America, Guyanacraton - Amazonian
DS1994-1006
1994
Leaman, D.E.Leaman, D.E., Baillie, P.W., Powell, McA.Precambrian Tasmania: a thin skinned devilExploration Geophysics, Australian Bulletin, Vol. 25, No. 1, March pp. 19-24TasmaniaGeophysics, Tectonics, Precambrian
DS2003-0778
2003
Leaman, D.E.Leaman, D.E.Discussion and reply: Shaping the Australian crust over the last 300 million years:Australian Journal of Earth Sciences, Vol. 50, pp. 645-50.AustraliaGeochronology, Gondwana, Tectonics
DS200412-1094
2003
Leaman, D.E.Leaman, D.E.Discussion and reply: Shaping the Australian crust over the last 300 million years: insights from fission track thermotectonic iAustralian Journal of Earth Sciences, Vol. 50, pp. 645-50.AustraliaGeochronology, Gondwana, Tectonics
DS1989-0863
1989
Leanloz, R.Leanloz, R.Phase transitions in the mantleNature, Vol. 340, No. 6230, July 20, p. 184GlobalMantle
DS202106-0953
2021
Leao-Santos, M.Li, Y., Sun, J., Shuling, L., Leao-Santos, M.A paradigm shift in magnetic data interpretation; increased value through magnetization inversions.Geophysics Leading Edge, Vol. 40, 2, pp. 89-98.Canada, South America, Brazilgeophysics

Abstract: Magnetic data are sensitive to both the induced magnetization in rock units caused by the present earth's magnetic field and the remanent magnetization acquired by rock units in past geologic time. Susceptibility is a direct indicator of the magnetic mineral content, whereas remanent magnetization carries information about the formation process and subsequent structural movement of geologic units. The ability to recover and use total magnetization, defined as the vectorial sum of the induced and remanent magnetization, therefore enables us to take full advantage of magnetic data. The exploration geophysics community has achieved significant advances in inverting magnetic data affected by remanent magnetization. It is now feasible to invert any magnetic data set for total magnetization. We provide an overview of the state of the art in magnetization inversion and demonstrate the informational value of inverted magnetization through a set of case studies from mineral exploration problems. We focus on the methods that recover either the magnitude of the total magnetization or the total magnetization vector itself.
DS1994-1007
1994
Lear, G.Lear, G.A comparison of two methods to assess diamond potential using major and trace element heavy mineral concentrate #2Msc. Thesis, University Of Tasmania, South Africa, Russia, YakutiaGlobalGeothermometry, Nickel thermometry
DS1994-1008
1994
Lear, G.M.Lear, G.M.A comparison of two methods to assess diamond potential using major and trace element analysis garnets. #1University of Tasmania, MSc. thesisSouth Africa, Russia, YakutiaGeochemistry eglogites, peridotites garnets, Thesis
DS1997-0660
1997
Learmont, R.D.Learmont, R.D.Mining must show that it is sustainableMining Engineering, Vol. 49, No. 1, Jan. pp. 11-13United StatesMining, Legal - tax
DS1998-1238
1998
LeatRiley, T.R., Pankhurst, Leat, Storey, FanningTime relationships of pre-breakup Gondwana magmatismJournal of African Earth Sciences, Vol. 27, 1A, p. 160. AbstractGondwanaMagmatism
DS1987-0492
1987
Leat, P.T.Morrison, M.A., Hendry, G.L., Leat, P.T.Regional and tectonic implications of parallel Caledonian and Permo Carboniferous lamprophyre dyke swarms from Lismore, ArdgourTransactions Royal Society. Edinburgh, Vol. 77, pp. 279-288ScotlandDyke, Shoshonite
DS1988-0412
1988
Leat, P.T.Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L., DickinSilicic magmas derived by fractional crystallizationfromMioceneminette, Elkhead Mountains, ColoradoMineralogical Magazine, Vol. 52, No. 368, pt. 5, December pp. 577-586ColoradoMinette
DS1988-0413
1988
Leat, P.T.Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L., DickinCompositionally -diverse Miocene -Recent rift related magmatism inJournal of Petrology, Special Volume 1988- Oceanic and Continental, pp. 351-377ColoradoTectonics, Rift
DS1989-0864
1989
Leat, P.T.Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L., DickinIdentification of magma sources in continental maficmagmatism: the Rio Grande RiftNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 160. AbstractColorado PlateauTectonics
DS1990-1459
1990
Leat, P.T.Thompson, R.N., Leat, P.T., Dickin, A.P., Morrison, M.A., HendryStrongly potassic mafic magmas from lithospheric mantle sources duringEarth and Planetary Science Letters, Vol. 98, pp. 139-153ColoradoMinettes, Chemistry
DS1991-0572
1991
Leat, P.T.Gibson, S.A., Thompson, R.N., Leat, P.T., Morrison, M.A., HendryUltrapotassic magmas along the flanks of the oligo-miocene Rio Grande @Proceedings of Fifth International Kimberlite Conference held Araxa June, pp. 133-135Colorado PlateauTectonics, Kimberlites, minettes
DS1991-0967
1991
Leat, P.T.Leat, P.T., Thompson, R.N., Morrison, M.A., Hendry, G.L., DickinAlkaline hybrid mafic magmas of the Yampa area, northwest Colorado, and their relationship to the Yellowstone mantle plume and lithospheric mantle domainsContributions to Mineralogy and Petrology, Vol. 107, No. 3, pp. 310-327ColoradoAlkaline rocks, Mantle plumes
DS1991-1725
1991
Leat, P.T.Thompson, R.N., Gibson, S.A., Leat, P.T.Overt and cryptic strongly potassic mafic liquids in the Neogene magmatism of the n.part of the Rio Grande Rift, USA: a lithospheric drip feed into asthenospheric soProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 420-422Arizona, Colorado PlateauPotassic lavas, basalts, Minette, Lamproite, Elkhead Mts.Leucite Hills
DS1992-0565
1992
Leat, P.T.Gibson, S.A., Thompson, R.N., Leat, P.T., Dickin, A.P., MorrisonAsthenosphere-derived magmatism in the Rio Grande rift, westerm USA:implications for continental break upGeological Society Special Publication Magmatism and the causes of the continental, No. 68, pp. 61-89Cordillera, Arizona, New MexicoTectonics, Rifting
DS1993-0541
1993
Leat, P.T.Gibson, S.A., Thompson, R.N., Leat, P.T., Morrison, M.A., HendryUltrapotassic magmas along the flanks of the Oligo-Miocene Rio GrandeJournal of Petrology, Vol. 34, No. 1, February pp. 187-228Mantle, Colorado PlateauUltrapotassic, Tectonics
DS1997-1152
1997
Leat, P.T.Thompson, R.N., Velde, D., Leat, P.T., Morrison, MitchellOligocene lamproite containing an Aluminum poor, Titanium rich biotite, Middle Park, northwest Colorado, USAMineralogical Magazine, No. 407, August pp. 557-572.ColoradoLamproite, Deposit - Middle Park area
DS1998-0833
1998
Leat, P.T.Larter, R.D., King, E.C., Leat, P.T., Reading, SmellieSouth Sandwich slices reveal much about arc structure, geodynamics andcomposition.Eos, Vol. 79, No. 24, June 16, p. 281, 284-5.GlobalGeodynamics - not specific to diamonds, Arc structure
DS1999-0718
1999
Leat, P.T.Storey, B.C., Leat, P.T., Kelley, S.Mantle plumes and Antartica New Zealand rifting: evidence from Mid Cretaceous mafic dykes.Journal of Geological Society of London, Vol. 156, No. 4, July 1, pp; 659-72.GlobalPlumes, Dikes
DS2001-1135
2001
Leat, P.T.Storey, B.C., Leat, P.T., Ferris, J.K.The location of mantle plume centers during the initial stages of Gondwana breakupGeological Society of America, Special Paper, Special Paper. 352, pp. 71-80.MantleRifting, tectonics, Gondwana, Plumes
DS2002-1340
2002
Leat, P.T.Riley, T.R., Leat, P.T.Ultramafic lamprophyres of the Ferrar large igneous province: evidence for a HIMU mantle component.18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.250,1.Antarctica, Pensacola MountainsLamprophyres
DS2003-1165
2003
Leat, P.T.Riley, T.R., Leat, P.T., Storey, B.C., Parkinson, H., Millar, H.Ultramafic lamprophyres of the Ferrar large igneous province: evidence for a HIMULithos, Vol. 66, 1-2, pp. 63-76.Mantle, AntarcticaUHP - ultrahigh pressure
DS2003-1166
2003
Leat, P.T.Riley, T.R., Leat, P.T., Storey, B.C., Parkinson, I.J., Millar, I.L.Ultramafic lamprophyres of the Ferrar large igneous province: evidence for a HIMULithos, Vol. 66, 1-2, Jan. pp.63-76.GreenlandBlank
DS2003-1167
2003
Leat, P.T.Riley, T.R., Leat, P.T., Storeym B.C., Parkinson, I.J., Millar, I.L.Ultramafic lamprohyres of the Ferrar large igneous province: evidence for HIMULithos, Vol. 66, 3-4, January, pp. 63-76.AntarcticaDykes, Geochronology
DS200412-1669
2003
Leat, P.T.Riley, T.R., Leat, P.T., Storey, B.C., Parkinson, I.J., Millar, I.L.Ultramafic lamprophyres of the Ferrar large igneous province: evidence for a HIMU mantle component.Lithos, Vol. 66, 1-2, Jan. pp.63-76.Europe, GreenlandLamprophyre
DS200412-1670
2003
Leat, P.T.Riley, T.R., Leat, P.T., Storey, B.C., Parkinson, I.J., Millar, I.L.Ultramafic lamprohyres of the Ferrar large igneous province: evidence for HIMU mantle component.Lithos, Vol. 66, 3-4, January, pp. 63-76.AntarcticaDykes Geochronology
DS200512-1084
2005
Leat, P.T.Thompson, R.N., Ottley, C.J., Smith, P.M., Pearson, D.G., Dickin, A.P., Morrison, M.A., Leat, P.T., Gibson, S.A.Source of the Quaternary alkalic basalts, picrites and basanites of the Potrillo volcanic field, New Mexico, USA: lithosphere or convecting mantle?Journal of Petrology, Vol. 46, 8, pp. 1603-1643.United States, New Mexico, Colorado PlateauConvection
DS200512-1085
2005
Leat, P.T.Thompson, R.N., Ottley, C.J., Smith, P.M., Pearson, D.G., Dickin, A.P., Morrison, M.A., Leat, P.T., Gibson, S.A.Source of the Quaternary alkaline basalts, picrites and basanites of the Potrillo volcanic field, New Mexico, USA: lithosphere or convecting mantle?Journal of Petrology, Vol. 46, 8, pp. 1603-1643.United States, New Mexico, Colorado PlateauPicrite, basanites
DS202004-0515
2020
Leat, P.T.Gibson, S.A., Rooks, E.E., Day, J.A., Petrone, C.M., Leat, P.T.The role of sub-continental mantle as both "sink" and "source" in deep Earth volatile cycles.Geochimica et Cosmochimica Acta, Vol. 275, pp. 140-162.Mantlecraton

Abstract: The extent to which Earth’s sub-continental lithospheric mantle modulates the flux of volatile elements from our planet’s deep interior to its atmosphere (via volcanism) is poorly constrained. Here, we focus on "off-craton" sub-continental lithospheric mantle because this long-lived reservoir potentially acts as both a volatile “sink” and “source” during major heating and rifting events. The sub-continental lithospheric mantle is primarily formed of peridotites with subordinate amounts of pyroxenites. While both lithologies are dominated by nominally-volatile-free mantle minerals, some of these phases have been shown to contain non-negligible amounts of H2O (e.g. 100’s of ppmw in clinopyroxene). Data for volatile elements other than Li are, however, limited. We present new, high-precision, in-situ Secondary Ion Mass Spectrometry analyses of H, F, Cl, Li and B in olivine and pyroxenes from well-characterised garnet- and spinel-bearing peridotites and pyroxenites (from southern Patagonia and the Antarctic Peninsula). Our study confirms that clinopyroxene is the main host of H2O and F. The maximum F contents we report (up to 154 ppmw) are higher than those in previous studies and occur in Ti-Cr diopsides in highly-metasomatised peridotites and Ti-Al augites from clinopyroxenite veins. Water contents of clinopyroxenes (up to 615 ppmw) are within the range previously published for continental mantle. Lithium concentrations are low (<5 ppmw) in all analysed phases and both Cl and B are below detection levels (14 ppmw and 0.03 ppmw, respectively). Unique to our study is the large variation in major- and trace-element concentrations of the clinopyroxenes, which allows us to place quantitative constraints on how volatiles are stored in the mantle. We demonstrate that: (i) F contents of clinopyroxenes closely correlate with Ti and (ii) and is systematic and inversely correlated with temperature. Despite the redistribution of volatiles during sub-solidus re-equilibration, we show that the first order control on the concentration of volatiles in clinopyroxene is the style of metasomatism, i.e. channellised flow versus reactive percolation. The mean bulk volatile contents of peridotites from Pali Aike and the Antarctic Peninsula (H2O?=?89?±?31 ppmw, F?=?16?±?11.2 ppmw and Li?=?2?±?0.7 ppmw) are within the range previously published for continental "off-craton" mantle. The pyroxenites have significantly higher mean bulk concentrations of H2O (260?±?59 ppmw), F (86?±?43 ppmw) and Li (1.0?±?0.35 ppmw). While the greater capacity of mantle pyroxenites to host H2O relative to the associated peridotites has previously been observed in global "off-craton" mantle xenolith suites (e.g. Oahu, Hawaii; eastern China and the Rio Grande Rift, SW USA), here we show for the first time that pyroxenites are also major hosts of F (but not Cl, Li or B). Because of their relatively low solidus temperatures, pyroxenites in "off-craton" settings will be readily re-mobilised during lithospheric extension (and heating). We suggest these pyroxene-rich mantle lithologies may be responsible for the elevated concentrations of H2O and F observed in basalts and volcanic gasses from major continental rift zones and flood basalt provinces, and hence an important consideration in models of global volatile cycles.
DS2002-0170
2002
Leaver, M.Bloom, L., Leaver, M.Using the correct control limits. Certified Reference MaterialsExplore, No. 115, April, pp. 3,4.GlobalGeochemistry - CRM
DS2002-0728
2002
LeBasHoenle, K., Tilton, G., LeBas, Duggen, GarbeSchonbergGeochemistry of oceanic carbonatites compared with continental carbonatites; mantle recycling of oceanic..Contribution to Mineralogy and Petrology, Vol.142, 5, pp.520-42.Mantle, OceanicCarbonatite - recycling crustal carbonate
DS1986-0488
1986
Lebas, M.J.Lebas, M.J.Diversification of carbonatite #1Geological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 94. (abstract.)GlobalCarbonatite
DS1987-0402
1987
Lebas, M.J.Lebas, M.J.Ultra-alkaline magmatism with or without riftingTectonophysics, Vol. 143, No. 1-3, November 15, pp. 75-84GlobalBlank
DS1987-0403
1987
Lebas, M.J.Lebas, M.J., Mian, I., Rex, D.C.Age and nature of carbonatite emplacement in North PakistanGeologische Rundschau, Vol. 76, No. 2, pp. 317-324PakistanCarbonatite
DS1992-0924
1992
LeBas, M.J.LeBas, M.J., Keller, J., Kejie, Tao, Wall, F., Williams, C.T., Zhang PeishanCarbonatite dykes at Bayan Obo, Inner Mongolia, ChinaMineralogy and Petrology, Vol. 46, No. 3, pp. 195-228ChinaCarbonatite, Deposit -Bayan Obo
DS1992-0925
1992
LeBas, M.J.LeBas, M.J., Le Maitre, R.W., Wooley, A.R.The construction of the total alkali-silica chemical classification of volcanic rocksMineralogy and Petrology, Vol. 46, No. 1, pp. 1-22GlobalClassification, alkaline, silicates, Volcanics -Alkali-silica
DS2001-0144
2001
LeBas, M.J.Buhn, B., Wall, F., LeBas, M.J.Rare element systematics of carbonatitic fluorapatites and their significance for carbonatite magma evolutionContributions to Mineralogy and Petrology, Vol. 141, No., 5, pp. 572-91.NamibiaCarbonatite - rare earth elements (REE).
DS200712-0607
2007
LeBas, M.J.LeBas, M.J., Xueming, Y., Taylor, R.N., Spior, B., Milton, J.A., Peishan, Z.New evidence from a calcite dolomite carbonatite dyke for the magmatic origin of the massive Bayan Obo ore bearing dolomite marble, Inner Mongolia China.Mineralogy and Petrology, Vol. 91, 3-4, pp. 287-China, MongoliaCarbonatite
DS1995-1870
1995
Lebed, N.I.Tarasyuk, O.N., Chashka, A.I., Smirnov, G.I., Lebed, N.I.Prospects of the Ukraine Territory diamondiferousnessProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 606-607.UKraineDiamond morphology, Deposit -Priazovski region
DS1930-0169
1934
Lebedeff, V.Lebedeff, V., Choubert, B.Les Terrasses du Moyen Congo Composition Mineralogique Dur Gravrir.Chronique de Mines, No. 28, PP. 218-222.Democratic Republic of Congo, Central AfricaStratigraphy, Heavy Minerals Concentrations
DS1930-0170
1934
Lebedeff, V.Lebedeff, V., Choubert, B.Etude de Quelques Concentris D'alluvions Modernes de L' AefSoc. Min. (france) Bulletin., PP. 244-248.West Africa, French Equatorial Africa, Central African RepublicAlluvial, Diamond, Heavy Minerals Concentrations
DS201807-1506
2018
Lebedev, A.Lebedev, A., Rodel, A.Application of dynamic simulation for the Gahcho Kue project. GPSS, LIMNSAIMM Diamonds - source to use 2018 Conference 'thriving in changing times'. June 11-13., pp. 259-284.Canada, Northwest Territoriesdeposit - Gahcho Kue
DS1960-0065
1960
Lebedev, A.A.Lebedev, A.A.Contribution to the Problem of Serpentinization of Kimberlites.Zap. Vses. Miner. Obshch., No. 2.RussiaBlank
DS1960-0262
1962
Lebedev, A.A.Lebedev, A.A.On the Hydrothermal Stage of Serpentinization of Kimberlites in Connection with the Discovery of Jarosite in Them.Akad. Nauk Sssr Fr. Yakut. Fil., No. 8.RussiaBlank
DS1960-0263
1962
Lebedev, A.A.Lebedev, A.A.The Hydrothermal Stage of Serpentinization of Kimberlites In Connection with a Find of Brucite in Them.Akad. Nauk Sssr Fr. Yakut. Fil., No. 8.RussiaBlank
DS1960-0264
1962
Lebedev, A.A.Lebedev, A.A.On the Composition of the Kimberlite-like Rocks of the Aldan Region.Mater. Geol. Polezn. Isk. Yakut., No. 9.RussiaBlank
DS1960-0356
1963
Lebedev, A.A.Ilupin, I.P., Lebedev, A.A.Subvolcanic Kimberlite Facies and the Formation of the Kelyphite Rim in Garnets.Sovetsk. Geol., No. L.RussiaBlank
DS1960-0366
1963
Lebedev, A.A.Lebedev, A.A.The Alkalinity and Differentiation of a Kimberlitic MagmaAkad. Nauk Sssr Sib. Div. Yakut. Branch, Ser. Geol., No. 9.RussiaBlank
DS1960-0367
1963
Lebedev, A.A.Lebedev, A.A., Smirnov, G.I.Serpentinization in KimberlitesIn: Geology of Diamond Deposits. Akad. Nauk Sssr., No. 9, PP. 103-205.RussiaBlank
DS1960-0470
1964
Lebedev, A.A.Lebedev, A.A.Serpentinization of Kimberlite Rocks of Yakutia and Some Problems of Their Genesis.Thesis, Yakutsk., RussiaKimberlite, Genesis
DS1960-0471
1964
Lebedev, A.A.Lebedev, A.A.Kimberlites of North Eastern USSR and their ProblemsLiverpool Geol. Journal, Vol. 4, PP. 87-L04.RussiaBlank
DS1950-0333
1957
Lebedev, A.P.Lebedev, A.P.Some Problems of the Petrology of the Diamond Bearing Rocks in the U.s.s.r.Geologii i Geofiziki, No. 11, 7P. ENG. TRANSL.Russia, SiberiaHistory, Prospecting, Petrography
DS2003-0779
2003
Lebedev, S.Lebedev, S., Chevrot, S., Van der Hilst, R.D.Correlation between shear speed structure and thickness of the mantle transition zonePhysics of the Earth and Planetary Interiors, Vol. 136, 1-2, pp. 25-40.MantleBlank
DS2003-0780
2003
Lebedev, S.Lebedev, S., Nolet, G.Upper mantle beneath SouthEast Asia from S velocity tomographyJournal of Geophysical Research, Vol. 08, 2, 10.1029/2001JB000073MantleGeophysics - seismics
DS200412-1095
2003
Lebedev, S.Lebedev, S., Chevrot, S.,Van der Hilst, R.D.Correlation between shear speed structure and thickness of the mantle transition zone.Physics of the Earth and Planetary Interiors, Vol. 136, 1-2, pp. 25-40.MantleGeophysics - seismics
DS200412-1096
2003
Lebedev, S.Lebedev, S., Nolet, G.Upper mantle beneath SouthEast Asia from S velocity tomography.Journal of Geophysical Research, Vol. 08, 2, 10.1029/2001 JB000073MantleGeophysics - seismics
DS200812-1214
2008
Lebedev, S.Visser, K., Trampert, J., Lebedev, S., Kennett, B.L.N.Probability of radial anisotropy in the deep mantle.Earth and Planetary Science Letters, Vol. 270, 3-4, pp. 241-250.MantleAnisotropy
DS200912-0150
2009
Lebedev, S.Darbyshire, F., Lebedev, S.Rayleigh wave velocity heterogeneity and multilayered azimuthal anisotropy of the Superior Craton, Ontario.Geophysical Journal International, Vol.176, 1, pp. 215-234.Canada, OntarioGeophysics
DS201112-0062
2011
Lebedev, S.Bartzsch, S., Lebedev, S., Meier, T.Resolving the lithosphere-asthenosphere boundary with seismic Rayleigh waves.Geophysical Journal International, In press,MantleGeophysics - seismics
DS201212-0543
2012
Lebedev, S.Pawlak, A., Eaton, D.w.,Darbyshire, F., Lebedev, S., Bastow, I.D.Crustal anisotropy beneath Hudson Bay from ambient noise tomography: evidence for post-orogenic lower crustal flow?Journal of Geophysical Research, in preparationCanada, Ontario, QuebecGeophysics - seismics
DS201212-0544
2012
Lebedev, S.Pawlak, A., Eaton, D.W., Darbyshire, F., Lebedev, S., Bastow, I.D.Crustal anisotropy beneath Hudson Bay from ambient noise tomography: evidence for post-orogenic lower crustal flow?Journal of Geophysical Research, Vol. 117, B8 B08301Canada, Ontario, QuebecTomography
DS201312-0529
2013
Lebedev, S.Lebedev, S., Adam, J.M-C., Meier, T.Mapping the Moho with seismic surface waves: a review, resolution analysis and recommended inversion strategies.Tectonophysics, Vol. 609, pp. 377-394.MantleMohorovic discontinuity
DS201312-0915
2013
Lebedev, S.Tirel, C., Brun, J-P, Burov, E., Wortel, M.J.R., Lebedev, S.A plate tectonics oddity: caterpillar walk exhumation of subducted continental crust.Geology, Vol. 41, 5, pp. 555-558.MantleSubduction
DS201412-0776
2014
Lebedev, S.Schaeffer, A.J., Lebedev, S.Imaging the North American continent using waveform inversion of global and USArray data.Earth and Planetary Science Letters, Vol. 402, pp. 26-41.United StatesGeophysics - seismics
DS201412-0864
2013
Lebedev, S.Sodoudi, F., Yuan, X., Kind, R., Lebedev, S., Adam, J., et al.Seismic evidence for stratification in composition and anisotropic fabric within the thick lithosphere of Kalahari craton.Geochemistry, Geophysics, Geosystems: G3, Vol. 14, 12, pp. 5393-5412.Africa, South AfricaGeophysics - seismics
DS201808-1783
2018
Lebedev, S.Ravenna, M., Lebedev, S., Fullea, J., Adam, J.Shear wave velocity structure of Southern Africa's lithosphere: variations in the thickness and composition of cratons and their effect on topography.Geochemistry, Geophysics, Geosystems, Vol. 19, 5, pp. 1499-1518.Africa, South Africacraton

Abstract: Cratons, the ancient cores of continents, have an unusually thick lithosphere (the tectonic plate beneath them). At least ?200 km thick, it has a highly anomalous composition, making it less dense than the surrounding mantle. Cratonic lithosphere can thus be cooled to much lower temperatures than elsewhere. Variations in this delicate buoyancy balance probably give rise to variations in the surface elevation across the Earth's stable continents. Lithospheric thickness and composition are key parameters, but both are notoriously difficult to determine. Here we use very accurate measurements of seismic surface?wave velocities and determine deep structure beneath cratons in southern Africa. We discover an unexpectedly strong, gradual thickening of the lithosphere from the central Kaapvaal Craton to the neighboring Limpopo Belt (from 200 to 300 km thick). Curiously, surface elevation decreases monotonically with increasing lithospheric thickness. This demonstrates the effect of the deep lithosphere on topography and gives us new information on the composition of the deepest parts of lithosphere.
DS1990-0792
1990
Lebedev, Ye.B.Kadik, A.A., Dorfman, A.M., Bagdasarov, N.Sh., Lebedev, Ye.B.Influence of pyroxenes on the melt distribution in the intergranular spacein a peridotiteGeochemical Int, Vol. 27, No. 3, pp. 131-134RussiaPyroxenes, Mantle melt
DS1987-0043
1987
Lebedeva, E.V.Belkanova, N.P., Eroshechev-Shak, V.A., Lebedeva, E.V., KaravaikoDissolution of kimberlite minerals by heterotrophusmicroorganisms.(Russian)Mikrobiologiya, (Russian), Vol. 56, No. 4, pp. 613-620RussiaBacterial breakdown
DS1989-1228
1989
Lebedeva, E.V.Platonova, N.P., Eroshchek-Shak, V.A., Lebedeva, E.V., KaravaikoThe formation of a mixed layer serpentine smectite structure in kimberlite under the effects of thiobacillus thiooxidans.(Russian)Mikrobiologica, (Russian), Vol. 58, No. 2, pp. 271-275RussiaKimberlite, Serpentinization
DS1993-0896
1993
Lebedeva, I.O.Lebedeva, I.O., Nedoskova, I.L.About the aeschynitization of pyrochlore from carbonatites of Buldymskymassif. (Urals Vyshnevye Mountains).(Russian)Proceedings of the Russian Mineralogical Society, (Russian), No. 2, pp. 69-74.RussiaCarbonatite
DS1986-0489
1986
Lebedeva, L.I.Lebedeva, L.I.Evolution of kimberlite magmatism of the Mirinskoe field.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 286, No. 1, pp. 175-177RussiaBlank
DS1986-0490
1986
Lebedeva, L.I.Lebedeva, L.I.Evolution of kimberlitic magmatism at the Mir site.(Russian)Doklady Academy of Sciences Nauk SSR, (Russian), Vol. 286, No. 1, pp. 175-177RussiaBlank
DS1989-0865
1989
Lebedeva, L.I.Lebedeva, L.I., Ilupin, I.P.Thorium in kimberlites of the Siberian Platform*(in Russian)Protessy Kontsentrir. Toriya V Zem Kore M., (Russian), pp. 9-18RussiaKimberlite, Thorium
DS1990-0910
1990
Lebedeva, L.I.Lebedeva, L.I., Nekrasova, I. YA., Shishlov, V.A.Characteristics of the composition of pyrite from kimberlites and enclosing rocks in Yakutia diamond province.(Russian)Mineral. Zhurn., (Russian), Vol. 12, No. 2, pp. 19-29RussiaKimberlites, Pyrite
DS1996-0821
1996
Lebedeva, L.I.Lebedeva, L.I., Nekrasov, I.Ya., Nikishova, L.V.Petrology of kimberlites of the Siberian and East European platformsInternational Geological Congress 30th Session Beijing, Abstracts, Vol. 2, p. 383.Russia, Siberia, skPetrology, Kimberlites
DS201112-0107
2011
Lebedeva, M.Brantley, S.L., Lebedeva, M.Learning to read the chemistry of regolith to understand the critical zone.Annual Review of Earth and Planetary Sciences, Vol. 39, pp. 387-416.TechnologyRegolith - geochemistry
DS201705-0845
2017
Lebedeva, N.Lebedeva, N., Kargin, A., Sazonova, L., Nosova, A.Geochemistry of clinopyroxene megacrysts from the Grib kimberlite pipe, Arkhangelsk province, Russia: metasomatic origin and genetic relationship with clinopyroxene phlogopite metasomatic xenoliths.European Geosciences Union General Assembly 2017, Vienna April 23-28, 1p. 220 AbstractRussia, Archangel, Kola PeninsulaDeposit - Grib

Abstract: Kimberlite is a composite rock that contains juvenile magmatic material and xenoliths of crustal and mantle rocks, including metasomatically reworked rocks and megacrysts. In spite of nearly 40-50 years of continuous study of kimberlites and SCLM, some aspects of their origin remain controversial. In particular, it is unclear yet whether the megacrysts are magmatic or metasomatic in origin and how they are related to kimberlite magmas. In this contribution, we compare the major (EMPA) and trace element (SIMS, LA-ICP-MS) compositions of clinopyroxene megacrysts from the Grib kimberlite (Arkhangelsk province, Russia) with clinopyroxenes from metasomatic clinopyroxene-phlogopite xenoliths and garnet peridotite xenoliths. The Grib kimberlite (376±3 Ma, Larionova et al., 2016) is located in the central part of the Arkhangelsk province (the northern part of the East European craton) in the Chernoozero kimberlite field. The geochemical composition of the kimberlites is similar to widespread South Africa group I kimberlites . The Grib kimberlite is well known for hosting a variety of mantle xenoliths, e.g., garnet peridotite, sheared peridotite, eclogite, metasomatised mantle material, as well as megacrysts of clinopyroxene, garnet, olivine, phlogopite, and ilmenite. The clinopyroxene megacrysts occur as rounded or angular grains up to 2 cm in size. They are usually surrounded by ultrafine kimberlite rim. The xenoliths of the metasomatic clinopyroxene-phlogopite rocks reach up to 6 cm in size and have a granoblastic texture. They consist of clinopyroxene (55 vol. %), phlogopite (45 vol. %) and minor calcite, barite, perovskite. Some clinopyroxene grains contain inclusion of relict olivine that is similar in composition to olivine from mantle-derived peridotite xenoliths within the Grib kimberlite (Sazonova et al., 2015). This suggests that these xenoliths could be formed by metasomatic reworking of SCLM peridotites. The megacryst clinopyroxene is compositionally similar to the clinopyroxene found in metasomatic xenoliths and corresponds to diopside. As compared to the typical clinopyroxene megacrysts worldwide, it has higher Mg# (>0.92), Cr# (0.21-0.62) and Ca# values (0.47-0.49) and lower Ti (659-1966 ppm) composition. The clinopyroxenes have (La/Sm)CI values from 0.58 to 1.57, and trace element patterns with deep negative Ti and shallow negative Zr-Hf anomalies. The major and trace-element compositions of these clinopyroxenes are very close to those of clinopyroxenes from garnet peridotite xenoliths in the Grib pipe (Kargin et al., 2016) that could be formed during the ascent and interaction of kimberlite mamas with a surrounding lithospheric mantle after crystallization of garnet and ilmenite megacrysts. Calculations showed that metasomatic agents in equilibrium with clinopyroxene megacrysts are similar in composition to kimberlite, which is consistent with proposed model. To sum up, we suggest that the formation of clinopyroxenes of megacrysts and mantle-derived clinopyroxene-phlogopite metasomatic xenoliths from the Grib kimberlite was related to the late-stage metasomatic reworking of SCLM by kimberlite magmas.
DS202005-0746
2020
Lebedeva, N.Lebedeva, N., Nosova, A.A., Kargin, A., Sazonova, L.V.Multi-stage evolution of kimberlite melt as inferred from inclusions in garnet megacrysts in the Grib kimberlite ( Arkangelsk region, Russia.Mineralogy and Petrology, doi: 10.1007/s00710- 020-00704-0 in press 16p. PdfRussia, Arkangeldeposit - Grib

Abstract: To provide new insights into the origin of garnet megacrysts and evolution of kimberlite melts, we studied in detail the polymineralic and monomineralic inclusions and their host garnets from the Grib kimberlite (Arkhangelsk diamond province, Russia). Low-Cr and high-Cr garnet megacrysts and eclogitic garnets contain abundant polymineralic and rare monomineralic inclusions. Monomineralic inclusions presented by clinopyroxene, ilmenite, olivine replaced by serpentine, were found exclusively within the low-Cr megacrysts. The composition of clinopyroxene exhibits geochemical equilibrium with the host garnet, indicating its primary origin during the formation of the megacryst assemblage. The low-Cr garnet-clinopyroxene mineral assemblage formed as a result of high-temperature, melt-associated mantle metasomatism by failed kimberlite within the lithospheric mantle (T = 1150 °C and P = 5.5 GPa). Polymineralic inclusions are characterised by a silicate or silicate-sulphate matrix. The central part of the silicate inclusions is filled by serpentine and contains ilmenite, spinel, perovskite, calcite and apatite. At the contact with host garnets, phlogopite, spinel and amphibole occur as reaction minerals. Composition of spinel and other minerals within inclusions with silicate matrix suggests that kimberlite melt was trapped at mantle pressures. Inclusions with silicate matrix were found in all garnets. The matrix of silicate-sulphate inclusions consists of silicate cryptocrystalline phases and sulphate minerals (celestine-barite) and contains calcite grains. The inclusions are distributed in some low-Cr garnet megacrysts and eclogitic garnet. The silicate-sulphate inclusions were crystallised from the late-stage kimberlite melt. Diverse reaction textures are evidences of disequilibrium between the host crystals and polymineralic inclusions and indicate that garnet and the hosted inclusions reacted with the ascending kimberlite melt. The silicate-sulphate inclusions with a thin rim of epidote within eclogitic garnets indicate that a kimberlite melt invaded the garnet and induced partial melting. The studied inclusions allow us to propose three stages of the Grib kimberlite evolution: 1) generation of garnet megacrysts and primary inclusions due to melt metasomatism, 2) reaction of the high-Ti kimberlite melt with garnet megacrysts (including their dissolution) and 3) alteration of the inclusions in garnet after kimberlite ascent.
DS202008-1414
2020
Lebedeva, N.Lebedeva, N., Nosova, A., Kargin, A., Larionova, Y., Sazonova, L., Tikhomirova, Y.Grib kimberlite peridotitic xenoliths: isotopic evidence of variable source of mantle metasomatism.Goldschmidt 2020, 1p. AbstractRussia, Kola Peninsuladeposit - Grib

Abstract: We present petrography and mineral chemistry for both phlogopite, from mantle-derived xenoliths (garnet peridotite, eclogite and clinopyroxene-phlogopite rocks) and for megacryst, macrocryst and groundmass flakes from the Grib kimberlite in the Arkhangelsk diamond province of Russia to provide new insights into multi-stage metasomatism in the subcratonic lithospheric mantle (SCLM) and the origin of phlogopite in kimberlite. Based on the analysed xenoliths, phlogopite is characterized by several generations. The first generation (Phl1) occurs as coarse, discrete grains within garnet peridotite and eclogite xenoliths and as a rock-forming mineral within clinopyroxene-phlogopite xenoliths. The second phlogopite generation (Phl2) occurs as rims and outer zones that surround the Phl1 grains and as fine flakes within kimberlite-related veinlets filled with carbonate, serpentine, chlorite and spinel. In garnet peridotite xenoliths, phlogopite occurs as overgrowths surrounding garnet porphyroblasts, within which phlogopite is associated with Cr-spinel and minor carbonate. In eclogite xenoliths, phlogopite occasionally associates with carbonate bearing veinlet networks. Phlogopite, from the kimberlite, occurs as megacrysts, macrocrysts, microcrysts and fine flakes in the groundmass and matrix of kimberlitic pyroclasts. Most phlogopite grains within the kimberlite are characterised by signs of deformation and form partly fragmented grains, which indicates that they are the disintegrated fragments of previously larger grains. Phl1, within the garnet peridotite and clinopyroxene-phlogopite xenoliths, is characterised by low Ti and Cr contents (TiO2 < 1 wt.%, Cr2O3 < 1 wt.% and Mg# = 100 × Mg/(Mg + Fe) > 92) typical of primary peridotite phlogopite in mantle peridotite xenoliths from global kimberlite occurrences. They formed during SCLM metasomatism that led to a transformation from garnet peridotite to clinopyroxene-phlogopite rocks and the crystallisation of phlogopite and high-Cr clinopyroxene megacrysts before the generation of host-kimberlite magmas. One of the possible processes to generate low-Ti-Cr phlogopite is via the replacement of garnet during its interaction with a metasomatic agent enriched in K and H2O. Rb-Sr isotopic data indicates that the metasomatic agent had a contribution of more radiogenic source than the host-kimberlite magma. Compared with peridotite xenoliths, eclogite xenoliths feature low-Ti phlogopites that are depleted in Cr2O3 despite a wider range of TiO2 concentrations. The presence of phlogopite in eclogite xenoliths indicates that metasomatic processes affected peridotite as well as eclogite within the SCLM beneath the Grib kimberlite. Phl2 has high Ti and Cr concentrations (TiO2 > 2 wt.%, Cr2O3 > 1 wt.% and Mg# = 100 × Mg/(Mg + Fe) < 92) and compositionally overlaps with phlogopite from polymict breccia xenoliths that occur in global kimberlite formations. These phlogopites are the product of kimberlitic magma and mantle rock interaction at mantle depths where Phl2 overgrew Phl1 grains or crystallized directly from stalled batches of kimberlitic magmas. Megacrysts, most macrocrysts and microcrysts are disintegrated phlogopite fragments from metasomatised peridotite and eclogite xenoliths. Fine phlogopite flakes within kimberlite groundmass represent mixing of high-Ti-Cr phlogopite antecrysts and high-Ti and low-Cr kimberlitic phlogopite with high Al and Ba contents that may have formed individual grains or overgrown antecrysts. Based on the results of this study, we propose a schematic model of SCLM metasomatism involving phlogopite crystallization, megacryst formation, and genesis of kimberlite magmas as recorded by the Grib pipe.
DS201612-2315
2016
Lebedeva, N.M.Larionova, Yu.O., Sazonova, L.V., Lebedeva, N.M., Nosova, A.A., Tretyachenko, V.V., Travin, A.V., Kargin, A.V., Yudin, D.S.Kimberlite age in the Arkhangelsk province, Russia: isotopic geochronologic Rb-Sr and 40Ar/39Ar and mineralogical dat a on phlogopite.Petrology, Vol. 24, 6, pp. 562-593.Russia, Archangel, Kola PeninsulaDeposit - Ermakovskaya-7, Grib, Karpinski

Abstract: The paper reports detailed data on phlogopite from kimberlite of three facies types in the Arkhangelsk Diamondiferous Province (ADP): (i) massive magmatic kimberlite (Ermakovskaya-7 Pipe), (ii) transitional type between massive volcaniclastic and magmatic kimberlite (Grib Pipe), and (iii) volcanic kimberlite (Karpinskii-1 and Karpinskii-2 pipes). Kimberlite from the Ermakovskaya-7 Pipe contains only groundmass phlogopite. Kimberlite from the Grib Pipe contains a number of phlogopite populations: megacrysts, macrocrysts, matrix phlogopite, and this mineral in xenoliths. Phlogopite macrocrysts and matrix phlogopite define a single compositional trend reflecting the evolution of the kimberlite melt. The composition points of phlogopite from the xenoliths lie on a single crystallization trend, i.e., the mineral also crystallized from kimberlite melt, which likely actively metasomatized the host rocks from which the xenoliths were captured. Phlogopite from volcaniclastic kimberlite from the Karpinskii-1 and Karpinskii-2 pipes does not show either any clearly distinct petrographic setting or compositional differentiation. The kimberlite was dated by the Rb-Sr technique on phlogopite and additionally by the 40Ar/39Ar method. Because it is highly probable that phlogopite from all pipes crystallized from kimberlite melt, the crystallization age of the kimberlite can be defined as 376 ± 3 Ma for the Grib Pipe, 380 ± 2 Ma for the Karpinskii-1 pipe, 375 ± 2 Ma for the Karpinskii-2 Pipe, and 377 ± 0.4 Ma for the Ermakovskaya-7 Pipe. The age of the pipes coincides within the error and suggests that the melts of the pipes were emplaced almost simultaneously. Our geochronologic data on kimberlite emplacement in ADP lie within the range of 380 ± 2 to 375 ± Ma and coincide with most age values for Devonian alkaline-ultramafic complexes in the Kola Province: 379 ± 5 Ma; Arzamastsev and Wu, 2014). These data indicate that the kimberlite was formed during the early evolution of the Kola Province, when alkaline-ultramafic complexes (including those with carbonatite) were emplaced.
DS201705-0863
2017
lebedeva, N.M.Nosova, A.A., Dubinina, E.O., Sazonova, L.V., Vargin, A.V., lebedeva, N.M., Khvostikov, V.A., Burmii, Zh.P., Kondrashov, I.A., Tretyachenko, V.V.Geochemistry and oxygen isotopic composition of olivine in kimberlites from the Arkhangelsk Province: contribution of mantle metasomatism.Petrology, Vol. 25, 2, pp. 150-180.Russia, Archangel, Kola PeninsulaDeposit - Grib, Pionerskaya

Abstract: The paper presents data on the composition of olivine macrocrysts from two Devonian kimberlite pipes in the Arkhangelsk diamond province: the Grib pipe (whose kimberlite belongs to type I) and Pionerskaya pipe (whose kimberlite is of type II, i.e., orangeite). The dominant olivine macrocrysts in kimberlites from the two pipes significantly differ in geochemical and isotopic parameters. Olivine macrocrysts in kimberlite from the Grib pipe are dominated by magnesian (Mg# = 0.92-0.93), Ti-poor (Ti < 70 ppm) olivine possessing low Ti/Na (0.05-0.23), Zr/Nb (0.28-0.80), and Zn/Cu (3-20) ratios and low Li concentrations (1.2-2.0 ppm), and the oxygen isotopic composition of this olivine ?18O = 5.64‰ is higher than that of olivine in mantle peridotites (?18O = 5.18 ± 0.28‰). Olivine macrocrysts in kimberlite from the Pionerskaya pipe are dominated by varieties with broadly varying Mg# = 0.90-0.93, high Ti concentrations (100-300 ppm), high ratios Ti/Na (0.90-2.39), Zr/Nb (0.31-1.96), and Zn/Cu (12-56), elevated Li concentrations (1.9-3.4 ppm), and oxygen isotopic composition ?18O = 5.34‰ corresponding to that of olivine in mantle peridotites. The geochemical and isotopic traits of low-Ti olivine macrocrysts from the Grib pipe are interpreted as evidence that the olivine interacted with carbonate-rich melts/fluids. This conclusion is consistent with the geochemical parameters of model melt in equilibrium with the low-Ti olivine that are similar to those of deep carbonatite melts. Our calculations indicate that the variations in the ?18O of the olivine relative the “mantle range” (toward both higher and lower values) can be fairly significant: from 4 to 7‰ depending on the composition of the carbonate fluid. These variations were formed at interaction with carbonate fluid, whose ?18O values do not extend outside the range typical of mantle carbonates. The geochemical parameters of high-Ti olivine macrocrysts from the Grib pipe suggest that their origin was controlled by the silicate (water-silicate) component. This olivine is characterized by a zoned Ti distribution, with the configuration of this distribution between the cores of the crystals and their outer zones showing that the zoning of the cores and outer zones is independent and was produced during two episodes of reaction interaction between the olivine and melt/fluid. The younger episode (when the outer zone was formed) likely involved interaction with kimberlite melt. The transformation of the composition of the cores during the older episode may have been of metasomatic nature, as follows from the fact that the composition varies from grain to grain. The metasomatic episode most likely occurred shortly before the kimberlite melt was emplaced and was related to the partial melting of pyroxenite source material.
DS201707-1344
2016
Lebedeva, N.M.Larionova, Y.O., Sazonova, L.V., Lebedeva, N.M., Nosova, A., Tretyachenko, V.V., Travin, A.V., Kargin, A.V., Yudin, D.S.Kimberlite age in the Arkhangelsk province, Russia: isotopic geochronologic Rb-Sr and 40Ar/39Ar and mineralogical dat a on phlogopite.Petrology, Vol. 24, 6, pp. 562-593.Russiageochronology

Abstract: The paper reports detailed data on phlogopite from kimberlite of three facies types in the Arkhangelsk Diamondiferous Province (ADP): (i) massive magmatic kimberlite (Ermakovskaya-7 Pipe), (ii) transitional type between massive volcaniclastic and magmatic kimberlite (Grib Pipe), and (iii) volcanic kimberlite (Karpinskii-1 and Karpinskii-2 pipes). Kimberlite from the Ermakovskaya-7 Pipe contains only groundmass phlogopite. Kimberlite from the Grib Pipe contains a number of phlogopite populations: megacrysts, macrocrysts, matrix phlogopite, and this mineral in xenoliths. Phlogopite macrocrysts and matrix phlogopite define a single compositional trend reflecting the evolution of the kimberlite melt. The composition points of phlogopite from the xenoliths lie on a single crystallization trend, i.e., the mineral also crystallized from kimberlite melt, which likely actively metasomatized the host rocks from which the xenoliths were captured. Phlogopite from volcaniclastic kimberlite from the Karpinskii-1 and Karpinskii-2 pipes does not show either any clearly distinct petrographic setting or compositional differentiation. The kimberlite was dated by the Rb–Sr technique on phlogopite and additionally by the 40Ar/39Ar method. Because it is highly probable that phlogopite from all pipes crystallized from kimberlite melt, the crystallization age of the kimberlite can be defined as 376 ± 3 Ma for the Grib Pipe, 380 ± 2 Ma for the Karpinskii-1 pipe, 375 ± 2 Ma for the Karpinskii-2 Pipe, and 377 ± 0.4 Ma for the Ermakovskaya-7 Pipe. The age of the pipes coincides within the error and suggests that the melts of the pipes were emplaced almost simultaneously. Our geochronologic data on kimberlite emplacement in ADP lie within the range of 380 ± 2 to 375 ± Ma and coincide with most age values for Devonian alkaline–ultramafic complexes in the Kola Province: 379 ± 5 Ma; Arzamastsev and Wu, 2014). These data indicate that the kimberlite was formed during the early evolution of the Kola Province, when alkaline–ultramafic complexes (including those with carbonatite) were emplaced.
DS201707-1353
2017
Lebedeva, N.M.Nosova, A., Tretyachenko, V.V., Sazonova, L.V., Kargin, A.V., Lebedeva, N.M., Khovostikov, V.A., Burmii, Zh.P., Kondrorashov, I.A., Tretyachenko, V.V.Geochemistry and oxygen isotopic composition of olivine in kimberlites from the Arkhangelsk province: contribution of mantle metasomatism.Petrology, Vol. 25, 2, pp. 150-180.Russia, Archangel, Kola Peninsuladeposit - Grib, Pionerskaya

Abstract: The paper presents data on the composition of olivine macrocrysts from two Devonian kimberlite pipes in the Arkhangelsk diamond province: the Grib pipe (whose kimberlite belongs to type I) and Pionerskaya pipe (whose kimberlite is of type II, i.e., orangeite). The dominant olivine macrocrysts in kimberlites from the two pipes significantly differ in geochemical and isotopic parameters. Olivine macrocrysts in kimberlite from the Grib pipe are dominated by magnesian (Mg# = 0.92–0.93), Ti-poor (Ti < 70 ppm) olivine possessing low Ti/Na (0.05–0.23), Zr/Nb (0.28–0.80), and Zn/Cu (3–20) ratios and low Li concentrations (1.2–2.0 ppm), and the oxygen isotopic composition of this olivine ?18O = 5.64‰ is higher than that of olivine in mantle peridotites (?18O = 5.18 ± 0.28‰). Olivine macrocrysts in kimberlite from the Pionerskaya pipe are dominated by varieties with broadly varying Mg# = 0.90–0.93, high Ti concentrations (100–300 ppm), high ratios Ti/Na (0.90–2.39), Zr/Nb (0.31–1.96), and Zn/Cu (12–56), elevated Li concentrations (1.9–3.4 ppm), and oxygen isotopic composition ?18O = 5.34‰ corresponding to that of olivine in mantle peridotites. The geochemical and isotopic traits of low-Ti olivine macrocrysts from the Grib pipe are interpreted as evidence that the olivine interacted with carbonate-rich melts/fluids. This conclusion is consistent with the geochemical parameters of model melt in equilibrium with the low-Ti olivine that are similar to those of deep carbonatite melts. Our calculations indicate that the variations in the ?18O of the olivine relative the “mantle range” (toward both higher and lower values) can be fairly significant: from 4 to 7‰ depending on the composition of the carbonate fluid. These variations were formed at interaction with carbonate fluid, whose ?18O values do not extend outside the range typical of mantle carbonates. The geochemical parameters of high-Ti olivine macrocrysts from the Grib pipe suggest that their origin was controlled by the silicate (water–silicate) component. This olivine is characterized by a zoned Ti distribution, with the configuration of this distribution between the cores of the crystals and their outer zones showing that the zoning of the cores and outer zones is independent and was produced during two episodes of reaction interaction between the olivine and melt/fluid. The younger episode (when the outer zone was formed) likely involved interaction with kimberlite melt. The transformation of the composition of the cores during the older episode may have been of metasomatic nature, as follows from the fact that the composition varies from grain to grain. The metasomatic episode most likely occurred shortly before the kimberlite melt was emplaced and was related to the partial melting of pyroxenite source material.
DS201709-2012
2017
Lebedeva, N.M.Kargin, A.V., Sazonova, L.V., Nosova, A.A., Lebedeva, N.M.The mantle metasomatism associated with kimberlite magmatism, the Grib kimberlite pipe, Arkhangelsk diamond province, Russia.Goldschmidt Conference, abstract 1p.Russia, Archangeldeposit - Grib

Abstract: Here we present major (EMPA) and trace element (SIMS, LA-ICP-MS) data for garnet and clinopyroxene from mantlederived xenoliths of coarse and sheared garnet peridotite [1, 2] and clinopyroxene-phlogopite metasomatic rocks from the Grib kimberlite, the Arkhangelsk diamond province, Russia, and provide new insights into the metasomatic processes that occur within the subcontinental lithospheric mantle (SCLM) during the kimberlite melts generation and ascent. The obtained data allowed us to reconstruct the following sequence of metasomatic events associated with the generation of the Grib kimberlite: 1. Ascent of high-temperature asthenospheric or mantle plume material resulted in a partial melting of a carbonated peridotite and led to the generation of high-temperature REEenriched proto-kimberlite melts containing significant amounts of carbonate, Fe-Ti and K-H2O. These protokimberlite melts started to interact with the surrounding mantle rocks during its evolution and ascent, and caused metasomatic modification of both coarse and sheared peridotites at the base of SCLM (T and P estimates are 1220°C and 70 kbar). 2. Further evolution of proto-kimberlite melts during the ascent and the interaction with the surrounding mantle (e.g. mantle-rock assimilation and/or percolative fractional crystallization) led to changes in the kimberlite composition from REE-enriched carbonate-dominated to carbonate-rich ultramafic silicate magmas with lower REE contents. 3. During the ascent, carbonate-rich ultramafic silicate kimberlite melts progressively metasomatised sorrounding SCLM from garnet-phlogopite peridotite through garnetphlogopite peridotite to clinopyroxene-phlogopite rocks under T and P estimated as 830°C and 40 kbar. At this stage, the fractionated of Fe-Ti-bearing megacrysts occurred.
DS201711-2522
2017
Lebedeva, N.M.Kargin, A.V., Sazonova, L.V., Nosova, A.A., Lebedeva, N.M., Tretyachenko, V.V., Abersteiner, A.Cr-rich clinopyroxene megacrysts from the Grib kimberlite, Arkangelsk province, Russia: relation to clinopyroxene-phlogopite xenoliths and evidence for mantle metasomatism by kimberlite melts.Lithos, in press available, 52p.Russia, Archangeldeposit - Grib

Abstract: To provide new insights into the origin of megacrysts and metasomatism of the subcontinental lithospheric mantle (SCLM), we present a detailed petrographic and geochemical investigation of clinopyroxene-phlogopite xenoliths and clinopyroxene megacrysts from the Grib kimberlite (Arkhangelsk diamond province, Russia). Clinopyroxene megacrysts and clinopyroxene from clinopyroxene-phlogopite xenoliths have similar petrography, major and trace element compositions, and are therefore classified as Cr-rich megacrysts. Geothermobarometry suggests that Cr-rich clinopyroxenes originate from within the SCLM (3.6-4.7 GPa and 764-922 °C). Phlogopite from clinopyroxene-phlogopite xenoliths have low-Ti and -Cr compositions that overlaps with phlogopite megacrysts from the Grib kimberlite. The clinopyroxene-phlogopite rocks within the SCLM are the main source for Cr-rich clinopyroxene and low-Ti phlogopite megacrysts in the Grib kimberlite matrix. Trace element compositions of studied Cr-rich clinopyroxenes have similar geochemical features to clinopyroxenes megacrysts occurrences worldwide and overlap with clinopyroxenes from phlogopite-garnet peridotite xenoliths from the Grib kimberlite. The strong depletion in Ti, Nb, Ta and to a lesser extent in Zr and Hf in clinopyroxene reflects equilibrium with Ti-oxides, such as ilmenite. The clinopyroxene-phlogopite xenoliths could be the final product of metasomatism of garnet peridotites within the SCLM beneath the Grib kimberlite. The calculated equilibrium of clinopyroxene melt compositions suggests that the metasomatic agents were derived from silicate-bearing kimberlite melts. The presence of veinlets infilled with kimberlitic mineral assemblages in clinopyroxene grains suggests that the clinopyroxene-phlogopite rocks experienced intense interactions with kimberlite melt after their formation, but before their entrainment into the host kimberlite magma. This interaction resulted in the formation of high-Ti and -Cr phlogopite and high-Ti clinopyroxene rims, zones and grains with spongy textures. Finally, we propose the sequence of metasomatic events that occurred in the SCLM and the subsequent formation of the Grib kimberlite.
DS202005-0754
2020
Lebedeva, N.M.Nosova, A.A., Kargin, A.V., Sazonova, L.V., Dubinina, E.O., Chugaev, A.V., Lebedeva, N.M., Yudin, D.S., Larionova, Y.O., Abersteiner, A., Gareev, B.I., Batalin, G.A.Sr-Nd-Pb isotopic systematic and geochronology of ultramafic alkaline magmatism of the southwestern margin of the Siberian craton: metasomatism of the sub-continental lithospheric mantle related to subduction and plume events.Lithos, Vol. 364-365, 21p. PdfRussia, Siberiadeposit - Ilbokich, Chadobets

Abstract: To provide new insights into the origin and evolution of ultramafic lamprophyres (UMLs) and their mantle source, we examined two UML (aillikite and damtjernite) occurrences of different ages in the western portion of the Siberian Craton (Ilbokich and Chadobets). New age, mineral and rock geochemistry, along with Sr-Nd-Pb-C-O isotope data was obtained. Our new 206Pb/238U perovskite age (399 ± 4 Ma) confirms the previously published Early Devonian age of the Ilbokich aillikite. RbSr isochron and 40Ar/39Ar dating yielded a Middle Triassic age (243 ± 3 Ma and 241 ± 1 Ma, respectively) for the Chadobets aillikites, indicating post-Trap emplacement of these rocks. Both UMLs are characterized by incompatible elements, including light rare earth element (LREE) enrichments (La is up to ×200 chondrite concentration), and strong fractionation of REEs ((La/Yb)n: 33-84). Despite the close geochemical affinity of both UMLs, the Nd isotopic compositions of aillikites, as well as the Pb isotopic composition of Chadobets and Ilbokich UMLs, do not overlap and are distinctly different from each other. The initial Sr and Nd isotopic compositions of the Ilbokich UMLs fall in within a narrow 87Sr/86Sr0 range (0.7032-0.7042) and ?Nd(T) (4.03-3.97). Chadobets UMLs have a similar Sr isotopic signature (87Sr/86Sr0: 0.7031-0.7043) and a more depleted Nd isotopic signature (?Nd(T) 4.09-5.08). The initial Pb isotope compositions of the Chadobets UMLs are moderately radiogenic, ranging between 206Pb/204Pb = 18.4-19.0, 208Pb/204Pb = 38.3-38.8, and are characterized by a narrow 207Pb/204Pb ratio between 15.5 and 15.6. The Ilbokich Pb isotope compositions are less variable and range between 206Pb/204Pb = 18.0-18.4, 208Pb/204Pb = 37.8-38.4 and 207Pb/204Pb ratios between 15.5 and 15.6. The oxygen isotopic composition of carbonate from both UMLs is characterized by highly variable ?18O values from +12.1 and up to +20.5‰ (SMOW). The isotopic composition of ?13C values range from ?1.3‰ to ?7.1. Based on the minor impact of crustal contamination in both aillikites, it is inferred that their radiogenic isotope composition reflects a mantle source signature. The mantle source of the Chadobets aillikites is likely to include carbonatitic magma as a metasomatic agent. In contrast, phlogopite-rich metasomes within the lithospheric mantle could have contributed more significantly to the Ilbokich aillikites. These metasomes could be formed during the Caledonian orogeny, which did not only affect the southwestern boundary of the Siberian Craton, but also expanded to the craton interior. This study provides additional support for the evolution of the south-western portion of the Siberian SCLM, ranging from mantle containing phlogopite enrichment domains during the Early Devonian to hydrous-phase reduced mantle in the Triassic due to the thermal impact of the Siberian Traps.
DS202006-0943
2020
Lebedeva, N.M.Novosa, A.A., Kargin, A.V., Sazonova, L.V., Dubinina, E.O., Chugaev, A.V., Lebedeva, N.M., Yudin, D.S., Larionova, Y.O., Abersteiner, A., Gareev, B.I., Batalin, G.A.Sr-N-Pb isotopic systematic and geochronology of ultramafic alkaline magmatism of the southwestern margin of the Siberian craton: metasomatism of the sub-continental lithospheric mantle related to subduction and plume events.Lithos, Vol. 364-365, 21p. PdfRussiaailikite, damjernite

Abstract: To provide new insights into the origin and evolution of ultramafic lamprophyres (UMLs) and their mantle source, we examined two UML (aillikite and damtjernite) occurrences of different ages in the western portion of the Siberian Craton (Ilbokich and Chadobets). New age, mineral and rock geochemistry, along with Sr-Nd-Pb-C-O isotope data was obtained. Our new 206Pb/238U perovskite age (399 ± 4 Ma) confirms the previously published Early Devonian age of the Ilbokich aillikite. RbSr isochron and 40Ar/39Ar dating yielded a Middle Triassic age (243 ± 3 Ma and 241 ± 1 Ma, respectively) for the Chadobets aillikites, indicating post-Trap emplacement of these rocks. Both UMLs are characterized by incompatible elements, including light rare earth element (LREE) enrichments (La is up to ×200 chondrite concentration), and strong fractionation of REEs ((La/Yb)n: 33-84). Despite the close geochemical affinity of both UMLs, the Nd isotopic compositions of aillikites, as well as the Pb isotopic composition of Chadobets and Ilbokich UMLs, do not overlap and are distinctly different from each other. The initial Sr and Nd isotopic compositions of the Ilbokich UMLs fall in within a narrow 87Sr/86Sr0 range (0.7032-0.7042) and ?Nd(T) (4.03-3.97). Chadobets UMLs have a similar Sr isotopic signature (87Sr/86Sr0: 0.7031-0.7043) and a more depleted Nd isotopic signature (?Nd(T) 4.09-5.08). The initial Pb isotope compositions of the Chadobets UMLs are moderately radiogenic, ranging between 206Pb/204Pb = 18.4-19.0, 208Pb/204Pb = 38.3-38.8, and are characterized by a narrow 207Pb/204Pb ratio between 15.5 and 15.6. The Ilbokich Pb isotope compositions are less variable and range between 206Pb/204Pb = 18.0-18.4, 208Pb/204Pb = 37.8-38.4 and 207Pb/204Pb ratios between 15.5 and 15.6. The oxygen isotopic composition of carbonate from both UMLs is characterized by highly variable ?18O values from +12.1 and up to +20.5‰ (SMOW). The isotopic composition of ?13C values range from ?1.3‰ to ?7.1. Based on the minor impact of crustal contamination in both aillikites, it is inferred that their radiogenic isotope composition reflects a mantle source signature. The mantle source of the Chadobets aillikites is likely to include carbonatitic magma as a metasomatic agent. In contrast, phlogopite-rich metasomes within the lithospheric mantle could have contributed more significantly to the Ilbokich aillikites. These metasomes could be formed during the Caledonian orogeny, which did not only affect the southwestern boundary of the Siberian Craton, but also expanded to the craton interior. This study provides additional support for the evolution of the south-western portion of the Siberian SCLM, ranging from mantle containing phlogopite enrichment domains during the Early Devonian to hydrous-phase reduced mantle in the Triassic due to the thermal impact of the Siberian Traps.
DS202008-1407
2020
Lebedeva, N.M.Kargin, A.V., Nosova, A.A., Sazonova, L.V., Peresetskaya, E.V., Golubeva, Yu.Yu., Lebedeva, N.M., Tretyachenko, V.V., Khvostikov, V.A., Burmii, J.P.Ilmenite from the Arkangelsk diamond province, Russia: composition, origin and indicator of diamondiferous kimberlites.Petrology, Vol. 28, 4, pp. 341-369. pdfRussia, Archangelilmenite

Abstract: To provide new insights into the origin and evolution of kimberlitic magmas with different diamond concentrations from the Arkhangelsk diamond province in northwestern Russia, we examined the major-and trace-element compositions of ilmenite from diamondiferous kimberlite of the Grib pipe and diamond barren kimberlites from the Kepino cluster (Stepnaya and TsNIGRI-Arkhangelskaya pipes). Ilmenite from diamond-barren kimberlites shows lower Mg, Ti, Cr, Ni and Cu concentrations with increase in both Fe 3+ and Fe 2+ and Nb, Ta, Zr, Hf, Zn and V concentrations. The main differences between kimberlites with different diamond contents are the Nb and Zr concentrations and their correlation patterns with Mg and Cr concentrations. Ilmenite from the Grib kimberlite has Zr concentrations <110 ppm, whereas ilmenite from the Kepino kimberlites has Zr concentrations >300 ppm. Ilmenite crystallisation within the Grib kimberlite occurred under increasing oxygen fugacity (fO 2), which may reflect assimilation of mantle peridotite by the kimberlitic magmas. Ilmenite from the Kepino kimberlites suggests its crystallisation under constant fO 2 , with the ilmenite composition being controlled by processes of fractional crystallisation of megacrystic minerals. These assumptions were confirmed with assimilation-fractional crystallisation calculations. On the basis of obtained data, we developed a model for the evolution of the kimberlitic magmas for both diamon-diferous and barren kimberlites. The diamond-bearing kimberlitic magmas were generated under intense interaction of kimberlitic magmas with the surrounding lithospheric mantle. It may be that during early modification of the lithospheric mantle by kimberlitic magmas as well as with kimberlitic magmas' local stretching and swift ascent, the capture of the mantle xenoliths was favoured over the crystallisation of phenocrysts. The formation of barren kimberlitic magmas may have occurred when the lithospheric mantle in the vicinity of ascending magmas was already geochemically equilibrated with them. It also is possible that the magma's ascent slowed under conditions of dominantly compressive stresses with crystallisation of olivine and other megacrystic phases.
DS202008-1415
2020
Lebedeva, N.M.Lebedeva, N.M., Nosova, A.A., Kargin, A.V., Sazonova, L.V.Multi-stage evolution of kimberlite melt as inferred from inclusions in garnet megacrysts in the Grib kimberlite ( Arkangelsk region, Russia).Mineralogy and Petrology, Vol. 114, 4, pp. 272-288. pdfRussia, Archangeldeposit - Grib

Abstract: To provide new insights into the origin of garnet megacrysts and evolution of kimberlite melts, we studied in detail the polymineralic and monomineralic inclusions and their host garnets from the Grib kimberlite (Arkhangelsk diamond province, Russia). Low-Cr and high-Cr garnet megacrysts and eclogitic garnets contain abundant polymineralic and rare monomineralic inclusions. Monomineralic inclusions presented by clinopyroxene, ilmenite, olivine replaced by serpentine, were found exclusively within the low-Cr megacrysts. The composition of clinopyroxene exhibits geochemical equilibrium with the host garnet, indicating its primary origin during the formation of the megacryst assemblage. The low-Cr garnet–clinopyroxene mineral assemblage formed as a result of high-temperature, melt-associated mantle metasomatism by failed kimberlite within the lithospheric mantle (T?=?1150 °C and P?=?5.5 GPa). Polymineralic inclusions are characterised by a silicate or silicate-sulphate matrix. The central part of the silicate inclusions is filled by serpentine and contains ilmenite, spinel, perovskite, calcite and apatite. At the contact with host garnets, phlogopite, spinel and amphibole occur as reaction minerals. Composition of spinel and other minerals within inclusions with silicate matrix suggests that kimberlite melt was trapped at mantle pressures. Inclusions with silicate matrix were found in all garnets. The matrix of silicate-sulphate inclusions consists of silicate cryptocrystalline phases and sulphate minerals (celestine–barite) and contains calcite grains. The inclusions are distributed in some low-Cr garnet megacrysts and eclogitic garnet. The silicate-sulphate inclusions were crystallised from the late-stage kimberlite melt. Diverse reaction textures are evidences of disequilibrium between the host crystals and polymineralic inclusions and indicate that garnet and the hosted inclusions reacted with the ascending kimberlite melt. The silicate-sulphate inclusions with a thin rim of epidote within eclogitic garnets indicate that a kimberlite melt invaded the garnet and induced partial melting. The studied inclusions allow us to propose three stages of the Grib kimberlite evolution: 1) generation of garnet megacrysts and primary inclusions due to melt metasomatism, 2) reaction of the high-Ti kimberlite melt with garnet megacrysts (including their dissolution) and 3) alteration of the inclusions in garnet after kimberlite ascent.
DS202010-1849
2020
Lebedeva, N.M.Kargin, A.V., Nosova, A.A., Sazonova, L.V., Peresetskaya, E.V., Golubeva, Yu.Yu., Lebedeva, N.M., Tretyachenko, V.V., Khvostikov, V.A., Burmii, J.P.Ilmenite from the Arkangelsk diamond province, Russia: composition, origin and indicator of diamondiferous kimberlites.Petrology, Vol. 28, 4, pp. 315-337. pdfRussia, Archangeldeposit - Grib, Kepino cluster

Abstract: To provide new insights into the origin and evolution of kimberlitic magmas with different diamond concentrations from the Arkhangelsk diamond province in north-western Russia, we examined the major- and trace-element compositions of ilmenite from diamondiferous kimberlite of the Grib pipe and diamond-barren kimberlites from the Kepino cluster (Stepnaya and TsNIGRI-Arkhangelskaya pipes). Ilmenite from diamond-barren kimberlites shows lower Mg, Ti, Cr, Ni and Cu concentrations with increase in both Fe3+ and Fe2+ and Nb, Ta, Zr, Hf, Zn and V concentrations. The main differences between kimberlites with different diamond contents are the Nb and Zr concentrations and their correlation patterns with Mg and Cr concentrations. Ilmenite from the Grib kimberlite has Zr concentrations <110 ppm, whereas ilmenite from the Kepino kimberlites has Zr concentrations >300 ppm. Ilmenite crystallisation within the Grib kimberlite occurred under increasing oxygen fugacity (fO2), which may reflect assimilation of mantle peridotite by the kimberlitic magmas. Ilmenite from the Kepino kimberlites suggests its crystallisation under constant fO2, with the ilmenite composition being controlled by processes of fractional crystallisation of megacrystic minerals. These assumptions were confirmed with assimilation-fractional crystallisation calculations. On the basis of obtained data, we developed a model for the evolution of the kimberlitic magmas for both diamondiferous and barren kimberlites. The diamond-bearing kimberlitic magmas were generated under intense interaction of kimberlitic magmas with the surrounding lithospheric mantle. It may be that during early modification of the lithospheric mantle by kimberlitic magmas as well as with kimberlitic magmas’ local stretching and swift ascent, the capture of the mantle xenoliths was favoured over the crystallisation of phenocrysts. The formation of barren kimberlitic magmas may have occurred when the lithospheric mantle in the vicinity of ascending magmas was already geochemically equilibrated with them. It also is possible that the magma’s ascent slowed under conditions of dominantly compressive stresses with crystallisation of olivine and other megacrystic phases.
DS202010-1856
2020
Lebedeva, N.M.Lebedeva, N.M., Nosova, A.A., Kargin, A.V., Larionova, Y.O., Sazonova, L.V., Tikhomirova, Y.S.S-Nd-O isotopic evidence of variable sources of mantle metasomatism in the subcratonic lithospheric mantle beneath the Grib kimberlite, northwestern Russia.Lithos, in press available, 54p. PdfRussia, Kola Peninsuladeposit - Grib

Abstract: To provide new insights into the type and extent of mantle metasomatism in the subcratonic lithospheric mantle, we examined the Sr-Nd-O isotopic compositions of orthopyroxene, clinopyroxene, garnet, ilmenite and phlogopite from sheared garnet lherzolite, granular garnet harzburgites and lherzolites and clinopyroxene-phlogopite rocks from the Grib kimberlite in the Arkhangelsk diamond province in northwestern Russia. Clinopyroxene and orthopyroxene from sheared garnet lherzolite initially have a close value of 87Sr/86Sr(t) (~0.7034) and close weak positive ?Nd. Orthopyroxene and clinopyroxene are in oxygen isotope equilibrium with coexisting olivine. Clinopyroxene from a garnet harzburgite has a low 87Sr/86Sr(t) isotope ratio of 0.70266. Clinopyroxene from granular garnet lherzolites has a relatively narrow variation in 87Sr/86Sr(t) (0.70456-0.70582) and considerably larger variations in ?Nd (?4.3???+1.0) isotope ratios. Garnet displays elevated initial 87Sr/86Sr(t) values (0.70540-0.70633). Ilmenite shows a narrow range in 87Sr/86Sr(t) (0.70497-0.70522) coupled with ?Nd values of +0.4 and +3.5. These isotopic data suggest granular garnet lherzolite of mantle metasomatism took place during the interaction of kimberlite melts with SCLM that contained mica-amphibole-rutile-ilmenite-diopside (MARID)-type metasomes. Clinopyroxenes from clinopyroxene-phlogopite (phlogopite wehrlite) xenoliths display a broader range in 87Sr/86Sr(t) (0.70486-0.70813) that is significantly higher than the kimberlite values and a circa-chondritic ?Nd (?0.1 ??+1.3) with a restricted ?18O range (5.11‰-5.33‰). More radiogenic Sr isotopic composition decoupled from Nd isotopes could have been induced by metasomatic melt/fluid related to a subducted material. The isotopic compositions of mantle minerals preserve Sr-Nd isotopic evidence of pre-kimberlite metasomatic events that were probably due to incomplete reequilibration with ultramafic carbonated melt. Based on mineral pairs Rb-Sr isochrons and a clinopyroxene-based Sm-Nd errochron, these mantle metasomatic events correspond to ~550-600?Ma and ~1200?Ma episodes of magmatic-thermal activity.
DS202108-1301
2021
Lebedeva, N.M.Nosova, A.A., Kopylova, M.G., Sazonova, L.V., Vozniak, A.A., Kargin, A.V., Lebedeva, N.M., Volkova, G.D., Peresetskaya, E.V.Petrology of lamprophyre dykes in the Kola alkaline carbonatite province.Lithos, Vol. 398-399. 106277Russia, Kola Peninsulacarbonatite

Abstract: The study reports petrography, bulk major and trace element compositions of lamprophyric Devonian dykes in three areas of the Kola Alkaline Carbonatite Province (N Europe). Dykes in one of these areas, Kandalaksha, are not associated with a massif, while dykes in Kandaguba and Turij Mys occur adjacent (< 5 km) to coeval central multiphase ultramafic alkaline?carbonatitic massifs. Kandalaksha dyke series consists of aillikites - phlogopite carbonatites and monchiquites. Kandaguba dykes range from monchiquites to nephelinites and phonolites; Turij Mys dykes represent alnöites, monchiquites, foidites, turjaites and carbonatites. Some dykes show extreme mineralogical and textural heterogeneity and layering we ascribe to fluid separation and crystal cumulation. Melt evolution of the dykes was modelled with Rhyolite-MELTS and compared with the observed order and products of the crystallization. Our results suggest that the studied rocks were related by fractional crystallization and liquid immiscibility. Primitive melts of aillikites or olivine melanephelinites initially evolved at P = 1.5-0.8 GPa without a SiO2 increase due to abundant clinopyroxene crystallization controlled by the CO2-rich fluid. At 1-1.1 GPa the Turij Mys melts separated immiscible carbonatite melt, which subsequently exsolved late carbonate-rich fluids extremely rich in trace elements. Kandaguba and Turij Mys melts continued to fractionate at lower pressures in the presence of hydrous fluid to the more evolved nephelinite and phonolite melts. The studied dykes highlight the critical role of the parent magma chamber in crystal fractionation and magma diversification. The Kandalaksha dykes may represent a carbonatite - ultramafic lamprophyre association, which fractionated at 45-20 km in narrow dykes on ascent to the surface and could not get more evolved than monchiquite. In contrast, connections of Kandaguba and Turij Mys dykes to their massif magma chambers ensured the sufficient time for fractionation, ascent and a polybaric evolution. This longevity generated more evolved rock types with the higher alkalinity and an immiscible separation of carbonatites.
DS1985-0750
1985
Lebedeva, S.I.Yefimov, A.F., Yeskova, YE.M., Lebedeva, S.I., Levin, V. YA.Type Compositions of Accessory Pyrochlore in a Ural Alkali ComplexGeochemistry International, Vol. 22, No. 1, pp. 68-75RussiaAlkaline Rocks
DS201909-2056
2019
Lebedeva-Ivanova, N.Lebedeva-Ivanova, N., Gaina, C., Minakov, A., Kashubin, S.ArcCRUST: Arctic crustal thickness from 3-D gravity inversion.Geochemistry, Geophysics, Geosystems, Vol. 20 doi.org/10.1029 /2018GC008098Globalgeophysics - gravity

Abstract: An excess or deficit of mass is reflected in the gravity anomaly data. Gravity anomalies measured by satellite and airborne and shipborne instruments show variations in topography and bathymetry, sedimentary thickness, basement rock density contrast, crustal thickness, and even mantle convection. Using new geophysical data and an improved 3?D gravity inversion method, we calculate the crustal thickness of oceanic domains in the High Arctic and northern North Atlantic. This model helps to better understand the tectonic structure of poorly surveyed and difficult to access Arctic regions. ArcCRUST can be used to better constrain the deeper Arctic region structure.
DS1988-0414
1988
Lebedeyeva, L.I.Lebedeyeva, L.I., Smyslov, A.A.Geochemical zoning of kimberlite and the enclosed rocks and its explorationsignificance.(Russian)In: Geol. criteria for the prediction and evaluation of ore deposits, Akad., pp. 86-96RussiaGeochemical zoning, Kimberlite
DS202102-0201
2021
Lebel, D.Lebel, D.Geological survey of Canada 8.0: mapping the journey towards predictive geoscience.Hill, P.R., Lebel, D., Hitzman, M., Smelror, M., Thorleifson, H. eds The changing role of Geological Surveys . GSL SP 499, Vol. 499, pp. 28-30. pdfCanadatechnology

Abstract: The Geological Survey of Canada (GSC) has been furthering the geoscientific understanding of Canada since its inception in 1842, the equivalent of seven generations ago. The evolution of the activities of the GSC over this period has been driven by evolving geographic, economic and political contexts and needs. Likewise, new technologies and evolving scientific methods and models shaped broadly the successive generations of GSC geoscience activities. The most recent GSC generation presented a mixed portfolio of large framework mapping geoscience programmes, and more targeted, hypothesis-driven geoscience research, and the development of decision support products for a range of government, industry and other stakeholders needs. Entering its eighth generation, the GSC and related organizations are embracing digital technologies for applications such as the evaluation of mineral resource potential, the evaluation of risks and the early warning of earthquakes. In order to do so, the GSC will need to develop new methods and systems in co-operation with other geological survey organizations, and target its data acquisition and research to further advance its ability to respond to the evolving needs of society to navigate geology through space and time, from the past to the present, and from the present to the future.
DS1998-0226
1998
Lebel, J.L.Cavey, G., Raven, W., Lebel, J.L.Metallic and industrial mineral assessment report on the exploration work in the Calling Lake area.Alberta Geological Survey, MIN 19980021AlbertaExploration - assessment, Cambridge Minerals, Ltd.
DS201612-2309
2016
Lebensohn, R.A.Kaercher, P., Miyagi, L., Kanitpanyacharoen, W., Zepeda-Alarcon, E., Wang, Y., Parkinson, D., Lebensohn, R.A., De Carlo, F., Wenk, H.R.Two phase deformation of lower mantle mineral analogs.Earth and Planetary Science Letters, Vol. 456, pp. 134-145.MantleBridgemanite

Abstract: The lower mantle is estimated to be composed of mostly bridgmanite and a smaller percentage of ferropericlase, yet very little information exists for two-phase deformation of these minerals. To better understand the rheology and active deformation mechanisms of these lower mantle minerals, especially dislocation slip and the development of crystallographic preferred orientation (CPO), we deformed mineral analogs neighborite (NaMgF3, iso-structural with bridgmanite) and halite (NaCl, iso-structural with ferropericlase) together in the deformation-DIA at the Advanced Photon Source up to 51% axial shortening. Development of CPO was recorded in situ with X-ray diffraction, and information on microstructural evolution was collected using X-ray microtomography. Results show that when present in as little as 15% volume, the weak phase (NaCl) controls the deformation. Compared to single phase NaMgF3 samples, samples with just 15% volume NaCl show a reduction of CPO in NaMgF3 and weakening of the aggregate. Microtomography shows both NaMgF3 and NaCl form highly interconnected networks of grains. Polycrystal plasticity simulations were carried out to gain insight into slip activity, CPO evolution, and strain and stress partitioning between phases for different synthetic two-phase microstructures. The results suggest that ferropericlase may control deformation in the lower mantle and reduce CPO in bridgmanite, which implies a less viscous lower mantle and helps to explain why the lower mantle is fairly isotropic.
DS1994-1385
1994
Lebeveva, E.V.Platonova, N.P., Karavaikenko, G.I., Lebeveva, E.V.Transformation of kimberlites by automorphic bacteriaMicrobiolog., Vol. 63, No.3, May-June pp., 264-268.GlobalKimberlites, Biology
DS2003-0019
2003
LeBihan, T.Andrault, D., Angel, R.J., Mosenfelder, J.L., LeBihan, T.Equation of state of stishovite to lower mantle pressuresAmerican Mineralogist, Vol. 88, 2,3pp. 301-7.MantleMineralogy
DS2002-1154
2002
LeBlanc, G.Norris, B., LeBlanc, G., Prevec, L.An alternative simple procedure to identify magnetic and other geophysical anomaliesSociety of Exploration Geophysicists, program abstracts, Vol. 72, pp. 712-715.AlbertaGeophysics - magnetics
DS200412-1444
2002
LeBlanc, G.Norris, B., LeBlanc, G., Prevec, L.An alternative simple procedure to identify magnetic and other geophysical anomalies due to kimberlite pipes.Society of Exploration Geophysicis, Vol. 72, pp. 712-715.Canada, AlbertaGeophysics - magnetics
DS1999-0400
1999
Leblanc, G.E.Leblanc, G.E., Morris, W.A.Aeromagnetics of southern Alberta within areas of hydrocarbon accumulationLithoprobe, No. 47, pp. 439-54.AlbertaGeophysics - magnetics not specific to diamonds, Tectonics
DS1991-0469
1991
LeBlanc, J.L.Farshad, F., LeBlanc, J.L.How to run a FORTRAN or a BASIC Computer program on PC'sGeobyte, Vol. 6, No. 2, pp. 37-39GlobalComputer, Programs -FORTRAN -PC's
DS1990-0911
1990
Leblanc, M.Leblanc, M., Curras, J., Gervilla, F., Temagoult, A., Torres-RuizLherzolite related mineralizationsTerra, Abstracts of International Workshop Orogenic Lherzolites and Mantle Processes, Vol. 2, December abstracts p. 133AlpsLherzolite, Mineralogy
DS1992-0926
1992
Leblanc, M.Leblanc, M., Nicolas, A.Ophiolitic chromititesInternational Geology Review, Vol. 34, No. 7, July pp. 653-686RussiaChromite, Ophiolite
DS200512-0607
2005
Leblanc, P.Leblanc, P.Protecting our diamonds... staying proactive ensures that this industry remains crime free.Canadian Diamonds, Winter pp. 22, 24.CanadaNews item - security, theft
DS200512-0608
2005
Leblanc, P.Leblanc, P.Diamond strategy moves forward. The third round table discussion meeting focused on the trademark, increasing participation by federal government.Canadian Diamonds, Summer, p. 20, 22.CanadaNews item - legal
DS200612-0779
2006
LeBlanc, P.LeBlanc, P.The Israeli example. Canada could learn from a country that doesn't produce a single carat of rough yet sustains a $ 7 billion industry.Canadian Diamonds, Summer, p. 10.Europe, IsraelNews item - diamond exchange
DS200612-0780
2006
LeBlanc, P.LeBlanc, P.An association is born.... The Diamond Manufacturers Association of Canada is one more indication of a maturing Down stream industry in this country.Canadian Diamonds, Winter, p. 10. (1p.)Canada, Northwest TerritoriesNews item - DMAC
DS200712-0608
2007
Leblanc, P.Leblanc, P.The Canadian advantage... Canada well placed to meet consumer demands of certification of diamond's characteristics and country of origin.Canadian Diamonds, Spring, p.12.CanadaCertification
DS201512-1904
2015
Leblanc, S.G.Chen, W., Leblanc, S.G., White, H.P., Milkovic, B., O'Keefe, H., Croft, B., Gunn, A., Boulanger, J.Caribou relevant environmental changes around the Ekati diamond mine measured in 2015.43rd Annual Yellowknife Geoscience Forum Abstracts, abstract p. 24.Canada, Northwest TerritoriesDeposit - Ekati

Abstract: How would a large open pit mine on caribou range (e.g., the Ekati Diamond Mine in the Bathurst caribou’s summer range) have influenced caribou? A traditional knowledge study on the cumulative impacts on the Bathurst caribou herd qualitatively described how mining activities might have influenced the herd (Mackenzie et al. 2013): caribou migration routes deflected away from the mines probably due to seeing mining activities or hearing the noises; and skinny caribou or abnormal smells and materials in caribou meat, liver, or the hide linings probably related to changes in caribou forage and quality of water and air. In other words, the potential influences of mining operations on caribou were most likely through altering what caribou can see, hear, smell (e.g., dusts and fine particle matter < 2.5 ?m (PM2.5) in the air, and from acidity in the soil), and taste (e.g., dust on foliage, vegetation composition change). Boulanger et al. (2012) estimated the size of a zone of influence (ZOI) of the Ekati-Diavik mining complex in the Bathurst caribou summer range, using caribou presence dataset. They also explored the mechanisms of ZOI using the spatial distribution of the total suspended particles, which was simulated with an atmospheric transport and dispersion model (Rescan, 2006). While these studies have added to our understanding of the possible impacts of mining operations on caribou, knowledge gaps remain. One outstanding gap is the lack of direct measurements about the caribou relevant environmental changes caused by mining operations. For example, exactly from how far away can caribou clearly see the vehicles driving on a mining road, or the buildings and the elevated waste piles in a camp? From how far away might caribou hear the noise caused by mining operations? To what spatial extent had the dusts and PM2.5 from mining operations influenced the tundra ecosystems? And how the dusts and PM2.5 from mining operations might have influenced caribou forage quality? Potentially these questions can be answered by in-situ measurements and satellite remote sensing. For example, studies have showed that it is possible to remotely sense PM2.5 distribution using twice-daily MODIS data at a spatial resolution of 1 km (Lyapustin et al., 2011; Chudnovsky et al., 2013; Hu et al., 2014). The objective of this study is thus to quantitatively measure these changes around the Ekati Diamond Mine, by means of in-situ surveys and satellite remote sensing. We conducted field surveys at more than 100 sites around the Ekati Diamond Mine during August 14-23, 2015, a collaborative effort of the NWT CIMP project entitled “Satellite Monitoring for Assessing Resource Development’s Impact on Bathurst Caribou (SMART)”, and the Dominion Diamond Ekati Corporation. In this presentation, we will report preliminary results and lessons learned from our first year’s study.
DS201607-1310
2016
Leblon, B.Ou, C., Leblon, B., Zhang, Yu., LaRocque, A., Webster, K., McLaughlin, J.Modelling and mapping permafrost at high spatial resolution using Land sat and Radarsat images in northern Ontario: model calibration and regional mapping.International Journal of Remote Sensing, Vol. 37, 12, pp. 2727-2779.Canada, OntarioNews item - permafrost

Abstract: Permafrost is an important ground thermal condition that has significant biophysical and socio-economic impacts. In order to better understand the distribution and dynamics of permafrost, there is a need to map permafrost at high spatial resolution. This study is part of a research project that aims to model and map permafrost using remote sensing images and the Northern Ecosystem Soil Temperature (NEST) model in the central part of the Hudson Bay Lowland in northern Ontario, Canada. The study area is near the southern margin of permafrost region where permafrost exists only in isolated patches. In this study, we ran the NEST model from 1932 to 2012 using a climate data set compiled from station observations and grid data sources. The model outputs were then compared to field observations acquired during 2009 -2012 at seven peat monitoring stations and two flux towers, which represent three major types of peatland in the study area (bog, fen, and palsa). The simulated soil temperatures at various depths show good agreement with the observations, and the simulated latent and sensible heat fluxes and net radiation are similar to the observations at the two flux towers. The model accurately shows the existence of permafrost only at palsa sites. Based on the general range of climate and ground conditions in this area, sensitivity tests indicate that the modelled permafrost conditions are sensitive to leaf area index, air temperature, precipitation, and soil texture. Therefore, the NEST model is capable of simulating ground temperature and permafrost conditions in where permafrost occurs only sporadically. A companion paper (part 2) uses the model with Landsat and Radarsat imagery to map the distribution and dynamics of permafrost in this area.
DS1860-0415
1883
Leboy, E.Leboy, E.Diamond SparrowParis:, 167P.GlobalMineralogy
DS201705-0846
2017
LeBreton, R.LeBreton, R.Dat a gathering and integration in geotechnical applications- the Diavik experience.Canadian Institute of Mining and Metallurgy, abstract, 1/4p.Canada, Northwest TerritoriesDeposit - Diavik
DS1993-0897
1993
Lebron, M.C.Lebron, M.C., Perfit, M.R.Stratigraphic and petrochemical dat a support subduction polarity reversalof the Cretaceous Caribbean Island ArcJournal of Geology, Vol. 101, No. 3, May pp. 389-396CaribbeanTectonic models, Calc-alkaline series
DS201906-1322
2019
LeCheminant, A.McCausland, P., Higgins, M., LeCheminant, A., Jourdan, F., Hamilton, M., Murphy, J.B.Laurentia during the mid-Edicacaran: paleomagnetism and 580 Ma age of the Saint Honore alkali intrusion and related dykes, Quebec. GAC/MAC annual Meeting, 1p. Abstract p. 141.Canada, Quebecdeposit - Saint Honore

Abstract: We sampled the mid-Ediacaran Saint-Honoré alkali intrusion and related dykes in the Saguenay City region of Québec for paleomagnetic and U-Pb, 40Ar/39Ar geochonologic study. 40Ar/39Ar geochronology of phlogopite separates from carbonatite of the central intrusion return plateau ages with a weighted mean of 578.3 ± 3.5 Ma. Baddeleyite from a phoscorite dyke provides a concordant age of 580.25 ± 0.87 Ma for the crystallization of the dykes associated with the St-Honoré intrusive complex. Paleomagnetic results from the intrusion itself and related carbonatite and lamprophyre dykes exhibit some streaking between higher to moderate inclination directions, even at the site level, after screening to remove a steep, present-day viscous remanence. The predominant St-Honoré mean direction (13 sites), which is primary (baked contact test on the host Lac St-Jean anorthosite), is D = 119, I = 72.3°; ?95 = 9.5°, retained at higher coercivity and to high unblocking temperatures by titanomagnetite. Assuming a geocentric axial dipole, this result places the St. Honoré locality at 57° S at ~ 580 Ma, implying that Laurentia straddled mid-paleolatitudes at that time. Notably, the paleopole location at 27.2° N, 320.7 E (dp = 15°, dm = 17°) is consistent with similar mid-Ediacaran age paleopoles which place Laurentia at mid- to high paleolatitudes. The Saint-Honoré result implies that Laurentia had moved from low latitude in the early Ediacaran to higher southern paleolatitudes by 580-570 Ma, and then back to low paleolatitudes by as early as 564 Ma. Viewed as apparent polar wander (APW), this motion traces an 'Ediacaran loop' that can also be seen in similar-aged paleomagnetic results from at least two other paleocontinents. The similar APW loops suggest a role for true polar wander in Ediacaran geodynamics, and perhaps help to define a longitudinally-constrained global Ediacaran paleogeography.
DS1985-0387
1985
Lecheminant, A.N.Lecheminant, A.N., Lecheminant, G.M.Phlogopite from 1.8 Ga Lamprophyres and Trachy andesites District of Keewatin, Petrologic Implications.Geological Association of Canada (GAC)., Vol. 10, P. A33, (abstract.).Canada, Northwest Territories, KeewatinShoshonitic Lamprophyres
DS1988-0415
1988
LeCheminant, A.N.LeCheminant, A.N., Miller, A.R., LeCheminant, G.M.Early Proterozoic alkaline igneous rocks, district ofKeewatin, Canada:petrogenesis and mineralizationGeological Society of London Spec. Publishing, Geochemistry and mineralization of, No. 33, pp. 219-240Canada, Northwest TerritoriesAlkaline rocks
DS1989-0866
1989
LeCheminant, A.N.LeCheminant, A.N., Heaman, L.M.Hotspot origin for giant radiating dyke swarms:evidence from the Mackenzie igneous events, CanadaNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 160. AbstractNorthwest TerritoriesDykes
DS1989-0867
1989
LeCheminant, A.N.LeCheminant, A.N., Heaman, L.M.Mackenzie igneous events, Canada: Middle Proterozoic hotspot magmatism associated with ocean openingEarth and Planetary Science Letters, Vol. 96, pp. 38-48Northwest Territories, SaskatchewanDykes, Geochronology
DS1990-1520
1990
LeCheminant, A.N.Villeneuve, M.E., LeCheminant, A.N.Kimzeyite (Zr-garnet) from alnoites at Ile Bizard and Oka Quebec:mineralogy and petrogenesisGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Vancouver 90 Program with Abstracts, Held May 16-18, Vol. 15, p. A135. AbstractQuebecAlnoite, Mineralogy
DS1991-0968
1991
LeCheminant, A.N.LeCheminant, A.N., Heaman, L.M.uranium-lead (U-Pb) (U-Pb) ages for the 1.27 Ga Mackenzie igneous events, Canada: support for aplume initiation modelGeological Association of Canada (GAC)/Mineralogical Association of Canada/Society Economic, Vol. 16, Abstract program p. A73Northwest TerritoriesGeochronology, Dykes
DS1992-0688
1992
LeCheminant, A.N.Heaman, L.M., LeCheminant, A.N.uranium-lead (U-Pb) (U-Pb) systematics of mantle derived zircon and baddeleyite xenocrysts:implications for excess 208Pb in the mantleV.m. Goldschmidt Conference Program And Abstracts, Held May 8-10th. Reston, p. A 49. abstractMantleGeochronology, Zircon, badeleyite
DS1992-0689
1992
LeCheminant, A.N.Heaman, L.M., LeCheminant, A.N., Rainbird, R.H.Nature and timing of Franklin igneous events, Canada: implications for a Late Proterozoic mantle plume and the break-up of LaurentiaEarth and Planetary Science Letters, Vol. 109, No. 1-2, March pp. 117-132GlobalMantle, Proterozoic
DS1992-0927
1992
Lecheminant, A.N.Lecheminant, A.N.Mapping and geochronology in the Baker Lake regionGeological Survey Canada Open File: project summaries Canada-northwest Territories agreement, OF 2484, March pp. 77-78Northwest TerritoriesBaker Lake, Geochronology
DS1993-0646
1993
LeCheminant, A.N.Heaman, L.M., LeCheminant, A.N.Paragenesis and uranium-lead (U-Pb) (U-Pb) systematics of baddeleyiteChemical Geology, Vol. 110, No. 1-3, November 25, pp. 95-126.GlobalGeochronology
DS1994-1009
1994
LeCheminant, A.N.LeCheminant, A.N., Van Breemen, O.uranium-lead (U-Pb) (U-Pb) ages of Proterozoic dyke swarms, Lac de Gras area, Northwest Territories: evidence for progressive break up of an Archean supercontinent.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.Northwest TerritoriesDyke, Supercontinent
DS1995-1076
1995
LeCheminant, A.N.LeCheminant, A.N., Van Breemen, O., Buchan, K.L.Proterozoic dyke swarms Lac de Gras Aylmer Lake area: regional distribution ages and PaleomagnetismGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Annual Meeting Abstracts, Vol. 20, p. A57 AbstractNorthwest TerritoriesPaleomagnetics, Dyke swarms
DS1995-1490
1995
LeCheminant, A.N.Peterson, T.D., Esperanca, S., LeCheminant, A.N.Geochemistry and origin of the Proterozoic ultrapotassic rocks of the Churchill Province, Canada.Mineralogy and Petrology, Vol. 51, No. 2/4, pp. 251-276.Northwest TerritoriesAlkaline rocks, Deposit -Churchill Province
DS1996-0108
1996
LeCheminant, A.N.Bedard, J.H., LeCheminant, A.N.Alnoites and related rocks, Montregian Hills alkaline igneous province, Quebec.Geological Survey of Canada, LeCheminant ed, OF 3228, pp. 117-121.QuebecAlnoites, Montregian Hills
DS1996-0822
1996
LeCheminant, A.N.LeCheminant, A.N., Bedard, J.H.Diamonds associated with ultramafic complexes and derived placersGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 171-176.Cordillera, British Columbia, AppalachiaUltramafic complexes
DS1996-0823
1996
LeCheminant, A.N.LeCheminant, A.N., Heaman, L.M., Van Breemen, O., et al.Mafic magmatism, mantle roots and kimberlites in the Slave CratonGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 161-169.Northwest TerritoriesCraton - dykes, plumes, rifting, Mackenzie Dyke swarm
DS1996-0824
1996
LeCheminant, A.N.LeCheminant, A.N., Kjarsgaard, B.A.Introduction to volume .. searching for diamonds in CanadaGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 5-10.CanadaHistory, Overview
DS1996-0825
1996
LeCheminant, A.N.LeCheminant, A.N., Richardson, D.G., Dilabio, R.N., et al.Searching for diamonds in Canada -forwardGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 1-4.CanadaHistory
DS1996-0826
1996
Lecheminant, A.N.Lecheminant, A.N., Richardson, D.G., DiLabio, RichardsonSearching for diamonds in Canada. See seperate referencesGeological Survey of Canada, Open file 3228, 268p. $ 52.00CanadaNatmap project, Diamond exploration areas
DS1996-1113
1996
LeCheminant, A.N.Peterson, T.D., LeCheminant, A.N.Ultrapotassic rocks of the Dubawnt Supergroup, District of Keewatin, northwest TerritoriesGeological Survey of Canada, LeCheminant ed, OF 3228, pp. 97-100.Northwest TerritoriesAlkaline rocks -ultrapotassic, Christopher Island Formation
DS1998-0840
1998
LeCheminant, A.N.LeCheminant, A.N., Heaman, L.M., Kretschmar, LeCouteurComplex origins and multiple ages of mantle zircon megacrysts from Canadian and South African kimberlites.7th International Kimberlite Conference Abstract, pp. 486-8.Northwest Territories, South Africascanning electron microscope (SEM) and backscatter electron (BSE) imaging on zircons, Deposit - Drybones Bay, Kaalvallei, Leceister
DS2001-0464
2001
LeCheminant, A.N.Heaman, L.M., LeCheminant, A.N.Anomalous uranium-lead (U-Pb) systematics in mantle derived baddeleyite xenocrysts from Ile Bizard: evidence ...Chemical Geology, Vol. 172, No. 1-2, Feb. pp. 77-93.QuebecGeochronology, High temperature radon diffusion
DS200912-0079
2009
LeCheminant, A.N.Buchan, K.L., LeCheminant, A.N., Van Breeman, O.Paleomagnetism and UPb geochronology of the Lac de Gras diabase dyke swarm, Slave Province, Canada: implications for relative drift of Slave and SuperiorCanadian Journal of Earth Sciences, Vol. 46, 5, May pp.361-379.Canada, Northwest TerritoriesPaleproterozoic
DS200912-0080
2009
LeCheminant, A.N.Buchan, K.L., LeCheminant, A.N., Van Breemen, O.Paleomagnetism and U-Pb geochronology of the Lac de Gras diabase dyke swarm, Slave Province Canada: implications for relative drift of Slave and Superior provinces in the Paleoproterozoic.Canadian Journal of Earth Sciences, Vol. 46, pp. 361-379.Canada, Northwest TerritoriesGeophysics
DS201607-1295
2016
LeCheminant, A.N.Ernst, R.E., Hamilton, M.A., Soderlund, U., Hanes, J.A., Gladkochub, D.P., Okrugin, A.V., Kolotilina, T., Mekhonoshin, A.S., Bleeker, W., LeCheminant, A.N., Buchan, K.L., Chamberlain, K.R., Didenko, A.N.Long lived connection between southern Siberia and northern Laurentia in the Proterozoic.Nature Geoscience, Vol. 9, 6, pp. 464-469.Canada, RussiaProterozoic

Abstract: Precambrian supercontinents Nuna-Columbia (1.7 to 1.3 billion years ago) and Rodinia (1.1 to 0.7 billion years ago) have been proposed. However, the arrangements of crustal blocks within these supercontinents are poorly known. Huge, dominantly basaltic magmatic outpourings and intrusions, covering up to millions of square kilometres, termed Large Igneous Provinces, typically accompany (super) continent breakup, or attempted breakup and offer an important tool for reconstructing supercontinents. Here we focus on the Large Igneous Province record for Siberia and Laurentia, whose relative position in Nuna-Columbia and Rodinia reconstructions is highly controversial. We present precise geochronology—nine U -Pb and six Ar -Ar ages—on dolerite dykes and sills, along with existing dates from the literature, that constrain the timing of emplacement of Large Igneous Province magmatism in southern Siberia and northern Laurentia between 1,900 and 720 million years ago. We identify four robust age matches between the continents 1,870, 1,750, 1,350 and 720 million years ago, as well as several additional approximate age correlations that indicate southern Siberia and northern Laurentia were probably near neighbours for this 1.2-billion-year interval. Our reconstructions provide a framework for evaluating the shared geological, tectonic and metallogenic histories of these continental blocks.
DS1985-0387
1985
Lecheminant, G.M.Lecheminant, A.N., Lecheminant, G.M.Phlogopite from 1.8 Ga Lamprophyres and Trachy andesites District of Keewatin, Petrologic Implications.Geological Association of Canada (GAC)., Vol. 10, P. A33, (abstract.).Canada, Northwest Territories, KeewatinShoshonitic Lamprophyres
DS1988-0415
1988
LeCheminant, G.M.LeCheminant, A.N., Miller, A.R., LeCheminant, G.M.Early Proterozoic alkaline igneous rocks, district ofKeewatin, Canada:petrogenesis and mineralizationGeological Society of London Spec. Publishing, Geochemistry and mineralization of, No. 33, pp. 219-240Canada, Northwest TerritoriesAlkaline rocks
DS1992-0080
1992
LeCheminant, G.M.Baragar, W.R.A., Mader, U., LeCheminant, G.M.Lac Leclair carbonatitic ultramafic volcanic centre, Cape Smith Belt, QuebecGeological Survey of Canada, Paper No. 92-1C, pp. 103-110Quebec, Labrador, UngavaCarbonatite, Lac Leclair
DS2001-0082
2001
LeCheminant, G.M.Baragar, W.R.A., Mader, U., LeCheminant, G.M.Paleoproterozoic carbonatitic ultrabasic volcanic rocks (meimechites) of Cape Smith Belt, Quebec.Canadian Journal of Earth Sciences, Vol. 38, No. 9, Sept. pp. 1313-34.Quebec, Ungava, LabradorLac Le Clair, Carbonatite, geochemistry, Lapilli tuffs
DS2001-0610
2001
LeckieKjarsgaard, B.A., Leckie, McNeil, Heaman, McIntyreCretaceous kimberlite chaos? Fort a la Corne revisited, reworked and resolvedSaskatchewan Open House abstracts, Nov. p. 27-8.SaskatchewanGeochronology, Deposit - Fort a la Corne
DS1996-0755
1996
Leckie, D.Kjarsgaard, B.A., Leckie, D.Emplacement and reworking of crater facies kimberlite in SaskatchewanGeological Survey of Canada Colloquium, Jan. 22-24th., Poster display onlySaskatchewanExploration, Crater facies
DS1996-0756
1996
Leckie, D.Kjarsgaard, B.A., Leckie, D., Mwunifumbo, J.Economic implications of multidisciplinary geological studies on Fort a la Corne kimberlite pipe # 169.Saskatchewan Minexpo'96 Symposium, p. 28. abstractSaskatchewanGeochemistry, Pipe # 169
DS1998-0097
1998
Leckie, D.Bedarski, J., Leckie, D., De Paoli, G.Gold recovery and kimberlite/diamond indicators from de Bonita Upland, Alberta.Geological Survey of Canada Open File, No. 3601, 7p. $ 10.50AlbertaGeochemistry, Mineralogy - indicators
DS1998-0100
1998
Leckie, D.Bednarski, J., Leckie, D., De Paoli, G.Gold recovery and kimberlite diamond indicators from Cripple Creek, Rocky Mountain Foothills, Alberta.Geological Survey of Canada (GSC) Open File, No. 3602, p. 6.AlbertaGeochemistry
DS1998-0101
1998
Leckie, D.Bednarski, J., Leckie, D., De Paoli, G.Gold recovery and kimberlite diamond indicators from Del Bonita Upland, Alberta.Geological Survey of Canada (GSC) Open File, No. 3602, p. 8.AlbertaGeochemistry
DS1998-0841
1998
Leckie, D.Leckie, D.Cretaceous diamond bearing kimberlites in the Mannville, Colorado and Wapiti groups: not only oil, gasCan. Soc. Pet. Geol. Reservoir, Vol. 25, No. 8, p. 7.Western CanadaDiamonds mentioned
DS1998-0842
1998
Leckie, D.Leckie, D., Bednarski, J., De Paoli, G.Gold recovery and kimberlite/diamond indicators from Rocky MountainFoothills, Alberta.Geological Survey of Canada Open File, No. 3602, 6p. $ 10.50AlbertaGeochemistry, Mineralogy - indicators
DS1992-0981
1992
Leckie, D.A.Macqueen, R.W., Leckie, D.A.Foreland basins and foldbeltsAmerican Association of Petroleum Geologists, Memoir 55, 460pCordilleraBook -ad, Basins
DS1993-0898
1993
Leckie, D.A.Leckie, D.A.A guidebook on Lower Cretaceous sedimentology and stratigraphy of southern Alberta -tectonic and eustatic implications and economic significanceGeological Survey Canada Open File, No. 2683, 73p. $ 14.60AlbertaSedimentology, Stratigraphy -Cretaceous
DS1995-0972
1995
Leckie, D.A.Kjarsgaard, B.A., Leckie, D.A., McIntyre, D.J., McNeilSmeaton kimberlite drill core, Fort a la Corne Field, SasakatchewanGeological Survey of Canada Open File, No. 3170, 55p.SaskatchewanDrill core analyses, stratigraphy, Deposit -Fort a la Corne
DS1996-0827
1996
Leckie, D.A.Leckie, D.A.Sedimentary re-working of Albian diamond bearing crater facies kimberlite in Saskatchewan.Geological Society of America (GSA) Abstracts, Vol. 28, No. 3, Feb. p. 75. abstractSaskatchewanKimberlite, Sedimentology
DS1997-0661
1997
Leckie, D.A.Leckie, D.A., Kjarsgaard, B.A., et al.Geology of late Cretaceous possible kimberlite at Mountain Lake - chemistry,petrology, indicator mineralGeological Survey of Canada Open file, No. 3441, 100p. 3 maps approx. $ 100.00AlbertaGeophysics, stratigraphy, Deposit - Mountain Lake area
DS1997-0662
1997
Leckie, D.A.Leckie, D.A., Kjarsgaard, B.A., Block, J., McIntyreEmplacement and reworking of Cretaceous diamond bearing crater facies kimberlite of central Saskatchewan.Geological Society of America (GSA) Bulletin., Vol. 109, No. 8, pp. 1000-20.SaskatchewanDiamond - genesis, structure, tectonics, Petrography
DS1997-0663
1997
Leckie, D.A.Leckie, D.A., Kjarsgaard, B.A., Pierce et al.Geology of Late Cretaceous possible kimberlite at Mountain Lake, chemistry, petrology....Geological Survey of Canada (GSC) Open File, No. 3441, 202p.AlbertaGeochemistry
DS1998-0843
1998
Leckie, D.A.Leckie, D.A., Bednarski, J., De Paoli, G.A report on gold recovery and kimberlite/ diamond indicators from a stream sample in the S. Rocky Mtns.Calgary Mining Forum, Apr. 8-9, p. 57. poster abstractAlbertaGeochemistry - heavy minerals
DS1998-0844
1998
Leckie, D.A.Leckie, D.A., Kjarsgaard, B.Diamond placer potential in western Canada: an assessment and ideas for exploration for mineral explorCalgary Mining Forum, Apr. 8-9, p. 28. abstractAlberta, Saskatchewan, Northwest TerritoriesPlacers, alluvials, Craton
DS1998-0845
1998
Leckie, D.A.Leckie, D.A., Nadon, Spirito, McCurdy, FriskeEvolution of fluvial landscapes in the Western Canada Foreland Basin; Late Jurassic to the modern...Geological Survey of Canada Open File, No. 2369Alberta, Northwest TerritoriesGeochemistry - regional stream sediment
DS1999-0365
1999
Leckie, D.A.Kjarsgaard, B.J., Leckie, D.A., McNeil, D., Heaman ...Cretaceous kimberlite chaos? Fort a la Corne revisited and resolved8th. Calgary Mining forum, 2p. abstractSaskatchewanKimberlite, Deposit - Fort a la Corne
DS1997-0173
1997
Leclair, A.Caty, J.L., Simard, A., Leclair, A.Le nouveau programme du Grand Nord - un regard vers l'avenirQuebec Department of Mines, DV 97-03, p. 9.QuebecExploration - assessment
DS1989-0868
1989
Leclair, A.D.Leclair, A.D.The third dimension of the central Kapuskasing uplift interpreted from geological and geophysical dataGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A102. (abstract.)OntarioTectonics, Kapuskasing Lithoprobe
DS1989-0869
1989
Leclair, A.D.Leclair, A.D., Poirier, G.G.The Kapuskasing uplift in the Kapuskasing area, OntarioGeological Survey of Canada Current Research, Paper No. 89-lC, pp. 225-234Ontario, MidcontinentStructure, Tectonics
DS1991-0969
1991
Leclair, A.D.Leclair, A.D., Percival, J.A., Milkereit, B., Green, A.G., West G.F.Seismic reflection profiles across major faults of the central KapuskasingUpliftGeological Association of Canada (GAC)/Mineralogical Association of Canada/Society Economic, Vol. 16, Abstract program p. A73OntarioTectonics, Geophysics -seismics
DS1992-0928
1992
Leclair, A.D.Leclair, A.D.Geology of the Kapuskasing-Groundhog-Missinaibi River area, Folyet andGeological Survey of Canada and Ontario Geological Survey, Open File No. 2515, 1 map 1: 250, 000 approx. $ 10.00OntarioKapuskasing area, Geology
DS1994-1010
1994
Leclair, A.D.Leclair, A.D., Percival, J.A., Green, A.G., et al.Seismic reflection profiles across the central Kapuskasing upliftCanadian Journal of Earth Sciences, Vol. 31, No. 7, July pp. 1016-1026.OntarioGeophysics -seismics, Tectonics -Kapuskasing uplift
DS1997-0664
1997
Leclair, A.D.Leclair, A.D., Lucas, S.B., et al.Regional mapping of Precambrian basement beneath Phanerozoic cover in southeastern Trans Hudson OrogenCanadian Journal of Earth Sciences, Vol. 34, No. 5, May pp. 618-634Manitoba, SaskatchewanPrecambrian, Orogeny - Trans Hudson
DS1997-0665
1997
Leclair, A.D.Leclair, A.D., Lucas, S.B., et al.Regional mapping of Precambrian basement beneath the Phanerozoic cover Trans Hudson Orogen.Canadian Journal of Earth Sciences, Vol. 34, No. 5, May pp. 618-634.Manitoba, SaskatchewanPrecambrian, Phanerozoic
DS1997-0666
1997
Leclair, A.D.Leclair, A.D., Viljoen, D.Geology of Precambrian basement beneath Phanerozoic cover, Flin Flon @Manitoba and SaskatchewanGeological Survey of Canada Open File, No. 3427, 1 poster $ 20.00Manitoba, SaskatchewanPoster, Basement - Phanerozoic
DS1997-0667
1997
Leclair, A.D.Leclair, A.D., Viljoen, D.Geology of Precambrian basement beneath the Phanerozoic cover, Flin Flonbelt, Manitoba and Saskatchewan.Geological Survey of Canada, Open file 3427 POSTER, approx. 20.00Manitoba, SaskatchewanPrecambrian basement, POSTER.
DS2001-0667
2001
Leclair, A.D.Leclair, A.D., Berclaz, David, Percival, J.Regional geological setting of Archean rocks in the northeastern Superior Province.Geological Association of Canada (GAC) Annual Meeting Abstracts, Vol. 26, p.84.abstract.Quebec, UngavaGeology - brief overview
DS1860-0899
1895
Leclerq, J.Leclerq, J.La Golconde AfricaineParis: A Travers L'afrique Australe., PP. 107-146.Africa, South AfricaTravelogue
DS1991-0970
1991
Lecolle, M.Lecolle, M., Derre, C., Nerci, K.The Proterozoic sulphide-alteration pipe of Sidi Flah and its host series.New dat a for the geotectonic evolution of the Pan-African belt in the eastern Anti-Atlas (Ore Geology Reviews, Vol. 6, No. 6, December pp. 501-536MoroccoSulphides, Deposit -Sidi Flah
DS1987-0762
1987
Lecorche, J.P.Vauchez, A., Kessler, S.F., Lecorche, J.P., Villeneuve, M.Southward extrusion tectonics during the Carboniferous Africa-North American collisionTectonophysics, Vol. 142, No. 2-4, November 1, pp. 317-322South AfricaTectonics
DS1991-0331
1991
Lecorche, J.P.Dallmeyer, R.D., Lecorche, J.P.The West African orogens and circum Atlantic correlativesSpringer-Verlag, 402pWest Africa, Spain, Europe, AppalachiaTectonics, structure, craton, orogeny, Terranes
DS1998-0840
1998
LeCouteurLeCheminant, A.N., Heaman, L.M., Kretschmar, LeCouteurComplex origins and multiple ages of mantle zircon megacrysts from Canadian and South African kimberlites.7th International Kimberlite Conference Abstract, pp. 486-8.Northwest Territories, South Africascanning electron microscope (SEM) and backscatter electron (BSE) imaging on zircons, Deposit - Drybones Bay, Kaalvallei, Leceister
DS1986-0654
1986
LeCouteur, P.C.Pride, K.R., LeCouteur, P.C., Mawer, A.B.Geology and mineralogy of the Aley carbonatite, Ospika Riverarea, BritishColumbiaThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 79, No. 891, July p. 32. (abstract.)British ColumbiaCarbonatite
DS1990-1169
1990
Lecouteur, P.C.Pederson, J.C., Lecouteur, P.C.The Thor Lake beryillium-rare metal deposits, Northwest Territories8th. IAGOD Symposium Guidebook, Held August 12-18th. Ottawa, Padgham, W.A., No. 13Northwest TerritoriesThor Lake, rare earth elements (REE).
DS1992-0929
1992
Lecouture, B.Lecouture, B., Whiten, W.J.Use of a rule based strategy to control a 7 foot cone crusherCommunition -theory and practice, S. Komar Kawatra ed., pp. 517-528.AustraliaMining -crusher, Deposit -Argyle Diamond Mines
DS1993-0899
1993
Lecuyer, C.Lecuyer, C., Gruau, G., Anhaeusser, C.R., Fourcade, S.The origin of fluids and the effects of metamorphism on the primary chemical compositions of Barberton komatiites: new evidence from geochemistry, isotopesEconomic Geology Research Unit, University of the Witwatersrand, Inf. Circular No. 272, 32pSouth AfricaGeochemistry, Komatiites
DS1994-1011
1994
Lecuyer, C.Lecuyer, C., Gruau, G., Anhaeusser, C.R., Fourcade, S.The origin of fluids and effects of metamorphism on the primary chemical compositions of Barberton komatiites: new evidenceGeochimica et Cosmochimica Acta, Vol. 58, No. 2, January pp. 1043South AfricaGeochemistry, Geochronology
DS1999-0271
1999
Lecuyer, C.Gruau, G., Bernard Griffiths, J., Lecuyer, C.The origin of U shaped rare earth patterns in ophiolite peridotites:assessing the role of secondary alterationGeochimica et Cosmochimica Acta, Vol. 62, No. 21-22, Nov. pp, 3545-60.CaliforniaMelt rock reaction, Trinity ophiolite - harzburgite, lherzolite
DS1999-0401
1999
Lecuyer, C.Lecuyer, C., Ricard, Y.Long term fluxes and budget of ferric iron: implications for the redox states of the Earth's mantleEarth and Planetary Science Letters, Vol. 165, No. 2, Jan. 30, pp. 197-212.MantleGeochemistry, Redox - ferric iron
DS200412-0347
2004
Lecuyer, C.Coltice, N., Simon, L., Lecuyer, C.Carbon isotope cycle and mantle structure.Geophysical Research Letters, Vol. 31, 5, March 16, DOI 10.1029/2003 GLO18873MantleTectonics
DS200512-0991
2005
Lecuyer, C.Simon, L., Lecuyer, C.Continental recycling: the oxygen isotope point of view.Geochemistry, Geophysics, Geosystems: G3, Vol. 6, doi. 10.1029/2005 GC000958MantleGeochronology, low temperature alteration
DS1994-1012
1994
Leddy, J.O.Leddy, J.O., Ashworth, P.J., Best, J.L.Mechanisms of anabranch avulsion within gravel bed braided rivers:observations of a scaled physical modelBest, and Bristow, Braided Rivers Geological Society of London, No. 75, pp. 119-127GlobalSedimentology, Geomorphology, Braided rivers
DS2000-0426
2000
Ledesma, A.Hurlimann, M., Ledesma, A.Mechanical relationship between catastrophic volcanic landslides and caldera collapses.Geophysical Research Letters, Vol. 27, No. 16, Aug. 15, pp.2393-6.Mantlevolcanism - magmatism
DS1982-0367
1982
Ledger, E.B.Ledger, E.B.Uranium Content of Selected Arkansaw Igneous RocksGeological Society of America (GSA), Vol. 14, No. 3, P. 115. (abstract.).United States, Gulf Coast, Arkansas, Hot Spring CountyGeochemistry, Phonolite, Lamprophyre
DS1990-1386
1990
ledneva, V.P.Sobolev, N.V., Abouassaleh, K., Kepezhinskas, K.B., ledneva, V.P.Lamprophyres of Cretaceous diatremes of the Syrian rift.(Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 314, No. 2, pp. 435-439SyriaLamprophyres, Diatremes
DS1992-0930
1992
Ledneva, V.P.Ledneva, V.P., Belyakov, L.P.New dat a on basalt volcanism in the Malaya Botuobuya district, westernYakutiaDoklady Academy of Sciences USSR, Earth Science Section, Vol. 314, No. 1-6, July 1992, pp. 126-129Russia, YakutiaBasalt, Malaya Botuobaya district
DS2000-0559
2000
Ledo, J.Ledo, J., Jones, A.G., Ferguson, I.J.Preliminary interpretations and implications for tectonics and deep geology of the Northern Cordillera..Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000 Conference, 4p. abstract.Northwest Territories, Yukon, AlbertaGeophysics - Magnetotellurics, Lithoprobe - SNORCLE.
DS2001-0668
2001
Ledo, J.Ledo, J., Jones, A.G.Regional electrical resistivity structure of the southern Canadian Cordillera and its physical interpretJournal of Geophysical Research, Vol. 106, No. 12, pp. 30,755-70.Cordillera, British Columbia, AlbertaGeophysics
DS2003-0666
2003
Ledo, J.Jones, A.G., Ledo, J., Ferguson, I.J.Lithospheric electrical structure of northwestern CanadaGeological Association of Canada Annual Meeting, Abstract onlyNorthwest TerritoriesGeophysics - seismics, Lithoprobe
DS2003-0781
2003
Ledo, J.Ledo, J., Jones, A.G., Craven, J.A.Electrical parameter maps of Canada8 Ikc Www.venuewest.com/8ikc/program.htm, Session 9, POSTER abstractCanada, Northwest TerritoriesGeophysics
DS200412-0926
2003
Ledo, J.Jones, A.G., Ledo, J., Ferguson, I.J.Lithospheric electrical structure of northwestern Canada.Geological Association of Canada Annual Meeting, Abstract onlyCanada, Northwest TerritoriesGeophysics - seismics Lithoprobe
DS200412-1097
2003
Ledo, J.Ledo, J., Jones, A.G., Craven, J.A.Electrical parameter maps of Canada.8 IKC Program, Session 9, POSTER abstractCanada, Northwest TerritoriesCraton studies Geophysics
DS200412-1098
2004
Ledo, J.Ledo, J., Jones, A.G., Ferguson, I.J., Wolynec, L.Lithospheric structure of the Yukon, northern Canadian Cordillera, obtained from magnetotelluric data.Journal of Geophysical Research, Vol. 109, B10, April 30, 10.1029/2003JB002516Canada, YukonGeophysics - magnetotelluric
DS200512-0486
2005
Ledo, J.Jones, A.G., Ledo, J., Ferguson, I.J.Electromagnetic images of the Trans-Hudson orogen: the North American Central Plains anomaly revealed.Canadian Journal of Earth Sciences, Vol. 42, 4, April pp. 457-478.Canada, Northwest TerritoriesGeophysics - EM
DS200512-0609
2005
Ledo, J.Ledo, J., Jones, A.G.Upper mantle temperature determined from combining mineral composition, electrical conductivity laboratory studies and magnetotelluric field observations:Earth and Planetary Science Letters, Vol. 236, 1-2, pp. 258-268.Canada, British Columbia, Alberta, Yukon, CordilleraGeophysics, geochemistry
DS200512-0610
2005
Ledo, J.Ledo, J., Jones, A.G.Upper mantle temperature determined from combining mineral composition, electrical conductivity laboratory studies and magnetotelluric field observations.Earth and Planetary Science Letters, Advanced in press,Canada, British Columbia, YukonIntermontane belt, Cordillera, geophysics
DS201412-0434
2014
Ledo, J.Jones, A.G., Ledo, J., Ferguson, I.J., Craven, J.A., Unswrth, M.J., Chouteau, M., Spratt, J.E., Enkin, R.The electrical resistivity of Canada's lithosphere and correlation with other parameters: contributions from lithoprobe and other programmes.Canadian Journal of Earth Sciences, Vol. 51, 6, pp. 573-617.CanadaGeophysics
DS1991-0971
1991
Ledru, P.Ledru, P., Lasserre, J-L., Manier, E., Mercier, D.The lower Proterozoic of northern Guiana: a revision of the lithology, transcurrent tectonics and sedimentary basin dynamicsBulletin Societe Geologique France, Vol. 162, No. 4, pp. 627-636GlobalBasin, Tectonics
DS1994-1013
1994
Ledru, P.Ledru, P., Johan, Milesi, TegyeyMarkers of the last stages of the PaleoProterozoic collision: evidence fora 2 Ga continent involving circum South Atlantic provinces.Pres. Res., Vol. 69, pp. 169-91.Brazil, Gabon, Guiana, French Guiana, West AfricaTectonics
DS1995-1077
1995
Ledru, P.Ledru, P., Milesi, J.P.Geology of Guyana and West AfricaReprint, 16pGlobalStructure, Paleoproterozoic
DS1995-1250
1995
Ledru, P.Milesi, J-P, Egal, E., Ledru, P., Vernhet, Y et al.Les mineralisations du Nord de la Guyana francaise dans leur cadregeologique.Chron. Recherche Min., No. 518, pp. 5-58.French GuianaGeology -3 p. english summary general geology, Metallogeny - mainly gold related
DS1997-0782
1997
Ledru, P.Milesi, J.P., Bouchot, V., Ledru, P.Cartographie et metallogenie 3D du Massif central francaisChron. Recherche Miniere, No. 528, Sept. pp. 3-12FranceMetallogeny, Mapping - hydrothermal, geochronology
DS1998-1520
1998
Ledru, P.Vanderhaege, O., Ledru, P., Milesi, J.P.Contrasting mechanism of crustal growth. Geodynamic evolution of Paleoproterozoic granite - greenstone beltPrecambrian Research, Vol. 92, No. 2, Oct.l, pp. 165-94GlobalTectonics, Greenstone belts
DS200512-1102
2004
Ledru, P.Trumbull, R.B., Vietor, T., Hahne, K., Wackerle, R., Ledru, P.Aeromagnetic mapping and reconnaissance geochemistry of the Early Cretaceous Henties Bay Outjo dike swarm, Etendeka Igneous Province, Namibia.Journal of African Earth Sciences, Vol. 40, 1-2, Sept. pp. 17-29.Africa, NamibiaGeophysics - magnetics, basaltic dikes, geochemistry
DS1988-0048
1988
LeeBehrendt, J.C., Green, A.G., Cannon, W.F., Hutchinson, D.R., LeeCrustal structure of the Midcontinent rift system: results from GLIMPCE deep seismic reflection profilesGeology, Vol. 16, No. 1, January pp. 81-85GlobalTectonics, GLIMPCE.
DS1992-0656
1992
LeeHalliday, A.N., Davies, G.R., Lee, D-C, Tommasini, S., Paslick, C.R.Lead isotope evidence for young trace element enrichment in the oceanic upper mantleNature, Vol. 359, No. 6396, October 15, pp. 623-626MantleGeochronology
DS1994-1021
1994
LeeLee, ZaunscherbDiamond exploration and production..Lee, Zaunscherb Mineral Resource INdustry Research, 3p.Colorado, Northwest Territories, Botswana, ZimbabweNews item -research report, Redaurum
DS1995-0682
1995
LeeGriffin, B.J., Rissanen, J., Pooley, G.D., Lee, DearnA new Diamondiferous eclogite bearing kimberlitic occurrence from FinlandProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 198-200.FinlandEclogite
DS2001-0651
2001
LeeLan, C.Y., Chung, S.L., Lo, Lee, Wang, Li, Van ToanFirst evidence for Archean continental crust in northern Vietnam and its implications for crustal ...Geology, Vol. 29, No. 3, Mar. pp.219-22.GlobalTectonic evolution, Geochronology, Yangtze Craton
DS2003-0786
2003
LeeLee, Mi Jung, Garcia, D., Moutte, J., Lee, J.K.Phlogopite and tetraferri phlogopite from phoscorite and carbonatite associations in theGeosciences Journal, Vol. 7, 1, March pp. 9-20.FinlandCarbonatite, Deposit - Sokli
DS200412-1104
2003
LeeLee, Mi Jung, Garcia, D., Moutte, J., Lee, J.K.Phlogopite and tetraferri phlogopite from phoscorite and carbonatite associations in the Sokli Massif, northern Finland.Geosciences Journal, Vol. 7, 1, March pp. 9-20.Europe, FinlandCarbonatite, Deposit - Sokli
DS200712-0204
2007
LeeCourtier, A.M., Jackson, Lawrence, Wang, Lee, Halama, Warren, Workman, Xu, Hirschmann, Larson, Hart, Lithgo-Bertelloni, Stixrude, ChenCorrelation of seismic and petrologic thermometers suggests deep thermal anomalies beneath hotspots.Earth and Planetary Science Letters, Vol. 264, 1-2, pp. 308-316.MantleGeothermometry
DS1998-0256
1998
Lee, A.Clark, A.H., Archibald, D.A., Lee, A., Farrar, HodgsonLaser probe 40 Ar-39 Ar ages of early and late stage alteration assemblages Rosario porphyry copper moly..Economic Geology, Vol. 93, No. 3, May pp. 326-37ChileGeochronology, copper, molybdenuM., Deposit - Rosario, Argon
DS2002-0763
2002
Lee, B.Jamieson, R.A., Beaumont, C., Nguyen, M.H., Lee, B.Interaction of metamorphism, deformation and exhumation in large convergent orogensJournal of Metamorphic Geology, Vol.20,1,pp. 9-24.GlobalOrogens - tectonics - not specific to diamonds
DS2002-0943
2002
Lee, C.Li, X.H., Zhou, H., Chung, S.L., Lo, Ch., Wei, G., Liu, Y., Lee, C.Geochemical and Sr Nd isotopic characteristics of Late Paleogene ultrapotassic magmatism in southeast Tibet.International Geology Review, Vol. 44, 6, pp. 559-74.TibetGeochemistry, geochronology, magmatism
DS200512-0611
2004
Lee, C.Lee, C., Bethel, J.S.Extraction, modelling and use of linear features for restitution of airborne hysperspectral imagery.Journal of Photogrammetry and Remote Sensing, Vol. 58, 5-6, July pp. 289-300.HYDICE, sensor modeling
DS201112-0573
2011
Lee, C.Lee, C., King, S.D.Dynamic buckling of subducting slabs reconcile geological and geophysical observations.Earth and Planetary Science Letters, Vol. 312, 3-4, pp. 360-370.MantleSubduction
DS201812-2838
2018
Lee, C.Lee, C., Worsley-Brown, L.Twenty years at the Ekati diamond mine: corporate social responsibility in action. CSR2018 Yellowknife Geoscience Forum , p. 47-48. abstractCanada, Northwest Territoriesdeposit - Ekati

Abstract: The Ekati Diamond Mine in the Northwest Territories is owned and operated by Dominion Diamond Mines, the largest Canadian independent diamond producer. The Ekati mine was the first diamond mine in Canada, and started production in October 1998. In 2018 the operation is celebrating its twenty year anniversary. In the presentation, we will look back on some of the milestones and achievements of the last two decades. We will also discuss the commitment of the company to make a positive difference in the North through Corporate Social Responsibility initiatives, including support for education, training, community development, business opportunities and respect for the environment. Some examples include: Community: Whether mining in northern Canada or sorting diamonds in India, we firmly believe that we can - and should - contribute to the social and economic well-being of the communities near our operations. Dominion's Indigenous partners and business operations are important stakeholders and we respect and value their rights, Traditional Knowledge (TK), and cultural heritage. Hiring, Training and Development: Dominion Diamond Mines is committed to ensuring that the Ekati mine is a welcoming workplace for all employees and that we remain an employer of choice, particularly among northerners and northern Indigenous communities. The company has a number of initiatives and policies to encourage northerners, representatives from Indigenous groups, and women to enter the mining industry. Environment: Throughout the mining process, Dominion Diamond keeps the land and water of the Ekati mine clean and safe for people, plants, and animals. We understand the importance of the Arctic tundra environment and we are committed to mining in the safest, most environmentally responsible way.
DS202012-2225
2020
Lee, C.Lee, C., Seoung, D., Cerpa, N.G.Effect of water solubilities on dehydration and hydration in subduction zones and water transport to the deep mantle: implications for natural subduction zones.Gondwana Research, Vol. 89, pp. 287-305. pdfMantlesubduction

Abstract: Understanding water transport by the subducting slab and the corner flow of the mantle wedge is a crucial topic because it is a prime control on seismic tremors, arc-to-intraplate volcanoes as well as on global water distribution in the mantle. However, most of previous studies focused on water transport by the subducting slab and did not quantitatively evaluated the amount of water carried by the corner flow into the deep mantle. Using two-dimensional numerical experiments, we model both the dehydration of the subducting slab and (de)hydration of the mantle wedge and quantify the amount of water transported by both of them. We use the water solubilities of basalt and peridotite derived from laboratory measurements and from thermodynamic calculations, and compare the implications of their differences. Our calculations show that the two models for the water solubilities of basalt result in either abundant or scarce free water through extensive or negligible dehydration of the sub-forearc oceanic crust, leading to a hydrated or a dry cold nose of the mantle wedge, respectively. Further, the oceanic crust of the subducting slab is almost dehydrated prior to reaching a depth of 250 km, regardless of subduction parameters and the models for the water solubilities of basalt. The dehydration depth of the lithospheric mantle of the subducting slab deepens with decreasing slab temperature. The lithospheric mantle of cold subducting slab (e.g., Northeast Japan) experiences partial dehydration at sub-backarc depths and transports the remaining bound water beyond a depth of 250 km, regardless of the models for the water solubilities of peridotite. Deep water transport by the corner flow of the mantle wedge is negligible regardless of the models for the water solubilities of peridotite. The water carried by the lithospheric mantle may be the cause of backarc and intraplate volcanoes in Northeast Asia.
DS1995-0752
1995
Lee, C.A.Harmer, R.E., Lee, C.A.Dorowa and Shawa carbonatites, ZimbabweGeological Society Africa 10th. Conference Oct. Nairobi, p. 123. Abstract.ZimbabweCarbonatite, Deposit -Dorowa, Shawa
DS2000-0028
2000
Lee, C.A.Armstrong, J.P., Lee, C.A.A compilation of publically available till sample locations and Kimberlite indicator mineral pick resultsDiand, Economic Series, 2000-3, 1 disc.Northwest TerritoriesMineral chemistry
DS2000-0029
2000
Lee, C.A.Armstrong, J.P., Lee, C.A.KIDD: a compilation of publically available till sample locations and picking results Slave Craton and environsnorthwest Territories Geology Division, DIAND., Open file 2000-003, $ 5.00Northwest Territories, NunavutGeochemistry - till samples
DS200712-0609
2007
Lee, C.A.Lee, C.A., Rollo, H.A., Jamieson, H.E.Rock water interaction and CO2 sequestration associated with kimberlite ore processing.Geological Association of Canada, Gac-Mac Yellowknife 2007, May 23-25, Volume 32, 1 pg. abstract p.47.TechnologyMineral processing
DS2003-1347
2003
Lee, C.G.Suga, T., Takeda, Y., Kono, K., Kishimoto, N., Bandouroko, V.V., Lee, C.G.Radiation effects in diamond induced by negative gold ionsNuclear Instruments and Methods in Physics Research Section B., Vol. 206, pp. 947-51.GlobalDiamond - radiation
DS200412-1947
2003
Lee, C.G.Suga, T., Takeda, Y., Kono, K., Kishimoto, N., Bandouroko, V.V., Lee, C.G.Radiation effects in diamond induced by negative gold ions.Nuclear Instruments and Methods in Physics Research Section B., Vol. 206, pp. 947-51.TechnologyDiamond - radiation
DS1993-0873
1993
Lee, C.H.Lambrecht, W.R., Lee, C.H., Segall, B., Angus, J.C., Sunkara, M.Diamond nucleation by hydrogenation of the edges of graphitic precursorsNature, Vol. 364, August 12, pp. 607-610.GlobalDiamond morphology
DS1993-0874
1993
Lee, C.H.Lambrect, W.R.L., Lee, C.H., Segall, B., Angus, J.C., Li, Z.Diamond nucleation by hydrogenation of the edges of graphitic precursorsNature, Vol. 364, No. 6438, August 12, pp. 607-610GlobalDiamond morphology, Graphite
DS1998-0246
1998
Lee, C.T.Chesley, J.T., Rudnick, R.L., Lee, C.T.Longevity of cratonic mantle beneath an active rift: Rhenium- Osmium (Re-Os) evidence from xenoliths from Tanzania....7th International Kimberlite Conference Abstract, pp. 149-151.TanzaniaTectonics - East African Rift, Geochronology, peridotite xenoliths
DS1998-0846
1998
Lee, C.T.Lee, C.T.Are inflected geotherms real?7th International Kimberlite Conference Abstract, pp. 489-91.MantleHTSP, Geothermometry, Peridotites, modeling
DS1998-0847
1998
Lee, C.T.Lee, C.T., Rudnick, R.L.The origin and demise of cratonic lithosphere: a geochemical perspective from the Tanzanian craton.7th International Kimberlite Conference Abstract, pp. 492-4.TanzaniaMelilitite, Deposit - Labait
DS1998-1264
1998
Lee, C.T.Rudnick, R.L., Chesley, J.T., Lee, C.T.Longevity of cratonic mantle beneath an active rift: Re Os evidence from xenoliths from Tanzanian East AfricaMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 1297-8.TanzaniaTectonics - riftig, Geochronology
DS1999-0130
1999
Lee, C.T.Chesley, J.T., Rudnick, R.L., Lee, C.T.Re Os systematics of mantle xenoliths from the East African Rift: age, structure and history Tanzanian....Geochimica et Cosmochimica Acta, Vol. 63, No. 7-8, Apr. 1, pp. 1203-18.TanzaniaCraton, Geochronology, Rifting
DS1999-0402
1999
Lee, C.T.Lee, C.T., Rudnick, R.L.Compositionally stratified cratonic lithosphere: petrology and geochemistry of peridotite xenoliths...7th International Kimberlite Conference Nixon, Vol. 2, pp. 503-21.TanzaniaXenoliths - peridotite, Deposit - Labait volcano
DS2000-0155
2000
Lee, C.T.Chesley, J.T., Rudnick, R.L., Lee, C.T.Geochemical evidence for plume metasomatism and old lithospheric mantle beneath the East African Rift.Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-164.Tanzania, East AfricaMetasomatism - xenoliths, Geophysics - seismic, tomography
DS2000-0560
2000
Lee, C.T.Lee, C.T., Rudnick, R.L., McDonough, W.F., Horn, I.Petrologic and geochemical investigation of carbonates in peridotite xenoliths from northeastern Tanzania.Contributions to Mineralogy and Petrology, Vol. 139, No. 4, pp. 470-84.TanzaniaGeochemistry, petrology, Peridotite xenoliths
DS2002-1375
2002
Lee, C.T.Rudnick, R.L., Lee, C.T.Osmium isotope constraints on tectonic evolution of the lithosphere in the southwestern United States.International Geology Review, Vol. 44, 6, pp. 501-11.United States, Colorado, CaliforniaGeochronology, tectonics
DS2003-0782
2003
Lee, C.T.Lee, C.T.Xenolith constraints on deep lithospheric dynamics beneath the central North AmericanGeological Association of Canada Annual Meeting, Abstract onlyGlobalXenoliths
DS2003-0783
2003
Lee, C.T.Lee, C.T., Brandon, A.D., Norman, M.Vanadium in peridotites as a proxy for paleo f02 during partial meltingGeochimica et Cosmochimica Acta, Vol. 67, 16, pp. 3045-64.GlobalPeridotites
DS200412-1099
2003
Lee, C.T.Lee, C.T.Xenolith constraints on deep lithospheric dynamics beneath the central North American Cordillera.Geological Association of Canada Annual Meeting, Abstract onlyUnited States, CanadaXenoliths
DS200412-1100
2003
Lee, C.T.Lee, C.T., Brandon, A.D., Norman, M.Vanadium in peridotites as a proxy for paleo f02 during partial melting.Geochimica et Cosmochimica Acta, Vol. 67, 16, pp. 3045-64.TechnologyPeridotite
DS200412-1439
2004
Lee, C.T.Niu, F., Levander, A., Cooper, C.M., Lee, C.T., Lenardic, A., James, D.E.Seismic constraints on the depth and composition of the mantle keel beneath the Kaapvaal craton.Earth and Planetary Science Letters, Vol. 224, 3-4, pp. 337-346.Africa, South AfricaGeophysics - seismics, boundary
DS200612-1013
2006
Lee, C.T.O'Neill, C., Lenardic, A., Moresi, L., Torsvik, T., Lee, C.T.The nature of subduction on the early Earth.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 458, abstract only.MantleSubduction
DS200712-0610
2007
Lee, C.T.Lee, C.T., Morton, D.M., Kistler, R.W., Baird, A.K.Petrology and tectonics of Phanerozoic continent formation: from island arcs to accretion and continental arc magmatism.Earth and Planetary Science Letters, Vol. 263, 3-4, pp. 370-387.MantleMagmatism
DS2002-0930
2002
Lee, C.T.A.Lee, C.T.A.Platinum group element geochemistry of peridotite xenoliths from the Sierra Nevada and the Basin and Range, California.Geochimica et Cosmochimica Acta, Vol. 66, 22, pp. 3987-4005.CaliforniaXenoliths - PGE
DS2003-0784
2003
Lee, C.T.A.Lee, C.T.A.Compositional variation of density and seismic velocities in natural peridotites at STPJournal of Geophysical Research, Vol. 108, B9, Sept. 25, 10.1029/2002JB002413.MantleGeophysics - seismics
DS200412-1101
2003
Lee, C.T.A.Lee, C.T.A.Compositional variation of density and seismic velocities in natural peridotites at STP conditions: implications for seismic imaJournal of Geophysical Research, Vol. 108, B9, Sept. 25, 10.1029/2002 JB002413.MantleGeophysics - seismics
DS200512-0612
2004
Lee, C.T.A.Lee, C.T.A.Are Earth's core and mantle on speaking terms?Science, No. 5693, Oct. 1, p. 64.MantleGeophysics
DS200512-0651
2005
Lee, C.T.A.Liu, Y., Gao, S., Lee, C.T.A., Hu, S., Liu, X.,Yuan, H.Melt peridotite interactions: links between garnet pyroxenite and high Mg# signature of continental crust.Earth and Planetary Science Letters, Vol. 234, pp. 39-57.MantleGeochemistry
DS200612-0600
2006
Lee, C.T.A.Horodyskyj, U.N., Lee, C.T.A.An arc origin for Archean high MgO eclogite xenoliths?Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 264, abstract only.MantleEclogite
DS200712-0789
2007
Lee, C.T.A.O'Neill, C., Lenardic, A., Moresi, L., Torsvik, T.H., Lee, C.T.A.Episodic Precambrian subduction.Earth and Planetary Science Letters, In press availableMantleSubduction
DS200712-0790
2007
Lee, C.T.A.O'Neill, C.O., Lenardic, A., Moresi, L., Torsvik, T.H., Lee, C.T.A.Episodic Precambrian subduction.Earth and Planetary Science Letters, Vol. 262, 3-4, Oct. 30, pp. 552-562.MantleSubduction
DS201112-0011
2011
Lee, C.T.A.Albaraede, F., Ballhaus, C., Lee, C.T.A., Yin, Q-Z., Blichert-Toft, J.The great volatile delivery to Earth.Goldschmidt Conference 2011, abstract p.420.MantleGeochronology - Pb
DS201501-0034
2015
Lee, C.T.A.Zheng, J.P., Lee, C.T.A., Lu, J.G., Zhao, J.H., Wu, Y.B., Xia, B., Li, X.Y., Zhang, J.F., Liu, Y.S.Refertilization driven destabilization of subcontinental mantle and the importance of initial lithospheric thickness for the fate of continents. Earth and Planetary Science Letters, Vol. 409, pp. 225-229.ChinaPeridotite
DS202003-0348
2020
Lee, C.W.Y.Lee, C.W.Y., Cheng, J., Yium Y.C., Chan, K., Lau, D., Tang, W.C., Cheng, K.W,m Kong, T., Hui, T.K.C., Jelezko, F.Correlation between EPR spectra and coloration of natural diamonds.Diamond & Related Materials, Vol. 103, 13p. PdfGlobaldiamond colour

Abstract: White diamonds color grading is one of the basic diamond evaluations. The color value based on a scale that ranges from D to Z, with D being the more colorless and more valuable, among other qualifications. As the diamond grade moves on this scale, its color appears more yellow progressively. This yellowish color, present only in Type I diamonds, is mainly due to the nitrogen related defects such as N3 center and C-center. The current color grading system is based on a visual method, where gemologist compares the sample with a Master Color set. However, this method is very subjective. Several defects responsible for light absorption in diamond are carrying electron spin and appear in Electron Paramagnetic Resonance (EPR) spectrum. In this study, we developed a new EPR based technique for a quantitative measurement of N3 center and C-center in diamond through quantitative EPR spectroscopy. The correlation between EPR spectra and color grades of diamond was established.
DS2000-0561
2000
Lee, Cin-ty.Lee, Cin-ty.Rhenium- Osmium (Re-Os) isotopic evidence for unusual Archean lithospheric mantle beneath Mojavia and refractory....Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-165.Colorado Plateau, CordilleraGeochronology
DS200812-0641
2008
Lee, C-T A.Lee, C-T A., Luffi, P., Hoink, T., Li, Z-X.,A., Lenardic, A.The role of serpentine in preferential craton formation in the late Archean by lithosphere underthrusting.Earth and Planetary Science Letters, Vol. 269, 1-2, May 15, pp. 96-104.MantleGeochronology - cratons
DS200412-1701
2002
Lee, C-T.Rudnick, R.L., Lee, C-T.Osmium isotope constraints on tectonic evolution of the lithosphere in the southwestern United States.International Geology Review, Vol. 44, 6, June pp. 501-511.United States, Colorado, Wyoming, New MexicoGeochronology
DS200512-0613
2004
Lee, C-T.Lee, C-T., Lenardic, A., Cooper, C., Niu, F., Levander, A.The role of chemical boundary layers in regulating the thermal thickness of continents and oceans.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 17-1, Vol. 36, 5, p. 46.MantleGeothermometry, xenoliths
DS200612-0783
2006
Lee, C-T.Lee, C-T., Poudjom Djomani, Y.H., Rondenay, S.Geochemical and geophysical probing of continental dynamics.Goldschmidt Conference 16th. Annual, S5-03 theme abstract 1/8p. goldschmidt2006.orgMantleConvection
DS201909-2057
2019
Lee, C-T.Lee, C-T., Dee, S.Does volcanism cause warming or cooling?Geology , Vol. 47, pp. 687-688.Globalvolcanism

Abstract: On million-year time scales, Earth’s climate fluctuates between warm and cool baselines. For example, the past 40 m.y. has been relatively cool and characterized by a permanent ice sheet on Antarctica, while the interval between 150 and 50 m.y. ago was characterized by warm temperatures and no permanent ice sheets (Royer et al., 2004; Zachos et al., 2008). What controls these fluctuations is debated, but to first order, the average surface temperature of Earth reflects the balance of incoming solar insolation (energy in) versus planetary albedo and greenhouse gas concentrations (energy out). It is generally thought that over the past billion years, the most important control on long-term climate is variations in greenhouse gases in the atmosphere, namely CO2 (Berner, 1991). What controls long-term CO2 are variations in geologic inputs and the efficiency of CO2 sequestration, the former through volcanic and metamorphic degassing and oxidative weathering of organic carbon, and the latter through silicate weathering (and eventual carbonate precipitation) and organic carbon burial. Importantly, the efficiency of silicate weathering and organic carbon burial is widely thought to scale directly and indirectly with atmospheric pCO2; CO2’s impact on global temperature and the hydrologic cycle serves as a negative feedback, enhancing (mitigating) carbon sequestration mechanisms given increased (decreased) inputs of CO2. As the residence time of CO2 in the exogenic system (ocean-atmosphere-biosphere) is on the order of 10-100 k.y., exogenic carbon contents on million-year time scales are at steady state, where inputs equal outputs (Berner and Caldeira, 1997). Changes in exogenic cabon over greater than million-year time scales thus reflect secular changes in the steady-state baseline, driven by changes in inputs and/or the kinetics of carbon sequestration (Fig. 1).
DS202201-0023
2021
Lee, C-T.Lenardic, A.,Jellinek, M.,Seales, J., Lee, C-T.Global tectonic and climatic fluctuations: from Pangea grounding to planetary speculation. * just for interestResearchgate , Dec. 51p. PdfGlobalGeotectonics

Abstract: The Earth's paleo-climate record indicates climate fluctuations, from cool to warm to cool conditions, over the last ~300 My. Over that time, the Earth's most recent super-continent, Pangea, formed and broke apart. Data constraints together with numerical models indicate that Pangea formation and breakup affected spatial and temporal patterns of heat loss from the Earths' interior. This, in turn, affected global tectonic and volcanic behavior. The tectonic/volcanic fluctuations can be linked to climate models to explore the degree to which they could drive long time scale (~100 My) climate variations. The coupled models indicate that Pangea-driven tectonic fluctuations can lead to climate fluctuations consistent with data constraints. Global variations in the tectonic behavior of the Earth, linked to climate variations, has implication for understanding how the internal evolution of a planet can affect surface environments. We will end with some speculations on how that could feed into planetary habitability.
DS201607-1305
2016
Lee, C-T. A.Lee, C-T. A., Yeung, L., McKenzie, N.R., Yokoyama, Y., Ozaki, K.Two step rise of atmospheric oxygen linked to the growth of continents. (carbon)Nature Geoscience, Vol. 9, 6, pp. 417-424.MantleCarbon

Abstract: Earth owes its oxygenated atmosphere to its unique claim on life, but how the atmosphere evolved from an initially oxygen-free state remains unresolved. The rise of atmospheric oxygen occurred in two stages: approximately 2.5 to 2.0 billion years ago during the Great Oxidation Event and roughly 2 billion years later during the Neoproterozoic Oxygenation Event. We propose that the formation of continents about 2.7 to 2.5 billion years ago, perhaps due to the initiation of plate tectonics, may have led to oxygenation by the following mechanisms. In the first stage, the change in composition of Earth's crust from iron- and magnesium-rich mafic rocks to feldspar- and quartz-rich felsic rocks could have caused a decrease in the oxidative efficiency of the Earth's surface, allowing atmospheric O2 to rise. Over the next billion years, as carbon steadily accumulated on the continents, metamorphic and magmatic reactions within this growing continental carbon reservoir facilitated a gradual increase in the total long-term input of CO2 to the ocean -atmosphere system. Given that O2 is produced during organic carbon burial, the increased CO2 input may have triggered a second rise in O2. A two-step rise in atmospheric O2 may therefore be a natural consequence of plate tectonics, continent formation and the growth of a crustal carbon reservoir.
DS200812-0660
2008
Lee, C-T.ALi, ZX., Lee, C-T.A, Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xeonoliths from the Colorado Plateau and vicinity: implications for the mantle rheology and hydration induced thinking of lithosphereJournal of Geophysical Research, Vol. 113, B9, B09210.MantleWater content
DS200612-0781
2005
Lee, C-T.A.Lee, C-T.A.Geochemical petrologic constraints on the origin of cratonic mantle.Benn, K., Mareschal, J-C., Condie, K.C. Archean Geodynamics and Environments, AGU Geophysical Monograph, No. 164, pp. 89-114.MantleGeochemistry, petrology
DS200612-0782
2006
Lee, C-T.A.Lee, C-T.A., Cheng, X., Horodyskyj, U.The development and refinement of continental arcs by primary basaltic magmatism, garnet pyroxenite accumulation, basaltic recharge and delamination:Contributions to Mineralogy and Petrology, Vol. 151, 2, Feb. pp. 222-242.United States, CaliforniaMagmatism - Sierra Nevada
DS200612-0806
2006
Lee, C-T.A.Levander, A., Niu, F., Lee, C-T.A., Cheng, X.Imag(in)ing the continental lithosphere.Tectonophysics, Vol. 416, 1-4, April 5, pp. 167-185.MantleGeophysics - seismics
DS200712-0004
2007
Lee, C-T.A.Agranier, A., Lee, C-T.A.Quantifying trace element disequilibration temperatures in mantle xenoliths and abyssal peridotites.Earth and Planetary Science Letters, Vol. 257, 1-2, May 15, pp. 290-298.MantleGeochemistry
DS200712-0611
2007
Lee, C-T.A.Lee, C-T.A., Chen, W-P.Possible density segregation of subducted oceanic lithosphere along a weak serpeninite layer and implications for composition stratification of mantle.Earth and Planetary Science Letters, Vol. 255, 3-4, March 30, pp. 357-366.MantleStratigraphy
DS200812-1325
2008
Lee, C-T.A.Zheng-Xue, A.L., Lee, C-T.A., Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xenoliths from the Colorado Plateau and vicinity: implications for mantle rheology and hydration induced thinning of continental lithosph.Journal of Geophysical Research, Vol. 113. B09210United States, Colorado PlateauPeridotite
DS200912-0098
2009
Lee, C-T.A.Canil, D., Lee, C-T.A.Were deep cratonic mantle roots hydrated in Archean oceans?Geology, Vol. 17, 7, July pp. 667-670.MantlePeridotite
DS201112-0574
2011
Lee, C-T.A.Lee, C-T.A., Luffi, P., Chin, E.J.Building and destroying continental mantle.Annual Review of Earth and Planetary Sciences, Vol. 39, pp. 59-90.MantleAccretion, subduction
DS201508-0362
2015
Lee, C-T.A.Lee, C-T.A., Anderson, D.L.Continental crust formation at arcs, the arclogite "delamination" cycle, and one origin for fertile melting anomalies in the mantle.Science Bulletin, DOI: 10.1007/s11434-015-088-6 online 16p.MantleEclogite
DS201508-0363
2015
Lee, C-T.A.Lee, C-T.A., McKenzie, N.R.Geochemistry: rise of the continents.Nature Geoscience, Vol. 8, pp. 506-507.MantlePlate Tectonics
DS201806-1257
2018
Lee, C-T.A.Tang, M., Erdman, M., Eldridge, G., Lee, C-T.A.The redox filter beneath magmatic orogens and the formation of the continental crust.Science Advances, Vol. 4, 5, 10.1126/ sciadv.eaar 4444Mantlemagmatism

Abstract: The two most important magmatic differentiation series on Earth are the Fe-enriching tholeiitic series, which dominates the oceanic crust and island arcs, and the Fe-depleting calc-alkaline series, which dominates the continental crust and continental arcs. It is well known that calc-alkaline magmas are more oxidized when they erupt and are preferentially found in regions of thick crust, but why these quantities should be related remains unexplained. We use the redox-sensitive behavior of europium (Eu) in deep-seated, plagioclase-free arc cumulates to directly constrain the redox evolution of arc magmas at depth. Primitive arc cumulates have negative Eu anomalies, which, in the absence of plagioclase, can only be explained by Eu being partly reduced. We show that primitive arc magmas begin with low oxygen fugacities, similar to that of mid-ocean ridge basalts, but increase in oxygen fugacity by over two orders of magnitude during magmatic differentiation. This intracrustal oxidation is attended by Fe depletion coupled with fractionation of Fe-rich garnet. We conclude that garnet fractionation, owing to its preference for ferrous over ferric iron, results in simultaneous oxidation and Fe depletion of the magma. Favored at high pressure and water content, garnet fractionation explains the correlation between crustal thickness, oxygen fugacity, and the calc-alkaline character of arc magmas.
DS201905-1080
2019
Lee, C-T.A.Tang, M., Lee, C-T.A., Rudnick, R.L., Condie, K.C.Rapid mantle convection drove massive crustal thickening in the late Archean. ( excluded kimberlites)Geochimica et Cosmochimica Acta, in press available, 32p.Asia, Tibet, Andesmelting

Abstract: The lithospheric mantle beneath Archean cratons is conspicuously refractory and thick compared to younger continental lithosphere (Jordan, 1988, Boyd, 1989; Lee and Chin, 2014), but how such thick lithospheres formed is unclear. Using a large global geochemical database of Archean igneous crustal rocks overlying these thick cratonic roots, we show from Gd/Yb- and MnO/FeOT-SiO2 trends that crustal differentiation required continuous garnet fractionation. Today, these signatures are only found where crust is anomalously thick (60-70?km), as in the Northern and Central Andes and Southern Tibet. The widespread garnet signature in Archean igneous suites suggests that thickening occurred not only in the lithospheric mantle but also in the crust during continent formation in the late Archean. Building thick crust requires tectonic thickening or magmatic inflation rates that can compete against gravitational collapse through lower crustal flow, which would have been enhanced in the Archean when geotherms were hotter and crustal rocks weaker. We propose that Archean crust and mantle lithosphere formed by thickening over mantle downwelling sites with minimum strain rates on the order of 10?13-10?12 s?1, requiring mantle flow rates associated with late Archean crust formation to be 10-100 times faster than today.
DS202006-0951
2020
Lee, C-T.A.Tang, M., Lee, C-T.A., Rudnick, R.L., Condie, K.C.Rapid mantle convection drove massive crustal thickening in the late Archean.Geochimica et Cosmochimica Acta, Vol. 278, pp. 6-15.Mantlecraton

Abstract: The lithospheric mantle beneath Archean cratons is conspicuously refractory and thick compared to younger continental lithosphere ( Jordan, 1988 , Boyd, 1989 ; Lee and Chin, 2014), but how such thick lithospheres formed is unclear. Using a large global geochemical database of Archean igneous crustal rocks overlying these thick cratonic roots, we show from Gd/Yb- and MnO/FeOT-SiO2 trends that crustal differentiation required continuous garnet fractionation. Today, these signatures are only found where crust is anomalously thick (60-70?km), as in the Northern and Central Andes and Southern Tibet. The widespread garnet signature in Archean igneous suites suggests that thickening occurred not only in the lithospheric mantle but also in the crust during continent formation in the late Archean. Building thick crust requires tectonic thickening or magmatic inflation rates that can compete against gravitational collapse through lower crustal flow, which would have been enhanced in the Archean when geotherms were hotter and crustal rocks weaker. We propose that Archean crust and mantle lithosphere formed by thickening over mantle downwelling sites with minimum strain rates on the order of 10?13-10?12 s?1, requiring mantle flow rates associated with late Archean crust formation to be 10-100 times faster than today.
DS202012-2226
2011
Lee, C-T.A.Lee, C-T.A., Luffi, P., Chin, E.J.Building and destroying continental mantle.Reviews in Advance *** NOTE DATE, Vol. 39, pp. 59-90. pdfMantlecratons

Abstract: Continents, especially their Archean cores, are underlain by thick thermal boundary layers that have been largely isolated from the convecting mantle over billion-year timescales, far exceeding the life span of oceanic thermal boundary layers. This longevity is promoted by the fact that continents are underlain by highly melt-depleted peridotites, which result in a chemically distinct boundary layer that is intrinsically buoyant and strong (owing to dehydration). This chemical boundary layer counteracts the destabilizing effect of the cold thermal state of continents. The compositions of cratonic peridotites require formation at shallower depths than they currently reside, suggesting that the building blocks of continents formed in oceanic or arc environments and became "continental" after significant thickening or underthrusting. Continents are difficult to destroy, but refertilization and rehydration of continental mantle by the passage of melts can nullify the unique stabilizing composition of continents.
DS1998-0848
1998
Lee, D.Lee, D., Reddicliffe, T., Scott Smith, B., Taylor, WardMerlin Diamondiferous kimberlite pipesBerkman, Mackenzie, Geol. Australia Papua New Guinea, AusIMM Mon. 22, pp. 461-466.AustraliaGeology, Deposit - Merlin
DS1986-0491
1986
Lee, D.C.Lee, D.C., Van Riessen, A., Terry, K.W.Trace element detection in individual mineral grainsProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 475-477GlobalDiamond exploration
DS1987-0530
1987
Lee, D.C.Nixon, P.H., Boyd, F.R., Lee, D.C.Western Australia-xenoliths from kimberlites and lamproitesin: Nixon, P.H. ed. Mantle xenoliths, J. Wiley, pp. 281-286Australiap. 284 analyses Skerring and Ellendale kimberlite
DS1989-0870
1989
Lee, D.C.Lee, D.C., Van Riessen, A., Terry, K.W.Trace elements in mineral grains from kimberlitic and non-kimberlitic sources using X-ray excited XRF in a scanning electron microscope (SEM)Geological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 2, pp. 1146-1153GlobalTrace elements, XRF.
DS1991-0972
1991
Lee, D.C.Lee, D.C., Boyd, F.R., Griffin, B.J., Reddicliffe, T.Coanjula diamonds, northern Territory, AustraliaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 231-233AustraliaMicrodiamonds, Microscopy, diamond morphology
DS1994-1014
1994
Lee, D.C.Lee, D.C., Boyd, S.R., Griffin, B.J., Griffin, B.W, Reddicliffe, T.Coanjuta diamonds, Northern Territory, AustraliaProceedings of Fifth International Kimberlite Conference, Vol. 2, pp. 51-68.AustraliaDiamond morphology, Deposit -Coanjuta
DS1995-1078
1995
Lee, D.C.Lee, D.C., Milledge, H.J., Redcliffe, T.H., Scott SmithThe Merlin kimberlites, Northern Territory, AustraliaProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 317-319.AustraliaPetrography, Deposit -Merlin, Bedevere, Palomides, Launfal, Excalibur
DS1996-0828
1996
Lee, D.C.Lee, D.C., Halliday, A.N., Davies, G.R., Essene, FittonMelt enrichment of shallow depleted mantle - detailed petrological trace element and isotopic study...Journal of Petrology, Vol. 37, No. 2, April pp. 415-441.GlobalMantle derived xenoliths, Megacrysts, petrology
DS1997-0525
1997
Lee, D.C.Hoyer, D., Lee, D.C.High intensity autogenous liberation of diamonds from kimberlite in the HICOM mill.Minerals Engineering, Vol. 10, No. 3, pp. 265-273.AustraliaMineral processing, Diamonds
DS2000-0017
2000
Lee, D.C.Amelin, Y., Lee, D.C., Halliday, A.N.Early middle Archean crustal evolution deduced from Lutetium - Hafnium and uranium-lead (U-Pb) isotopic studies.Geochimica et Cosmochimica Acta, Vol. 64, No. 24, Dec. 1, pp. 4205-26.MantleTectonics, Geochronology
DS2003-0785
2003
Lee, D.C.Lee, D.C., Maddren, J., Griffin, B.J.The importance of chromite morphology in diamond exploration8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, POSTER abstractAustraliaBlank
DS200412-1102
2003
Lee, D.C.Lee, D.C., Maddren, J., Griffin, B.J.The importance of chromite morphology in diamond exploration.8 IKC Program, Session 8, POSTER abstractAustraliaDiamond exploration
DS1960-0330
1963
Lee, D.E.Coleman, R.G., Lee, D.E.Glaucophane Bearing Metamorphic Rock Types of the Cazadero Area, California.Journal of PETROLOGY, Vol. 4, PP. 260-301.United States, California, West CoastBlank
DS1960-0529
1965
Lee, D.E.Coleman, R.G., Lee, D.E., Beatty, L.B., Brannock, W.W.Eclogites and Eclogites -- their Differences and SimilaritieGeological Society of America (GSA) Bulletin., Vol. 76, No. 5, PP. 483-508.GlobalEclogites
DS1989-0050
1989
Lee, D.K.Baag, C., Lee, D.K.Absence of magnetic anomalies due to seepage -induced 'magnetotelluriceffects' and implications for sulfide self potentialsGeophysics, Vol. 54, No. 9, September pp. 1174-1179GlobalGeophysics, S-P.
DS1996-0829
1996
Lee, D-K.Lee, D-K., Grand, S.P.Upper mantle shear structure beneath the Colorado Rocky MountainsJournal of Geophysical Research, Vol. 101, No. B10, Oct. 10, pp. 22, 233-44.Colorado, WyomingTectonics, Structure
DS1991-0336
1991
Lee, F.E.Daniels, L.R.M., Jennings, C.M.H., Lee, F.E., Blaine, J.L.The geology of the M1 kimberlite, southern BotswanaProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 58-59BotswanaExploration, Kimberlite
DS1991-1016
1991
Lee, G.Lowman, P.D.Jr., Whiting, P.J., Short, N.M., Lohmann, A.M., Lee, G.Fracture patterns on the Canadian shield: a lineament study with landsat and orbital radar imagery.Proceedings of the Seventh International Conference on Basement Tectonics, held, pp. 139-160.CanadaLandsat remote sensing, Structure, tectonics, lineaments
DS1994-0445
1994
Lee, G.Dove, A., Lee, G.Breccia filled diatreme in Permian Illawarra coal measures and Triassicstrata, Kandos, New South Wales.Royal Soc. New South Wales Journal, Vol. 127, pp. 39-45.Australia, New South WalesDiatreme, Xenoliths
DS201603-0394
2016
Lee, H.Lee, H., Muirjead, J.D., Fischer, T.P., Ebinger, C.J., Kattenhorn, S.A., Sharp, Z.D., Kianji, G.Massive and prolonged deep carbon emissions associated with continental rifting.Nature Geoscience, Vol. 9, pp. 145-149.MantleCarbon

Abstract: Carbon from Earth’s interior is thought to be released to the atmosphere mostly via degassing of CO2 from active volcanoes1, 2, 3, 4. CO2 can also escape along faults away from active volcanic centres, but such tectonic degassing is poorly constrained1. Here we use measurements of diffuse soil CO2, combined with carbon isotopic analyses to quantify the flux of CO2 through fault systems away from active volcanoes in the East African Rift system. We find that about 4?Mt?yr?1 of mantle-derived CO2 is released in the Magadi-Natron Basin, at the border between Kenya and Tanzania. Seismicity at depths of 15-30?km implies that extensional faults in this region may penetrate the lower crust. We therefore suggest that CO2 is transferred from upper-mantle or lower-crustal magma bodies along these deep faults. Extrapolation of our measurements to the entire Eastern rift of the rift system implies a CO2 flux on the order of tens of megatonnes per year, comparable to emissions from the entire mid-ocean ridge system2, 3 of 53-97?Mt?yr?1. We conclude that widespread continental rifting and super-continent breakup could produce massive, long-term CO2 emissions and contribute to prolonged greenhouse conditions like those of the Cretaceous.
DS1950-0143
1953
Lee, H.A.Lee, H.A.Two Types of Till and Other Glacial Problems in the Edmunston Grand Falls Region, New Brunswick, Quebec, Maine.Ph.d. Thesis, University Chicago, 113P.Canada, New Brunswick, United States, Maine, AppalachiaGlaciology
DS1960-0368
1963
Lee, H.A.Lee, H.A.Glacial Fans in Till from the Kirkland Lake Fault: a Methodof Gold Exploration.Geological Survey of Canada (GSC) PAPER., No. 63-45, 36P.Canada, OntarioBlank
DS1960-0566
1965
Lee, H.A.Lee, H.A.Buried Valleys Near Kirkland Lake, OntarioGeological Survey of Canada (GSC) PAPER., No. 65-14, PP. 18-20.Canada, OntarioBlank
DS1960-0567
1965
Lee, H.A.Lee, H.A.Investigations of Eskers for Mineral ExplorationGeological Survey of Canada (GSC) PAPER., No. 65-14, PP. 1-17.Canada, Ontario, Kirkland LakeProspecting, Heavy Minerals, Geochemistry
DS1960-0858
1967
Lee, H.A.Lee, H.A.Glaciofocus ResearchGeological Survey of Canada (GSC) PAPER., No. 67-1A, P. 149.Canada, OntarioBlank
DS1960-0977
1968
Lee, H.A.Lee, H.A.Glaciofocus and the Munro Esker of Northern OntarioGeological Survey of Canada (GSC) PAPER., No. 68-1A, P. 173.Canada, OntarioBlank
DS1960-0978
1968
Lee, H.A.Lee, H.A.An Ontario Kimberlite Occurrence Discovered by Application Of the Glaciofocus Method to a Study of the Munro Esker.Geological Survey of Canada (GSC) PAPER., No. 68-7, 3P.Canada, OntarioBlank
DS1960-0979
1968
Lee, H.A.Lee, H.A., Lawrence, D.E.A New Occurrence of Kimberlite in Gauthier TownshipGeological Survey of Canada (GSC) PAPER., No. 68-22, 16P.Canada, OntarioGeology
DS1960-1151
1969
Lee, H.A.Lee, H.A.Further Notes on the Munro Esker, OntarioGeological Survey of Canada (GSC) PAPER., No. 69-1A, P. 43.Canada, OntarioBlank
DS1970-0854
1973
Lee, H.A.Wolfe, W.J., Lee, H.A.Heavy Mineral Indicators in Alluvial and Esker Gravels of The Moose River Basin, James Bay Lowlands, District of CochraneOntario Department of Mines miscellaneous PAPER., No. 56, 24P.Canada, OntarioBlank
DS1975-0212
1975
Lee, H.A.Wolfe, W.J., Lee, H.A., Hicks, W.D.Heavy Mineral Indicators in Alluvial and Esker Gravels of The Moose River Basin, James Bay Lowlands.Ontario Geological Survey Geology Report, No. 126, 60P.Canada, Ontario, James Bay LowlandsProspecting, Geochemistry, Sextant, Coral Rapids, Wacousta
DS1993-0900
1993
Lee, J.Lee, J.Kimberlitic garnet and ilmenite chemistry at Kakong, Botswana: an exploration case historyProspectors and Developers Diamond Workshop, held March 27th, Toronto, BotswanaGeochemistry, Garnet, ilmenite
DS1994-1697
1994
Lee, J.Stock, J.M., Lee, J.Do microplates in subduction zones have a geological record?Tectonics, Vol. 13, No. 6, Dec. pp. 1472-1485.MantleSubduction zones
DS1994-1698
1994
Lee, J.Stock, J.M., Lee, J.Do microplates in subduction zones leave a geological record?Tectonics, Vol. 13, No. 6, Dec. pp. 1472-1487MantleSubduction, Plate tectonics
DS1995-0422
1995
Lee, J.Dixon, T.H., Robaudo, S., Lee, J., Reheis, M.C.Constraints on present day Basin and Range deformation from space geodesyTectonics, Vol. 14, No. 4, August pp. 755-772Cordillera, Basin and RangeTectonics, Deformation zones
DS201502-0072
2015
Lee, J.Lee, J., Jung, H.Lattice- preferred orientation of olivine found in diamond bearing garnet peridotites in Finsch, South Africa and implications for seismic anisotropy.Journal of Structural Geology, Vol. 70, Jan. pp. 12-22.Africa, South AfricaDeposit - Finsch
DS201511-1859
2014
Lee, J.A.Lee, J.A., Caudill, S.B., Mixon, F.G.Jr.Shine bright like a diamond: a hedonic model of grading and pricing an experience good. ( diamonds)Applied Economics, Vol. 46, 16, pp. 1829-1838.GlobalDiamond market

Abstract: Diamonds are generally evaluated on the basis of sensory characteristics, such as carat (weight), colour, clarity and cut. However, given the experience goods nature of diamonds, few consumers grasp how the sensory characteristics of these stones are evaluated by the gemological grading laboratories that independently issue diamond reports. This study extends prior research by determining whether diamonds graded by certain gemological laboratories are subject to pricing premiums or discounts in online retail markets. Regression models employing a sample of 169 483 real-time diamond offerings from online diamond retailers (e.g. Blue Nile, James Allen and Adiamor) find significant price discounts attributable to diamonds graded by the European Gemological Laboratory USA in relation to diamonds graded by the Gemological Institute of America (GIA) and significant price premiums attributable to diamonds graded by the American Gem Society in relation to diamonds graded by the GIA.
DS2001-0669
2001
Lee, J.B.Lee, J.B.FALCON gravity gradiometer technologyExploration Geophysics, Vol. 32, No. 3-4, pp. 247-51.GlobalGeophysics - gravity, Falcon
DS1994-0371
1994
Lee, J.E.Daniels, L.R.M., Jennings, C.M.H., Lee, J.E., Blaine, J.L., Billington, F.R.The geology of crater volcanics and sediments associated with the M1kimberlite, southwest Botswana.Proceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 129-139.BotswanaKimberlite, Deposit -M1
DS200912-0431
2009
Lee, J.E.Lee, J.E., Jennings, C.M.H., Blaine, J.L.The GOPE 25 kimberlite discovery, Botswana, predicated on four ilmenite grains from reconnaissance soil samples: a case history.Explore, No. 143, June pp. 1-7.Africa, BotswanaCase history - GOPE 25
DS201012-0286
2010
Lee, J.E.Hood, W.C., Lee, J.E.Diamond exploration at Wekusko Lake.Manitoba Mining Review, pp. 29-31.Canada, ManitobaDikes
DS200712-0801
2007
Lee, J.H.Park, G.S., Bae, S.C., Granick, S., Lee, J.H., Bae, S.D., Kim, T., Zuo, J.M.Naturally formed epitaxial diamond crystals in rubies.Diamond and Related Materials, Vol. 16, 2, pp. 397-400 Ingenta 1070685098TechnologyDiamond morphology
DS200612-0785
2006
Lee, J.I.Lee, M.J., Lee, J.I., Garcia, D., Moutte, J., Williams, C.T., Wall, F., Kim, Y.Pyrochlore chemistry from the Sokli phoscorite carbonatite complex, Finland: implications for the genesis of phoscorite and carbonatite association.Geochemical Journal, Vol. 40, 1, pp. 1-14.Europe, FinlandCarbonatite
DS200612-0786
2006
Lee, J.I.Lee, M.J., Lee, J.I., Hur, S.D., Kim, Y., Moutte, J., Balaganskaya, E.Sr Nd Pb isotopic compositions of the Kovdor phoscorite carbonatite complex, Kola Peninsula, NW Russia.Lithos, in press availableRussia, Kola PeninsulaCarbonatite, geochronology, FOZO, plume lithosphere
DS200712-0612
2006
Lee, J.I.Lee, M.J., Lee, J.I., Hur, S.D., Kim, Y., Moutte, J., Balaganskaya, E.Sr Nd Pb isotopic composition of the Kovdor phoscorite carbonatite Kola Peninsula, NW Russia.Lithos, Vol. 91, 1-4, pp. 250-261.RussiaGeochronology, carbonatite
DS2003-0786
2003
Lee, J.K.Lee, Mi Jung, Garcia, D., Moutte, J., Lee, J.K.Phlogopite and tetraferri phlogopite from phoscorite and carbonatite associations in theGeosciences Journal, Vol. 7, 1, March pp. 9-20.FinlandCarbonatite, Deposit - Sokli
DS200412-1104
2003
Lee, J.K.Lee, Mi Jung, Garcia, D., Moutte, J., Lee, J.K.Phlogopite and tetraferri phlogopite from phoscorite and carbonatite associations in the Sokli Massif, northern Finland.Geosciences Journal, Vol. 7, 1, March pp. 9-20.Europe, FinlandCarbonatite, Deposit - Sokli
DS1986-0338
1986
Lee, J.K.W.Hanes, J.A., Archibald, D.A., Lee, J.K.W.Reconnaissance 40 Ar-39 Ar geochronology of Kapuskasing,Matachewan and Hearst diabase dikes in the Kapuskasing structural zone and adjacent AbitibiGeological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 77. (abstract.)Ontario, QuebecTectonics, Geochronology, Argon, Dyke
DS1989-0871
1989
Lee, J.K.W.Lee, J.K.W.High resolution 40Ar/39Ar dating with a laser:techniques and application to rocks from the Kapuskasing structural zone, OntarioCentral Canada Geological Conference, A forum for current graduate, p. 41. (Abstract only)OntarioGeochronology
DS1990-0912
1990
Lee, J.K.W.Lee, J.K.W., Onstott, T.C., Hanes, J.A.An 40 Ar/39Ar investigation of the contact effects of a dyke intrusion, Kapuskasing structural zone OntarioContributions to Mineralogy and Petrology, Vol. 105, No. 1, pp. 87-105OntarioKapuskasing Zone, Geochronology, Argon
DS200712-0953
2006
Lee, J.K.W.Schmidt, P.W., Williams, G.E., Camacho, A., Lee, J.K.W.Assembly of Proterozoic Australia: implications of a revised pole for the 1070 Ma Alcurra dyke swarm, central Australia.Geophysical Journal International, Vol. 167, 2, pp. 626-634.AustraliaPaleomagnetism
DS200412-0568
2004
Lee, J.N.Fouch, M.J., Silver, P.G., Lee, J.N.Small scale variations in seismic anisotropy near Kimberley, South Africa.Geophysical Journal International, Vol. 157, 2, pp. 764-774.Africa, South AfricaGeophysics - seismics
DS1930-0306
1939
Lee, J.S.Lee, J.S.The Geology of ChinaThomas Murby And Co. London; Nordeman Publ Co. New York, 507P.ChinaRegional Geology
DS200712-0800
2007
Lee, J-H.Par, G-S., Bae, S.C., Granick, S., Lee, J-H., Bae, S-D, Kim, T., Zuo, J.M.Naturally formed epitaxial diamond crystals in rubies.Diamond and Related Materials, Vol. 16, 2, Feb., pp. 397-400.TechnologyDiamond crystallography, rubies
DS1982-0121
1982
Lee, K.Briceno, H.O., Lee, K.Application of Land sat Dat a to Geologic Mapping Tropical Jungle Environment, Caroni River Basin, Venezuela.International Symposium on Remote Sensing of Environment Proceedings, 16TH. Vol. 1, PP. 123-133.GlobalSide, Scanning Radar, Diamonds
DS200612-0787
2005
Lee, K.Lee, W.S., Sato, H., Lee, K.Scattering coefficients in the mantle revealed from the seismogram envelope analysis based on the multiple isotropic scattering model.Earth and Planetary Science Letters, In pressMantleGeophysics - seismics, mantle heterogeneity, radiative
DS201201-0854
2011
Lee, K.C.Lee, K.C., Sprague, M.R., Sussman, B.J., Nunn, J., Langford, N.K., Jin, X-M., Champoin, T., et al.Entangling microscopic diamonds at room temperature. ( quantum technology)Science, Vol. 334, no. 6060, Dec. 2, pp. 1253-1256.TechnologyQuantum state of diamonds
DS1992-0931
1992
Lee, K.D.Lee, K.D., Cohen, Y.Fractal attraction. A fractal design system for the MacintoshAcademic Press, 80p. and disc. approx. $ 50.00BookComputer, Program -Fractal design system
DS1989-0046
1989
Lee, K.H.Augustin, A.M., Kennedy, W.D., Morrison, H.F., Lee, K.H.A theoretical study of surface to borehole electromagnetic logging incased holesGeophysics, Vol. 54, No. 1, January pp. 90-99GlobalGeophysics, electromagnetic
DS1993-0901
1993
Lee, K.H.Lee, K.H., Xie, G.O.A new approach to imaging with low frequency electromagnetic fieldsGeophysics, Vol. 58, No. 6, June pp. 780-796GlobalGeophysics, Imaging
DS200412-1103
2004
Lee, K.K.Lee, K.K., O'Neill, B., Panero, W.R., Shim, S.H., Benedetti, L.R., Jeanloz, R.Equations of state of the high pressure phases of a natural peridotite and implications for the Earth's lower mantle.Earth and Planetary Science Letters, Vol. 223, 3-4, pp. 381-393.MantlePeridotite, magnesiowustite
DS200612-0784
2006
Lee, K.K.M.Lee, K.K.M., Steinle-Neumann, G.High pressure alloying of iron and xenon: 'missing' Xe in the Earth's core?Journal of Geophysical Research, Vol. 111, B2, B02202 Feb 8MantleMineralogy
DS200712-1041
2007
Lee, K.K.M.Steinle-Neumann, G., Lee, K.K.M., Akber-Knutson, S.Potassium partitioning in the lowermost mantle from ab-initio computations.Plates, Plumes, and Paradigms, 1p. abstract p. A971.MantleGeodynamics
DS201012-0428
2009
Lee, K.K.M.Lee, K.K.M.The enigma of 'D'.Nature, Vol. 462, Dec. 10, pp. 731-732.MantleCore, boundary
DS201909-2033
2019
Lee, K.K.M.Deng, J., Karki, B.B., Ghosh, D.B., Lee, K.K.M.First principles study of FeO2Hx solid and melt system at high pressures: implications for ultralow-velocity zones. ( Lower mantle may have a wet bottom** citation note) Journal of Geophysical Research: Solid Earth, Vol. 124, pp. 4566-4575.Mantleboundary

Abstract: Ultralow?velocity zones (ULVZs) are 5-40?km?thick patches lying above Earth's core-mantle boundary. They are characterized with anomalously low seismic velocities compared with the ambient mantle and may contain important clues on the thermochemical evolution of the Earth. A recent experimental study argued that ULVZs may be caused by the accumulation of pyrite?type FeO2Hx (P phase) at the bottom of the mantle. Here for the first time, we systematically study the thermoelastic properties of both FeO2Hx solid and liquid phases. We find that P phase is likely melted near the core-mantle boundary and thus cannot be the source of ULVZs. Furthermore, in order for the molten product of P phase to cause ULVZs, the dense and nearly inviscid melts must be dynamically stable and confined within the ULVZs, which requires that the mantle is highly viscous and/or convects vigorously.
DS201910-2255
2019
Lee, K.K.M.Du, Z., Deng, J., Miyazaki, Y., Mao, H-k., Karki, B.B., Lee, K.K.M.Fate of hydrous Fe-silicate melt in Earth's deep mantle.Geophysical Research Letters, Vol. 46, doi.org/ 10.1029/ 2019GL083633Mantlemelting

Abstract: Planetary?scale melting is ubiquitous after energetic impacts early in Earth's history. Therefore, determining key melt properties, such as density, is of great significance to better understand Earth's formation and subsequent evolution. In this study, we performed state?of?art first?principles molecular dynamics simulations to examine the density of deep mantle melts, namely, hydrous Fe?rich silicate melts. We find that such hydrous melts can be gravitationally stable near Earth's core?mantle boundary given their likely high iron content. This has great implications for Earth's thermochemical evolution, as well as Earth's volatile cycle.
DS201911-2520
2019
Lee, K.K.M.Du, Z., Deng, J., Miyazaki, Y., Mao, H-K., Karki, B.B., Lee, K.K.M.Fate of hydrous Fe-rich silicate melt in Earth's deep mantle.Geophysical Research Letters, Vol. 46, 16, pp. 9466-9473.Mantlewater

Abstract: Planetary-scale melting is ubiquitous after energetic impacts early in Earth's history. Therefore, determining key melt properties, such as density, is of great significance to better understand Earth's formation and subsequent evolution. In this study, we performed state-of-art first-principles molecular dynamics simulations to examine the density of deep mantle melts, namely, hydrous Fe-rich silicate melts. We find that such hydrous melts can be gravitationally stable near Earth's core-mantle boundary given their likely high iron content. This has great implications for Earth's thermochemical evolution, as well as Earth's volatile cycle.
DS1998-0592
1998
Lee, M.Harte, B., Hutchison, M.T., Lee, M., Harris, J.W.Inclusions of (Mg, Fe) O in mantle diamonds7th International Kimberlite Conference Abstract, pp. 308-10.South Africa, Australia, Zimbabwe, Brazil, LesothoTrace elements, mineralogy, Deposit - Sao Luiz, magnesium, iron
DS201412-0219
2014
Lee, M.Edwards, P., Lee, M.Cathodluminescence hyper spectral imaging in geoscience.GAC/MAC short Course, MayTechnologyCathodluminescence
DS1999-0403
1999
Lee, M.J.Lee, M.J., Garcia, D., Moutte, Wall, Williams, WoolleyPyrochlore and whole rock chemistry of carbonatites and phoscorites at Sokli Finland.Stanley, SGA Fifth Biennial Symposium, pp. 651-4.FinlandCarbonatite, Deposit - Sokli
DS2001-0670
2001
Lee, M.J.Lee, M.J., Garcia, Moutte, Wall, Williams, WoolleyPyrochlore chemistry and the transition from Calcium carbonatites and phoscorites to magnesium-iron carbonatites..Journal of South African Earth Sciences, Vol. 32, No. 1, p. A 24 (abs)FinlandCarbonatite, Sokli Complex
DS200612-0785
2006
Lee, M.J.Lee, M.J., Lee, J.I., Garcia, D., Moutte, J., Williams, C.T., Wall, F., Kim, Y.Pyrochlore chemistry from the Sokli phoscorite carbonatite complex, Finland: implications for the genesis of phoscorite and carbonatite association.Geochemical Journal, Vol. 40, 1, pp. 1-14.Europe, FinlandCarbonatite
DS200612-0786
2006
Lee, M.J.Lee, M.J., Lee, J.I., Hur, S.D., Kim, Y., Moutte, J., Balaganskaya, E.Sr Nd Pb isotopic compositions of the Kovdor phoscorite carbonatite complex, Kola Peninsula, NW Russia.Lithos, in press availableRussia, Kola PeninsulaCarbonatite, geochronology, FOZO, plume lithosphere
DS200712-0612
2006
Lee, M.J.Lee, M.J., Lee, J.I., Hur, S.D., Kim, Y., Moutte, J., Balaganskaya, E.Sr Nd Pb isotopic composition of the Kovdor phoscorite carbonatite Kola Peninsula, NW Russia.Lithos, Vol. 91, 1-4, pp. 250-261.RussiaGeochronology, carbonatite
DS200712-0983
2007
Lee, M.J.Shin, D.B., Lee, M.J.Oxygen and sulfur isotope characteristics of the Salmagora Complex, Kola Peninsula.Plates, Plumes, and Paradigms, 1p. abstract p. A932.Russia, Kola PeninsulaIjolite, Meliltolite
DS200812-1056
2008
Lee, M.J.Shin, D.B., Oh, Y.B., Lee, M.J.Petrological and geochemical characteristics of the Hongcheon carbonatite phoscorite, Korea.Goldschmidt Conference 2008, Abstract p.A861.Asia, KoreaCarbonatite
DS1992-0570
1992
Lee, M.R.Gilmour, I., Russell, S.S., Arden, J.W., Lee, M.R., Franchi, I.A.Terrestrial carbon and nitrogen isotopic ratios from Cretaceous-Tertiary boundary nanodiamondsScience, Vol. 258, December 4, pp. 1624-1626GlobalGeochronology, Nanodiamonds
DS1992-1315
1992
Lee, M.R.Russell, S.S., Pillenger, C.T., Arden, J.W., Lee, M.R.A new type of meteoritic diamond in the enstatite chondrite AbeeScience, Vol. 256, No. 5054, April 10, pp. 206-209GlobalMeteorites, Diamond
DS200612-1030
2005
Lee, M.R.Parsons, I., Lee, M.R.Minerals are not just chemical compounds.The Canadian Mineralogist, Vol. 43, 6, Dec. pp. 1959-1992.TechnologyGeochemistry - microtexture. solutions, weathering
DS201012-0429
2010
Lee, M.R.Lee, M.R.Transmission electron microscopy (TEM) of Earth and planetary materials: a review.Mineralogical Magazine, Vol. 74, Feb. 1, pp. 1-27.TechnologyMineralogy - TEM
DS1989-0010
1989
Lee, M.W.Agena, W.F., Lee, M.W., Grow, J.A.Reprocessing of the COCORP dat a recorded across the Wichita Mountain Uplift and the Anadarko Basin in southern OklahomaUnited States Geological Survey (USGS) Open File, No. 89-0357, 20p. $ 3.50GlobalGeophysics, Tectonics -COCORP
DS1990-1043
1990
Lee, M.W.Milkereit, B., Green, A.G., Lee, M.W., Agena, W.F., Spencer, C.Pre- and post stack migration of Glimpce reflection dataTectonophysics, Vol. 174, No. 1/2, March 1, pp. 1-14Ontario, MichiganGeophysics -Seismics, Glimpce
DS1992-0744
1992
Lee, M.W.Hutchinson, D.R., Lee, M.W., Behrendt, J., Cannon, W.F., GreenVariations in the reflectivity of the Moho transition zone beneath The midcontinent Rift System of North America. Results from true amplitude GlimpcedataJournal of Geophysical Research, Vol. 97, No. B4, April 10, pp. 4721-4738MidcontinentGeophysics -seismics, Tectonics
DS1992-0649
1992
Lee, M.Y.Haimson, B.C., Lee, M.Y.Stress measurements in Quimby granite and the state of stress in The western midcontinentGeological Society of America (GSA) Abstract Volume, Vol. 24, No. 4, April p. 17. abstract onlyIowaMidcontinent Rift, Structure
DS1991-0217
1991
Lee, M.Y.W.Cannon, W.F., Lee, M.Y.W., Hinze, W.J., Schulz, K.J., Green, A.G.Deep crustal structure of the Precambrian basement beneath northern LakeMichigan, midcontinent North AmericaGeology, Vol. 19, No. 3, March pp. 207-210MichiganTectonics, Structure -crustal
DS1981-0263
1981
Lee, R.J.Lee, R.J.Diamond Production in GuyanaJournal of Gemology AND PROCEEDINGS of THE GEMMOLOGICAL ASSOCIAT, Vol. 17, No. 7, PP. 465-479.GuyanaKimberlite, Production, Diamond
DS1982-0368
1982
Lee, R.J.Lee, R.J., Aquitaine australia minerals ltd., MIMETS EXPLORATION PTY.El 2528 Grass Plains Nt Annual Report 1980-1981Northern Territory Geological Survey Open File Report, No. CR 82/298, 17P.Australia, Northern TerritoryProspecting, Geophysics
DS201502-0073
2015
Lee, S.Lee, S., Suh, J., Park, H-D.BoreholeAR: a mobile tablet application for effective borehole database visualization using an augmented reality technology.Computers & Geosciences, Vol. 76, pp. 41-49.TechnologyNot specific to diamonds
DS201511-1886
2015
Lee, S.J.Tarum, A., Lee, S.J., Yap, C.M., Finkelstein, K.D., Misra, D.S.Impact of impurities and crystal defects on the performance of CVD diamond detectors.Diamond and Related Materials, in press available, 6p.TechnologySynthetics - Radiation detectors

Abstract: Radiation detectors based on diamond are highly favored for particle physics research due to the superior radiation hardness. In this work, we investigate the influence of impurities and crystalline imperfections on the charge collection efficiency (CCE) of single crystal diamond. Seventeen (17) ultra-low fluorescent diamond samples grown by microwave plasma chemical vapor deposition method from IIa Technologies PTE LTD are pre-selected for this study. The measured CCE of all samples using 241Am (?-particles) as ionizing source are analyzed together with the concentration of trace impurities and crystalline imperfection in the crystal. The amounts of impurities are quantified from integrated fluorescence intensity arising from the nitrogen vacancies (NV) created during different CVD growth process conditions. The crystal imperfections are assessed by X-ray rocking curves from X-ray topography images obtained at the Cornell High Energy Synchrotron Source. The CCE decays rapidly as the intensity of NV (INV), phonon sideband approaches that of diamond 2nd order Raman peak which follows the relation: View the MathML sourceCCEINV=100/1+INV1.052. The energy resolution, ?E/E (ratio of the energy spectrum width to the most probable peak) highly correlates with broader rocking curve width distribution. Prime novelty statement: This work provides an understanding on the most important factors that contribute to degradation of charge collection efficiency (CCE) in diamond based detectors and sensors. The CCE decays rapidly as the intensity of nitrogen vacancy phonon sideband approaches that of diamond 2nd order Raman peak which follows the relation: View the MathML sourceCCEINV=100/1+INV1.052. The energy resolution, that is the ratio of the energy spectrum width to the most probable peak, highly correlates with broader X-ray rocking curve width distribution.
DS1997-0149
1997
Lee, S.K.Buselli, G., Lee, S.K.Modeling of drill-hole TEM responses from multiple targetsExploration Geophysics, Bulletin of Australian, Vol. 27, No. 2-3, Sept. pp. 141-154GlobalGeophysics - TEM, copper, lead, zinc, nickel, Model
DS200812-0642
2008
Lee, S.K.Lee, S.K., Lin, J.F., Cai, Y.Q., Hiraoka, N., Eng, P.J., Okuchi, T., Mao, H., Meng, Y., Hu, M.Y.,Chow, P.X ray Raman scattering study of MgSi)3 glass at high pressure: implication for triclustered MgSiO3 melt in Earth's mantle.Proceedings of National Academy of Sciences USA, Vol. 105, 23, June 10, pp. 7925-7929.MantleMelting
DS201808-1744
2018
Lee, S.K.Fu, S., Yang, J., Zhang, Y., Okuschi, T., McCammon, C., Kim, H-I., Lee, S.K., Lin, J-F.Abnormal elasticity of Fe bearing bridgmanite in the Earth's lower mantle.Geophysical Research Letters, Vol. 45, 10, pp. 4725-4732.Mantlebridgmanite

Abstract: Seismic heterogeneities in the Earth's lower mantle have been attributed to thermal and/or chemical variations of constituent minerals. Bridgmanite is the most abundant lower?mantle mineral and contains Fe and Al in its structure. Knowing the effect of Fe on compressional and shear wave velocities (VP, VS) and density of bridgmanite at relevant pressure?temperature conditions can help to understand seismic heterogeneities in the region. However, experimental studies on both VP and VS of Fe?bearing bridgmanite have been limited to pressures below 40 GPa. In this study, VP and VS of Fe?bearing bridgmanite were measured up to 70 GPa in the diamond anvil cell. We observed drastic softening of VP by ~6(±1)% at 42.6-58 GPa and increased VS at pressures above 40 GPa. We interpret these observations as due to a spin transition of Fe3+. These observations are different to previous views on the effect of Fe on seismic velocities of bridgmanite. We propose that the abnormal sound velocities of Fe?bearing bridgmanite could help to explain the seismically observed low correlation between VP and VS in the mid?lower mantle. Our results challenge existing models of Fe enrichment to explain the origin of Large Low Shear Velocity provinces in the lowermost mantle.
DS1994-1015
1994
Lee, S.M.Lee, S.M.Diamonds -everyone's best friendSampe. J., #PA176, Vol. 29, No. 6, Nov-Dec. 2p.GlobalEconomics, News item
DS201511-1822
2015
Lee, S.R.G.J.Bartels, A., Nielsen, T.F.D., Lee, S.R.G.J., Upton, B.G.J.Petrological and geochemical characteristics of Mesoproterozoic dyke swarms in the Gardar Province, south Greenland: evidence for a major sub-continental lithospheric mantle component in the generation of the magmas.Mineralogical Magazine, Vol. 79, 4, pp. 909-939.Europe, GreenlandDike swarms

Abstract: The Mesoproterozoic Gardar Province in South Greenland developed in a continental rift-related environment. Several alkaline intrusions and associated dyke swarms were emplaced in Archaean and Ketilidian basement rocks during two main magmatic periods at 1300-1250 Ma and 1180-1140 Ma. The present investigation focuses on mafic dykes from the early magmatic period (‘Older Gardar’) and the identification of their possible mantle sources. The rocks are typically fine- to coarse-grained dolerites, transitional between tholeiitic and alkaline compositions with a general predominance of Na over K. They crystallized from relatively evolved, mantle-derived melts and commonly show minor degrees of crustal contamination. Selective enrichment of the large ion lithophile elements Cs, Ba and K and the light rare-earth elements when compared to high field-strength elements indicate significant involvement of a sub-continental lithospheric mantle (SCLM) component in the generation of the magmas. This component was affected by fluid-dominated supra-subduction zone metasomatism, possibly related to the Ketilidian orogeny ~500 Ma years prior to the onset of Gardar magmatism. Melt generation in the SCLM is further documented by the inferential presence of amphibole in the source region, negative calculated ?Nd(i) values (?0.47 to ?4.40) and slightly elevated 87Sr/86Sr(i) (0.702987 to 0.706472) ratios when compared to bulk silicate earth as well as relatively flat heavy rare-earth element (HREE) patterns ((Gd/Yb)N = 1.4-1.9) indicating melt generation above the garnet stability field. The dyke rocks investigated show strong geochemical and geochronological similarities to pene-contemporaneous mafic dyke swarms in North America and Central Scandinavia and a petrogenetic link is hypothesized. Considering recent plate reconstructions, it is further suggested that magmatism was formed behind a long-lived orogenic belt in response to back-arc basin formation in the time interval between 1290-1235 Ma.
DS1994-1016
1994
Lee, S.S.Lee, S.S., Minsek, D.W., Vestyck, D.J., Chen, P.Growth of diamond from atomic hydrogen and a supersonic free jet of methylradicals.Science, Vol. 263, March 14, pp. 1596-1598.GlobalDiamond synthesis
DS2003-0787
2003
Lee, S.T.Lee, S.T., Lifshitz, Y.The road to diamond wafersNature, No. 6948, July 31, p. 500.GlobalDiamond - materials, synthesis
DS200412-1105
2003
Lee, S.T.Lee, S.T., Lifshitz, Y.The road to diamond wafers.Nature, No. 6948, July 31, p. 500.TechnologyDiamond - materials, synthesis
DS1993-0937
1993
Lee, T.Lumadyo, E., McCabe, R., Harder, S., Lee, T.Borneo: a stable portion of the Eurasian margin since the EoceneJournal of Southeast Asian Earth Sciences, Vol. 8, No. 104, pp. 225-231.GlobalPaleomagnetics, Structure
DS1995-1079
1995
Lee, T.Lee, T.Resource/ reserve statements -due diligence by directorsAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, No. 95-106, 9pGlobalEconomics, Legal -due diligence, ore reserves
DS1988-0416
1988
Lee, T.A.Lee, T.A.Disclosure- resource/reserve statements -moving into the ninetiesAusIMM Sydney Branch, Minerals and Exploration at the Crossroads held, pp. 81-88. Database # 17359GlobalOre reserves
DS2003-1120
2003
Lee, T.Y.Qian, Q., Chu, M.F., Chung, S.L., Lee, T.Y., Xiong, X.M.Was Triassic continental subduction solely responsible for the generation of MesozoicInternational Geology Review, Vol. 45, 7, July pp. 659-70.ChinaMagmatism - UHP
DS200412-1604
2003
Lee, T.Y.Qian, Q., Chu, M.F., Chung, S.L., Lee, T.Y., Xiong, X.M.Was Triassic continental subduction solely responsible for the generation of Mesozoic mafic magmas and mantle source enrichmentInternational Geology Review, Vol. 45, 7, July pp. 659-70.ChinaMagmatism - UHP
DS200412-1605
2003
Lee, T-Y.Qian, Q., Chung, S-L., Lee, T-Y., Wen, D.J.Mesozoic high Ba Sr granitoids from North China: geochemical characteristics and geological implications.Terra Nova, Vol. 15, pp. 272-278.ChinaUHP - Dabie Sulu orogen
DS200612-1347
2005
Lee, V.E.Speziale, S., Milner, A., Lee, V.E., Clark, S.M.Iron spin transition in Earth's mantle.Proceedings of National Academy of Science USA, Vol. 102, no. 50, Dec. 13, p. 17918.MantleGeochemistry
DS1994-1017
1994
Lee, W.Lee, W., Wyllie, P.J.Experimental dat a on liquid immiscibility, crystal fractionation and origin of calciocarbonatites and natro.International Geology Review, Vol. 36, No. 9, Sept., pp. 797-819.GlobalPetrology -experimental, Carbonatite, natroCarbonatite
DS1994-1018
1994
Lee, W.Lee, W., Wyllie, P.J.Conditions for formation of immiscible carbonate rich magmas from primitive magnesian nephelinites.Geological Society of America (GSA) Abstract Volume, Vol. 26, No. 7, ABSTRACT only p. A224.MantleExperimental petrology, Nephelinite
DS1997-0668
1997
Lee, W.Lee, W., Wyllie, J.Liquid immiscibility between nephelinite and carbonatite from 1.0 to 2.5GPa compared mantle melt...Contrib. Mineralogy and Petrology, Vol. 127, No. 1-2, pp. 1-16.MantleCarbonatite, Nephelinite
DS1992-0932
1992
Lee, W.H.Lee, W.H.Descriptions of seismic array componentsUnited States Geological Survey (USGS) Open File, No. 92-0598, 111p. and 1 disc $ 26.75GlobalGeophysics -seismics, Descriptions of array components
DS1993-0902
1993
Lee, W.H.Lee, W.H., Dodge, D.A.A course on PC based seismic networksUnited States Geological Survey (USGS) Open File, No. 92-0441, 535p. $ 81.00GlobalGeophysics -seismics, Course notes
DS200612-0125
2006
Lee, W.H.Ben-Zion, Y., Lee, W.H.Advances in studies of heterogeneities in the Earth's lithosphere.Springer, April, 640p. $ 79.95 ISBN 3-7643-7579-5MantleBook - seismics ( earthquakes)
DS1994-1019
1994
Lee, W.J.Lee, W.J., Wyllie, P.J.The generation of Na-rich carbonatite magmas at crustal conditionsEos, Annual Meeting November 1, Vol. 75, No. 44, p.720. abstractGlobalCarbonatite
DS1994-1020
1994
Lee, W.J.Lee, W.J., Wyllie, P.J.Experimental dat a bearing on liquid immiscibility, crystal origin calciocarbonatites....International Geology Review, Vol. 36, No. 9, Sept. pp. 797-819.GlobalCarbonatite, NatroCarbonatite
DS1997-0669
1997
Lee, W.J.Lee, W.J., Wyllie, P.J.Liquid immiscibility in the join NaAlSiO4 nickel AlSi3O8 CaCos at 1 GPA:implications for crustal carbonatites.Journal of Petrology, Vol. 38, No. 9, Sept. 1, pp. 1113-1136.GlobalMineral chemistry, Carbonatite
DS1997-1272
1997
Lee, W.J.Wyllie, P.J., Lee, W.J.Experimental illustration of how crustal carbonatites form via silicate carbonate liquid immiscibility.Geological Association of Canada (GAC) Abstracts, MantleCarbonatite
DS1997-1273
1997
Lee, W.J.Wyllie, P.J., Lee, W.J.Primary calciocarbonatite magmas from the mantle? Not according to experimental phase equilibrium data.Geological Association of Canada (GAC) Abstracts, MantleCarbonatite, Petrology - experimental
DS1998-0849
1998
Lee, W.J.Lee, W.J., Wyllie, P.J.Processes of crustal carbonatite formation by liquid immiscibility anddifferentiation, elucidated models..Journal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 2005-13.MantleCarbonatite, nephelinite, sovite, Petrology - experimental
DS1998-1601
1998
Lee, W.J.Wyllie, P.J., Lee, W.J.Kimberlites, carbonatites, peridotites and silicate carbonate liquidimmiscibility, explained in system..7th International Kimberlite Conference Abstract, pp. 974-6.GlobalExperimental petrology, Carbonatite
DS1998-1602
1998
Lee, W.J.Wyllie, P.J., Lee, W.J.Model system controls on conditions for formation of magnesiocarbonatite and calco carbonatite magmas...Journal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 1885-94.MantleCarbonatite, Magmatism
DS1999-0811
1999
Lee, W.J.Wyllie, P.J., Lee, W.J.Kimberlites, carbonatites, peridotites and silicate carbonate liquid immiscibility explained in parts....7th International Kimberlite Conference Nixon, Vol. 2, pp. 923-32.GlobalSystem ( CaO-(Na2O+K2O)-(MgO+FeO)-(SiO2+Al20)-Co2, Melting - melilitites
DS200612-0787
2005
Lee, W.S.Lee, W.S., Sato, H., Lee, K.Scattering coefficients in the mantle revealed from the seismogram envelope analysis based on the multiple isotropic scattering model.Earth and Planetary Science Letters, In pressMantleGeophysics - seismics, mantle heterogeneity, radiative
DS1998-0282
1998
Lee, Y.Cranganu, C., Lee, Y., Deming, D.Heat flow in Oklahoma and the south central United StatesJournal of Geophysical Research, Vol. 103, No. 11, Nov. 10, pp. 27107-22.GlobalGeothermometry
DS1975-0553
1977
Lee. FLee. FStream System Analyses for Streams in the Woorragee Area, Buckworth, Northeastern Victoria.Private Report, 3P.Australia, VictoriaDiamond, Geomorphology
DS202002-0218
2019
Leech, M.Sonin, V., Leech, M., Chepurov, A., Zhimulev, E., Chepurov, A.Why are diamonds preserved in UHP metamorphic complexes? Experimental evidence for the effect of pressure on diamond graphitization.International Geology Review, Vol. 61, 4, pp. 504-519.Russia, Chinacoesite, UHP

Abstract: The preservation of metastable diamond in ultrahigh-pressure metamorphic (UHPM) complexes challenges our understanding of the processes taking place during exhumation of these subduction zone complexes. The presence of diamonds in UHPM rocks implies that diamonds remained metastable during exhumation, and within thermodynamic stability of graphite for an extended period. This work studies the influence of pressure on the surface graphitization rate of diamond monocrystals in carbonate systems to understand the preservation of microdiamond during exhumation of UHP subduction complexes. Experiments were performed with 2-3 mm synthetic diamond monocrystals at 2-4 GPa in ????3 (1550°?) and ?2??3 (1450°?) melts using a high-pressure multi-anvil apparatus. The highest rate of surface graphitization took place at 2 GPa; diamond crystals were almost completely enveloped by a graphite coating. At 4 GPa, only octahedron-shaped pits formed on flat {111} diamond crystal faces. Our results demonstrate that the surface graphitization rate of diamonds in the presence of carbonate melts at 1450-1550°C increases with decreasing pressure. Decreased pressure alone can graphitize diamond regardless of exhumation rate. Metastable diamond inclusions survive exhumation with little or no graphitization because of excess pressure up to 2 GPa acting on them, and because inclusions are protected from interaction with C-O-H fluid.
DS1996-0830
1996
Leech, M.L.Leech, M.L., Ernst, G.W.Carbon isotope compositions for graphite from the Maksyutov Complex, South Ural Mountains, Russia.Geological Society of America, Abstracts, Vol. 28, No. 7, p. A-46RussiaEclogite, Metamorphic rocks
DS1998-0850
1998
Leech, M.L.Leech, M.L., Ernst, W.G.Graphite pseudomorphs after diamond? a carbon isotope and spectroscopic study of graphite cuboids ...Geochimica et Cosmochimica Acta, Vol. 62, No. 12, pp. 2143-54.Russia, UralsMaksyutov Complex, Diamond genesis, graphite
DS2000-0562
2000
Leech, M.L.Leech, M.L.Arrested development: eclogitization, delamination and tectonic collapseGeological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-32.NorwayEclogites, Subduction - slab
DS2001-0671
2001
Leech, M.L.Leech, M.L.Arrested orogenic development: eclogitization, delamination, and tectonic collapse.Earth and Planetary Science Letters, Vol. 185, No. 1-2, Feb.15, pp.149-59.MantleEclogite, Tectonics
DS2003-0137
2003
Leech, M.L.Bostick, B.C., Jones, R.E., Ernst, W.G., Chen, C., Leech, M.L., Beane, R.J.Low temperature microdiamond aggregates in the Maksyutov metamorphic complexAmerican Mineralogist, Vol. 88, pp. 1709-17.Russia, UralsGeochemistry
DS200412-0185
2003
Leech, M.L.Bostick, B.C., Jones, R.E., Ernst, W.G., Chen, C., Leech, M.L., Beane, R.J.Low temperature microdiamond aggregates in the Maksyutov metamorphic complex, South Ural Mountains, Russia.American Mineralogist, Vol. 88, pp. 1709-17.Russia, UralsGeochemistry
DS200412-1106
2004
Leech, M.L.Leech, M.L., Willingshofer, E.Thermal modeling of the UHP Maksyutov Complex in the South Urals.Earth and Planetary Science Letters, Vol. 226, 1-2, Sept. 30, pp. 85-99.Russia, UralsGeothermometry
DS200612-0788
2006
Leech, M.L.Leech, M.L., Webb, L.E., Yang, T.N.Diachronous histories for the Dabie Sulu orogen from high temperature geochronology.Geological Society of America, Special Paper, No. 403, pp. 1-22.ChinaUHP
DS200612-1515
2006
Leech, M.L.Webb, L.E., Leech, M.L., Yang, T.N.49 Ar 39 Ar thermochronology of the Sulu terrane: Late Triassic exhumation of high and ultrahigh pressure rocks -implications for Mesozoic tectonics East Asia.Geological Society of America, Special Paper, No. 403, pp. 77-92.ChinaUHP
DS200612-1516
2006
Leech, M.L.Webb, L.E., Leech, M.L., Yang, T.N.40 Ar 39 Ar thermochronology of the Sulu terrane: Late Triassic exhumation of high and UHP rocks and implications for Mesozoic tectonics in East Asia.Geological Society of America Special Paper, No. 403, pp. 77-92.ChinaUHP - Sulu, Dabie, geothermometry
DS1990-0111
1990
Leeder, M.R.Alexander, J., Leeder, M.R.Geomorphology and surface tilting in an active extensional basin, southwestMontana, USAJournal of the Geological Society of London, Vol. 147, pt. 3, May pp. 461-468MontanaGeomorphology, Basin
DS1980-0214
1980
Leelanandam, C.Leelanandam, C., Ratnakar, J.Ocellar Lamprophyres from the Purimetla Alkaline Pluton, Prakassam District, Andhra Pradesh.Quarterly Journal of Geology MIN. METL. SOC. INDIA., Vol. 52, No. 3, PP. 77-79.India, Andhra PradeshLamprophyre
DS1981-0264
1981
Leelanandam, C.Leelanandam, C.Some Observations on the Alkaline Province in Andhra PradeshCurrent Science., Vol. 50, No. 18, PP. 799-802.India, Andhra PradeshRelated Rocks
DS1989-0872
1989
Leelanandam, C.Leelanandam, C.The Prakasam alkaline province in Andhra Pradesh, IndiaJournal of Geological Society India, Vol. 34, July pp. 25-45IndiaAlkaline rocks, PrakasaM.
DS1989-0873
1989
Leelanandam, C.Leelanandam, C., Srinivasan, T.P., Ratnakar, J.The sub-alkaline and alkaline rocks of the Settupallecomplex, Prakasamdistrict, Andhra Pradesh IndiaGeological Society of India, Memoir, Editor C. LeelanandaM., No. 15, pp. 241-265IndiaAlkaline rocks, Fayalite
DS1989-1254
1989
Leelanandam, C.Ratnakar, J., Leelanandam, C.Petrology of the alkaline plutons from the eastern and southern peninsulaIndiaGeological Society of India, Memoir, Editor C. LeelanandaM., No. 15, pp. 145-176IndiaAlkaline rocks, Tectonics, list of alkali
DS1989-1464
1989
Leelanandam, C.Subrahmanyam, N.P., Leelanandam, C.Differentiation due to probable initial immiscibility in the Musala Pluton of the Mundwara alkali igneousComplex, Rajasthan, IndiaGeological Society of India, Memoir, Editor C. LeelanandaM., No. 15, pp. 25-46IndiaAlkaline rocks, Pseudoleucite
DS201112-0559
2011
Leelanandam, C.Kumar, K.V., Leelanandam, C., Ernst, W.G.Formation and fragmentation of the Paleoproterozoic supercontinent Columbia: evidence from the Eastern Ghats granulite belt, southeast India.International Geology Review, Vol. 53, 11-12, pp. 1297-1311.IndiaRodinia
DS201112-0560
2011
Leelanandam, C.Kumar, K.V., Leelanandam, C., Ernst, W.G.Formation and fragmentation of the Paleoproterozoic supercontinent Columbia: evidence from the Eastern Gnats granulite belt, southeast India.International Geology Review, Vol. 53, no. 11-12, pp. 1297-1311.IndiaTectonics
DS200912-0416
2008
Leelandandam, C.Kumar, K.V., Leelandandam, C.Evolution of the eastern Ghats belt, India: a plate tectonic perspective.Journal of the Geological Society of India, Vol. 72, 6, pp. 720-749,IndiaTectonics
DS202007-1158
2020
Leelawatanasuk, T.Leelawatanasuk, T., Atichat, W., Pisutha-Arnond, V., Sutthirat, C., Jakkawanvibul, J., GITTwo decades of GIT's ruby and sapphire color standards.incolorMagazine.com, Vol. winter pp. 96-103.Asia, Thailandsapphire colour
DS1983-0449
1983
Leeman, W.P.Menzies, M.A., Leeman, W.P., Hawkesworth, C.J.Isotope Geochemistry of Cenozoic Volcanic Rocks Reveals Mantle Heterogeneity Below Western UsaNature., Vol. 303, No. 5914, PP. 205-209.United StatesGenesis, Geochemistry
DS1988-0218
1988
Leeman, W.P.Fitton, J.G., James, D., Kempton, P.D., Ormerod, D.S., Leeman, W.P.The role of lithospheric mantle in the generation of late Cenozoic basic magmas in the Western UnitedStatesJournal of Petrology, Special Volume 1988- Oceanic and Continental, pp. 331-349United States, Colorado PlateauHopi Buttes
DS1989-1135
1989
Leeman, W.P.Norman, M.D., Leeman, W.P.Geochemical evolution of eastern Bahia, Brasil: aprobable early Proterozoic subduction-related magmatic arcEarth and Planetary Science Letters, Vol. 94, No. 1/2, August pp. 78-96IdahoGeochemistry, Magma
DS1990-1068
1990
Leeman, W.P.Morris, J.D., Leeman, W.P., Tera, F.The subducted component in island arc lavas: constraints from Berylium isotopes and Boron-Berylium systematicsNature, Vol. 344, No. 6261, March 1, pp. 31-36GlobalPlate tectonics, Island arcs -Beryllium /boron
DS1992-0933
1992
Leeman, W.P.Leeman, W.P., Oldow, J.S., Hart, W.K.Lithosphere-scale thrusting in the western U.S. Cordillera as constrained by Sr and neodymium isotopic transitions in Neogene volcanic rocksGeology, Vol. 20, No. 1, January pp. 63-66Idaho, Oregon, NevadaGeochronology, Tectonics -thrusts
DS1992-0934
1992
Leeman, W.P.Leeman, W.P., Sisson, V.B., Reid, M.R.Boron geochemistry of the lower crust: evidence from granulite terranes and deep crustal xenolithsGeochimica et Cosmochimica Acta, Vol. 56, No. 2, February pp. 775-788MantleGeochemistry, Xenoliths
DS1992-1084
1992
Leeman, W.P.Moran, A.E., Sisson, V.B., Leeman, W.P.Boron depletion during progressive metamorphism: implications for subduction processes #1Earth and Planetary Science Letters, Vol. 111, No. 2-4, July pp. 319-330Globalmetamorphism, Subduction processes
DS1992-1085
1992
Leeman, W.P.Moran, A.E., Sisson, V.B., Leeman, W.P.Boron depletion during progressive metamorphism: implications for subduction processes #2Earth and Planetary Science Letters, Vol. 111, pp. 331-349New MexicoKilbourne Hole material, Tectonics
DS1993-0634
1993
Leeman, W.P.Harry, D.L., Sawyer, D.S., Leeman, W.P.The mechanics of continental extension in western North America:Earth and Planetary Science Letters, Vol. 117, pp. 59-71Nevada, CordilleraTectonics, Structure Great Basin
DS1993-0903
1993
Leeman, W.P.Leeman, W.P., Harry, D.L.A binary source model for extension related magmatism in the Great Basin, western North AmericaScience, Vol. 262, December 3, pp. 1550-1554Cordillera, NevadaGreat Basin, Tectonics
DS1995-0760
1995
Leeman, W.P.Harry, D.L., Leeman, W.P.Partial melting of melt metasomatized subcontinental mantle and magmA source potential of lower lithosphere.Journal of Geophysical Research, Vol. 100, No. B6, June 10, pp. 10, 255-10, 270.MantleMetasomatism
DS1996-0439
1996
Leeman, W.P.Ertan, I.E., Leeman, W.P.Metasomatism of Cascades subarc mantle: evidence from a rare phlogopiteortho pyroxenite xenolith.Geology, Vol. 24, No. 5, May pp. 451-454.GlobalXenoliths, Mantle -upper mantle
DS1996-0831
1996
Leeman, W.P.Leeman, W.P., Sisson, V.B.Geochemistry of boron and its implications for crustal and mantleprocessesReviews in Mineralogy, Vol. 33, pp. 645-708MantleBoron, Geochemistry
DS1996-1236
1996
Leeman, W.P.Ryan, J.G., Leeman, W.P., Morris, J.D., Langmuir, C.H.The boron systematics of intraplate lavas: implications for crust and mantle evolution.Geochimica et Cosmochimica Acta, Vol. 60, No. 3, Feb. pp. 415-422.MantleBoron
DS1998-0851
1998
Leeman, W.P.Leeman, W.P., Ertan, I.E.Diverse invasive melts in Cascadia mantle xenoliths: no subductionconnection.Mineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 875-6.GlobalSubduction, Websterite
DS1998-0852
1998
Leeman, W.P.Leeman, W.P., Tonarini, S.Fluids in subduction zone magmatism: implications of boron geochemistryMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 873-4.MantleGeochemistry - boron, Subduction
DS1999-0124
1999
Leeman, W.P.Chan, L.H., Leeman, W.P., You, C.F.Lithium isotopic composition of Central American volcanic arc lavas:implications for modificationChemical Geology, Vol. 160, No. 4, Sept. 2, pp. 255-80.GlobalMantle, Slab derived fluids
DS200612-0003
2005
Leeman, W.P.Aeoluslee, C.T., Leeman, W.P., Canil, D., Li, Z.X.Similar V/Sc systematics in MORB and Arc basalts: implications for the oxygen fugacities of their mantle source regions.Journal of Petrology, Vol. 46, 11, pp. 2313-2336.MantlePetrology
DS200612-1161
2006
Leeman, W.P.Righter, K., Leeman, W.P., Hervig, R.L.Partitioning of Ni, Co and V between spinel structured oxides and silicate melts: importance of spinel composition.Chemical Geology, in pressTechnologyMantle melting
DS200612-1446
2006
Leeman, W.P.Turner, S., Tonarini, S., Bindeman, L., Leeman, W.P., Schaefer, B.F.Boron and oxygen isotopic evidence for recycling of subducted components through the Earth's mantle since 2.5 Ga.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 28, abstract only.MantleSubduction
DS2003-0303
2003
Leeming, P.M.Crowe, W.A., Nash, C.R., Harris, L.B., Leeming, P.M., Rankin, L.R.The geology of the Rengali province: implications for the tectonic development ofJournal of Asian Earth Sciences, Vol. 21, 7, pp. 697-710.IndiaTectonics - not specific to diamonds
DS200412-0390
2003
Leeming, P.M.Crowe, W.A., Nash, C.R., Harris, L.B., Leeming, P.M., Rankin, L.R.The geology of the Rengali province: implications for the tectonic development of northern Orissa, India.Journal of Asian Earth Sciences, Vol. 21, 7, pp. 697-710.IndiaTectonics - not specific to diamonds
DS1991-0048
1991
Leers, D.Bachmann, P.K., Leers, D., Lydtin, H.Towards a general concept of diamond chemical vapour depositionDiamond and Related Materials, Vol. 1, No. 1, pp. 1-12GlobalCVD., Overview to date of methods
DS2002-0937
2002
Lees, J.Levin, V., Park, J., Brandon, M., Lees, J., Peyton, V., Gordeev, E., Ozerv, A.Crust and upper mantle of Kamchatka from teleseismic receiver functionsTectonophysics, Vol. 358, 1-4, pp. 233-265.MantleGeophysics - seismics
DS200412-0411
2004
Lees, J.M.Davaille, A., Lees, J.M.Thermal modeling of subducted plates: tear and hotspot at the Kamchatka corner.Earth and Planetary Science Letters, Vol. 226, 3-4, Oct. 15, pp. 293-304.RussiaGeophysics - seismics, dynamics, hotpots, lithosphere
DS200712-0613
2007
Lees, J.M.Lees, J.M.Seismic tomography of magmatic systems.Journal of Volcanology and Geothermal Research, Vol. 167, 1-4, pp. 36-56.MantleGeophysics - seismics
DS200412-1107
2004
Lees, R.N.Lees, R.N.VALMIN - an evolving code.AUSIMM Bulletin, March-April, p. 70-72.AustraliaLegal - valuation code
DS200512-0838
2004
Lees, T.C.Penny, S.R., Allen, R.M., Harrison, S., Lees, T.C., Murphy, F.C., Norman, A.R., Roberts, P.A.A global scale exploration risk analysis technique to determine the best mineral belts for exploration.Transactions of Institute of Mining and Metallurgy, Vol. 113, September pp. 183-194.Economics - risk analysis
DS1994-0124
1994
Lefebrve, D.Beaumier, M., Rivard, P., Lefebrve, D.Contribution de la geochimie et geophysique a la recherche de diamants longdu rift lac Temiscamingue.Quebec Min. Mines, MB 94-63, 19p.QuebecGeochemistry, geophysics, Guigues kimberlite
DS200612-0789
2006
Lefebrve, N.Lefebrve, N., Kurszlaukis, S.Contrasting eruptive styles of the 147 kimberlite, Fort a la Corne, Saskatchewan, Canada.Emplacement Workshop held September, 5p. extended abstractCanada, SaskatchewanDeposit - FALC, volcanism
DS2000-0682
2000
LefebvreMoorhead, J., Beaumier, M., Lefebvre, Bernier, MartelKimberlites, lineaments et rifts crustaux au Quebec #2Quebec Department of Mines, Report, 69p.QuebecKimberlites, tectonics, lineaments, rifts, Area - overviews
DS1990-0947
1990
Lefebvre, E.J.Loncarevic, B.D., Feininger, T., Lefebvre, E.J.The Sept-Iles layered mafic intrusion: geophysical expressionCanadian Journal of Earth Sciences, Vol. 27, No. 4, April pp. 501-512QuebecGeophysics, Layered intrusion
DS202104-0570
2021
Lefebvre, G.Charles, N., Tuduri, J., Lefebvre, G., Pourret, O., Gaillard, F., Goodenough, K.Ressources en terres rares de l'Europe et du Groenland: un potential minier remarquable mais tabou?In: Boulvais, P., Decree, S. Eds. Ressources metalliques: cadre geodynamique et exemples remarquables. ISTE Science Pub. Researchgate, 97p. pdfEurope, GreenlandREE
DS200512-0614
2005
Lefebvre, N.Lefebvre, N., Kopylova, M., Kivi, K.Archean calc-alkaline lamprophyres of Wawa, Ontario, Canada: unconventional Diamondiferous volcaniclastic rocks.Precambrian Research, Vol. 138, pp. 57-87.Canada, Ontario, WawaGreenstone Belt, geochronology, cinder cones
DS200612-0321
2006
Lefebvre, N.De Stefano, A., Lefebvre, N., Kopylova, M.Enigmatic diamonds in Archean calc-alkaline lamprophyres of Wawa, southern Ontario, Canada.Contributions to Mineralogy and Petrology, Vol. 151, 2, pp. 158-173.Canada, Ontario, WawaGeochemistry, FTIR spectroscopy, mineral inclusions
DS200612-1092
2006
Lefebvre, N.Pittari, A., Cas, R.A.F., Lefebvre, N., Web, K., Kurszlaukis, S.Facies characteristics and architecture of Body 219, Fort a la Corne, Saskatchewan: implications for kimberlitic mass flow processes in a marine setting.Emplacement Workshop held September, 5p. abstractCanada, SaskatchewanDeposit - Body 219, geology
DS200812-0643
2008
Lefebvre, N.Lefebvre, N., Kurszlaukis, S.Contrasting eruption styles of the 147 kimberlite, Fort a la Corne, Saskatchewan, canada.Journal of Volcanology and Geothermal Research, Vol. 174, 1-3, pp. 171-185.Canada, SaskatchewanVolcanic complex, emplacement, phreatomagmatic,turbidite
DS200812-0901
2008
Lefebvre, N.Pittari, A., Cas, R.A.F., Lefebvre, N., Robey, J., Kurszlaukis, S., Webb, K.Eruption processes and facies architecture of the Orion Central kimberlite volcanic complex, Fort a la Corne: kimberlite mass flow deposits in a sedimentary basin.Journal of Volcanology and Geothermal Research, Vol. 174, 1-3, pp. 152-170.Canada, SaskatchewanMegaturbidite, sedimentary basins, diatremes
DS201112-0575
2003
Lefebvre, N.Lefebvre, N.Volcaniclastic breccia and diamonds of Wawa, N. Ontario.University of British Columbia, Msc. thesis, 230p.Canada, Ontario, WawaThesis - note availability based on request via author
DS201501-0026
2015
Lefebvre, N.Pittari, A., Cas, R.A.F., Lefebvre, N., Kurszlaukis, S.Alteration styles in the Orion Central Volcanic Complex, Fort a la Corne kimberlite field, Saskatchewan, and their effects on primary volcaniclastic textures: implications for facies mapping and diamond exploration.Economic Geology, Vol. 110, pp. 146-171.Canada, SaskatchewanDeposit - Orion Central Volcanics
DS2003-0788
2003
Lefebvre, N.S.Lefebvre, N.S., Kopylova, M.G., Kivi, K.R.Diamondiferous volcaniclastic debris flows of Wawa, Ontario, CanadaGeological Association of Canada Annual Meeting, Abstract onlyOntario, WawaPetrology
DS2003-0789
2003
Lefebvre, N.S.Lefebvre, N.S., Kopylova, M.G., Kivi, K.R., Barnett, R.L.Diamondiferous volcaniclastic debris flows of Wawa, Ontario, Canada8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractOntario, WawaKimberlite geology and economics
DS200412-1108
2003
Lefebvre, N.S.Lefebvre, N.S.,Kopylova, M.G., Kivi, K.R.Diamondiferous volcaniclastic debris flows of Wawa, Ontario, Canada.Geological Association of Canada Annual Meeting, Abstract onlyCanada, Ontario, WawaPetrology
DS200512-0565
2005
Lefebvre, N.S.Kopylova, M.G., Lefebvre, N.S., De Stefano, A., Kivi, K.Archean lamprophyric rocks of Wawa: diamonds in a convergent margin.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Ontario, WawaAlkaline rocks, subduction, breccia, cathodluminescence
DS200512-0615
2004
Lefebvre, N.S.Lefebvre, N.S.Petrology, volcanology and diamonds of Archean calc-alkaline lamprophyres, Wawa, Ontario, Canada.University of British Columbia, Msc. Thesis 269p.Canada, Ontario, WawaLamprophyre, diamondiferous
DS201312-0530
2013
Lefebvre, N.S.Lefebvre, N.S., White, J.D.L.Unbedded diatreme deposits reveal maar-diatreme forming eruptive processes: Standing Rocks West, Hopi Buttes, Navajo Nation, USA.Bulletin of Volcanology, Vol. 75, pp. 739-United States, Wyoming, Colorado PlateauDiatreme
DS1999-0491
1999
LefevbreMoorhead, J., Beaumier, M., Lefevbre, Bernier, MartelKimberlites, lineaments et rifts crustaux au Quebec #1Quebec Ministere des Ressources naturelles, (in French), MB99-35, approx. 60p.Quebec, Ungava, LabradorKimberlite, Tectonics, structure, fields, lineaments
DS1990-0913
1990
LeFever, R.D.LeFever, R.D.MARKOV: a BASIC program for numerical analysis of sequential dat a on themicrocomputerComputers and Geosciences, Vol. 16, No. 2, pp. 141- 152GlobalComputer, Program -MARKOV
DS1990-0914
1990
Lefevere, L.V.Lefevere, L.V.1. a seismotectonic study of the middle America subduction zone. 2.Lithosphere and upper mantle structure of the Canadian shield in eastern NorthAmerPh.d. Thesis, California Institute of Technology, 163p. (Geological Society of Canada (GSC) listing)Ontario, AppalachiaGeophysics -seismics, Tectonics
DS1989-0874
1989
LeFevre, L.V.LeFevre, L.V., Helmberger, D.V.Upper mantle P velocity structure of the Canadian shieldJournal of Geophysical Research, Vol. 94, No. B 12, December 10, pp. 17, 749-17, 765CanadaMantle, Structure
DS1983-0111
1983
Leff, C.E.Arvidson, R.E., Guiness, E.A., Leff, C.E.New Perspectives on the Crustal Structure of MissouriGeological Society of America (GSA), Vol. 15, No. 6, P. 517. (abstract.).GlobalMid Continent
DS1900-0579
1907
Leffman, H.Leffman, H.Diamond Mining; January, 1907Journal of the Franklin Institute, Vol. 164, PP. 407-412. ALSO: Mining and Scientific PressGlobalMining Engineering, Cutting Diamonds
DS1910-0071
1910
Leffman, H.Leffman, H.Diamond Mining; May, 1910Eng. Club Philadelphia Proceedings, Vol. 27, PP. 96-103. ALSO: MINING WORLD, Vol. 32, MAY 21ST.GlobalMining Engineering
DS1994-1022
1994
Lefftz, M.Lefftz, M., Sabadini, R., Legros, H.Mantle rheology, viscomagnetic coupling at the core mantle boundary and differential rotation of the core induced by Pleistocene deglaciation.Geophys. Journal of International, Vol. 117, No. 1, April pp. 1-18.MantleBoundary, Rheology
DS1975-0124
1975
Lefond, J.S.Lefond, J.S.Industrial Minerals and RocksAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME), 4TH. EDITION 1360P.GlobalDiamond Chapter, Kimberley
DS1983-0532
1983
Lefond, S.J.Reckling, K., Hoy, R.B., Lefond, S.J.Diamonds; Industrial Minerals and Rocks, 1983Industrial Minerals And Rocks, Fifth Edition, New York: A.i., PP. 653-676.GlobalReview, History, Production, Mineral Economics, Mining Engineering
DS1998-0853
1998
Lefort, J.P.Lefort, J.P.Paleozoic splitting, rotation and reamalgamation of the northern edge of Paleozoic Gondwana.Journal of African Earth Sciences, Vol. 27, 1A, p. 130. AbstractGondwanaArmorica
DS2002-0931
2002
Lefort, J.P.Lefort, J.P., Aifa, T.Evidence for circum terrestrial loop of the Apwp of the west African Craton between 2.2 ad 0.9 Ga: its temporary amalgamation to Columbia and Rodinia.11th. Quadrennial Iagod Symposium And Geocongress 2002 Held Windhoek, Abstract p. 32.Africa, Gondwana, RodiniaGeochronology, Reguibat Uplift
DS200412-1109
2004
LeFort, J.P.LeFort, J.P., Aifa, T., Bourrouilh, R.Paleomagnetic and paleontologic evidence for an antipodal position of the West African Craton and of norther Chin a in Rodinia puComptes Rendus Geoscience, Vol. 336, 2, Feb. pp. 159-165.ChinaGeophysics - magnetism
DS200512-0245
2005
Lefort, J.P.Dostal, J., Keppie, J.D., Hamilton, M.A., Araab, E.M., Lefort, J.P., Murphy, J.B.Crustal xenoliths in Triassic lamprophyre dykes in western Morocco: tectonic implications for the Rheic Ocean suture.Geological Magazine, Vol. 142, 2, pp. 159-172.Africa, MoroccoLamprophyre
DS200912-0345
2009
LeGall, B.Jourdan, F., Betrand, H., Fraud, G., LeGall, B., Watkeys, M.K.Lithospheric mantle evolution monitored by overlapping large igneous provinces: case study in southern Africa.Lithos, Vol. 107. 3-4, pp. 257-268.Africa, South AfricaMagmatism
DS201112-0576
2011
Legaree, A.Legaree, A.Celebrating 20 years of diamonds at BHP Billiton.Diamonds in Canada Magazine, Northern Miner, November pp. 20-21.Canada, Northwest TerritoriesHistory - Ekati
DS1984-0448
1984
Legat, M.Legat, M.The Shapiro DiamondLondon: Souvenir Press, 285P.South AfricaFiction, Kimberley, Adventure
DS1994-0802
1994
Legault, F.Hynes, A., Francis, D., Legault, F.Basalt petrochemistry as a probe of crustal thickness in the Hudson BayArc, Quebec.Earth and Planetary Science Letters, Vol. 127, No. 1-4, October pp. 11-24.QuebecGeochemistry, Crustal thickness
DS1994-1023
1994
Legault, F.Legault, F., Francis, D., Hynes, A., Budkewitsch, P.Proterozoic continental volcanism in the Belcher Islands: implications For the evolution Circum UngavaCanadian Journal of Earth Sciences, Vol. 31, pp. 1536-49.Quebec, Ungava, Labrador, Belcher Islandsvolcanism., Fold Belt
DS201705-0844
2016
Legault, J.Kwan, K., Legault, J.Tli Kwi Cho shootout. III GeophysicsSEG Annual Meeting Dallas, 14 ppt.Canada, Northwest TerritoriesDeposit - Tli Kwi Cho
DS201807-1478
2018
Legault, J.Bournas, N., Prikhodko, A., Plastow, G., Legault, J., Polianichko, V., Treshchev, S.Exploring for kimberlite pipes in the Cuango area, Angola using helicopter-borne EM survey.AEM2018/7th International Workshop on Airborne electromagnetics, Held June 17-20, 4p.Africa, Angolageophysics - TEM
DS201012-0337
2010
Legault, J.M.Kaminski, V., Legault, J.M., Kumar, H.The Drybones kimberlite: a case study of VTEM and ZTEM airborne EM results.21st International Geophysical Conference and Exhibition Sydney NSW Australia, August 22-25, Extended abstract 5p.Canada, Northwest TerritoriesGeophysics - Drybones pipe
DS1988-0070
1988
Legeley, A.Bonvalot, S., Villeneurve, M., Legeley, A., Albouy, Y.Leve gravimetrique du sud-ouest du craton Ouest -Africain.(in French)C.r. Academy Of Science Paris, Vol. 307, ser. II, pp. 1863-1868GlobalGeophysics-gravity, Tectonics
DS1990-1262
1990
Legendre, J.J.Roullet, G., Raphanaud, J., Legendre, J.J.A user friendly microcomputer program for modeling convex polyhedraComputers and Geosciences, Vol. 16, No. 4, pp. 461-516GlobalComputer, Program -model polyhedra
DS1992-0150
1992
Legendre, P.Bourgault, G., Marcotte, D., Legendre, P.The multivariate (Co) variogram as a spatial weighting function in classification methodsMathematical Geology, Vol. 24, No. 4, pp. 463-478GlobalComputer, cobalt, Program -Multivariate variograM.
DS1997-0706
1997
Legg, C.Maas, R., Nicholls, I.A., Legg, C.Igneous and metamorphic enclaves in the S type Deddick granodiorite Lach lanfold belt, petrographic, geochem.Journal of Petrology, Vol. 38, No. 7, July pp. 815-842AustraliaGeochronology, crustal melting, Magma mixing
DS1988-0714
1988
Legg, K.Tzeng, Y., Kung, P.J., Zee, R., Legg, K., Solnick-Legg, H., BurnsSpiral hollow cathode plasma assisted diamond depositionAppl. Phys. Letters, Vol. 53, No. 23, pp. 2326-2327GlobalDiamond coatings, Diamond applications
DS1998-0854
1998
Leggatt, P.B.Leggatt, P.B., Klinkert, P.S.The application of airborne electromagnetic methods - search for buried kimberlites - Diamondiferous gravels.7th International Kimberlite Conference Abstract, pp. 495-6.Northwest Territories, South AfricaGeophysics - electromagnetic, Deposit - Willy-Nilly, Point Lake, Kalahari sands
DS1860-1039
1898
Leggett, T.H.Leggett, T.H.Diamond Mining in South Africa; September, 1898Cassier's Engineering Magazine., Vol. 14, No. 5, SEPT., PP. 371-393.Africa, South AfricaMining Methods
DS1988-0393
1988
Legkova, G.V.Kvasnitsa, V.N., Taran, M.N., Smirnov, G.I., Legkova, G.V.Violet red zircon from kimberlite.(Russian)Mineral. Zhurnal, (Russian), Vol. 42, No. 2, pp. 12-17LesothoDiamond morphology, Zircon
DS1988-0742
1988
Legkova, G.V.Voznyak, D.K., Kvasnitsa, V.N., Kharkiv, A.D., Legkova, G.V.First find of the inclusion of saline magmatic solution into the crystalsof kimberlite zircon.(Russian)Mineral. Zhurn., (Russian), Vol. 10, No. 4, pp. 15-22RussiaMineralogy, Fluid inclusions, Zircon
DS1991-1574
1991
Legkova, G.V.Shramenko, I.F., Legkova, G.V., Ivanitskiy, V.P., Kostyuchenko, N.S.Mineralogical and geochemical studies of the petrogenesis of the ChernigovcarbonatitesGeochemistry International, Vol. 28, No. 8, pp. 102-109RussiaCarbonatite, Geochemistry
DS1991-1575
1991
Legkova, G.V.Shramenko, I.F., Legkova, G.V., Ivanitsky, V.P., Kostyuchenko, N.G.Petrogenesis of carbonatites of Chernigovsky complex according to dat a of mineralogical geochemical studies.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 1, January pp. 113-120RussiaCarbonatite, Geochemistry
DS1983-0400
1983
Legokova, G.V.Legokova, G.V., Krochuk, V.M. ETAL.Characteristics of chemical composition of the crystalline shape of amphiboles and pyroxenes of carbonatites in the Azov searegion.(Russian)Mineral. Zhurn., (Russian), Vol. 5, No. 4, pp. 69-75RussiaCarbonatite
DS202111-1772
2021
Legostaeva, Y.R.Legostaeva, Y.R., Gololobova, A.G.Long-term geochemical monitoring of the soil cover in the impact zone of diamond mining enterprises: a case study in the Nakyn kimberlite field, Russia.Environmental Monitoring Assessment, Vol. 193, 337, 6p. PdfRussiadeposit - Nakyn

Abstract: The most severe disturbance of the earth’s surface occurs when the open-cut method of mineral deposits mining is used. The geoecological situation was assessed based on the nature of the soil cover based on the example of an industrial site of a diamond mining and processing plant located in the permafrost zone. During the period from 2007 to 2018, the soil cover of the industrial site is characterized by polyelement contamination. In the surface, soil horizons were an increase in the concentrations of mobile forms of Mn, Zn, Cd, Cr, Co, and Ni. It is identified that AO, ABcr, and CR are the accumulation horizons if the soil profile is preserved. Mobile forms Mn, Zn, Ni, Cr, Co, and As can migrate along with the soil profile to a depth of 40-50 cm depending on the amount of soil organic matter, the degree of its decomposition, and the scale of the cryoturbation. Research in 2018 allowed us to localize and confirm the increase in the area of contamination of the industrial site. Areas with an extremely dangerous category of soil cover contamination increased by 3 times compared to 2014. The results obtained are the basis for a more detailed study of the horizons of geochemical accumulation and the creation of artificial geochemical barriers with the development of technologies for the subsequent extraction of useful components.
DS1997-0647
1997
LeGrand, H.E.LaMoreaux, P.E., Powell, W.J., LeGrand, H.E.Environmental and legal aspects of karst areasEnvironmental Geology, Vol. 29, No. 1-2, Jan. 1, pp. 23-36GlobalEnvironment, Karst
DS1997-0462
1997
Legrand, J.M.Hackspacher, P.C., Dantas, E.L., Legrand, J.M.Northwestern Over thrusting and related lateral escape during the Brasiliano Orogeny north of Patos lineamentInternational Geology Review, Vol. 39, No. 7, July, pp. 609-638.Brazil, BorboremaTectonics, Orogeny
DS2002-0447
2002
Legras, B.Farnetani, C.G., Legras, B., Tackley, P.J.Mixing and deformations in mantle plumesEarth and Planetary Science Letters, Vol.196, 1-2, Feb.28, pp. 1-15.MantlePLumes - review
DS2000-0563
2000
Legros, F.Legros, F., Kelfoun, K., Marti, J.The influence of conduit geometry on the dynamics of caldera forming eruptions.Earth and Planetary Science Letters, Vol. 179, No. 1, June 15, pp. 53-62.Globalvolcanism - calderas, PhreatomagmatisM.
DS1994-1022
1994
Legros, H.Lefftz, M., Sabadini, R., Legros, H.Mantle rheology, viscomagnetic coupling at the core mantle boundary and differential rotation of the core induced by Pleistocene deglaciation.Geophys. Journal of International, Vol. 117, No. 1, April pp. 1-18.MantleBoundary, Rheology
DS200812-0810
2008
Legtonen, M.L.O'Brien, H.E., Legtonen, M.L., Grimmer, S.G., McNulty, K., Peltonen, P., Kontinen, A.Kimberlites in Finland. Geology of kimberlites, carbonatites and alkaline rocks. Seitapera kimberlite and Jormua ophiolite complex.9th. IKC Field Trip Guidebook, CD 58p.Europe, FinlandGuidebook - kimberlites, carbonatites
DS1990-0934
1990
Leguey, S.Lifante, G., Jaque, F., Hoyos, M.A., Leguey, S.Testing of colourless natural diamonds by room temperature opticalabsorptionJournal of Gemology, Vol. 22, No. 3, July, pp. 142-146GlobalNatural diamonds, Absorption
DS201112-0577
2011
Lehbib, S.Lehbib, S., Arribas, A., Melgarejo, J.C., Martin, R.F.Rare element minerals of the alkaline suites of the western Sahara.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterAfricaAlkalic
DS201112-0578
2011
Lehbib, S.Lehbib, S., Arribas, A., Melgarejo, J.C., Martin, R.F.Rare element minerals of the alkaline suites of the western Sahara.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.96-98.Africa, MauritaniaCarbonatite
DS201112-0579
2011
Lehbib, S.Lehbib, S., Arribas, A., Melgarejo, J.C., Martin, R.F.Rare element minerals of the alkaline suites of the western Sahara.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.96-98.Africa, MauritaniaCarbonatite
DS1995-0060
1995
Lehert, K.Arndt, N., Lehert, K., Vasilev, Y.Meimechites: highly magnesian lithosphere contaminated alkaline magmas from deep subcontinental mantle.Lithos, Vol. 34, No. 1-3, Jan. pp. 41-60.MantleMeimechites, Alkaline rocks
DS1930-0307
1939
Lehigh, B.L.Lehigh, B.L.Guidebook to Places of Geologic Interest in Lehigh ValleyPennsylvania Geological Survey Bulletin., No. G-16, SER. 4, 47P.Appalachia, PennsylvaniaGeology, Guidebook
DS201012-0430
2010
Lehman, B.Lehman, B., Burgess, R., Frei, D., Belyatsky, B., Mainkar, D., Chalapthi Rao, N.V., Heaman, L.M.Diamondiferous kimberlites in central India synchronous with Deccan flood basalts.Earth and Planetary Science Letters, Vol. 290, 1-2, Feb. 15, pp. 142-149.IndiaMineral chemistry
DS201601-0010
2015
Lehman, B.Chalapathai Rao, N.V., Atiullah, Burgess, A.R.,Nanda, P., Choudhary, A.K., Sahoo, S., Lehman, B., Chahong, N.Petrology, 40Ar/39Ar, Sr-Nd isotope systematics, and geodynamic significance of an ultrapotassic ( lamproitic) dyke with affinities to kamafugite from the easternmost margin of the Bastar Craton, India.Mineralogy and Petrology, in press available, 25p.IndiaLamproites - Nuapada field

Abstract: We report the mineralogy, bulk-rock geochemistry, 40Ar/39Ar (whole-rock) age and radiogenic (Sr and Nd) isotope composition of an ultrapotassic dyke from Sakri (Nuapada lamproite field) located at the tectonic contact between the easternmost margin of the Bastar craton and Eastern Ghats Mobile Belt, India. The Sakri dyke has a mineralogy which strongly resembles a lamproite sensu stricto (viz.,Ti-rich phlogopite, Na-poor diopside, Fe-rich sanidine, ulvospinel trend and Sr-rich apatite). However, its bulk-rock major element geochemical characteristics (viz., extreme silica-undersaturated nature) resemble sensu lato kamafugite from Toro Ankole, Uganda, East African Rift, and Alto Paranaiba Province, Brazil. The Sakri dyke also displays certain compositional peculiarities (viz., high degree of evolution of mica composition from phlogopite to biotite, elevated titanium and aluminum in clinopyroxene and significantly lower bulk Mg#) when compared to the ultrapotassic rocks from various Indian cratons. 40Ar/39Ar dating gave a plateau age of 1045?±?9 Ma which is broadly similar to that of other Mesoproterozoic (i) lamproites from the Bastar and Bundelkhand cratons, and (ii) kimberlites from the Eastern Dharwar craton. Initial bulk-rock Sr (0.705865-0.709024) and Nd (0.511063-0.511154) isotopic ratios reveal involvement of an ‘enriched’ source region with long-term incompatible element enrichment and a depleted mantle (TDM) Nd model age of 2.56 Ga straddling the Archaean-Proterozoic chronostratigraphic boundary. The bulk-rock incompatible trace element ratios (Ta/Yb, Th/Yb, Rb/Ba and Ce/Y) of the Sakri ultrapotassic dyke negate any significant influence of crustal contamination. Small-degree melting (1 to 1.5 %) of a mixed garnet-facies and spinel-facies phlogopite lherzolite can account for its observed REE concentrations. Whereas the emplacement of the Sakri ultrapotassic dyke is related to the amalgamation of the supercontinent of Rodinia, its overlapping geochemical characteristics of lamproite and kamafugite (also displayed by two other lamproites of the Nuapada field at Amlidadar and Parkom) are linked to the emplacement in a unique geological setting at the craton-mobile belt contact and hence of geodynamic significance.
DS1950-0224
1955
Lehman, O.Lehman, O.Look Beyond the WindCape Town: Howard Timmins, 183P.Southwest Africa, Namibia, South AfricaDiamond, Biography, History, Littoral Diamond Placers, Oyster Line
DS1960-0568
1965
Lehman, O.Lehman, O.Hans Merensky ein Deutschen Pionier in SuedafrikaGoettingen: K.w. Schuetz, 256P.Southwest Africa, Namibia, South AfricaLittoral Diamond Placers, Oyster Line, Kimberley, Biography
DS2002-1726
2002
LehmannWinkler, B., Knorr, Kahle, Vontobel, Lehmann, HennionNeutron imaging and neutron tomography as non-destructive tools to study bulk rock samples.European Journal of Mineralogy, Vol.14,2,pp.349-54.GlobalTechnology
DS2002-1727
2002
LehmannWinkler, B., Knorr, Kahle, Vontobel, Lehmann, HennionNeutron imaging and neutron tomography as non-destructive tools to study bulk rock samples.European Journal of Mineralogy, Vol. 14,pp.349-54., Vol. 14,pp.349-54.GlobalTomography - neutron imaging - not specific to diamonds
DS2002-1728
2002
LehmannWinkler, B., Knorr, Kahle, Vontobel, Lehmann, HennionNeutron imaging and neutron tomography as non-destructive tools to study bulk rock samples.European Journal of Mineralogy, Vol. 14,pp.349-54., Vol. 14,pp.349-54.GlobalTomography - neutron imaging - not specific to diamonds
DS200812-1027
2008
LehmannSchulmann, K., Lexa, O., Stipska, P., Racek, M., Tajcmanova, L., Konpasek, Edel, Peschler, LehmannVertical extension and horizontal channel flow of orogenic lower crust: key exhumation mechanisms in large hot orogens?Journal of Metamorphic Geology, In press availableEurope, MantleGeophysics - bouguer
DS1987-0404
1987
Lehmann, B.Lehmann, B.Molybdenum distribution in Precambrian rocks of the Colorado mineral beltMineralium Deposita, Vol.22, No.1, pp. 47-52ColoradoCarbonatite
DS2000-0872
2000
Lehmann, B.Schultz, F., Lehmann, B., Rossling, R., Tawackoli, S.Alkaline rocks and diamonds in the eastern Andes of BoliviaIgc 30th. Brasil, Aug. abstract only 1p.BoliviaAlluvial, lamprophyres, Ayopaya Province of Cochabamba
DS2003-0867
2003
Lehmann, B.Mainkar, D., Lehmann, B., Haggerty, S.E.Discovery of the very large crater facies kimberlite system of Tokapal, Bastar District8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractIndiaKimberlite geology and economics, Deposit - Tokapal
DS200512-0948
2004
Lehmann, B.Schultz, F., Lehmann, B., Tawackoli, S., Rossling, R., Belyatsky, B., Dulski, P.Carbonatite diversity in the Central Andes: the Ayopaya alkaline province, Bolivia.Contributions to Mineralogy and Petrology, Vol. 148, 4, pp. 391-408.South America, BoliviaCarbonatite
DS200612-0790
2006
Lehmann, B.Lehmann, B., Mainkar, D., Belyatsky, B.The Tokapal Crater facies kimberlite system, Chhattisgarh, India: reconnaissance petrography and geochemistry.Journal of the Geological Society of India, Vol. 68, 1, pp. 9-18.IndiaDeposit - Tokopal
DS200712-0614
2007
Lehmann, B.Lehmann, B., Kumar, K.The Tokpal crater facies kimberlite system, Chhattisgarh, India, comment and reply.Journal of Geological Society of India, Vol. 69, 1, p. 194.IndiaDeposit - Tokpal
DS200812-0701
2008
Lehmann, B.Mainkar, D., Lehmann, B., Burgess, R., Belyatsky, B.The Diamondiferous Behradih kimberlite pipe, Raipur district, Chhattisgarh, India.9IKC.com, 3p. extended abstractIndiaBastar Craton, Mainpur field
DS201012-0100
2010
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Mainkar, D., Belyatsky, B.Petrogenesis of the end Cretaceous Diamondiferous Behradih kimberlite, central India: implication for the plume lithosphere interactions in the Bastar craton?International Dyke Conference Held Feb. 6, India, 1p. AbstractIndiaMineral chemistry
DS201012-0101
2010
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Mainkar, D., Belyatsky, B.Petrogenesis of the end Cretaceous Diamondiferous Behradih orangeite pipe: implications for mantle plume - lithosphere interaction in the Bastar craton, India.Contributions to Mineralogy and Petrology, Vol. 161, pp. 721-742.IndiaOrangeite
DS201012-0431
2010
Lehmann, B.Lehmann, B., Burgess, R., Frei, D., Belyatsky, B., Mainkar, D., Chalapthi Rao, N.V., Heaman, L.M.Diamondiferous kimberlites in central India synchronous with Deccan flood basalts.International Dyke Conference Held Feb. 6, India, 1p. AbstractIndiaDharwar and Bundelkhand cratons
DS201112-0164
2011
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B.Kimberlites, flood basalts and mantle plumes: new insights from the Deccan Large Igneous Province.Earth Science Reviews, Vol. 107, 3-4, pp. 207-444.IndiaBastar Craton , Reunion mantle plume, link
DS201112-0165
2011
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B.Kimberlites, flood basalts and mantle plumes: new insights from the Deccan large igneous province ( LIP).Earth Science Reviews, In press available 10p.IndiaIn space and time - related
DS201112-0166
2011
Lehmann, B.ChalapathiRao, N.V., Lehmann, B.Kimberlites, flood basalts and mantle plumes: new insights from the Deccan Large Igneous Province.Goldschmidt Conference 2011, abstract p.639.IndiaOrangeites, Bastar Craton
DS201212-0016
2012
Lehmann, B.Antonov, A.V., Lepekhina, E.N., Belyatsky, B.V., Lehmann, B.Kimberlitic zircon: results of magma interaction.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaDeposit - Bastar
DS201212-0118
2012
Lehmann, B.Chalapathi Rao, N.V., Creaser, R.A., Lehmann, B.Reconnaissance RE-OS isotope study of Indian kimberlites and lamproites: implications for their mantle source regions.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaGeochronology
DS201212-0119
2012
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Belousova, E., Frei, D., Mainkar, D.Petrology, bulk rock geochemistry, indicator mineral composition and zircon U-Pb geochronology of the end Cretaceous Diamondiferous Mainpur orangeites, Bastar Craton, Central India.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractIndiaDeposit - Mainpur
DS201212-0120
2012
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Mainkar, D., Panwar, B.K.Diamond facies chrome spinel from the Tokapal kimberlite, Indravati basin, central India and its petrological significance.Mineralogy and Petrology, Vol. 105, 3-4, pp. 121-133.IndiaDeposit - Tokapal
DS201212-0121
2012
Lehmann, B.Chalapathi Rao, N.V., Paton, C., Lehmann, B.Origin and diamond prospectivity of Mesoproterozoic kimberlites from the Narayanpet field, eastern Dharwar Craton southern India: insights from groundmass mineralogy, bulk chemistry and perovskite oxybarometry.Geological Journal, Vol. 47, 2-3, pp. 186-212.IndiaDeposit - Narayanpet
DS201212-0432
2012
Lehmann, B.Mainkar, D., Gupta, T., Patel, S.C., Lehmann, B., Diwan, P., Kaminsky, F.V.Physical and infrared characteristics of diamonds from Bahradih kimberlite, Bastar Craton, India.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaDeposit - Behradih
DS201312-0138
2013
Lehmann, B.Chalapathi Rao, N.V., Creaser, R.A., Lehmann, B., Panwar, B.K.Re-Os isotope study of Indian kimberlites and lamproites: implications for their mantle source regions and cratonic evolution.Chemical Geology, Vol. 353, pp. 36-47.IndiaCraton, Dharwar, Bastar - Kodomali orangeite
DS201312-0139
2013
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B.Petrology, bulk-rock geochemistry, indicator mineral composition and zircon U-Pb geochronology of the end-Cretaceous Diamondiferous Mainpur orangeites, Bastar craton, central India.Proceedings of the 10th. International Kimberlite Conference, Vol. 1, Special Issue of the Journal of the Geological Society of India,, Vol. 1, pp. 93-121.IndiaDeposit - Mainpur
DS201312-0140
2014
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Balaram, V.Platinum group elements (PGE) geochemistry of Deccan orangeites, Bastar craton, central India: implication for a non-terrestrial origin for irridium enrichment at the K-Pg boundary.Journal of Asian Earth Sciences, Vol. 84, pp. 24-33.IndiaOrangeites
DS201312-0142
2013
Lehmann, B.Chalapathi Rao, N.V., Wu, F-Y., Mitchell, R.H., Li, Q-L., Lehmann, B.Mesoproterozoic U-Pb ages, trace element and Sr-Nd isotopic composition of perovskite from kimberlites of the Eastern Dharwar craton, southern India: distinct mantle sources and a Wide spread 1.1 Ga Tectonomagmatic event.Chemical Geology, Vol. 353, pp. 48-64.IndiaPerovskite ages, SCLM
DS201412-0117
2014
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Balaram, V.Platinum-group elements ( PGE) geochemistry of Deccan orangeites, Bastar craton, central India: implication for a non-terrestrial origin for iridium enrichment at the K-Pg boundary.Journal of Asian Earth Sciences, Vol. 84, Apr. 15, pp. 24-33.IndiaOrangeites
DS201412-0118
2013
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Panwar, B.K., Kumar, A., Mainkar, D.Tokapal tuff facies kimberlite, Baston craton, central India: a nickel prospect?Journal of the Geological Society of India, Vol. 82, 6, pp. 595-600.IndiaDeposit - Tokapal
DS201508-0346
2015
Lehmann, B.Chalapathi Rao, N.V., Atiullah, Kumar, A., Sahoo, S., Nanda, P., Chahong, N., Lehmann, B., Rao, K.V.S.Petrogenesis of Mesoproterozoic lamproite dykes from the Garledinne (Banganapalle) cluster, south western Cuddapah Basin, southern India.Mineralogy and Petrology, in press available 22p.IndiaLamproite

Abstract: We report mineral chemistry and whole-rock major and trace-element geochemistry for a recent find of Mesoproterozoic (~1.4 Ga) lamproites from the Garledinne (Banganapalle) cluster, south-western part of the Paleo-Mesoproterozoic Cuddapah Basin, southern India. The Garledinne lamproites occur as WNW-ESE-trending dykes that have undergone varying degree of pervasive silicification and carbonate alteration. Nevertheless, their overall texture and relict mineralogy remain intact and provide important insights into the nature of their magmas. The lamproite dykes have porphyritic to weakly porphyritic textures comprising pseudomorphed olivine macrocrysts and microphenocrysts, titanian phlogopite microphenocrysts, spinel having a compositional range from chromite to rarely magnesiochromite, Sr-rich apatite and niobian rutile. The Garledinne and other Cuddapah Basin lamproites (Chelima and Zangamarajupalle) collectively lack sanidine, clinopyroxene, potassic richterite, and titanite and are thus mineralogically distinct from the nearby Mesoproterozoic lamproites (Krishna and Ramadugu) in the Eastern Dharwar Craton, southern India. The strong correlation between various major and trace elements coupled with high abundances of incompatible and compatible trace elements imply that alteration and crustal contamination have had a limited effect on the whole-rock geochemistry (apart from K2O and CaO) of the Garledinne lamproites and that olivine fractionation played an important role in their evolution. The Garledinne lamproites represent small-degree partial melts derived from a refractory (previously melt extracted) peridotitic mantle source that was subsequently metasomatised (enriched) by carbonate-rich fluids/melts within the garnet stability field. The involvement of multiple reservoirs (sub-continental lithospheric mantle and asthenosphere) has been inferred in their genesis. The emplacement of the Garledinne lamproites is linked to extensional events, across the various Indian cratons, related to the break-up of the Proterozoic supercontinent of Columbia.
DS201509-0389
2015
Lehmann, B.Chalapathi Rao, N.V., Dongre, A., Wu, F-Y., Lehmann, B.A Late Cretaceous ( ca.90Ma) kimberlite event in southern India: implication for sub-continental lithospheric mantle evolution and diamond exploration. WajrakarurGondwana Research, in press available 12p.IndiaDeposit - Timmasamudram
DS201604-0598
2016
Lehmann, B.Chalapathi Rao, N.V., Atiullah, Burgess, R., Nanda, P., Choudhary, A.K., Sahoo, S., Lehmann, B., Chahong, N.Petrology, 40Ar/39Ar age, Sr-Nd isotope systematics, and geodynamic significance of an ultrapotassic ( lamproitic) dyke with affinities to kamafugite from the easternmost margin of the Bastar Craton, India.Mineralogy and Petrology, in press available, 25p.IndiaDeposit - Sakri Nuapada

Abstract: We report the mineralogy, bulk-rock geochemistry, 40Ar/39Ar (whole-rock) age and radiogenic (Sr and Nd) isotope composition of an ultrapotassic dyke from Sakri (Nuapada lamproite field) located at the tectonic contact between the easternmost margin of the Bastar craton and Eastern Ghats Mobile Belt, India. The Sakri dyke has a mineralogy which strongly resembles a lamproite sensu stricto (viz.,Ti-rich phlogopite, Na-poor diopside, Fe-rich sanidine, ulvospinel trend and Sr-rich apatite). However, its bulk-rock major element geochemical characteristics (viz., extreme silica-undersaturated nature) resemble sensu lato kamafugite from Toro Ankole, Uganda, East African Rift, and Alto Paranaiba Province, Brazil. The Sakri dyke also displays certain compositional peculiarities (viz., high degree of evolution of mica composition from phlogopite to biotite, elevated titanium and aluminum in clinopyroxene and significantly lower bulk Mg#) when compared to the ultrapotassic rocks from various Indian cratons. 40Ar/39Ar dating gave a plateau age of 1045?±?9 Ma which is broadly similar to that of other Mesoproterozoic (i) lamproites from the Bastar and Bundelkhand cratons, and (ii) kimberlites from the Eastern Dharwar craton. Initial bulk-rock Sr (0.705865-0.709024) and Nd (0.511063-0.511154) isotopic ratios reveal involvement of an ‘enriched’ source region with long-term incompatible element enrichment and a depleted mantle (TDM) Nd model age of 2.56 Ga straddling the Archaean-Proterozoic chronostratigraphic boundary. The bulk-rock incompatible trace element ratios (Ta/Yb, Th/Yb, Rb/Ba and Ce/Y) of the Sakri ultrapotassic dyke negate any significant influence of crustal contamination. Small-degree melting (1 to 1.5 %) of a mixed garnet-facies and spinel-facies phlogopite lherzolite can account for its observed REE concentrations. Whereas the emplacement of the Sakri ultrapotassic dyke is related to the amalgamation of the supercontinent of Rodinia, its overlapping geochemical characteristics of lamproite and kamafugite (also displayed by two other lamproites of the Nuapada field at Amlidadar and Parkom) are linked to the emplacement in a unique geological setting at the craton-mobile belt contact and hence of geodynamic significance.
DS201609-1710
2016
Lehmann, B.Chalapathi Rao, N.V., Dongre, A., Wu, F-Y., Lehmann, B.A Late Cretaceous ( ca.90Ma) kimberlite event in southern India: implication for sub-continental lithospheric mantle evolution and diamond exploration.Gondwana Research, Vol. 35, pp. 378-389.India, MadagascarDeposit - Wajrakarur

Abstract: We report groundmass perovskite U -Pb (SIMS) ages, perovskite Nd isotopic (LA-ICPMS) composition and bulk-rock geochemical data of the Timmasamudram diamondiferous kimberlite cluster, Wajrakarur kimberlite field, in the Eastern Dharwar craton of southern India. The kimberlite pipes gave similar Mesoproterozoic ages of 1086 ± 19 Ma (TK-1, microcrystic variant) and 1119 ± 12 Ma (TK-3). However, a perovskite population sampled from the macrocrystic variant of TK-1 gave a much younger Late Cretaceous age of ca. 90 Ma. This macrocrystic kimberlite phase intrudes the Mesoproterozoic microcrystic phase and has a distinct bulk-rock geochemistry. The Nd-isotope composition of the ~ 1100 Ma perovskites in the cluster show depleted ?Nd(T) values of 2.1 ± 0.6 to 6.7 ± 0.3 whereas the ~ 90 Ma perovskites have enriched ?Nd(T) values of ? 6.3 ± 1.3. The depleted-mantle (DM) model age of the Cretaceous perovskites is 1.2 Ga, whereas the DM model age of the Proterozoic perovskites is 1.2 to 1.5 Ga. Bulk-rock incompatible trace element ratios (La/Sm, Gd/Lu, La/Nb and Th/Nb) of all Timmasamudram kimberlites show strong affinity with those from the Cretaceous Group II kimberlites from the Bastar craton (India) and Kaapvaal craton (southern Africa). As the Late Cretaceous age of the younger perovskites from the TK-1 kimberlite is indistinguishable from that of the Marion hotspot-linked extrusive and intrusive igneous rocks from Madagascar and India, we infer that all may be part of a single Madagascar Large Igneous Province. Our finding constitutes the first report of Cretaceous kimberlite activity from southern India and has significant implications for its sub-continental lithospheric mantle evolution and diamond exploration programs.
DS201612-2295
2016
Lehmann, B.Dongre, A., Chalapathi Rao, N.V., Viljoen, K.S., Lehmann, B.Petrology, genesis and geodynamic implication of the Mesoproterozoic- Late Cretaceous Timmasamudram kimberlite cluster, Wajrakarur field, eastern Dharwar craton, southern India.Geoscience Frontiers, in press availableIndiaDeposit - Timmasamudram

Abstract: New mineralogical and bulk-rock geochemical data for the recently recognised Mesoproterozoic (ca. 1100 Ma) and late Cretaceous (ca. 90 Ma) kimberlites in the Timmasamudram cluster (TKC) of the Wajrakarur kimberlite field (WKF), Eastern Dharwar Craton, southern India, are presented. On the basis of groundmass mineral chemistry (phlogopite, spinel, perovskite and clinopyroxene), bulk-rock chemistry (SiO2, K2O, low TiO2, Ba/Nb and La/Sm), and perovskite Nd isotopic compositions, the TK-1 (macrocrystic variety) and TK-4 (microcrystic variety) kimberlites in this cluster are here classified as orangeites (i.e. Group II kimberlites), with geochemical characteristics that are very similar to orangeites previously described from the Bastar Craton in central India, as well as the Kaapvaal Craton in South Africa. The remaining kimberlites (e.g., TK-2, TK-3 and the TK-1 microcrystic variant), are more similar to other 1100 Ma, Group I-type kimberlites of the Eastern Dharwar Craton, as well as the typical Group I kimberlites of the Kaapvaal Craton. Through the application of geochemical modelling, based on published carbonated peridotite/melt trace element partition coefficients, we show that the generation of the TKC kimberlites and the orangeites results from low degrees of partial melting of a metasomatised, carbonated peridotite.
DS201702-0202
2017
Lehmann, B.Chalapathi Rao, N.V., Lehmann, B., Belyatsky, B., Warnsloh, J.M.The Late Cretaceous Diamondiferous pyroclastic kimberlites from the Fort a La Corne (FALC) field, Saskatchewan craton, Canada: petrology, geochemistry and genesis.Gondwana Research, In press available 91p.Canada, SaskatchewanDeposit - Fort a La Corne

Abstract: The article gives new experimental data on spectral characteristics of photoluminescence of natural diamonds extracted from deep horizons of Mir and Internatsionalnaya Pipes, Republic of Sakha (Yakutia) depending on composition of basic and additional optically active structural defects in crystals and on temperature during spectrum recording, considering kinetics of luminescence. It is hypothesized on applicability of low-temperature effects to enhance efficiency of photoluminescence separation of diamond crystals.
DS201707-1319
2017
Lehmann, B.Dongre, A., Chalapathi Rao, N.V., Viljpoen, K.S., Lehmann, B.Petrology, genesis and geodynamic implication of the Mesoproterozoic - Late Cretaceous Timmasamudram kimberlite cluster, Wajrakarur field, eastern Dharwar Craton, southern India.Geoscience Frontiers, Vol. 8, pp. 541-553.Indiadeposit - Timmasamudram

Abstract: New mineralogical and bulk-rock geochemical data for the recently recognised Mesoproterozoic (ca. 1100 Ma) and late Cretaceous (ca. 90 Ma) kimberlites in the Timmasamudram cluster (TKC) of the Wajrakarur kimberlite field (WKF), Eastern Dharwar Craton, southern India, are presented. On the basis of groundmass mineral chemistry (phlogopite, spinel, perovskite and clinopyroxene), bulk-rock chemistry (SiO2, K2O, low TiO2, Ba/Nb and La/Sm), and perovskite Nd isotopic compositions, the TK-1 (macrocrystic variety) and TK-4 (Macrocrystic variety) kimberlites in this cluster are here classified as orangeites (i.e. Group II kimberlites), with geochemical characteristics that are very similar to orangeites previously described from the Bastar Craton in central India, as well as the Kaapvaal Craton in South Africa. The remaining kimberlites (e.g., TK-2, TK-3 and the TK-1 microcrystic variant), are more similar to other 1100 Ma, Group I-type kimberlites of the Eastern Dharwar Craton, as well as the typical Group I kimberlites of the Kaapvaal Craton. Through the application of geochemical modelling, based on published carbonated peridotite/melt trace element partition coefficients, we show that the generation of the TKC kimberlites and the orangeites results from low degrees of partial melting of a metasomatised, carbonated peridotite. Depleted mantle (TDM) Nd perovskite model ages of the 1100 Ma Timmasamudram kimberlites show that the metasomatic enrichment of their source regions are broadly similar to that of the Mesoproterozoic kimberlites of the EDC. The younger, late Cretaceous (ca. 90 Ma) TK-1 (macrocrystic variant) and TK-4 kimberlites, as well as the orangeites from the Bastar Craton, share similar Nd model ages of 1100 Ma, consistent with a similarity in the timing of source enrichment during the amalgamation of Rodinia supercontinent. The presence of late Cretaceous diamondiferous orangeite activity, presumably related to the location of the Marion hotspot in southern India at the time, suggests that thick lithosphere was preserved, at least locally, up to the late Cretaceous, and was not entirely destroyed during the breakup of Gondwana, as inferred by some recent geophysical models.
DS201909-2070
2019
Lehmann, B.Pandey, R., Pandey, A., Chalapathi Rao, N.V., Belyatsky, B., Choudhary, A.K., Lehmann, B., Pandit, D., Dhote, P.Petrogenesis of end-Cretaceous/Early Eocene lamprophyres from the Deccan Large igneous province: constraints on plume-lithosphere interaction and the post-Deccan lithosphere-asthenosphere boundary ( LAB) beneath NW India.Lithos, Vol. 346-347, 19p. PdfIndiaplumes

Abstract: We present petrology, geochemistry and radiogenic isotope (Sr and Nd) data of thirteen post-Deccan lamprophyre dykes in the Narmada rift zone from the Chhotaudepur alkaline province of the Deccan Large Igneous Province (DLIP). Mineralogically, these dykes show affinity towards alkaline (sannaite and camptonite) as well as ultramafic (damtjernite) varieties of lamprophyres. Their major oxides and certain trace element ratios increase with increasing silica content highlighting the strong influence of fractionation processes. Their Nb/U and Ce/Pb ratios are similar to the mantle array defined by MORBs and OIBs and suggests an uncontaminated nature. Major oxide (K2O, Na2O, SiO2 and TiO2) contents show geochemical similarity towards shoshonitic volcanic series, whereas elevated Zr/Hf and Nb/La coupled with suppressed Rb/Nb and Zr/b display their affinity towards HIMU-type intraplate basalts. Their radiogenic initial 87Sr/86Sr (0.706034-0.710582) and sub-chondritic initial ?Nd (?8.6 to 2.1) are akin to those of the (i) ca. 65?Ma Ambadongar carbonatite, NW India, and (ii) ca. 65?Ma orangeites from Bastar Craton, central India, highlighting an enriched lithospheric mantle source. REE inversion modeling suggests ~3% enrichment of an undepleted mantle followed by small degrees of melting of this enriched mantle source are sufficient- as in the case of ocean island basalts (OIB)- to reproduce their observed REE concentrations. Their TDM Nd model ages (564-961?Ma) are consistent with widespread convergent margin-related magmatism during the amalgamation of the Rodinia supercontinent. We propose that enriched lithospheric mantle developed during the Neoproterozoic was metasomatized by small-volume CO2-rich melts imparting a HIMU-type geochemical character during Late Cretaceous, when the mantle plume (viz., Réunion) responsible for the flood basalt eruption, impinged at the base of the NW Indian lithosphere. From the presence of F-rich apatite and high K/Rb in mica, we infer the (i) presence of F-phlogopite in their source regions, and (ii) that the depth of post-Deccan lithosphere-asthenosphere boundary (LAB) beneath NW India was at least ~100?km at ca. 65?Ma.
DS202103-0389
2020
Lehmann, B.Kumar, A., Talukdar, D., Chalapathi Rao, N.V., Burgess, R., Lehmann, B.Mesoproterozoic 40Ar-39Ar ages of some lamproites from the Cuddapah Basin and eastern Dharwar craton, southern India: implications for diamond provenance of the Banganapalle conglomerates, age of the Kurnool Group and Columbia tectonics.Geological Society, London, Special Publication , 10.1144/SP513- 2020-247 53p. PdfIndialamproites

Abstract: We report Mesoproterozoic 40Ar-39Ar (whole-rock) ages of lamproites from (i) the Ramadugu field (R4 dyke : 1434 ± 19 Ma and R5 dyke: 1334 ± 12 Ma) and the Krishna field (Pochampalle dyke: 1439 ± 3 Ma and Tirumalgiri dyke: 1256 ± 12 Ma) from the Eastern Dharwar Craton (EDC) and (ii) the Garledinne (1433 ± 8 Ma) and the Chelima (1373 ± 6 Ma) dykes from within the Paleo-Mesoproterozoic Cuddapah Basin, southern India. The ages reported for the Ramadugu and Tirumalgiri lamproites constitute their first radiometric dates. Ages of the Pochampalle and the Chelima lamproites from this study are broadly comparable to their previously reported 40Ar-39Ar (phlogopite) ages of c. 1500 Ma and 1418 ± 8 Ma, respectively. The ages of all these lamproites are much older than those of the (i) c. 1.1 Ga kimberlites from the Wajrakarur and Narayanpet fields of the EDC and (ii) c. 1.09 Ga lamproitic dykes at Zangamarajupalle which intrude the Cumbum Formation of the Cuddapah Basin. However, the age of the Tirumalgiri lamproite (c. 1256 Ma) is similar to that of the Ramannapeta lamproite (c. 1224 Ma) within the Krishna field. Our study provides evidence for protracted ultrapotassic (lamproitic) magmatism from c. 1.43 to 1.1 Ga over a widespread area (c. 2500 km2) in and around the Cuddapah Basin and the EDC. Implications of the obtained new ages for the diamond provenance of the Banganapalle Conglomerates, the age of the Kurnool Group and for the timing of break-up of the Paleo-Mesoproterozoic supercontinent of Columbia/Nuna are explored.
DS202202-0203
2022
Lehmann, B.Kumar, A., Talukdar, D., Chalapathi Rao, N.V., Burgess, R., Lehmann, B.Mesoproterozoic 40Ar-39Ar ages of some lamproites from the Cuddapah basin and eastern Dharwar craton, southern India: implications for diamond provenance of the Banganapalle conglomerates, age of the Kurnool Group and Columbia tectonics.Geological Society of London Special Publication 513, pp. 157-178.Indialamproites

Abstract: We report Mesoproterozoic 40Ar-39Ar (whole-rock) ages of lamproites from (i) the Ramadugu field (R4 dyke : 1434 ± 19 Ma and R5 dyke: 1334 ± 12 Ma) and the Krishna field (Pochampalle dyke: 1439 ± 3 Ma and Tirumalgiri dyke: 1256 ± 12 Ma) from the Eastern Dharwar Craton (EDC) and (ii) the Garledinne (1433 ± 8 Ma) and the Chelima (1373 ± 6 Ma) dykes from within the Paleo-Mesoproterozoic Cuddapah Basin, southern India. The ages reported for the Ramadugu and Tirumalgiri lamproites constitute their first radiometric dates. Ages of the Pochampalle and the Chelima lamproites from this study are broadly comparable to their previously reported 40Ar-39Ar (phlogopite) ages of c. 1500 Ma and 1418 ± 8 Ma, respectively. The ages of all these lamproites are much older than those of the (i) c. 1.1 Ga kimberlites from the Wajrakarur and Narayanpet fields of the EDC and (ii) c. 1.09 Ga lamproitic dykes at Zangamarajupalle which intrude the Cumbum Formation of the Cuddapah Basin. However, the age of the Tirumalgiri lamproite (c. 1256 Ma) is similar to that of the Ramannapeta lamproite (c. 1224 Ma) within the Krishna field. Our study provides evidence for protracted ultrapotassic (lamproitic) magmatism from c. 1.43 to 1.1 Ga over a widespread area (c. 2500 km2) in and around the Cuddapah Basin and the EDC. Implications of the obtained new ages for the diamond provenance of the Banganapalle Conglomerates, the age of the Kurnool Group and for the timing of break-up of the Paleo-Mesoproterozoic supercontinent of Columbia/Nuna are explored.
DS1990-0238
1990
Lehmann, E.K.Brice, W.C., Lehmann, E.K., Beck, J.W., Knoll, A.Mining in Minnesota: balancing environmental protection and economicdevelopmentAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, No. 90-26, 10pMinnesotaLaw, Mining regulations
DS200512-0949
2004
Lehmann, F.Schultz, F., Lehmann, F., Tawackoli, S.Carbonatite diversity in the central Andes: the Ayopaya alkaline province, Bolivia.Contributions to Mineralogy and Petrology, Vol. 148, 4, pp. 391-425.South America, BoliviaCarbonatite
DS1983-0656
1983
Lehmann, J.Zwahr, H., Lehmann, J.Presence of Zeolite in Dolerite with Spessartite of Klunst Near Ebersbach, Saxony.Funndgrube., Vol. 19, No. 1, PP. 11-19.East GermanyLamprophyre, Carbonatite
DS1950-0284
1956
Lehmann, O.Lehmann, O.Hans MerenskyGoettingen: Schuetz Verlag, 256P., ILLUS.South AfricaBiography, Kimberley
DS200712-0615
2007
Lehnert, K.Lehnert, K., Walker, D., Sarbas, B.EarthChem - geochemistry dat a network.Plates, Plumes, and Paradigms, 1p. abstract p. A559.TechnologyDatabase
DS1992-0935
1992
Lehnert-ThielLehnert-Thiel, Loewer, R., Orr, R.G., Robertshaw, P.Diamond bearing kimberlites in Saskatchewan, Canada: the Fort a la Corne case historyThe Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Exploration Mining Geology, Vol. 1, No. 4, October pp. 391-403SaskatchewanGeology, history, Deposit- Fort a la Corne area
DS1991-0973
1991
Lehnert-Thiel, K.Lehnert-Thiel, K.Fort a la Corne kimberlites -exploration case historyConference registration The Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Xerox Tower Suite 1210, 3400 de Maissoneuve, Sept. 5-13, 1991 Fax 514 939-2714SaskatchewanFort a la Corne, Kimberlites
DS1991-1270
1991
Lehnert-Thiel, K.Orr, R., Lehnert-Thiel, K.Diamond exploration in Saskatchewan, Canada. *GERBraunkohle, (in German), Vol. 43, No. 6, June pp. 15-18SaskatchewanBrief overview activities, Uranerz
DS200812-0614
2008
Lehonen, M.Kukkonen, I.T., Kuusisto, M., Lehonen, M., Peltonen, P.Delamination of eclogitized lower crust: control on the crust-mantle boundary in the central Fennoscandian shield.Tectonophysics, Vol. 457, pp. 111-127.Europe, FinlandKimberlites discussed
DS200612-0791
2005
Lehtinen, M.Lehtinen, M., Nurmi, P., Ramo, O.T.Precambrian geology of Finland.Elsevier , 750p. $ 190.00Europe, FinlandBook - geology
DS200612-0792
2005
Lehtonen, M.Lehtonen, M.Kimberlites in Finland: information about the mantle of the Karelian Craton and implications for diamond exploration.Thesis, 'University of Helsiki, Academic Dissertation, 31p.Europe, FinlandLamproite, geochemistry, till, Kaavi, Kuopio
DS200612-0793
2005
Lehtonen, M.Lehtonen, M.Rare earth element characteristics of pyrope garnets from the Kaavi-Kuopio kimberlites - implications for mantle metasomatism.Geological Survey of Finland Bulletin, Vol. 77, 1, pp. 31-47.Europe, FinlandMetasomatism
DS200912-0432
2009
Lehtonen, M.Lehtonen, M., O'Brien, H., Peltonen, P., Kukkonen, I., Ustinov, V., Verzhak, V.Mantle xenocrysts from the Arkangelskaya kimberlite (Lomonosov); constraints on the composition and thermal state of the Diamondiferous lithospheric mantle.Lithos, in press availableRussia, Kola Peninsula, ArchangelDeposit - Lomonosov
DS200912-0870
2009
Lehtonen, M.Zozulya, D.R., Mitrofanov, F.P., Peltonen, P., O'Brien, H., Lehtonen, M., Kalachev, V.Yu.Lithospheric mantle structure and diamond prospects in the Kola region: chemical and thermobarometric analyses of kimberlite pyrope.Doklady Earth Sciences, Vol. 427, 5, pp. 746-750.Russia, Kola PeninsulaGeothermometry
DS200912-0872
2009
Lehtonen, M.Zozulya, D.R., Peltonen, P., O'Brien, H., Lehtonen, M.Lithospheric roots and asthenospheric upwarps of the NE Baltic Shield: spatial controls for kimberlitic and alkaline magmatism.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractEurope, Baltic Shield, Kola PeninsulaMagmatism
DS200912-0873
2009
Lehtonen, M.Zozulya, D.R., Peltonen, P., O'Brien, H., Lehtonen, M.Mantle depth facies of high pressure pyroxene in the Kola region.Doklady Earth Sciences, Vol. 424, 1, pp. 52-56.Russia, Kola PeninsulaMineralogy
DS201012-0432
2009
Lehtonen, M.Lehtonen, M., O'Brien, H.Mantle transect of the Karelian craton from margin to core based on P-T dat a from garnet and clinopyroxene xenocrysts in kimberlites.Bulletin of the Geological Society of Finland, Vol. 81, pp. 79-102.Europe, FinlandGeochemistry
DS201012-0897
2009
Lehtonen, M.Zozulya, D.R., O'Brien, H., Peltonen, P., Lehtonen, M.Thermobarometry of mantle derived garnets and pyroxenes of Kola region ( NW Russia): lithosphere composition, thermal regime and diamond prospectivity.Bulletin of the Geological Society of Finland, Vol. 81, pp. 143-158.Russia, Kola PeninsulaGeothermometry
DS201012-0898
2009
Lehtonen, M.Zozulya, D.R., O'Brien, H., Peltonen, P., Lehtonen, M.Thermobarometry of mantle derived garnets and pyroxenes of Kola region ( NW Russia): lithosphere composition, thermal regime and diamond prospectivity.Bulletin of the Geological Society of Finland, Vol. 81, pp. 143-158.Russia, Kola PeninsulaGeothermometry
DS201212-0526
2012
Lehtonen, M.O'Brien, H., Lehtonen, M.Craton mantle formation and structure of eastern FIn land mantle: evidence from kimberlite-derived mantle xenoliths, xenocrysts and diamonds.Springer Lecture Notes in Earth Sciences From the Earth's core to Outer space, editor Haapala, I., Vol. 137, pp. 61-80.Europe, FinlandKimberlite xenoliths
DS201811-2588
2018
Lehtonen, M.Lehtonen, M.Gemstones of Finland. Diamond bearing kimberlites pp. 175-193.Geological Survey of Finland, 344p. Europe, Finlandgemology
DS200912-0869
2009
Lehtonen, M.A.Zozulya, D.A.R.A., Peltonen, S.A.P.A., O'Brien, H.A., Lehtonen, M.A.Kimberlite depth facies of high pressure pyroxene in the Kola region.Doklady Earth Sciences, Vol. 425, 2, pp. 350-352.Russia, Kola PeninsulaUHP
DS2002-0932
2002
Lehtonen, M.L.Lehtonen, M.L., Marmo, J.S.Exploring for kimberlites in glaciated terrains using chromite in Quaternary till - a regional case study from northern Finland.Journal of Geochemical Exploration, Vol. 76, 3, pp. 155-74.FinlandGeochemistry - chomites
DS2003-0790
2003
Lehtonen, M.L.Lehtonen, M.L., Marmo, J.S.Glacial dispersion study of kimberlitic material in Quaternary till from the Lahtojoki8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, POSTER abstractFinlandDeposit - Lahtojoki
DS2003-0791
2003
Lehtonen, M.L.Lehtonen, M.L., O'Brien, H.E., Peltonen, P., Johanson, B.S., Pakkanen, L.K.Layered mantle at the edge of the Karelian craton: P-T of mantle xenocrysts and8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractFinlandBlank
DS2003-1025
2003
Lehtonen, M.L.O'Brien, H.E., Lehtonen, M.L., Spencer, R.G., Birnie, A.C.Lithospheric mantle eastern Finland, a 240 km 3D transect8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, AbstractFinlandDiamond exploration - geophysics, seismics
DS200412-1110
2003
Lehtonen, M.L.Lehtonen, M.L., Marmo, J.S.Glacial dispersion study of kimberlitic material in Quaternary till from the Lahtojoki pipe, eastern Finland.8 IKC Program, Session 8, POSTER abstractEurope, FinlandDiamond exploration Deposit - Lahtojoki
DS200412-1111
2004
Lehtonen, M.L.Lehtonen, M.L., O'Brien, H.E., Peltonen, B.S., Johanson, B.S., Pakkanen, L.K.Layered mantle at the Karelian Craton margin: P T of mantle xenocrysts and xenoliths from the Kaavi Kuopio kimberlites, Finland.Lithos, Vol. 77, 1-4, Sept. pp. 593-608.Europe, FinlandLithosphere, thermometry
DS200412-1112
2003
Lehtonen, M.L.Lehtonen, M.L., O'Brien, H.E., Peltonen, P., Johanson, B.S., Pakkanen, L.K.Layered mantle at the edge of the Karelian craton: P-T of mantle xenocrysts and xenoliths from eastern FIn land kimberlites.8 IKC Program, Session 6, POSTER abstractEurope, FinlandMantle petrology
DS200412-1456
2003
Lehtonen, M.L.O'Brien, H.E., Lehtonen, M.L., Spencer, R.G., Birnie, A.C.Lithospheric mantle eastern Finland, a 240 km 3D transect.8 IKC Program, Session 8, AbstractEurope, FinlandDiamond exploration - geophysics, seismics
DS200512-0616
2005
Lehtonen, M.L.Lehtonen, M.L., Marmo, J.S., Nissinen, A.J., Johanson, B.S., Pakkanen, L.K.Glacial dispersal studies using indicator minerals and till geochemistry around two eastern FIn land kimberlites.Journal of Geochemical Exploration, Vol. 87, 1, Oct. pp. 19-43.Europe, Finland, FennoscandiaKaavi-Kuopio, Kuhmo, geochemistry, Pipe 7, Karelian
DS200512-0617
2005
Lehtonen, M.L.Lehtonen, M.L., Pakkanen, L.K., Johanson, B.S., Lallukka, H.M.EMP analyses of kimberlite indicator minerals from Pipe 7 and Dyke 16 kimberlites and the basal till surrounding them.Geological Survey of Finland, Open File M 41.2/2005/2.Europe, FinlandGeochemistry
DS1990-0407
1990
LeHuray, A.P.Dixon, P.R., LeHuray, A.P., Rye, D.M.Basement geology and tectonic evolution of Ireland as deduced from leadisotopesJournal of the Geological Society of London, Vol. 147, No. 1, pp. 121-132IrelandGeochronology, Tectonics
DS200612-0794
2006
Lei, J.Lei, J., Zhao, D.Global P wave tomography: on the effect of various mantle core phases.Physics of the Earth and Planetary Interiors, Vol. 154, 1, Jan. 16, pp. 44-69.Mantle, HawaiiGeophysics - seismics, tomography
DS200612-0795
2006
Lei, J.Lei, J., Zhao, D.A new insight into the Hawaiian plume.Earth and Planetary Science Letters, Vol. 241, 3-4, Jan. 31, pp. 438-453.Mantle, HawaiiHotspot, tomography
DS200712-0616
2007
Lei, J.Lei, J., Zhao, D.Teleseismic P wave tomography and the upper mantle structure of the central Tien Shan orogenic belt.Physics of the Earth and Planetary Interiors, Vol. 162, 3-4, pp. 165-185.Asia, ChinaGeophysics - seismics
DS200712-0617
2007
Lei, J.Lei, J., Zhao, D.Teleseismic P wave tomography and the upper mantle structure of the central Tien Shan orogenic belt.Physics of the Earth and Planetary Interiors, Vol. 162, 3-4, pp. 165-185.Asia, ChinaGeophysics - seismics
DS201811-2597
2018
Lei, X.Ohuchi, T., Lei, X., Higo, Y., Tange, Y., Sakai, T., Fujino, K.Semi-brittle behavior of wet olivine aggregates: the role of aqueous fluid in faulting at upper mantle pressures.Contributions to Mineralogy and Petrology, Vol. 173, 21p. Doi.org/10.1007/s00410-018-1515-9Mantlesubduction

Abstract: The role of aqueous fluid in fracturing in subducting slabs was investigated through a series of deformation experiments on dunite that was undersaturated (i.e., fluid-free) or saturated with water (i.e., aqueous-fluid bearing) at pressures of 1.0-1.8 GPa and temperatures of 670-1250 K, corresponding to the conditions of the shallower regions of the double seismic zone in slabs. In situ X-ray diffraction, radiography, and acoustic emissions (AEs) monitoring demonstrated that semi-brittle flow associated with AEs was dominant and the creep/failure strength of dunite was insensitive to the dissolved water content in olivine. In contrast, aqueous fluid drastically decreased the creep/failure strength of dunite (up to ~ 1 GPa of weakening) over a wide range of temperatures in the semi-brittle regime. Weakening of the dunite by the aqueous fluid resulted in the reduction of the number of AE events (i.e., suppression of microcracking) and shortening of time to failure. The AE hypocenters were located at the margin of the deforming sample while the interior of the faulted sample was aseismic (i.e., aseismic semi-brittle flow) under water-saturated conditions. A faulting (slip rate of ~ 10?³ to 10?? s?¹) associated with a large drop of stress (?? ~ 0.5 to 1 GPa) and/or pressure (?P ~ 0.5 GPa) was dominant in fluid-free dunite, while a slow faulting (slip rate < 8 × 10?? s?¹) without any stress/pressure drop was common in water-saturated dunite. Aseismic semi-brittle flow may mimic silent ductile flow under water-saturated conditions in subducting slabs.
DS1990-0915
1990
Lei, Z.Lei, Z., Todd, D.The development of China's mining industry and its relevance to the worldmarketCrs Perspectives, No. 33, July pp. 8-10ChinaEconomics, Markets
DS200412-1113
2004
Lei, Z.Lei, Z., Jinhua, H., Yifei, D., Yulong, L.Assortment of deep mantle fluids and their products in kimberlites from China.Acta Geologica Sinica, Vol. 78, 1, pp. 118-120.ChinaGeochemistry, mineral chemistry
DS1992-0455
1992
Lei ZhaoFengxiang Lu, Lei Zhao, Jianpin ZhengPaleozoic mantle characteristics beneath North Chin a PlatformProceedings of the 29th International Geological Congress. Held Japan August 1992, Vol. 1, abstract p. 178-179. cont'dChinaShengli No. 1 pipe, Kimberlite, diamond inclusions
DS2002-0933
2002
Leibecker, J.Leibecker, J., Getzmeier, A., Honig, M., Kuras, O., Soyer, W.Evidence of electrical anisotropic structures in the lower crust and the upper mantleEarth and Planetary Science Letters, Vol. 202, 2, pp. 289-302.EuropeGeophysics - seismics
DS1991-1261
1991
Leibovitt, D.P.Omoumi, H., Smith, D.G.W., Leibovitt, D.P.Computer assisted retrieval of gem localities and associated dataGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC)/SEG Annual Meeting May 27-29. Toronto, Ontario, Abstract, Vol. 16, p. A93. AbstractGlobalGem locations, Computer databank
DS1990-1377
1990
Leibovitz, D.P.Smith, D.G.W., Leibovitz, D.P.MinIdent: a user's manual for mineral identificationAstimex Scientific, 100p. and discs $ 995.00GlobalMineralogy -computer Program, Program -MinIdent
DS1920-0391
1928
Leichner, G.Leichner, G.Unter Brasilianischen DiamantsuchernLeipzig: Wilhelm Goldmann., 195P.BrazilKimberlite, Kimberley, Fiction
DS1995-1080
1995
Leick, A.Leick, A.GPS satellite surveyingJohn Wiley, 560p. approx. $ 70.00 United StatesGlobalBook -ad, GPS surveying
DS1996-0832
1996
Leighton, M.W.Leighton, M.W.Interior cratonic basins: a record of regional tectonic influencesGeological Society of America (GSA) Special Paper, No. 308, pp. 77-94.MidcontinentTectonics, Craton
DS1975-1113
1979
Leighton, V.L.Leighton, V.L., Mccallum, M.E.Rapid Evaluation of Heavy Minerals in Stream Sediments of The Prairie Divide Area of Northern Colorado. a Tool for Kimberlite Exploration.United States Geological Survey (USGS) OPEN FILE., No. 79-761, 1 MAP WITH ABSTRACT AND RESULTS.United States, Colorado, Wyoming, State LineGeochemistry, Prospecting, Heavy Minerals, Techniques
DS201512-1899
2015
Leijd, M.Bluemel, B., Dunn, C., Hart, C., Leijd, M.Biogeochemical expressions of buried REE mineralization at Norra Karr, southern Sweden.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 231-240.TechnologyRare earths

Abstract: Biogeochemical exploration is an effective but underutilized method for delineating covered mineralization. Plants are capable of accumulating rare earth elements (REEs) in their tissue, and ferns (pteridophytes) are especially adept because they are one of the most primitive land plants, therefore lack the barrier mechanisms developed by more evolved plants. The Norra Kärr Alkaline Complex, located in southern Sweden approximately 300km southwest of Stockholm, is a peralkaline nepheline syenite enriched in heavy rare earth elements (HREEs). The deposit, roughly 300m wide, 1300m long, and overlain by up to 4 m of Quaternary sediments, has been well-defined by diamond drilling. The inferred REE mineral resource, over 60 million tonnes averaging 0.54% Total Rare Earth Oxide (TREO), is dominantly hosted within the pegmatitic “grennaite” unit, a eudialyte-catapleiite-aegerine nepheline syenite. Vegetation and soil samples were collected from the surficial environment above Norra Kärr to address four key questions: which plant species is the most effective biogeochemical exploration medium; what are the annual and seasonal REE variations in that plant; how do the REEs move through the soil profile; and into which part of the plant are they concentrated. Athyrium filix-femina (lady fern) has the highest concentration of LREEs and HREEs (up to 125.17ppm Ce and 1.03ppm Dy) in its dry leaves; however, there is better contrast between background and anomalous areas in Dryopteris filix-mas (wood fern), which makes it the preferred biogeochemical sampling medium. The REE content in all fern species was shown to decrease from root > frond > stem, and chondrite normalized REE patterns within the plant displayed preferential fractionation of the LREEs in the fronds relative to the roots. Samples collected from an area directly overlying the deposit had up to five times greater HREE content (0.74ppm Dy) in August than the same plants did in June (0.14ppm Dy). The elevated REE content and distinct contrast to background demonstrate that biogeochemical sampling is an effective method for REE exploration in this environment.
DS201512-1964
2015
Leijd, M.Saxon, M., Leijd, M., Forrester, K., Berg, J.Geology, mineralogy, and metallurgical processing of the Norra Karr heavy REE deposit, Sweden.Symposium on critical and strategic materials, British Columbia Geological Survey Paper 2015-3, held Nov. 13-14, pp. 97-108.Europe, SwedenRare earths

Abstract: The Norra Kärr peralkaline complex is about 300 km southwest of Stockholm in southern Sweden (Fig. 1). As the only heavy REE deposit in the European Union, Norra Kärr is signifi cant for the security of future REE, zirconium (Zr) and hafnium (Hf) supply (European Commission’s European Rare Earths Competency Network; ERECON, 2015). The project is well serviced by power and other infrastructure that will allow year-round mining and processing. A four-lane highway links Scandinavia to mainland Europe and passes with 1km of Norra Kärr. The skill-rich cities of Linköping and Jönköping, lie within daily commuting distances from Norra Kärr. A rail line that passes within 30 km of the site may be used to transport feed stocks and products. If Norra Kärr is developed, European REE users will no longer require substantial material stockpiles to deal with market uncertainties.
DS202006-0927
2020
Leinenweber, K.Ko, B., Prakapenka, V., Kunz, M., Prescher, C., Leinenweber, K., Shim, S-H.Mineralogy and density of Archean volcanic crust in the mantle transition zone.Physics of the Earth and Planetary Interiors, Vol. 305, 13p. PdfMantledensity

Abstract: The composition of Archean volcanic crust can be characterized by a higher Mg/Si ratio than modern mid-ocean ridge basalt (MORB), because of the higher degree melting from the warmer mantle in the Archean. Although modern MORB may become less dense than the surrounding mantle beneath the mantle transition zone (MTZ), the Mg-rich composition of Archean volcanic crust may result in the different density, and therefore different sinking behavior near the MTZ. In order to understand the compositional effect of Archean volcanic crust on the sinking behaviors and the scale of mantle mixing in the Archean, we investigated the mineralogy and density of Archean volcanic crust near the MTZ (470-910 km-depth). We conducted experiments at 19-34 GPa and 1400-2400 K using the laser-heated diamond anvil cell (LHDAC) combined with in-situ X-ray diffraction (XRD). The in-situ XRD and the chemical analysis revealed that Archean volcanic crust forms garnet and ringwoodite (84 and 16 vol%, respectively), which gradually transforms to Brg and CaPv (82 and 18 vol%, respectively) at 23-25 GPa and 1800 K. Our in-situ XRD experiments allowed us to measure the volumes of stable phases and to estimate their densities at high pressure and temperature. The results suggest that Archean volcanic crust maintains greater density than the pyrolitic mantle in the Archean regardless of temperature at 20-34 GPa (570-850 km-depth), promoting further sinking into the deeper mantle in the Archean. We also considered the density of the subducting slab in the Archean. The density model showed that the subducting slab is still denser or at least equally dense as the surrounding pyrolitic mantle in the Archean.
DS202008-1410
2020
Leinenweber, K.Ko, B., Prakapenka, V., Kunz, M., Prescher, C., Leinenweber, K., Shim, S-H.Mineralogy and density of Archean volcanic crust in the mantle transition zone.Physics of the Earth and Planetary Interiors, Vol. 305, 13p. PdfMantlesubduction

Abstract: The composition of Archean volcanic crust can be characterized by a higher Mg/Si ratio than modern mid-ocean ridge basalt (MORB), because of the higher degree melting from the warmer mantle in the Archean. Although modern MORB may become less dense than the surrounding mantle beneath the mantle transition zone (MTZ), the Mg-rich composition of Archean volcanic crust may result in the different density, and therefore different sinking behavior near the MTZ. In order to understand the compositional effect of Archean volcanic crust on the sinking behaviors and the scale of mantle mixing in the Archean, we investigated the mineralogy and density of Archean volcanic crust near the MTZ (470-910 km-depth). We conducted experiments at 19-34 GPa and 1400-2400 K using the laser-heated diamond anvil cell (LHDAC) combined with in-situ X-ray diffraction (XRD). The in-situ XRD and the chemical analysis revealed that Archean volcanic crust forms garnet and ringwoodite (84 and 16 vol%, respectively), which gradually transforms to Brg and CaPv (82 and 18 vol%, respectively) at 23-25 GPa and 1800 K. Our in-situ XRD experiments allowed us to measure the volumes of stable phases and to estimate their densities at high pressure and temperature. The results suggest that Archean volcanic crust maintains greater density than the pyrolitic mantle in the Archean regardless of temperature at 20-34 GPa (570-850 km-depth), promoting further sinking into the deeper mantle in the Archean. We also considered the density of the subducting slab in the Archean. The density model showed that the subducting slab is still denser or at least equally dense as the surrounding pyrolitic mantle in the Archean.
DS202010-1832
2020
Leinenweber, K.Chen, H., Leinenweber, K., Prakapenka, V., Kunz, M., Bechtel, H.A., Liu, Z., Shim, S-H.Phase transformation of hydrous ringwoodite to the lower-mantle phases and the formation of hydrous silica.American Mineralogist, Vol. 105, pp. 1342-1348. pdfMantlebridgmanite

Abstract: To understand the effects of H2O on the mineral phases forming under the pressure-temperature conditions of the lower mantle, we have conducted laser-heated diamond-anvil cell experiments on hydrous ringwoodite (Mg2SiO4 with 1.1 wt% H2O) at pressures between 29 and 59 GPa and temperatures between 1200 and 2400 K. Our results show that hydrous ringwoodite (hRw) converts to crystalline dense hydrous silica, stishovite (Stv) or CaCl2-type SiO2 (mStv), containing 1 wt% H2O together with Brd and MgO at the pressure-temperature conditions expected for shallow lower-mantle depths between approximately 660 to 1600 km. Considering the lack of sign for melting in our experiments, our preferred interpretation of the observation is that Brd partially breaks down to dense hydrous silica and periclase (Pc), forming the phase assembly Brd + Pc + Stv. The results may provide an explanation for the enigmatic coexistence of Stv and Fp inclusions in lower-mantle diamonds.
DS202205-0716
2022
Leinenweber, K.Shim, S-H., Chizmeshya, A., Leinenweber, K.Water in the crystal structure of CaSiO3 perovskite.American Mineralogist, Vol. 107, pp. 631-641.Mantleperovskite

Abstract: While the water storage capacities of the upper 700 km depths of the mantle have been constrained by high-pressure experiments and diamond inclusion studies, the storage capacity of the lower mantle remains controversial. A recent high-pressure experimental study on CaSiO3 perovskite, which is the third most abundant mineral in the lower mantle, reported possible storage of H2O up to a few weight percent. However, the substitution mechanism for H in this phase remains unknown. We have conducted a series of density functional theory calculations under static-lattice conditions and high pressures to elucidate hydration mechanisms at the atomic scale. All of the possible dodecahedral (Ca2+ ? 2H+) and octahedral (Si4+ ? 4H+) substitution configurations for a tetragonal perovskite lattice have very small energy differences, suggesting the coexistence of multiples of H configurations in CaSiO3 perovskite at mantle pressures and temperatures. The dodecahedral substitutions decrease the bulk modulus, resulting in a smaller unit-cell volume of hydrous CaSiO3 perovskite under pressure, consistent with the experimental observations. Although the octahedral substitutions also decrease the bulk modulus, they increase the unit-cell volume at 1 bar. The H atoms substituted in the dodecahedral sites develop much less hydrogen bonding with O atoms, leading to a large distortion in the neighboring SiO6 octahedra. Such distortion may be responsible for the non-cubic peak splittings observed in experiments on hydrous CaSiO3 perovskite. Our calculated infrared spectra suggest that the observed broad OH modes in CaSiO3 perovskite can result from the existence of multiples of H configurations in the phase. Combined with the recent experimental results, our study suggests that CaSiO3 can be an important mineral phase to consider for the H2O storage in the lower mantle.
DS201809-2086
2018
Leinenweber. K.Shim, S-H., Nisr, C., Chen, H., Leinenweber. K., Chizmeshya, A., Prakapenka, V., Kunz, M., Bechtel, H., Liu, Z.Hydrous silica in the lower mantle. BridgemaniteGoldschmidt Conference, 1p. AbstractMantlewater

Abstract: While mineral phases stable in the mantle transition zone (such as wadsleyite and ringwoodite) can store up to 3 wt% H2O, those in the lower mantle such as bridgmanite and ferropericlase can contain a very small amount (<50 ppm). While such dramatic differences can lead to dehydration/hydration and hydrous melting at 660-km depth in the mantle [1,2] it is uncertain how much water can be transported and stored at these depths. In order to answer this question, we have conducted a series of high pressure experiments in laser-heated diamondanvil cell and multi-anvil press combined with X-ray diffraction, infrared spectroscopy, laser Raman spectroscopy, and secondary ion mass spectrometry. Initially we examined the water storage capacity of dense (Al free) silica polymorphs at high pressure and temperature. We found that water can dramatically reduce the rutile-type to CaCl2-type phase transition from 55 GPa to 25 GPa and stabilize a new "disordered inverse" inverse NiAs-type phase at pressures above 50 GPa, which is not stable in dry SiO2 system. The CaCl2-type and NiAs-type silica polymorphs contain up to 8 wt% of H2O at 1400-2100 K up to at least 110 GPa. We next explored the effects of water on the mineralogy of the lower mantle and found that hydrous Mg2SiO4 ringwoodite (1 wt% H2O) breaks down to silica + bridgmanite + ferropericlase at pressures up to 60 GPa and 2100 K. The recovered silica samples contain 0.3-1.1 wt% H2O, suggesting that water stabilizes silica even under Si-undersaturated systems because of their large water storage capacity. Therefore, our observations support the stability of silica in hydrous regions in the pyrolitic lower mantle. In the subducting oceanic crust (basalt and sediment), silica represents 20-80% of the mineralogy. Because its stability range spans the mantle transition zone to the deep mantle, hydrous silica is expected to play a major role in the transport and storage of water in the deep mantle.
DS1994-1024
1994
Leinz, R.W.Leinz, R.W., Hoover, D.B.Ideal CHIM with the newly developed NEOCHIM electrodeExlore, No. 83, pp. 10-15GlobalGeochemistry, Mineral deposit technology
DS1950-0144
1953
Leiper, H.Leiper, H.Octahedral Diamond Crystal Found in Canon Diablo Arizona Meteorite.Mineralogical Hobbyist., Vol. 2, No. 1, PP. 9 and 22.ArizonaKimberlite, Rocky Mountains
DS1950-0334
1957
Leiper, H.Leiper, H.Arkansaw Diamonds. #1Journal of GEMOLOGY, Vol. 6, No. 2, PP. 63-71. ALSO: Lapidary Journal, Vol. 11, PP.United States, Gulf Coast, Arkansas, PennsylvaniaMorphology, Diamond Occurrence
DS1960-0694
1966
Leiper, H.Leiper, H.Former Texas Oil Driller Sells Out Undersea Diamond Dredging Firm to de Beers.Lapidary Journal, Vol. 19, No. 11, FEBRUARY, PP. 1282-1284.Southwest Africa, NamibiaDiamond Mining Recovery, Submarine Diamond Placers
DS1960-0695
1966
Leiper, H.Leiper, H.America's Only Diamond Bearing Peridotite PipeLapidary Journal, Vol. 20, PP. 714-733.United States, Gulf Coast, Arkansas, PennsylvaniaBlank
DS1975-0947
1979
Leiper, W.Blaauw, C., White, C.G., Leiper, W., Clarke, D.B.Mossbauer Analysis of Synthetic DjerfisheriteMineralogical Magazine., Vol. 43, No. 328, PP. 552-553.GlobalRelated Mineralogy, Techniques
DS201712-2736
2017
Leisgang, I.Weis, U., Schwager, B., Stoll, B., Nohl, U., Karlowski, P., Leisgang, I., Zwillich, F., Joachum, K.P.Geostandards and Geoanalytical Research bibliographic review 2016 ( geoanalyses, controls)Geostandards and Geoanalyical Review, Nov. 17, in press availableTechnologyreview

Abstract: This bibliographic review covers the research contained in twenty-one scientific journals with important contributions to geoanalysis and related scientific fields (Table 1, Figure 1). The relevance of well characterised reference materials (RMs) used as calibration materials or quality control samples for precise and accurate analyses is widely known and has often been described, for example, by Jochum and Enzweiler (2014).
DS1860-0167
1872
Leisure HourLeisure HourDiamond from AfricaLeisure Hour., P. 768.Africa, South AfricaHistory
DS1860-0169
1872
Leisure HourLeisure HourThe Diamond Fields of South Africa (1872)Leisure Hour., PP. 679-682.Africa, South Africa, Cape ProvinceTravelogue, History
DS1860-0451
1885
Leisure HourLeisure HourTrue Story of Finding the First Cape DiamondLeisure Hour., OCTOBER PP. 686-687.Africa, South AfricaHistory
DS1995-1081
1995
Leitch, A.M.Leitch, A.M.Effects of temperature and mantle dynamics on estimates of the thermal conductivity in the deep mantle.Physics of the Earth and Plan. Interiors, Vol. 89, pp. 89-108.MantleCore mantle boundary
DS1997-0670
1997
Leitch, A.M.Leitch, A.M., Cordery, M.J., Davies, G.F., Campbell, I.Flood basalts from eclogite bearing mantle plumesSouth African Journal of Geology, Vol. 100, 4, Dec. pp. 311-318MantleConvection, melt, Plumes
DS1997-0671
1997
Leitch, A.M.Leitch, A.M., Cordery, M.J., Davies, G.F., Campbell, I.Flood basalts from eclogite bearing mantle plumesSouth African Journal of Geology, Vol. 100, 4, Dec. pp. 311-318.MantleConvection, melt, Plumes
DS1998-0855
1998
Leitch, A.M.Leitch, A.M., Davies, G.F., Wells, M.A plume head melting under a rifting marginEarth and Planetary Science Letters, Vol. 161, No. 1-4, Sept. 1, pp. 161-178.MantleHot spot, Tectonics
DS2000-0564
2000
Leitch, A.M.Leitch, A.M., Davies, G.F., Moresi, L.N.Mantle plumes meets bumpy lithosphereGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) 2000 Conference, 1p. Abstract.MantleGeophysics - tomography, Mantle convection
DS2001-0672
2001
Leitch, A.M.Leitch, A.M., Davies, G.F.Mantle plumes and flood basalts: enhanced melting from plume ascent and an eclogite component.Journal of Geophysical Research, Vol. 106, No.2, Feb.10, pp. 2047-60.MantlePlumes, Eclogites
DS1990-0916
1990
Leitch, C.H.B.Leitch, C.H.B., Day, S.J.NEWGRES: a Turbo Pascal program to solve a modified version of Gresens'hydrothermal alteration equationComputers and Geosciences, Vol. 16, No. 7, pp. 925-932GlobalComputer, Program -NEWGRES
DS1992-0013
1992
Leitch, E.C.Allan, A.D., Leitch, E.C.The nature and origin of eclogite blocks in serpentinite from the TamworthBelt, New England Fold Belt, eastern AustraliaAustralian Journal of Earth Sciences, Vol. 39, No. 1 , February pp. 29-35AustraliaTectonics, Eclogite
DS1998-0227
1998
Leitch, E.C.Cawood, P.A., Leitch, E.C.Going down: subduction initiation in the proto-Pacific and relationship to end Neoproterozoic global events.Journal of African Earth Sciences, Vol. 27, 1A, p. 42. AbstractGondwanaTectonics, Subduction
DS1998-1152
1998
LeitePereira, R.S., Wheelock, G., Bizzi, L., Silva, LeiteAlluvial diamond potential of Paleo drainage systems in the headwaters Of the Sao Francisco River, Minas Gerais7th. Kimberlite Conference abstract, pp. 684-6.Brazil, Minas GeraisAlluvials, Deposit - Sao Francisco
DS1994-1025
1994
Leite, .A.D.Leite, .A.D., Chemale, F. Jr.A possible pre-568 Ma slab of upper mantle in the Cerro Mantiqueirasregion: evidences from harzburgites..International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 140-141.BrazilMantle, Subduction, deformation, microtextures
DS201712-2716
2017
Leite, A.A.Pereira, R.S., Fuck, R.A., Soares Franca, O., Leite, A.A.Evidence of young, proximal and primary (YPP) diamond source occurring in alluviums in the Santa Antonio do Bonito, Santo Inacio and Douradhinho rivers in Coromandel region, Minas Gerais.Brazilian Journal of Geology, Vol. 47, 3, pp. 383-401.South America, Brazildeposit - Alta Paranaiba

Abstract: Magmatism associated with the Alto Paranaíba structural high comprises kimberlites, kamafugites, and alkaline complexes, forming an approximately 400 x 150 km NW-SE belt in the southern São Francisco Craton. Dating of some intrusions reveals ages between 120 and 75 Ma. Chemical analyses of garnet recovered in alluvium from traditional diamond digging areas indicate peridotitic garnet windows in Três Ranchos and Coromandel. Six hundred and eighty (680) diamonds acquired or recovered during mineral exploration in the digging areas of Romaria, Estrela do Sul, Três Ranchos and Coromandel show unique characteristics, certain populations indicating young, proximal and primary sources (YPP). Analyses of 201 stones from Santo Antônio do Bonito, Santo Inácio and Douradinho rivers alluvium, Coromandel, present no evidence of transport, characterizing a proximal source. Within these river basins, exposures of the Late Cretaceous Capacete Formation basal conglomerate contain mainly small rounded and/or angular quartzite pebbles and of basic and ultrabasic rocks, as well as kimberlite minerals (garnet, ilmenite, spinel, sometimes diamond). A magnetotelluric profile between the Paraná and Sanfranciscana basins shows that the thick underlying lithosphere in the Coromandel region coincides with the peridotitic garnet window and with a diamond population displaying proximal source characteristics. Diamond-bearing kimberlite intrusions occur in different areas of Alto Paranaíba.
DS201907-1567
2017
Leite, A.A.Pereira, R.G., Fuck, R.A., Franca, O.S., Leite, A.A.Evidence of young, proximal and primary ( YPP) diamond source occurring in alluviums in the Sant Antonio do Bonito, Santo Inacio and Dourahinho rivers in the Coromandel region, Minas Gerais.Brazil Journal of Geology, Vol. 47, 3, pp. 383-401. pdfSouth America, Brazilkimberlites, kamafugites, Tres Ranchos, Coromandel

Abstract: Magmatism associated with the Alto Paranaíba structural high comprises kimberlites, kamafugites, and alkaline complexes, forming an approximately 400 x 150 km NW-SE belt in the southern São Francisco Craton. Dating of some intrusions reveals ages between 120 and 75 Ma. Chemical analyses of garnet recovered in alluvium from traditional diamond digging areas indicate peridotitic garnet windows in Três Ranchos and Coromandel. Six hundred and eighty (680) diamonds acquired or recovered during mineral exploration in the digging areas of Romaria, Estrela do Sul, Três Ranchos and Coromandel show unique characteristics, certain populations indicating young, proximal and primary sources (YPP). Analyses of 201 stones from Santo Antônio do Bonito, Santo Inácio and Douradinho rivers alluvium, Coromandel, present no evidence of transport, characterizing a proximal source. Within these river basins, exposures of the Late Cretaceous Capacete Formation basal conglomerate contain mainly small rounded and/or angular quartzite pebbles and of basic and ultrabasic rocks, as well as kimberlite minerals (garnet, ilmenite, spinel, sometimes diamond). A magnetotelluric profile between the Paraná and Sanfranciscana basins shows that the thick underlying lithosphere in the Coromandel region coincides with the peridotitic garnet window and with a diamond population displaying proximal source characteristics. Diamond-bearing kimberlite intrusions occur in different areas of Alto Paranaíba.
DS1960-1152
1969
Leite, C.R.Leite, C.R.Cristalografia E Mineralogia Do Diamante Da Regiao Do Triangulo Miniero.Ph.d. Thesis, University Sao Paulo, 101P.Brazil, Minas GeraisCrystallography
DS1984-0449
1984
Leite, C.R.Leite, C.R., Barelli, N., Sardela, I.A.Oriented Enstatite Inclusions in Natural DiamondMineralogical Magazine., Vol. 48, No. 348, PT. 3, SEPT. PP. 459-461.BrazilMineralogy
DS1998-0856
1998
Leite, J.A.D.Leite, J.A.D., Hartman, L.A., Chemale, F.Shrimp uranium-lead (U-Pb) zircon geochronology of Neoproterozoic juvenile and crustal reworked terranes in southernmostInternational Geology Review, Vol. 40, No. 8, Aug. 1, pp. 688-721BrazilGeochronology, Tectonics
DS1999-0297
1999
Leite, J.A.D.Hartmann, L.A., Leite, J.A.D., McNaughton, N.J., SantosDeepest exposed crust of Brasil- SHRIMP established three eventsGeology, Vol. 27, No. 10, Oct. pp. 947-50.Brazil, Rio Grande do SulGeochronology, Shield
DS2000-0392
2000
Leite, J.A.D.Hartmann, L.A., Leite, J.A.D., Da Silva, Remus et al.Advances in SHRIMP geochronology and their impact on understanding tectonic and metallogenic evolution....Australian Journal of Earth Sciences, Vol. 47, No. 5, Oct. pp. 829-44.BrazilGeochronology, Metallogeny
DS1920-0452
1929
Leite De CastroLeite De CastroCompanhia de Diamantes de Angola. Noticia Succinta Sobre a Sua Constituicao Concessoes Obtidas E Trabalhos Realizados Em Angola. #2Lisboa:, 50P.AngolaKimberlite
DS1920-0453
1929
Leite de castro, E.Leite de castro, E.Companhia de Diamantes de Angola. Noticia Succinta Sobre a Sua Constituicao Concessoes Obtidas E Trabalhos Realizadoz Em Angola. #1Lisbon:, Central Africa, AngolaBlank
DS2001-1072
2001
LeitesShumilova, T.G., Mikhalitsyn, Bukalov, LeitesInvestigation of the ordering of skeletal diamonds from the Kumdykol deposit by Raman spectroscopy and lumin.Doklady Academy of Sciences, Vol. 378, No. 4, May-June pp. 390-3.RussiaDiamond - morphology, Luminesence
DS1993-0904
1993
Leitz, E.P.Leitz, E.P., Neal, C.R.chromium-poor megacrysts: cognate or xenocrystal?American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 637.MantleXenoliths, Experimental petrology
DS1999-0404
1999
Lejeune, A.M.Lejeune, A.M., Bottinga, Y., Richet, P.Rheology of bubble bearing magmasEarth and Planetary Science Letters, Vol. 166, No. 1-2, Feb. 28, pp. 71-84.GlobalMagmatism
DS200912-0183
2009
Lejeunesse, P.Doornbos, C., Heaman, L.M., Doupe, J.P., England, J., Simonetti, A., Lejeunesse, P.The first integrated use of in situ U Pb geochronology and geochemical analyses to determine long distance transport of glacial erratics from maIn land Canada into western Arctic Archipelgo.Canadian Journal of Earth Sciences, Vol. 46, 2, pp. 101-122.Canada, Melville PeninsulaGeochronology - western Arctic Archipelago
DS201312-0513
2013
Lekgoathi, M.Kramers, J.D., Andreoli, M.A.G., Atanasova, M., Belyanin, G.A., Block, D.L., Franklyn, C., Harris, C., Lekgoathi, M., Montross, C.S., Ntsoane, T., Pischedda, V., Segonyane, P., Viljoen, K.S., Westraadt, J.E.Unique chemistry of a diamond bearing pebble from the Libyan desert glass strewnfield, SW Egypt: evidence for a shocked comet fragment.Earth and Planetary Science Letters, Vol.382, pp. 21-31.Africa, EgyptShock diamonds
DS201012-0176
2010
Lekic, V.Dziewonski, A.M., Lekic, V., Romanowicz, B.A.Mantle anchor structure: an argument for bottom up tectonics.Earth and Planetary Science Letters, Vol. 299, pp. 69-79.MantleSubduction
DS201112-0580
2011
Lekic, V.Lekic, V., French, S.W., Fischer, K.M.Lithospheric thinning beneath rifted regions of southern California.Science, Vol. 334, 6057, pp. 783-787.United States, CaliforniaTectonics
DS201112-0581
2011
Lekic, V.Lekic, V., Romanowicz, B.Inferring upper mantle structure by full waveform tomography with the spectral element method.Geophysical Journal International, Vol. 185, 2, May pp. 799-831.MantleGeophysics - seismics
DS201112-0582
2011
Lekic, V.Lekic, V., Romanowicz, B.Tectonic regionalization without a priori information: a cluster analysis of upper mantle tomography.Earth and Planetary Science Letters, Vol. 308, 1-2, pp. 151-160.MantleTomography
DS201212-0400
2012
Lekic, V.Lekic, V., Cottaar, S., Dziewonski, A., Romanowicz, B.Cluster analysis of global lower mantle tomography: a new class of structure and implications for chemical heterogeneity.Earth and Planetary Science Letters, Vol. 357-358, pp. 68-77.MantleBoundary
DS201312-0877
2013
Lekic, V.Sramek, O., McDonough, W.F., Kite, E.S., Lekic, V., Dye, S.T., Zhong, S.Geophysical and geochemical constraints on geoneutrino fluxes from Earth's mantle.Earth and Planetary Science Letters, Vol. 361, pp. 356-366.MantleTomography
DS201412-0369
2014
Lekic, V.Hopper, E., Ford, H.A., Fischer, K.M., Lekic, V., Fouch, M.J.The lithosphere-asthenosphere boundary and the tectonic and magmatic history of the northwestern United States.Earth and Planetary Science Letters, Vol. 402, pp. 69-81.United StatesGeophysics - seismics
DS201412-0503
2014
Lekic, V.Lekic, V., Fischer, K.M.Contrasting lithospheric signatures across the western United States revealed by Sp receiver functions.Earth and Planetary Science Letters, Vol. 402, pp. 90-98.United States, Colorado PlateauGeophysics - seismics
DS201601-0041
2015
Lekic, V.Rudolph, M.L., Lekic, V., Lithgow-Bertelloni, C.Viscosity jump in Earth's mid-mantle.Science, Vol. 350, 6266, pp. 1349-1352.MantleGeophysics - seismics

Abstract: The viscosity structure of Earth’s deep mantle affects the thermal evolution of Earth, the ascent of mantle plumes, settling of subducted oceanic lithosphere, and the mixing of compositional heterogeneities in the mantle. Based on a reanalysis of the long-wavelength nonhydrostatic geoid, we infer viscous layering of the mantle using a method that allows us to avoid a priori assumptions about its variation with depth. We detect an increase in viscosity at 800- to 1200-kilometers depth, far greater than the depth of the mineral phase transformations that define the mantle transition zone. The viscosity increase is coincident in depth with regions where seismic tomography has imaged slab stagnation, plume deflection, and changes in large-scale structure and offers a simple explanation of these phenomena.
DS201702-0193
2016
Lekic, V.Ballmer, M.D., Schumacher, L., Lekic, V., Thomas, C., Ito, G.Compositional layering with the large slow shear wave velocity provinces in the lower mantle.Geochemistry, Geophysics, Geosystems: G3, Vol. 17, 2, pp. 5056-5077.MantleGeophysics - seismics

Abstract: The large low shear-wave velocity provinces (LLSVP) are thermochemical anomalies in the deep Earth's mantle, thousands of km wide and ?1800 km high. This study explores the hypothesis that the LLSVPs are compositionally subdivided into two domains: a primordial bottom domain near the core-mantle boundary and a basaltic shallow domain that extends from 1100 to 2300 km depth. This hypothesis reconciles published observations in that it predicts that the two domains have different physical properties (bulk-sound versus shear-wave speed versus density anomalies), the transition in seismic velocities separating them is abrupt, and both domains remain seismically distinct from the ambient mantle. We here report underside reflections from the top of the LLSVP shallow domain, supporting a compositional origin. By exploring a suite of two-dimensional geodynamic models, we constrain the conditions under which well-separated "double-layered" piles with realistic geometry can persist for billions of years. Results show that long-term separation requires density differences of ?100 kg/m3 between LLSVP materials, providing a constraint for origin and composition. The models further predict short-lived "secondary" plumelets to rise from LLSVP roofs and to entrain basaltic material that has evolved in the lower mantle. Long-lived, vigorous "primary" plumes instead rise from LLSVP margins and entrain a mix of materials, including small fractions of primordial material. These predictions are consistent with the locations of hot spots relative to LLSVPs, and address the geochemical and geochronological record of (oceanic) hot spot volcanism. The study of large-scale heterogeneity within LLSVPs has important implications for our understanding of the evolution and composition of the mantle.
DS202005-0758
2020
Lekic, V.Ritsema, J., Lekic, V.Heterogeneity of seismic wave velocity in Earth's mantle.Annual Review of Earth and Planetary Sciences, Vol.48, 25p. PdfMantlegeophysics - seismics

Abstract: Seismology provides important constraints on the structure and dynamics of the deep mantle. Computational and methodological advances in the past two decades improved tomographic imaging of the mantle and revealed the fine-scale structure of plumes ascending from the core-mantle boundary region and slabs of oceanic lithosphere sinking into the lower mantle. We discuss the modeling aspects of global tomography including theoretical approximations, data selection, and model fidelity and resolution. Using spectral, principal component, and cluster analyses, we highlight the robust patterns of seismic heterogeneity, which inform us of flow in the mantle, the history of plate motions, and potential compositionally distinct reservoirs. In closing, we emphasize that data mining of vast collections of seismic waveforms and new data from distributed acoustic sensing, autonomous hydrophones, ocean-bottom seismometers, and correlation-based techniques will boost the development of the next generation of global models of density, seismic velocity, and attenuation. Seismic tomography reveals the 100-km to 1,000-km scale variation of seismic velocity heterogeneity in the mantle. Tomographic images are the most important geophysical constraints on mantle circulation and evolution.
DS202007-1173
2020
Lekic, V.Ritsema, J., Lekic, V.Heterogeneity of seismic wave velocity in Earth's mantle.Annual Review of Earth and Planetary Sciences, Vol. 48, 1, pp. w77-401.Mantlegeophysics - seismics

Abstract: Seismology provides important constraints on the structure and dynamics of the deep mantle. Computational and methodological advances in the past two decades improved tomographic imaging of the mantle and revealed the fine-scale structure of plumes ascending from the core-mantle boundary region and slabs of oceanic lithosphere sinking into the lower mantle. We discuss the modeling aspects of global tomography including theoretical approximations, data selection, and model fidelity and resolution. Using spectral, principal component, and cluster analyses, we highlight the robust patterns of seismic heterogeneity, which inform us of flow in the mantle, the history of plate motions, and potential compositionally distinct reservoirs. In closing, we emphasize that datamining of vast collections of seismic waveforms and new data from distributed acoustic sensing, autonomous hydrophones, ocean-bottom seismometers, and correlation-based techniques will boost the development of the next generation of global models of density, seismic velocity, and attenuation.
DS1975-0881
1978
Lelann, F.Tixeront, M., Lelann, F., Horn, R., Scolari, G.Ilmenite Prospection on the Continental Shelf of Senegal: Methods and Results.Marine Mining, Vol. 1, No. 3, PP. 171-187.GlobalDiamond Mining Recovery, Marine Placers, Alluvials
DS1975-1114
1979
Lelann, F.Lelann, F., Ulrich, J.The Vibrocoring Technique and Continental Shelf Survey: The french Geological Survey (brgm)'s Experience.Resources Minerales Sous Marines, Scolari, G. Editor., French Geological Survey (BRGM) No. 7, PP. 217-232.South Africa, Southwest Africa, West Africa, NamibiaDiamond Mining Recovery, Alluvials, Marine Placers
DS1995-1082
1995
Lele, S.Lele, S.Inner product matrices, kriging and nonparametric estimation of SOURCE[ Mathematical GeologyMathematical Geology, Vol. 27, No. 5, pp. 673-692GlobalGeostatistics, Kriging
DS201512-1909
2015
Leleu, B.De Lamotte, F., Fourdan, D., Leleu, B., Leparmentier, S., Clarens, F.Style of rifting and the stages of Pangea.Tectonics, Vol. 34, 5, pp. 1009-1029.MantlePangea

Abstract: Pangea results from the progressive amalgamation of continental blocks achieved at 320?Ma. Assuming that the ancient concept of “active” versus “passive” rifting remains pertinent as end-members of more complex processes, we show that the progressive Pangea breakup occurred through a succession of rifting episodes characterized by different tectonic evolutions. A first episode of passive continental rifting during the Upper Carboniferous and Permian led to the formation of the Neo-Tethys Ocean. Then at the beginning of Triassic times, two short episodes of active rifting associated to the Siberian and Emeishan large igneous provinces (LIPs) failed. The true disintegration of Pangea resulted from (1) a Triassic passive rifting leading to the emplacement of the central Atlantic magmatic province (200?Ma) LIP and the subsequent opening of the central Atlantic Ocean during the lowermost Jurassic and from (2) a Lower Jurassic active rifting triggered by the Karoo-Ferrar LIP (183?Ma), which led to the opening of the West Indian Ocean. The same sequence of passive then active rifting is observed during the Lower Cretaceous with, in between, the Parana-Etendeka LIP at 135?Ma. We show that the relationships between the style of rifts and their breakdown or with the type of resulting margins (as magma poor or magma dominated) are not straightforward. Finally, we discuss the respective role of mantle global warming promoted by continental agglomeration and mantle plumes in the weakening of the continental lithosphere and their roles as rifting triggers.
DS201506-0268
2015
Leleu, S.Frizon de Lamotte, D., Fourdan, B., Leleu, S., Leparmentier, F., de Clarens, P.Style of rifting and the stages of Pangea break up.Tectonics, Vol. 34, 5, pp. 1009-1029.Global, RussiaPangea
DS1994-0957
1994
Leliukh, M.J.Kryuchkov, A.I., Leliukh, M.J., Krasinets, S.S., Afansiev, V.P.Two unusual Paleozoic kimberlite diatremes in the Daldyn-Alakit region Of the Siberian PlatformProceedings of Fifth International Kimberlite Conference, Vol. 1, pp. 34-39.Russia, SiberiaDaldyn-Alakit, Kimberlite diatremes
DS1986-0054
1986
Lelj, F.Barone, V., Lelj, F., Russo, N., Toscano, M.A theoretical study of relaxation and reconstruction of the(III) surface of diamondSurface Science, Vol. 162, No. 1-3, Oct. pp. 169-174GlobalDiamond morphology
DS201904-0719
2019
Lelong, G.Boulard, E., Harmand, M., Guyot, F., Lelong, G., Morard, D., Cabaret, D., Boccato, S., Rosa, A.D., Briggs, R., Pascarelli, S., Fiquet, G.Ferrous iron under oxygen rich conditions in the deep mantle.Geophysical Research Letters, Vol. 46, 3, pp. 1348-1356.MantleUHP

Abstract: Iron oxides are important end?members of the complex materials that constitute the Earth's interior. Among them, FeO and Fe2O3 have long been considered as the main end?members of the ferrous (Fe2+) and ferric (Fe3+) states of iron, respectively. All geochemical models assume that high oxygen concentrations are systematically associated to the formation of ferric iron in minerals. The recent discovery of O22? peroxide ions in a phase of chemical formula FeO2Hx stable under high?pressure and high?temperature conditions challenges this general concept. However, up to now, the valences of iron and oxygen in FeO2Hx have only been indirectly inferred from a structural analogy with pyrite FeS2. Here we compressed goethite (FeOOH), an Fe3+?bearing mineral, at lower mantle pressure and temperature conditions by using laser?heated diamond?anvil cells, and we probed the iron oxidation state upon transformation of FeOOH in the pressure-temperature stability field of FeO2Hx using in situ X?ray absorption spectroscopy. The data demonstrate that upon this transformation iron has transformed into ferrous Fe2+. Such reduced iron despite high oxygen concentrations suggests that our current views of oxidized and reduced species in the lower mantle of the Earth should be reconsidered.
DS1995-1083
1995
Lelukh, M.I.Lelukh, M.I., Vasiliev, A.A., Kryuchkov, A.I., Cherny, S.D.New dat a on morphology of kimberlite bodiesProceedings of the Sixth International Kimberlite Conference Almazy Rossii Sakha abstract, p. 10, 11.Russia, YakutiaStructure - pipe, Deposit -Rot Front, Yakutskaya
DS201012-0405
2010
Lelukh, M.I.Kornilova, V.P., Spetsius, Z.V., Lelukh, M.I., Gerasimchuk, A.V.Pecularities of garnets from kimberlites of Nakynsky field, Yakutia.International Mineralogical Association meeting August Budapest, abstract p. 571.Russia, YakutiaChemistry - Mayaskaya, Nuyrbinskaya pipes
DS1998-0857
1998
Leluyh, M.I.Leluyh, M.I., Kostrovitsky, S.I., Bezborodov, S.M.et al.Kimberlites and related rocks of Anabar region, Yakutia, Russia7th International Kimberlite Conference Abstract, pp. 497-9.Russia, YakutiaGeology, geochronology, Deposit - Anabar area
DS1998-1173
1998
LelyoukhPodvysotsky, V.T., Zuev, V.M., Nikulin, LelyoukhConception of formation of magmatogene and terrigenous diamondiferous formations ancient platforms - forecast7th. Kimberlite Conference abstract, pp. 696-8.RussiaCraton, Magmatism
DS1991-0935
1991
Lelyukh, M.I.Kryuchokov, A.I., Nikulin, V.I., Krasinets, S.S., Lelyukh, M.I.Conditions of localization and structure of a new kimberlite body in the Aikhal area (Siberian platform)Soviet Geology and Geophysics, Vol. 32, No. 5, pp. 52-58Russia, SiberiaKimberlite, structure, Aikhal area
DS1995-1352
1995
Lelyukh, M.I.Nikulin, V.I., Von der Flaas, G.S., Lelyukh, M.I.The stages of the native diamond deposits formation (Siberian platform)Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 399-401.Russia, Siberia, YakutiaDiamond genesis, Tectonics
DS1998-1548
1998
Lelyukh, M.I.Vladykin, N.V., Lelyukh, M.I., Tolstov, A.V.Lamproites of the Anabar region, northern rimming of the SiberianPlatform7th International Kimberlite Conference Abstract, pp. 946-8.Russia, SiberiaLamproites, chemistry, Deposit - Pinabarie
DS2003-1430
2003
Lelyukh, M.I.Vladykin, N.V., Lelyukh, M.I., Tolstov, A.V., Serov, V.P.Petrology of kimberlite lamproite carbonatite rock association, east Prianabar'e (8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractRussiaBlank
DS200412-2062
2003
Lelyukh, M.I.Vladykin, N.V., Lelyukh, M.I., Tolstov, A.V., Serov, V.P.Petrology of kimberlite lamproite carbonatite rock association, east Prianabar'e ( Russia).8 IKC Program, Session 7, POSTER abstractRussiaKimberlite petrogenesis
DS1860-0636
1889
Lemaire, C.Lemaire, C., Dupont.Carte des Mines D'or et de le Diamant du CapRev. France De L'etranger Et Des Colonies (paris), SEPT. 1Africa, South Africa, Griqualand WestDiamond Occurrence
DS1985-0388
1985
Lemeyre, J.Lemeyre, J.Generation of Alkaline Magmas by Pressure Release in Within plate Oceanic and Continental Province.Geological Society of America (GSA), Vol. 17, No. 3, P. 164. (abstract.).West AfricaGenesis
DS201804-0715
2018
Lemiere, B.Lemiere, B.A review of pXRF ( field portable X-ray fluoresence) applications for applied geochemisty.Journal of Geochemical Exploration, Vol. 188, pp. 350-362.Technologyflourescence
DS1995-0913
1995
LemieuxKanesewich, E.R., Burianyk, Dubuc, Lemieux, KalantzisThree dimensional seismic reflection studies of the Alberta basementCanadian Journal of Exploration Geophysics, Vol. 31, No. 1-2, pp. 1-10.AlbertaGeophysics - seismics, Tectonics
DS1989-0304
1989
Lemieux, A.Cranstone, D., Lemieux, A.Current results of exploration financed with flow-through shares - just the tip of the iceberg! (Brief two page overview)Canadian Mineral Industry Report, January pp. 30-32. (l graph) Database # 17757CanadaEconomics, Flow through -brief
DS1989-0875
1989
Lemieux, A.Lemieux, A., Bouchard, J.G., Cranstone, D.A.Canadian Mines: perspective from 1988. Production, development andexplorationEnergy Mines and Resources, Mineral Bulletin No. 221, 45p. Database # 17921CanadaEconomics, Exploration
DS1990-0369
1990
Lemieux, A.Cranstone, D., Lemieux, A.Some uses of mineral resource dat a for policy analysisPreprint 4th. International Conference on Geoscience Information Ottawa June, 45pGlobalEconomics, MIneral resource data
DS1992-0936
1992
Lemieux, A.Lemieux, A.Worldwide mineral properties Canadian mining industry. Can. companies have8500 properties in 60 countries- graphic presentation dat a obtained from Min-Met Canada LtWorld Mineral Notes, Vol. 8, No. 4, September pp. 12-26CanadaMining Industry activities, Property status -graphic histograms
DS1993-0296
1993
Lemieux, A.Cranstone, D., Lemieux, A.Canadian exploration and mine investment in the global contextProspectors and Developers Exploration and Development Highlights 1992, Vol. 5, pp. 5-8CanadaEconomics, Investment -exploration
DS1994-0354
1994
Lemieux, A.Cranstone, D., Lemieux, A., Vallee, M.Canadian exploration and mine investmentProspectors and Developers Association of Canada (PDAC) Exploration and Development Highlights, March 1994, pp. 3-8CanadaExploration activities and investment, Overview
DS1995-0366
1995
Lemieux, A.Cranstone, D., Lemieux, A.Canada in a global contextProspectors and Developers Association of Canada (PDAC) Annual Publishing Exploration and Dev. Highlights, March pp. 4-5, 7, 9, 10CanadaEconomics, Mining activity 1994
DS1997-0672
1997
Lemieux, A.Lemieux, A.Canada's global mining presenceCanadian Minerals Yearbook 1996, 22pCanadaEconomics, Exploration, mining, discoveries, legal
DS1998-0858
1998
Lemieux, A.Lemieux, A.Canadian firms dominate world exploration arena in 1997Prospectors and Dev. Association Annual, March pp. 42-46CanadaMines - projects - listing by name, company, commodity, Discoveries
DS2002-0934
2002
Lemieux, G.Lemieux, G., Harnois, L., Berclaz, A., Stevenson, R., SharmaCharacterisation petrochimique des dykes de lamprophyre et de carbonate region du Lac Aigneau.Quebec Ministere des Resources Naturelles, (FRE), GM 56659, 23p.QuebecPetrology
DS1996-1334
1996
Lemieux, J.Smith, R.S., Annan, A.P., Lemieux, J., Pederson, R.N.Application of a modified GEOTEM (R) system to reconnaissance exploration for kimberlites Point LakeGeophysics, Vol. 61, No. 1, Jan-Feb. pp. 82-92.Northwest TerritoriesGeophysics -GEOTEM., Kimberlites -Point Lake
DS1999-0405
1999
Lemieux, S.Lemieux, S.Seismic reflection expression and tectonic significance of Late Cretaceous extensional faulting ....Lithoprobe, No. 47, pp. 375-90.Alberta, Western Canada Sedimentary basinGeophysics - seismics not specific to diamonds
DS2000-0565
2000
Lemieux, S.Lemieux, S., Cook, F.A., Ross, G.M.Crustal geometry and tectonic evolution of southern Alberta basement, from new seismic reflection ...Canadian Journal of Earth Sciences, In pressAlberta, Western CanadaTectonics, Archean Medicine Hat Block, Geophysics - seismics
DS2000-0566
2000
Lemieux, S.Lemieux, S., Ross, G.M., Cook, F.A.Crustal geometry and tectonic evolution of the Archean crystalline basement beneath the southern Alberta ...Canadian Journal of Earth Sciences, Vol.37, no11, Nov.pp.1473-91.Alberta, southernTectonics - Precambiran, Archean, Geophysics - seismics, self potential
DS1994-1026
1994
Lemmen, D.S.Lemmen, D.S., Duk-Rodkin, A., Bednarski, J.M.Late glacial drainage systems along the northwestern margin of the Laurentide ice sheet.Quat. Science Reviews, Vol. 13, pp. 805-828.Northwest Territories, British Columbia, MontanaGeomorphology
DS2003-0133
2003
Lemmetty, T.J.Borradaile, G.J., Lemmetty, T.J., Werner, T.Apparent polar wander paths and the close of late Archean crustal transpressionJournal of Geophysical Research, Vol. 108, B8,Aug. 30., 2405 10.1029/2002JB002379OntarioGeophysics, geochronology
DS200412-0183
2003
Lemmetty, T.J.Borradaile, G.J., Lemmetty, T.J., Werner, T.Apparent polar wander paths and the close of late Archean crustal transpression, northern Ontario.Journal of Geophysical Research, Vol. 108, B8,Aug. 30., 2405 10.1029/2002 JB002379Canada, OntarioGeophysics Geochronology
DS1996-0833
1996
Lemmons, J.F.Jr.Lemmons, J.F.Jr., Berry, D.Sustainability in a materials worldNonrenewable Resources, Vol. 5, No. 4, Dec. pp. 277-284GlobalEconomics, Natural resources, material flow, cycles
DS1998-0859
1998
Lemoine, F.G.Lemoine, F.G., Pavlis, N.K., Kenyon et al.New high resolution model developed for earth's gravitational fieldEos, Vol. 79, No. 9, March 3, pp. 113, 117-8.GlobalGravity, GEOSAT.
DS1910-0072
1910
Lemoine, J.Lemoine, J.Los Diamantes Sud-americanosParis: Louis Michaud., 280P.South America, BrazilKimberlite
DS1990-0917
1990
Lemoine, S.Lemoine, S., Tempier, P., Bassot, J.P., Caen-vachette, M., VialetteThe Burkinian orogenic cycle, precursor of the Eburnian orogeny in WestAfricaGeological Journal, Vol. 25, pp. 171-188Ghana, Ivory Coast, Burkina Faso, west AfricaTectonics, Orogeny
DS2003-0792
2003
Lemon, A.M.Lemon, A.M., Jones, N.L.Building solid models from boreholes and user defined cross sectionsComputers and Geosciences, Vol. 29, 5, pp. 547-555.GlobalComputer - program not specific to diamonds
DS200412-1114
2003
Lemon, A.M.Lemon, A.M., Jones, N.L.Building solid models from boreholes and user defined cross sections.Computers & Geosciences, Vol. 29, 5, pp. 547-555.TechnologyComputer - program not specific to diamonds
DS1985-0715
1985
Lemon, R.R.Watson, I., Lemon, R.R.Geomorphology of a Coastal Desert: the Namib, Southwest Africa/ NamibiaJournal of Coastal Research, Vol. 1, No. 4, pp. 329-342Southwest Africa, NamibiaGeomorphology
DS1991-0314
1991
LemosCosta, M.L., Fonseca, L.R., Angelica, R.S., Lemos, V.P., LemosGeochemical exploration of the Maicuru alkaline-ultramafic-carbonatitecomplex, northern BrasilJournal of Geochemical Exploration, Special Publications Geochemical Exploration, Vol. 40, No. 1-3, pp. 193-204GlobalCarbonatite, Maicuru
DS1991-0314
1991
Lemos, V.P.Costa, M.L., Fonseca, L.R., Angelica, R.S., Lemos, V.P., LemosGeochemical exploration of the Maicuru alkaline-ultramafic-carbonatitecomplex, northern BrasilJournal of Geochemical Exploration, Special Publications Geochemical Exploration, Vol. 40, No. 1-3, pp. 193-204GlobalCarbonatite, Maicuru
DS201212-0339
2012
Lemotlo, L.Jelsma, H.,Krishnan, S.U., Perritt, S.,Kumar, M., Preston, R., Winter, F., Lemotlo, L., Costa, J., Van der Linde, G., Facatino, M., Posser, A., Wallace, C., Henning, A., Joy, S., Chinn, I., Armstrong, R., Phillips, D.Kimberlites from central Angola: a case stidy of exploration findings.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, AngolaOverview of kimberlites
DS201412-0427
2013
Lemotlo, L.Jelsma, H., Krishnan, U., Perritt, S., Preston, R., Winter, F., Lemotlo, L., van der Linde, G., Armstrong, R., Phillips, D., Joy, S., Costa, J., Facatino, M., Posser, A., Kumar, M., Wallace, C., Chinn, I., Henning, A.Kimberlites from central Angola: a case study of exploration findings.Proceedings of the 10th. International Kimberlite Conference, Vol. 2, pp. 173-190.Africa, AngolaExploration - kimberlites
DS2001-0647
2001
Lemouel, J.L.Labroose, S., Poirier, J.P., Lemouel, J.L.The age of the inner coreEarth and Planetary Science Letters, Vol. 190, No. 3-4, pp. 111-123.MantleCore - boundary, Geochronology
DS1999-0406
1999
Lenardic, . A.Lenardic, . A., Moresi, L.N.Some thoughts on the stability of cratonic lithosphere: effects of bouyancy and viscosity.Journal of Geophysical Research, Vol. 104, No.6, June 10, pp. 12747-58.MantleCraton
DS1995-1084
1995
Lenardic, A.Lenardic, A., Kaula, W.M.Mantle dynamics and the heat flow into the earth's continentsNature, Vol. 370, No. 6558, Dec. 14, pp. 709-10.MantleHeat flow, Geodynamics
DS1997-0673
1997
Lenardic, A.Lenardic, A.On the heat flow variation from Archean cratons to Proterozoic mobilebeltsJournal of Geology Research, Vol. 102, No. 1, Jan. 10, pp. 709-721GlobalCraton, Mobile belts
DS2001-0673
2001
Lenardic, A.Lenardic, A., Moresi, L.Heat flow scaling for mantle convection below a conductivity lidGeophysical Research Letters, Vol. 28, No. 7, April 1, pp. 1311-14.MantleConvection
DS2001-0674
2001
Lenardic, A.Lenardic, A., Moresi, L.Resolving seemingly inconsistent modeling results regarding continental heat flow.Geophysical Research Letters, Vol. 28, No. 7, April 1, pp. 1311-14.MantleHeat flow
DS2002-0774
2002
Lenardic, A.Jellinek, A.M., Lenardic, A., Manga, M.The influence of interior mantle temperature on the structure of plumes: heads for Venus, tails for Earth.Geophysical Research Letters, Vol. 29, 10, DOI 10.1029/2001GL014624MantleHot spots, plumes
DS2003-0793
2003
Lenardic, A.Lenardic, A., Moresi, L.N., Muhlhaus, H.Longevity and stability of cratonic lithosphere: insights from numerical simulations ofJournal of Geophysical Research, Vol. 108, 6, 10.1029/2002JB001859MantleConvection
DS200412-0361
2004
Lenardic, A.Cooper, C.M., Lenardic, A., Moresi, L.The thermal structure of stable continental lithosphere within a dynamic mantle.Earth and Planetary Science Letters, Vol. 222, 3-4, June, 15, pp. 807-817.MantleConvection, heat flux, geothermometry
DS200412-1115
2003
Lenardic, A.Lenardic, A., Moresi, L.N., Muhlhaus, H.Longevity and stability of cratonic lithosphere: insights from numerical simulations of coupled mantle convection and continentaJournal of Geophysical Research, Vol. 108, 6, 10.1029/2002 JB001859MantleConvection
DS200412-1439
2004
Lenardic, A.Niu, F., Levander, A., Cooper, C.M., Lee, C.T., Lenardic, A., James, D.E.Seismic constraints on the depth and composition of the mantle keel beneath the Kaapvaal craton.Earth and Planetary Science Letters, Vol. 224, 3-4, pp. 337-346.Africa, South AfricaGeophysics - seismics, boundary
DS200512-0613
2004
Lenardic, A.Lee, C-T., Lenardic, A., Cooper, C., Niu, F., Levander, A.The role of chemical boundary layers in regulating the thermal thickness of continents and oceans.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 17-1, Vol. 36, 5, p. 46.MantleGeothermometry, xenoliths
DS200512-0618
2005
Lenardic, A.Lenardic, A., Moresi, L.N., Jellinek, A.M., Manga, M.Continental insulation, mantle cooling, and the surface area of oceans and continents.Earth and Planetary Science Letters, Vol. 234, 3-4, pp. 317-333.MantleGeothermometry
DS200612-0274
2005
Lenardic, A.Cooper, C.M., Lenardic, A., Levander, A., Moresi, L.Creation and preservation of cratonic lithosphere: seismic constraints and geodynamic models.Benn, K., Mareschal, J-C., Condie, K.C. Archean Geodynamics and Environments, AGU Geophysical Monograph, No. 164, pp. 75-88.MantleGeophysics - seismics, tectonics
DS200612-0275
2006
Lenardic, A.Cooper, C.M., Lenardic, A., Moresi, L.Effects of continental insulation and the partitioning of heat producing elements on the Earth's heat loss.Geophysical Research Letters, Vol. 33, 13, July 16, L13313,MantleGeothermometry
DS200612-0796
2005
Lenardic, A.Lenardic, A.Continental growth and the Archean paradox.Benn, K., Mareschal, J-C., Condie, K.C. Archean Geodynamics and Environments, AGU Geophysical Monograph, No. 164, pp. 33-46.MantleArchean
DS200612-0797
2006
Lenardic, A.Lenardic, A., Cooper, C.M., Moresi, L., Levander, A.Making, keeping and may be even losing ancient continental lithosphere.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 13. abstract only.MantleAccretion
DS200612-0798
2006
Lenardic, A.Lenardic, A., Richards, M.A., Busse, F.H.Depth dependent rheology and the horizontal length scale of mantle convection.Journal of Geophysical Research, Vol. 111, B7 B07404MantleGeophysics - seismics
DS200612-0799
2006
Lenardic, A.Lenardic, A., Richards, M.A., Busse, P.H.Depth dependent rheology and the horizontal length scale of mantle convection.Journal of Geophysical Research, Vol. 111, B7 B07404MantleGeophysics - seismics
DS200612-0804
2006
Lenardic, A.Levander, A., Lenardic, A., Karlstrom, K.E.Structure of the continental lithosphere.Brown, M., Rushmer, T., Evolution and differentiation of the continental crust, Cambridge Publ., Chapter 2,MantleStructure
DS200612-0805
2006
Lenardic, A.Levander, A., Lenardic, A., Karstrom, K.Structure of the continental lithosphere.Evolution and differentiation of Continental Crust, ed. Brown, M., Rushmer, T., Cambridge Univ. Press, Chapter 2, pp. 21-66.MantleTectonics
DS200612-1013
2006
Lenardic, A.O'Neill, C., Lenardic, A., Moresi, L., Torsvik, T., Lee, C.T.The nature of subduction on the early Earth.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 458, abstract only.MantleSubduction
DS200712-0789
2007
Lenardic, A.O'Neill, C., Lenardic, A., Moresi, L., Torsvik, T.H., Lee, C.T.A.Episodic Precambrian subduction.Earth and Planetary Science Letters, In press availableMantleSubduction
DS200712-0790
2007
Lenardic, A.O'Neill, C.O., Lenardic, A., Moresi, L., Torsvik, T.H., Lee, C.T.A.Episodic Precambrian subduction.Earth and Planetary Science Letters, Vol. 262, 3-4, Oct. 30, pp. 552-562.MantleSubduction
DS200812-0481
2008
Lenardic, A.Hoink, T., Lenardic, A.Three dimensional mantle convection simulations with a low viscosity asthenosphere and the relationship between heat flow and the horizontal length scaleGeophysical Research Letters, Vol. 35, 10, May 28, L10304MantleConvection
DS200812-0641
2008
Lenardic, A.Lee, C-T A., Luffi, P., Hoink, T., Li, Z-X.,A., Lenardic, A.The role of serpentine in preferential craton formation in the late Archean by lithosphere underthrusting.Earth and Planetary Science Letters, Vol. 269, 1-2, May 15, pp. 96-104.MantleGeochronology - cratons
DS200812-0660
2008
Lenardic, A.Li, ZX., Lee, C-T.A, Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xeonoliths from the Colorado Plateau and vicinity: implications for the mantle rheology and hydration induced thinking of lithosphereJournal of Geophysical Research, Vol. 113, B9, B09210.MantleWater content
DS200812-0821
2008
Lenardic, A.O'Neill, C.J., Lenardic, A., Griffin, W.L., O'Reilly, S.Y.Dynamics of cratons in an evolving mantle.Lithos, Vol. 102, 3-4, pp.12-24.MantleGeotectonics
DS200812-1325
2008
Lenardic, A.Zheng-Xue, A.L., Lee, C-T.A., Peslier, A.H., Lenardic, A., Mackwell, S.J.Water contents in mantle xenoliths from the Colorado Plateau and vicinity: implications for mantle rheology and hydration induced thinning of continental lithosph.Journal of Geophysical Research, Vol. 113. B09210United States, Colorado PlateauPeridotite
DS200912-0433
2009
Lenardic, A.Lenardic, A., Jellinek, A.M.Tails of two plume types in one mantle.Geology, Vol. 37, 2, pp. 127-130.MantlePlume, hotspots
DS200912-0550
2009
Lenardic, A.O'Neill, C., Lenardic,A., Jellinek, A.M., Moresi, L.Influence of supercontinents on deep mantle flow.Gondwana Research, Vol. 15, 3-4, pp. 276-287.MantleMelting
DS201012-0552
2010
Lenardic, A.O'Neill, C.J., Kobussen, A., Lenardic, A.The mechanics of continental lithosphere-asthenosphere coupling.Lithos, Vol. 120, 1-2, Nov. pp. 55-62.MantleGeodynamics
DS201012-0553
2010
Lenardic, A.O'Neill, C.J., Kobussen, A., Lenardic, A.The mechanics of continental lithosphere - asthenosphere coupling.Lithos, in press available, 30p.EuropeGeophysics - geodynamics
DS201112-0757
2011
Lenardic, A.O'Neill, C., Lenardic, A., Condie, K.The punctuated evolution of the Earth: geodynamic constraints and model predictions.Goldschmidt Conference 2011, abstract p.1557.MantlePrecambrian crustal record
DS201112-0905
2011
Lenardic, A.Sandu, C., Lenardic, A., O'Neill, C.J., Cooper, C.M.Earth's evolving stress state and the past, present, and future stability of cratonic lithosphere.International Geology Review, In press, availableMantleConvection
DS201112-0906
2011
Lenardic, A.Sandu, C., Lenardic, A., O'Neill, C.J., Cooper, C.M.Earth's evolving stress state and the past, present and future stability of cratonic lithosphere.International Geology Review, Vol. 53, 11-12, pp. 1392-1402.GlobalCraton
DS201112-0907
2011
Lenardic, A.Sandu, C., Lenardic, A., O'Neill, C.J., Cooper, C.M.Earth's evolving stress state and the past, present, and future stability of cratonic lithosphere.International Geology Review, Vol. 53, no. 11-12, pp. 1392-1402.MantleCraton
DS201212-0261
2012
Lenardic, A.Griffin, W., Carbonell, R., Lenardic, A.The crust-mantle lithosphere system.34igc.org, Session abstractMantleGeodyanmics
DS201212-0304
2012
Lenardic, A.Hoink, T., Lenardic, A., Richards, M.Depth dependent viscosity and mantle stress amplification: implicaions for the role of the asthenosphere in maintaining plate tectonics.Geophysical Journal International, in press availableMantleConvection
DS201212-0401
2012
Lenardic, A.Lenardic, A.On the partitioning of mantle heat loss below oceans and continents over time and its relationship to the Archean paradox.Geophysical Journal International, 34, 3, pp. 706-720.MantleGeothermometry
DS201503-0165
2015
Lenardic, A.O'Neill, C., Lenardic, A., Condie, K.C.Earth's punctuated tectonic evolution: cause and effect.Geological Society of London Special Publication: Continent formation through time., No. 389, pp. 17-40.MantleGeotectonics
DS201702-0224
2017
Lenardic, A.Lenardic, A.Plate tectonics: a supercontinental boost.Nature Geoscience, Vol. 10, pp. 4-5.PangeaTectonics

Abstract: 180 million years ago Earth's continents were amalgamated into one supercontinent called Pangaea. Analysis of oceanic crust formed since that time suggests that the cooling rate of Earth was enhanced in the wake of Pangaea's dispersal.
DS201807-1524
2018
Lenardic, A.Semple, A.G., Lenardic, A.Plug flow in the Earth's asthenosphere.Earth and Planetary Science Letters, Vol. 496, pp. 29-36.Mantlerheology, tectonics

Abstract: Recent seismic observations, focused on mantle flow below the Pacific plate, indicate the presence of two shear layers in the Earth's asthenosphere. This is difficult to explain under the classic assumption of asthenosphere flow driven by plate shear from above. We present numerical mantle convection experiments that show how a power law rheology, together with dynamic pressure gradients, can generate an asthenosphere flow profile with a near constant velocity central region bounded above and below by concentrated shear layers (a configuration referred to as plug flow). The experiments show that as the power law dependence of asthenosphere viscosity is increased from 1 to 3, maximum asthenosphere velocities can surpass lithosphere velocity. The wavelength of mantle convection increases and asthenosphere flow transitions from a linear profile (Couette flow) to a plug flow configuration. Experiments in a 3D spherical domain also show a rotation of velocity vectors from the lithosphere to the asthenosphere, consistent with seismic observations. Global mantle flow remains of whole mantle convection type with plate and asthenosphere flow away from a mid-ocean ridge balanced by broader return flow in the lower mantle. Our results are in line with theoretical scalings that mapped the conditions under which asthenosphere flow can provide an added plate driving force as opposed to the more classic assumption that asthenosphere flow is associated with a plate resisting force.
DS201809-2081
2018
Lenardic, A.Richards, M.A., Lenardic, A.The Cathles parameter (Ct): a geodynamic definition of the asthenosphere and implications for the nature of plate tectonics.Researchgate, researchgate.net/ publication/ 326722590 46p.Mantlegeophysics

Abstract: A weak asthenosphere, or low viscosity zone (LVZ) underlying Earth’s lithosphere has historically played an important role in interpreting isostasy, post-glacial rebound (PGR), and the seismic low velocity zone, as well as proposed mechanisms for continental drift, plate tectonics, and post-seismic relaxation (PSR). Careful consideration of the resolving power of PGR, PSR, and geoid modeling studies suggests a sublithospheric LVZ perhaps ~100-200 km thick with a viscosity contrast of ~100-1000. Ab initio numerical models of plate-like boundary layer motions in mantle convection also suggest a key role for the LVZ. Paradoxically, a thinner LVZ with a strong viscosity contrast is most effective in promoting plate-like surface motions. These numerical results are explained in terms of the reduction in horizontal shear dissipation due to an LVZ, and a simple scaling theory leads to somewhat non-intuitive model predictions. For example, an LVZ causes stress magnification at the base of the lithosphere, enhancing plate boundary formation. Also, flow within the LVZ may be driven by the plates (Couette flow), or pressure-driven from within the mantle (Poiseuille flow), depending upon the degree to which plates locally inhibit or drive underlying mantle convection. For studies of the long-wavelength geoid, PGR, and mantle convection, a simple dimensionless parameter controls the effect of the LVZ. This “Cathles parameter” is given by the expression Ct=v*(D/L)3, where v* is the viscosity contrast and D is the thickness of the LVZ, and L is the flow wavelength, emphasizing the tightly-coupled, largely un-resolvable tradeoff between LVZ thickness and viscosity contrast.
DS201810-2343
2018
Lenardic, A.Lenardic, A.The diversity of tectonic modes and thoughts about transitions between them. Philosphical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences, Vol. 376 doi:10.1098/rsta.2017.0416Mantletectonics

Abstract: Plate tectonics is a particular mode of tectonic activity that characterizes the present-day Earth. It is directly linked to not only tectonic deformation but also magmatic/volcanic activity and all aspects of the rock cycle. Other terrestrial planets in our Solar System do not operate in a plate tectonic mode but do have volcanic constructs and signs of tectonic deformation. This indicates the existence of tectonic modes different from plate tectonics. This article discusses the defining features of plate tectonics and reviews the range of tectonic modes that have been proposed for terrestrial planets to date. A categorization of tectonic modes relates to the issue of when plate tectonics initiated on Earth as it provides insights into possible pre-plate tectonic behaviour. The final focus of this contribution relates to transitions between tectonic modes. Different transition scenarios are discussed. One follows classic ideas of regime transitions in which boundaries between tectonic modes are determined by the physical and chemical properties of a planet. The other considers the potential that variations in temporal evolution can introduce contingencies that have a significant effect on tectonic transitions. The latter scenario allows for the existence of multiple stable tectonic modes under the same physical/chemical conditions. The different transition potentials imply different interpretations regarding the type of variable that the tectonic mode of a planet represents. Under the classic regime transition view, the tectonic mode of a planet is a state variable (akin to temperature). Under the multiple stable modes view, the tectonic mode of a planet is a process variable. That is, something that flows through the system (akin to heat). The different implications that follow are discussed as they relate to the questions of when did plate tectonics initiate on Earth and why does Earth have plate tectonics.
DS201811-2589
2017
Lenardic, A.Lenardic, A.The diversity of tectonic modes and thoughts about transitions between them.Philosophical Transactions Royal Society A, Vol. A376: doi://dx.doi.org/10.1098/rsta.2017.0416 23p.Mantleplate tectonics

Abstract: Plate tectonics is a particular mode of tectonic activity that characterizes the present-day Earth. It is directly linked to not only tectonic deformation but also magmatic/volcanic activity and all aspects of the rock cycle. Other terrestrial planets in our Solar System do not operate in a plate tectonic mode but do have volcanic constructs and signs of tectonic deformation. This indicates the existence of tectonic modes different from plate tectonics. This article discusses the defining features of plate tectonics and reviews the range of tectonic modes that have been proposed for terrestrial planets to date. A categorization of tectonic modes relates to the issue of when plate tectonics initiated on Earth as it provides insights into possible pre-plate tectonic behaviour. The final focus of this contribution relates to transitions between tectonic modes. Different transition scenarios are discussed. One follows classic ideas of regime transitions in which boundaries between tectonic modes are determined by the physical and chemical properties of a planet. The other considers the potential that variations in temporal evolution can introduce contingencies that have a significant effect on tectonic transitions. The latter scenario allows for the existence of multiple stable tectonic modes under the same physical/chemical conditions. The different transition potentials imply different interpretations regarding the type of variable that the tectonic mode of a planet represents. Under the classic regime transition view, the tectonic mode of a planet is a state variable (akin to temperature). Under the multiple stable modes view, the tectonic mode of a planet is a process variable. That is, something that flows through the system (akin to heat). The different implications that follow are discussed as they relate to the questions of when did plate tectonics initiate on Earth and why does Earth have plate tectonics.This article is part of a discussion meeting issue 'Earth dynamics and the development of plate tectonics'.
DS201812-2839
2018
Lenardic, A.Lenardic, A.The diversity of tectonic modes and thoughts about transitions between them.Philosphical Transactions of the Royal Society, Aug. 9, http://dx.doi.org/10.1098/rsta.2017.0416 23p.Mantleplate tectonics
DS201812-2872
2018
Lenardic, A.Richards, M.A., Lenardic, A.The Cathles parameter ( Ct): a geodynamic definition of the asthenosphere and implications for the nature of plate tectonics.researchgate.com, doi:10.1029/2018 /GC007664 46p.Mantlegeodynamics

Abstract: The Earth's global system of tectonic plates move over a thin, weak channel ("low viscosity zone") in the mantle immediately underlying the plates. This weak channel is commonly referred to as the asthenosphere, and its presence accounts for a number of important Earth observations, including isostasy (e.g., support for the uplift of large mountain ranges), the shape of the Earth's gravity field, the response of the Earth's surface to the removal of large ice sheets ("postglacial rebound"), and the relationship between plate motions and underlying thermal convection in the mantle. In this paper, we show that these phenomena can be understood in terms of a single unifying parameter consisting of the viscosity contrast between the asthenosphere and the underlying mantle, and the cube of the thickness of the asthenosphere. We propose to call this the "Cathles parameter" in recognition of the author who first recognized its importance in postglacial rebound studies.
DS201902-0267
2019
Lenardic, A.Deales, J., Lenardic, A., Moore, W.Assessing the intrinsic uncertainty and structural stability of planetary models: 1) parameterized thermal/tectonic history models.Researchgate preprint, 21p. Pdf availableMantlegeothermometry

Abstract: Thermal history models, that have been used to understand the geological history of Earth, are now being coupled to climate models to map conditions that allow planets to maintain surface water over geologic time - a criteria considered crucial for life. However, the lack of intrinsic uncertainty assessment has blurred guidelines for how thermal history models can be used toward this end. A model, as a representation of something real, is not expected to be complete. Unmodeled effects are assumed to be small enough that the model maintains utility for the issue(s) it was designed to address. The degree to which this holds depends on how unmodeled factors affect the certainty of model predictions. We quantify this intrinsic uncertainty for several parameterized thermal history models (a widely used subclass of planetary models). Single perturbation analysis is used to determine the reactance time of different models. This provides a metric for how long it takes low amplitude, unmodeled effects to decay or grow. Reactance time is shown to scale inversely with the strength of the dominant feedback (negative or positive) within a model. A perturbed physics analysis is then used to determine uncertainty shadows for model outputs. This provides probability distributions for model predictions and tests the structural stability of a model. That is, do model predictions remain qualitatively similar, and within assumed model limits, in the face of intrinsic uncertainty. Once intrinsic uncertainty is accounted for, model outputs/predictions and comparisons to observational data should be treated in a probabilistic way.
DS201902-0312
2018
Lenardic, A.Richards, M.A., Lenardic, A.The Cathles Parameter ( Ct): a geodynamic definition of the asthenosphere and implications for the nature of plate tectonics.Geochemistry, Geophysics, Geosystems, Vol. 19, 12, pp. 4858-4875.Mantleplate tectonics

Abstract: The Earth's global system of tectonic plates move over a thin, weak channel (flow?viscosity zone) in the mantle immediately underlying the plates. This weak channel is commonly referred to as the asthenosphere, and its presence accounts for a number of important Earth observations, including isostasy (e.g., support for the uplift of large mountain ranges), the shape of the Earth's gravity field, the response of the Earth's surface to the removal of large ice sheets (postglacial rebound), and the relationship between plate motions and underlying thermal convection in the mantle. In this paper, we show that these phenomena can be understood in terms of a single unifying parameter consisting of the viscosity contrast between the asthenosphere and the underlying mantle, and the cube of the thickness of the asthenosphere. We propose to call this the "Cathles parameter" in recognition of the author who first recognized its importance in postglacial rebound studies.
DS201908-1781
2019
Lenardic, A.Jellinek, A.M., Lenardic, A., Pierrehumbert, R.T.Ice, fire or fizzle: the climate footprint of Earth's supercontinental cycles.Geochemistry, Geophysics, Geosystems, in press, 59p. PdfMantleNuna
DS201909-2058
2019
Lenardic, A.Lenardic, A., Weller, M., Hoink, T., Seales, J.Toward a boot strap hypothesis of plate tectonics: feedbacks between plates, the asthenosphere, and the wavelength of mantle convection.Physics of the Earth and Planetary Interiors, in press avaialable, 72p. PdfMantleplate tectonics

Abstract: The solid Earth system is characterized by plate tectonics, a low viscosity zone beneath plates (the asthenosphere), and long wavelength flow in the convecting mantle. We use suites of numerical experiments to show: 1) How long wavelength flow and the operation of plate tectonics can generate and maintain an asthenosphere, and 2) How an asthenosphere can maintain long wavelength flow and plate tectonics. Plate subduction generates a sub-adiabatic temperature gradient in the mantle which, together with temperature-dependent viscosity, leads to a viscosity increase from the upper to the lower mantle. This allows mantle flow to channelize in a low viscosity region beneath plates (an asthenosphere forms dynamically). Flow channelization, in turn, stabilizes long wavelength convection. The degree of dynamic viscosity variations from the upper to the lower mantle increases with the wavelength of convection and drops toward zero if the system transitions from plate tectonics to a single plate planet. The plate margin strength needed to initiate that transition increases for long wavelength cells (long wavelength flow allows plate tectonics to exist over a wider range of plate margin strength). The coupled feedbacks allow for a linked causality between plates, the asthenosphere, and the wavelength of mantle flow, with none being more fundamental than the others and the existence of each depending on the others. Under this hypothesis, the asthenosphere is defined by an active process, plate tectonics, which maintains it and is maintained by it and plate tectonics is part of an emergent, self-sustaining flow system that bootstraps itself into existence.
DS201910-2279
2019
Lenardic, A.Lenardic, A., Weller, M.B., Seales, J., Hoink, T.Toward a boot strap hypothesis of plate tectonics: feedbacks between plate tectonics, the asthenosphere, and the wavelength of mantle convection.Physics of the Earth and Planetary Interiors, in press available, 57p. PdfMantleplate tectonics

Abstract: The solid Earth system is characterized by plate tectonics, a low viscosity zone beneath plates (the asthenosphere), and long wavelength flow in the convecting mantle. We use suites of numerical experiments to show: 1) How long wavelength flow and the operation of plate tectonics can generate and maintain an asthenosphere, and 2) How an asthenosphere can maintain long wavelength flow and plate tectonics. Plate subduction generates a sub-adiabatic temperature gradient in the mantle which, together with temperature-dependent viscosity, leads to a viscosity increase from the upper to the lower mantle. This allows mantle flow to channelize in a low viscosity region beneath plates (an asthenosphere forms dynamically). Flow channelization, in turn, stabilizes long wavelength convection. The degree of dynamic viscosity variations from the upper to the lower mantle increases with the wavelength of convection and drops toward zero if the system transitions from plate tectonics to a single plate planet. The plate margin strength needed to initiate that transition increases for long wavelength cells (long wavelength flow allows plate tectonics to exist over a wider range of plate margin strength). The coupled feedbacks allow for a linked causality between plates, the asthenosphere, and the wavelength of mantle flow, with none being more fundamental than the others and the existence of each depending on the others. Under this hypothesis, the asthenosphere is defined by an active process, plate tectonics, which maintains it and is maintained by it and plate tectonics is part of an emergent, self-sustaining flow system that bootstraps itself into existence.
DS201910-2296
2019
Lenardic, A.Semple, A., Lenardic, A.The seismic signature of pressure driven flow in the Earth's asthenosphere.AGU Fall Meeting, 1p. AbstractMantlegeophysics - seismic
DS201911-2540
2019
Lenardic, A.Lenardic, A., Weller, M.B., Hoink, T., Seales, J. Toward a boot strap hypothesis of plate tectonics: feedbacks between plates, the asthenosphere, and the wavelength of mantle convection.Physics of the Earth and Planetary Interiors, in press 10.1016/j.pepi.2019.106299 18p. PdfMantleconvection

Abstract: The solid Earth system is characterized by plate tectonics, a low viscosity zone beneath plates (the asthenosphere), and long wavelength flow in the convecting mantle. We use suites of numerical experiments to show: 1) How long wavelength flow and the operation of plate tectonics can generate and maintain an asthenosphere, and 2) How an asthenosphere can maintain long wavelength flow and plate tectonics. Plate subduction generates a sub-adiabatic temperature gradient in the mantle which, together with temperature-dependent viscosity, leads to a viscosity increase from the upper to the lower mantle. This allows mantle flow to channelize in a low viscosity region beneath plates (an asthenosphere forms dynamically). Flow channelization, in turn, stabilizes long wavelength convection. The degree of dynamic viscosity variations from the upper to the lower mantle increases with the wavelength of convection and drops toward zero if the system transitions from plate tectonics to a single plate planet. The plate margin strength needed to initiate that transition increases for long wavelength cells (long wavelength flow allows plate tectonics to exist over a wider range of plate margin strength). The coupled feedbacks allow for a linked causality between plates, the asthenosphere, and the wavelength of mantle flow, with none being more fundamental than the others and the existence of each depending on the others. Under this hypothesis, the asthenosphere is defined by an active process, plate tectonics, which maintains it and is maintained by it and plate tectonics is part of an emergent, self-sustaining flow system that bootstraps itself into existence.
DS202003-0343
2020
Lenardic, A.Jellinek, M., Lenardic, A., Pierrehumbert, R.T.Ice, fire, or fizzle: the climate footprint of Earth's supercontinental cycles.Geochemistry, Geophysics, Geosystems, Vol. 21, 2, 66p. PdfMantlegeodynamics

Abstract: Supercontinent assembly and breakup can influence the rate and global extent to which insulated and relatively warm subcontinental mantle is mixed globally, potentially introducing lateral oceanic?continental mantle temperature variations that regulate volcanic and weathering controls on Earth's long?term carbon cycle for a few hundred million years. We propose that the relatively warm and unchanging climate of the Nuna supercontinental epoch (1.81.3 Ga) is characteristic of thorough mantle thermal mixing. By contrast, the extreme cooling?warming climate variability of the Neoproterozoic Rodinia episode (10.63 Ga) and the more modest but similar climate change during the Mesozoic Pangea cycle (0.30.05 Ga) are characteristic features of the effects of subcontinental mantle thermal isolation with differing longevity. A tectonically modulated carbon cycle model coupled to a one?dimensional energy balance climate model predicts the qualitative form of Mesozoic climate evolution expressed in tropical sea?surface temperature and ice sheet proxy data. Applied to the Neoproterozoic, this supercontinental control can drive Earth into, as well as out of, a continuous or intermittently panglacial climate, consistent with aspects of proxy data for the Cryogenian?Ediacaran period. The timing and magnitude of this cooling?warming climate variability depends, however, on the detailed character of mantle thermal mixing, which is incompletely constrained. We show also that the predominant modes of chemical weathering and a tectonically paced abiotic methane production at mid?ocean ridges can modulate the intensity of this climate change. For the Nuna epoch, the model predicts a relatively warm and ice?free climate related to mantle dynamics potentially consistent with the intense anorogenic magmatism of this period.
DS202005-0759
2020
Lenardic, A.Seales, J., Lenardic, A.Deep water cycling and multi-stage cooling of the Earth.Researchgate preprint, 32p. PdfMantlegeothermometry

Abstract: Paleo-temperature data indicates that the Earth's mantle did not cool at a constant rate over geologic time. Post magma ocean cooling was slow with an onset of more rapid mantle cooling between 2.5 and 3.0 Gyr. We explore the hypothesis that this multi-stage cooling is a result of deep water cycling coupled to thermal mantle convection. As warm mantle ascends, producing melt, the mantle is dehydrated. This tends to stiffens the mantle, which slows convective vigor causing mantle heating. At the same time, an increase in temperature tends to lower mantle viscosity which acts to increase convective vigor. If these two tendencies are in balance, then mantle cooling can be weak. If the balance is broken, by a switch to a net rehydration of the mantle, then the mantle can cool more rapidly. We use coupled water cycling and mantle convection models to test the viability of this hypothesis. We test models with different parameterizations to allow for variable degrees of plate margin strength. We also perform a layered uncertainty analysis on all the models to account for input, parameter, and structural model uncertainties. Within model and data uncertainty, the hypothesis that deep water cycling, together with a combination of plate strength and mantle viscosity resisting mantle overturn, can account for paleo data constraints on mantle cooling.
DS202008-1440
2020
Lenardic, A.Seales, J., Lenardic, A.Deep water cycling and the multi-stage cooling of the Earth.Preprint, doi:101340/RG2.2.25986.63683 32p. PdfMantlethermal convection

Abstract: Paleo-temperature data indicates that the Earth's mantle did not cool at a constant rate over geologic time. Post magma ocean cooling was slow with an onset of more rapid mantle cooling between 2.5 and 3.0 Gyr. We explore the hypothesis that this multi-stage cooling is a result of deep water cycling coupled to thermal mantle convection. As warm mantle ascends, producing melt, the mantle is dehydrated. This tends to stiffens the mantle, which slows convective vigor causing mantle heating. At the same time, an increase in temperature tends to lower mantle viscosity which acts to increase convective vigor. If these two tendencies are in balance, then mantle cooling can be weak. If the balance is broken, by a switch to a net rehydration of the mantle, then the mantle can cool more rapidly. We use coupled water cycling and mantle convection models to test the viability of this hypothesis. We test models with different parameterizations to allow for variable degrees of plate margin strength. We also perform a layered uncertainty analysis on all the models to account for input, parameter, and structural model uncertainties. Within model and data uncertainty, the hypothesis that deep water cycling, together with a combination of plate strength and mantle viscosity resisting mantle overturn, can account for paleo data constraints on mantle cooling.
DS202008-1441
2020
Lenardic, A.Semple, A., Lenardic, A.On the robustness of asthenosphere plug flow in mantle convection models with plate like behaviour.Researchgate, 11p. PdfMantleconvection

Abstract: Conventional wisdom holds that the motion of tectonic plates drives motion in the Earth’s rocky interior (i.e., in the Earth’s asthenosphere). Recent seismological observations have brought this view into question as they indicate that the velocity of the asthenosphere can exceed tectonic plate velocity. This suggests that interior motions can drive plate motions. We explore models of coupled plate tectonics and interior motions to address this discrepancy. The models reveal that the coupling between plates and the asthenosphere is not an issue of plates drive asthenosphere motion or asthenosphere motion drives plates. Both factors work in tandem with the balance being a function of plate margins strength and asthenosphere rheology. In particular, a power-law viscosity allows pressure gradients to generate interior flow that can locally drive plate motion. The models also reveal a hysteresis effect that allows different tectonic states (plate tectonics versus a single plate planet) to exist at the same parameter conditions. This indicates that history and initial conditions can play a role in determining if a planet will or will not have plate tectonics.
DS202009-1640
2020
Lenardic, A.Lenardic, A., Seales, J., Weller, M.B.Convective and tectonic plate velocities in a mixed heating mantle.Researchgate, July 29p. Pdf doi:101002 /essoar.10503603.1Mantleplate tectonics

Abstract: Mantle convection and, by association, plate tectonics is driven by the transport of heat from a planetary interior. This heat may come from the internal energy of the mantle or may come from the core beneath and in general there will be contributions from both sources. Past investigations of such mixed-mode heating have revealed unusual behavior that confounds our intuition based on boundary layer theory applied to end-member cases. In particular, the addition of internal heat to a bottom-heated system causes a decrease in convective velocity despite an increase in surface heat flow. We investigate this behavior using a suite of numerical experiments and develop a scaling for velocity in the mixed-heating case. We identify a significant planform transition as internal heating increases from sheet-like to plume-like downwellings that impacts both heat flux and convective velocities. More significantly, we demonstrate that increased internal heating leads not only to a decrease in internal velocities but also a decrease in the velocity of the upper thermal boundary layer (a model analog of the Earth's lithosphere). This behavior is connected to boundary layer interactions and is independent of any particular rheological assumptions. In simulations with a temperature-dependent viscosity and a finite yield stress, increased internal heating does not cause an absolute decrease in surface velocity but does cause a decrease in surface velocity relative to the purely bottom or internally heated cases as well as a transition to rigid-lid behavior at high heating rates. The differences between a mixed system and end-member cases have implications for understanding the connection between plate tectonics and mantle convection and for planetary thermal history modeling.
DS202010-1874
2020
Lenardic, A.Semple, A., Lenardic, A.The robustness of pressure-driven asthenospheric flow in mantle convection models with plate-like behavior.Geophysical Research Letters, 10.1029/2020/GL089556 11p. PdfMantleconvection

Abstract: It is generally thought that tectonic plates drive motion in the Earth's rocky interior. Recent observations have challenged this view as they indicate that interior motion can drive tectonic plates. Models of coupled tectonics and interior flow are used to address this discrepancy. The models reveal that the question of “does plate tectonics drive interior flow or does interior flow drive plate tectonics” may be ill founded as both possibilities may be active at the same time. The balance between the two drivers is found to depend on plate margin strength. The models also reveal that different tectonic modes can exist under the same physical conditions. This indicates a planet's initial state can determine if it will or will not have plate tectonics.
DS202101-0032
2020
Lenardic, A.Semple, A.G., Lenardic, A.Feedbacks between a non-Newtonian upper mantle, mantle viscosity structure and mantle dynamics.Geophysical Journal International, Vol. 224, 2, pp. 961-972.Mantlegeophysics - seismics

Abstract: Previous studies have shown that a low viscosity upper mantle can impact the wavelength of mantle flow and the balance of plate driving to resisting forces. Those studies assumed that mantle viscosity is independent of mantle flow. We explore the potential that mantle flow is not only influenced by viscosity but can also feedback and alter mantle viscosity structure owing to a non-Newtonian upper-mantle rheology. Our results indicate that the average viscosity of the upper mantle, and viscosity variations within it, are affected by the depth to which a non-Newtonian rheology holds. Changes in the wavelength of mantle flow, that occur when upper-mantle viscosity drops below a critical value, alter flow velocities which, in turn, alter mantle viscosity. Those changes also affect flow profiles in the mantle and the degree to which mantle flow drives the motion of a plate analogue above it. Enhanced upper-mantle flow, due to an increasing degree of non-Newtonian behaviour, decreases the ratio of upper- to lower-mantle viscosity. Whole layer mantle convection is maintained but upper- and lower-mantle flow take on different dynamic forms: fast and concentrated upper-mantle flow; slow and diffuse lower-mantle flow. Collectively, mantle viscosity, mantle flow wavelengths, upper- to lower-mantle velocities and the degree to which the mantle can drive plate motions become connected to one another through coupled feedback loops. Under this view of mantle dynamics, depth-variable mantle viscosity is an emergent flow feature that both affects and is affected by the configuration of mantle and plate flow.
DS202106-0951
2021
Lenardic, A.Le Pichon, X., Jellinek, M., Lenardic, A., Sengor, A.M.C., Imren, C.Pangea migration.Tectonics, e2020TC006585 42p. PdfMantleplate tectonics

Abstract: We confirm the proposition of Le Pichon et al. (2019) that Pangea was ringed by a hemispheric subduction girdle from its formation 400 Ma to its dispersal 100 Ma. We quantify the northward migration, that we attribute to True Polar Wander (TPW), of its axis of symmetry, between 400 Ma and 150 Ma, from southern latitudes to the equatorial zone. The spatial stabilizing within the equatorial zone of the axis of symmetry in a fixed position with respect to lower mantle, was marked by alternating CW and CCW oscillations between 250 Ma and 100 Ma that we relate to tectonic events. A subduction girdle is predicted to set up lateral temperature gradients from relatively warm sub-Pangean mantle to cooler sub-oceanic mantle. Over time, this effect acts to destabilize the Pangea landmass and its associated subduction girdle. Quantitatively, a scaling theory for the stability of the subduction girdle against mantle overturn constrains the maximum magnitude of sub-Pangean warming before breakup to be order 100 oC, consistent with constraints on Pacific-Atlantic oceanic crustal thickness differences. Our predictions are in line with recent analyses of Jurassic-Cretaceous climate change and with existing models for potential driving forces for a TPW oscillation of Pangea across the equator. The timing and intensity of predicted sub-Pangean warming potentially contributed to the enigmatically large Siberian Traps and CAMP flood basalts at 250 Ma and 201 Ma, respectively.
DS202201-0023
2021
Lenardic, A.Lenardic, A.,Jellinek, M.,Seales, J., Lee, C-T.Global tectonic and climatic fluctuations: from Pangea grounding to planetary speculation. * just for interestResearchgate , Dec. 51p. PdfGlobalGeotectonics

Abstract: The Earth's paleo-climate record indicates climate fluctuations, from cool to warm to cool conditions, over the last ~300 My. Over that time, the Earth's most recent super-continent, Pangea, formed and broke apart. Data constraints together with numerical models indicate that Pangea formation and breakup affected spatial and temporal patterns of heat loss from the Earths' interior. This, in turn, affected global tectonic and volcanic behavior. The tectonic/volcanic fluctuations can be linked to climate models to explore the degree to which they could drive long time scale (~100 My) climate variations. The coupled models indicate that Pangea-driven tectonic fluctuations can lead to climate fluctuations consistent with data constraints. Global variations in the tectonic behavior of the Earth, linked to climate variations, has implication for understanding how the internal evolution of a planet can affect surface environments. We will end with some speculations on how that could feed into planetary habitability.
DS202201-0037
2021
Lenardic, A.Seales, J., Lenardic, A.Deep-water recycling, planetary self-regulation, and the maintenance of melting on Earth. * just for interestResearchgate , Dec. 22p. PdfMantlewater
DS202205-0702
2022
Lenardic, A.Lenardic, A., J. SealesInternal planetary feedbacks, mantle dynamics, and plate tectonics.Researchgate preprint Chapter from book Elsevier, March 61p. PdfMantlegeodynamics

Abstract: Isolating planetary feedbacks, and feedback analysis, are prevalent aspects of climate and Earth surface process science. An under appreciation of internal planet feedbacks, and feedback analysis for plate tectonics research, motivate this chapter. We review feedbacks that influence the Earth's thermal evolution and expand them to include magmatic history and planetary water budgets. The predictions from feedback models are shown to be consistent with petrological constraints on the Earth's cooling. From there, we isolate feedbacks that connect structural elements within the mantle dynamics and plate tectonics system. The feedbacks allow for a reciprocal causality between plates, plumes, the asthenosphere, and mantle flow patterns, with each element being co-dependent on the others. The linked elements and feedbacks define plate tectonics are part of a self-sustaining flow system that can bootstrap itself into existence. Within that framework, plate tectonics involves the co-arising of critical system factors. No single factor is the cause of another. Rather, they emerge with the links between them and the generation of functional elements coincides, within relatively narrow time windows, with the co-emergence of factors that are critical for the maintenance of the elements themselves. What emerges is not a tectonic state but a process. That is, a set of feedbacks that can transform the tectonics of a planet and/or maintain plate tectonics. The feedback functions are not permanent but can operate over extended time frames such that plate tectonics can remain stable. The nature of the feedbacks, and their stability, can be studied at various levels of detail but questions of origin can become ill-defined. Observational tests of a feedback framework for plate tectonics and mantle dynamics are presented, along with research paths that apply feedback methodology to solid planet dynamics and comparative planetology.
DS202205-0714
2022
Lenardic, A.Seales, J., Lenardic, A.Plate tectonics, mixed heating convection and the divergence of mantle and plume temperatures.Researchgate preprint, 12p. PdfMantlegeothermometry

Abstract: Petrological data indicate that upper mantle and mantle plume temperatures diverged 2.5 billion years ago. This has been interpreted as plate tectonics initiating at 2.5 Ga with Earth operating as a single plate planet before then. We take an Occam’s razor view that the continuous operation of plate tectonics can explain the divergence. We validate this hypothesis by comparing petrological data to results from mixed heating mantle convection models in a plate tectonic mode of mantle cooling. The comparison shows that the data are consistent with plate tectonics operating over geologic history.
DS202205-0715
2022
Lenardic, A.Seals, J., Lenardic, A., Garrido, J.Plate tectonics, mixed heating convection and the divergence.Researchgate preprint, 12p. PdfMantleplate tectonics

Abstract: Petrological data indicate that upper mantle and mantle plume temperatures diverged 2.5 billion years ago. This has been interpreted as plate tectonics initiating at 2.5 Ga with Earth operating as a single plate planet before then. We take an Occam’s razor view that the continuous operation of plate tectonics can explain the divergence. We validate this hypothesis by comparing petrological data to results from mixed heating mantle convection models in a plate tectonic mode of mantle cooling. The comparison shows that the data are consistent with plate tectonics operating over geologic history.
DS201812-2894
2018
Lenauer, I.Ugalde, H., Milkereit, B., Lenauer, I., Morris, W.A., Mirza, A.M., Elliott, B.Airborne Mag/EM data integration of Slave province kimberlites, NWT.2018 Yellowknife Geoscience Forum , p. 84. abstractCanada, Northwest Territoriesgeophysics - Mag, EM

Abstract: As part of the Slave Province Geophysical, Surficial Materials and Permafrost Study, the Northwest Territories Geological Survey (NTGS) commissioned high resolution geophysical surveys in the Slave Geological Province (SGP). This work focuses on the analysis of six horizontal gradient magnetic and frequency domain EM (FDEM) surveys that were flown from February to March 2017 (Munn Lake, Margaret Lake, Zyena Lake, Lac de Gras West, Big Blue and Mackay Lake). All surveys were acquired at 75 m line spacing with nominal terrain clearance of 60 m to maintain bird height of 25 m. They total 4,580 line-km. We use the FDEM data to locate areas of potential remanent magnetization, and thus additional areas that could be related to kimberlite bodies. The area is part of the central Slave Craton, which is dominated by Archean granitoid rocks and Archean metasedimentary rocks. Heaman et al. (2013) identifies several distinct domains based on kimberlite ages in the area. Central Slave is characterized by Tertiary/Cretaceous age kimberlites, whereas the southern part exhibits kimberlites of Cambrian age. This have important implications for the orientation of the remanent magnetization vector. The methodology involves the use of a homogeneous half-space model to invert the data for dielectric permittivity, relative magnetic permeability, apparent resistivity and magnetic susceptibility. Using this model, we calculated Conductivity-Depth-Images (CDIs) for all the EM data. The susceptibility distribution from the EM data (MagEM) is then plotted against an apparent susceptibility derived from the total field data for the main survey via standard FFT calculation (MagTMI). Major differences between both distributions are usually associated to remanence. Once we identify areas of potential remanent magnetization, we use Helbig analysis to estimate the direction of magnetization. The validity of this model is verified by comparison of the computed remanence direction with the appropriate Apparent Polar Wander Path (APWP). We find a good correlation of APWP directions with the estimated remanence, however, a viscous remanence component subparallel to the present's day Earth field is sometimes required. Finally, we show the integration of these results with a structural interpretation of the aeromagnetic data and potential alteration zones derived from Aster imagery for all 6 blocks
DS200712-1212
2007
Lenaz, D.Zaccarini, F., Thalhammer, O.A.R., Princivalle, F., Lenaz, D., Stanley, C.J., Garuti, G.Djerfisherite in the Guli dunite complex, Polar Siberia: a primary or metasomatic phase?Canadian Mineralogist, Vol. 45, 5, Oct. pp. 1201-1211.RussiaMetasomatism
DS200812-0790
2008
Lenaz, D.Nedii, Z., Princivalle, F., Lenaz, D., Toth, T.M.Crystal chemistry of clinopyroxene and spinel from mantle xenoliths hosted in late Mesozoic lamprophyres ( Villany Mts, S. Hungary).Neues Jahrbuch fur Mineralogie, Vol. 185, 1, pp. 1-10.Europe, HungaryLamprophyre
DS200912-0434
2009
Lenaz, D.Lenaz, D., Logvinova, A.M., Princivalle, F., Sobolev, N.V.Structural parameters of chromite included in diamond and kimberlites from Siberia: a new tool for discriminating ultramafic source.American Mineralogist, Vol. 94, 7, pp. 1067-1070.Russia, SiberiaDiamond inclusions
DS201012-0433
2010
Lenaz, D.Lenaz, D., Skogby, H., Logvinova, A.M., Princivalle, F., Sobolev, N.V.Fe3+ Fe tot ratio in the mantle: a micro-Mossbauer study of chromites included in diamond and kimberlites.International Mineralogical Association meeting August Budapest, abstract p. 431.Russia, YakutiaOxidation state
DS201312-0531
2013
Lenaz, D.Lenaz, D., Skogby, H., Logvinova, A.M., Sobolev, N.V., Princivalle, F.A micro-Mossbauer study of chromites included in diamond and other mantle related rocks.Physics and Chemistry of Minerals, Vol. 40, 9, pp. 671-679.Russia, SiberiaSpectroscopy - diamond
DS201412-0504
2013
Lenaz, D.Lenaz, D., Skogby, H., Logvinova, A., Sobolev, N., Princivalle, F.A micro-mossbauer study of chromites included in diamond and other mantle related rocks.Physics and Chemistry of Minerals, Vol. 40, 9, pp. 671-679.Russia, SiberiaDiamond inclusions
DS201412-0919
2014
Lenaz, D.Taran, M.N., Parisi, F., Lenaz, D., Vishnevskyy, A.A.Synthetic and natural chromium-bearing spinels: an optical spectroscopy study.Physics and Chemistry of Minerals, Vol. 41, 8, pp. 593-602.TechnologySpinel
DS201705-0872
2017
Lenaz, D.Rollinson, H., Adetunji, J., Lenaz, D., Szilas, K.Archean chromitites show constant Fe3+/Efe in Earth's asthenospheric mantle since 3.8 Ga.Journal of Petrology, in press available 42p.Europe, Greenland, Africa, ZimbabweMelting, Fiskenaesset Compex, Ujaragssuit, Limpopo belt
DS201910-2288
2019
Lenaz, D.Nestola, F., Zaffiro, G., Mazzucchelli, M.L., Nimis, P., Andreozzi, G.B., Periotto, B., Princivalle, F., Lenaz, D., Secco, L., Pasqualetto, L., Logvinova, A.M., Sobolev, N.V., Lorenzetti, A., Harris, J.W.Diamond inclusion system recording old deep lithosphere conditions at Udachnaya ( Siberia).Nature Research, Vol. 9, 12586 8p. PdfRussia, Siberiadeposit - Udachnaya

Abstract: Diamonds and their inclusions are unique fragments of deep Earth, which provide rare samples from inaccessible portions of our planet. Inclusion-free diamonds cannot provide information on depth of formation, which could be crucial to understand how the carbon cycle operated in the past. Inclusions in diamonds, which remain uncorrupted over geological times, may instead provide direct records of deep Earth’s evolution. Here, we applied elastic geothermobarometry to a diamond-magnesiochromite (mchr) host-inclusion pair from the Udachnaya kimberlite (Siberia, Russia), one of the most important sources of natural diamonds. By combining X-ray diffraction and Fourier-transform infrared spectroscopy data with a new elastic model, we obtained entrapment conditions, Ptrap?=?6.5(2) GPa and Ttrap?=?1125(32)-1140(33) °C, for the mchr inclusion. These conditions fall on a ca. 35?mW/m2 geotherm and are colder than the great majority of mantle xenoliths from similar depth in the same kimberlite. Our results indicate that cold cratonic conditions persisted for billions of years to at least 200?km in the local lithosphere. The composition of the mchr also indicates that at this depth the lithosphere was, at least locally, ultra-depleted at the time of diamond formation, as opposed to the melt-metasomatized, enriched composition of most xenoliths.
DS1990-0906
1990
Lendent, D.Lavreau, J., Poidebin, J.L., Lendent, D., Liegeois, J.P., Weis, D.Contribution to the geochronology of the basement of the Central AfricanRepublicJournal of African Earth Sciences, Vol. 11, No. 1/2, pp. 69-82Central African RepublicGeochronology, Tectonics
DS201212-0246
2012
Lendrick, M.A.Giuliani, A.,Kamenetsky, V.S., Lendrick, M.A., Phillips, D., Goemann, K.Nickel-rich metasomatism of the lithospheric mantle by pre-kimberlitic alkali-S-Cl-rich C-O-H fluids.Contributions to Mineralogy and Petrology, in press available 17p.MantleMetasomatism
DS201506-0288
2015
Lene, A.Nkono, C., Femenias, O., Lene, A., Mercier, J-C., Ngounouno, F.Y., Demaiffe, D.Relationship between the fractal dimension of orthopyroxene distribution and the temperature in mantle xenoliths.Geological Journal, in press availableRussia, PolandXenoliths
DS200412-1949
2004
Leng, D.Sutherland, D., Leng, D., Hoffman, E.SGH - a soil gas hydrocarbon method to locate kimberlite pipes - a case study.Geological Association of Canada Abstract Volume, May 12-14, SS14-02 p. 261.abstractTechnologyGeochemistry
DS1996-1084
1996
Leng, M.J.Pearce, N.J.G., Leng, M.J.The origin of carbonatites and related rocks from the Igaliko dyke swarm, Gardar Province, South Greenland.Lithos, Vol. 39, pp. 21-40.GreenlandCarbonatite, Geochemistry, geochronology
DS1997-0894
1997
Leng, M.J.Pearce, N.J.G., Leng, M.J., Emeleus, C.H., Bedford, C.M.The origins of carbonatites and related rocks from the Gronnedal Ikanepheline syenite complex. C-O-Sr evid.Mineralogical Magazine, No. 407, August pp. 515-530.Greenland, south GreenlandCarbonatite
DS2003-0290
2003
Leng, M.J.Coulson, I.M., Goodenough, K.M., Pearce, N.J.G., Leng, M.J.Carbonatites and lamprophyres of the Gardar Province - a window to the sub-GardarMineralogical Magazine, Vol. 67, 5, pp. 855-872.GreenlandCarbonatite
DS200412-0377
2003
Leng, M.J.Coulson, I.M., Goodenough, K.M., Pearce, N.J.G., Leng, M.J.Carbonatites and lamprophyres of the Gardar Province - a window to the sub-Gardar mantle?Mineralogical Magazine, Vol. 67, 5, pp. 855-72.Europe, GreenlandCarbonatite
DS200612-1614
2006
Leng, W.Zhong, S., Leng, W.Dynamics of mantle plumes and their implications for the heat budget and composition of the mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 22, abstract only.MantleGeothermometry
DS200712-0618
2007
Leng, W.Leng, W., Zhong, S.Constraints on the Earth's mantle heat budget from mantle plumes.Plates, Plumes, and Paradigms, 1p. abstract p. A560.MantleGeothermometry
DS200812-0644
2008
Leng, W.Leng, W., Zhong, S.Controls on plume heat flux and plume excess temperature.Journal of Geophysical Research, Vol. 113, B 2 B04408MantleGeothermometry
DS200812-0645
2008
Leng, W.Leng, W., Zhong, S.Controls on plume heat flux and plume excess temperature.Journal of Geophysical Research, Vol. 113, B4, B04408MantlePlume
DS200912-0435
2009
Leng, W.Leng, W., Zhong, S.More constraints on internal heating rate of the Earth's mantle from plume observations.Geophysical Research Letters, Vol. 36, 2, L02306MantleThermometry
DS201012-0434
2010
Leng, W.Leng, W., Zhong, S.Surface subsidence caused by mantle plumes and volcanic loading in large igneous provinces.Earth and Planetary Science Letters, Vol. 291, 1-4, pp. 201-214.MantleHotspots
DS201012-0891
2010
Leng, W.Zhang, N., Zhong, S., Leng, W.A model for the evolution of the Earth's mantle structure since the early Paleozoic.Journal of Geophysical Research, Vol. 115, no. B6, B060401MantleGeodynamics
DS201312-0376
2013
Leng, W.Helmberger, D., Chu, R., Leng, W., Gurnis, M.Hidden hotspot track beneath eastern United States.Goldschmidt 2013, AbstractUnited States, KentuckyKimberlite
DS201412-1003
2014
Leng, W.Yang, T., Leng, W.Dynamics of hidden hotspot tracks beneath the continental lithosphere.Earth and Planetary Science Letters, Vol. 401 pp. 294-300.MantlePlume
DS201807-1508
2018
Leng, W.Liu, H., Wang, W., Jia, X., Leng, W., Wu, Z., Sun, D.The combined effects of post-spinel and post-garnet phase transitions on mantle plume dynamics.Earth and Planetary Science Letters, Vol. 496, pp. 80-88.Mantleperovskite, hotspots

Abstract: Mineralogical studies indicate that two major phase transitions occur near the depth of 660 km in the Earth's pyrolitic mantle: the ringwoodite (Rw) to perovskite (Pv) + magnesiowüstite (Mw) and the majorite (Mj) to perovskite (Pv) phase transitions. Seismological results also show a complicated phase boundary structure at this depth in plume regions. However, previous geodynamical modeling has mainly focused on the effects of the Rw-Pv+Mw phase transition on plume dynamics and has largely neglected the effects of the Mj-Pv phase transition. Here, we develop a 3-D regional spherical geodynamic model to study the combined influence of these two phase transitions on plume dynamics. Our results show the following: (1) A double phase boundary occurs in the high-temperature center of the plume, corresponding to the double reflections in seismic observations. Other plume regions feature a single, flat uplifted phase boundary, causing a gap of high seismic velocity anomalies. (2) Large amounts of relatively low-temperature plume materials can be trapped in the transition zone due to the combined effects of phase transitions, forming a complex truncated cone shape. (3) The Mj-Pv phase transition greatly enhances the plume penetration capability through 660-km phase boundary, which has a significant influence on the plume dynamics. Our results provide new insights which can be used to better constrain the 660-km discontinuity variations, seismic wave velocity structure and plume dynamics in the mantle transition zone. The model can also help to estimate the mantle temperature and Clapeyron slopes at the 660 km phase boundary.
DS202009-1626
2011
Lenhardt, N.Eriksson, P.G., Lenhardt, N., Wright, D.T., Mazumder, R., Bumby, A.J.Late Neoarchean-paleoproterozoic supracrustal basin-fills of the Kaapvaal craton: relevance of the supercontinent cycle, the "Great Oxidation Event" and "Snowball Earth?". Note Date*** glaciationMarine and Petroleum Geology, Vol. 28, pp. 1385-1401.Africa, South Africageomorphology

Abstract: The application of the onset of supercontinentality, the “Great Oxidation Event” (GOE) and the first global scale glaciation in the Neoarchaean-Palaeoproterozoic as panacea-like events providing a framework or even chronological piercing points in Earth’s history at this time, is questioned. There is no solid evidence that the Kaapvaal craton was part of a larger amalgamation at this time, and its glacigenic record is dominated by deposits supporting the operation of an active hydrological cycle in parallel with glaciation, thereby arguing against the “Snowball Earth Hypothesis”. While the Palaeoproterozoic geological record of Kaapvaal does broadly support the GOE, this postulate itself is being questioned on the basis of isotopic data used as oxygen-proxies, and sedimentological data from extant river systems on the craton argue for a prolongation of the greenhouse palaeo-atmosphere (possibly in parallel with a relative elevation of oxygen levels) which presumably preceded the GOE. The possibility that these widespread events may have been diachronous at the global scale is debated.
DS200412-0427
2004
Lenharo, S.L.R.De Toledo, M.C.M., Lenharo, S.L.R., Ferrari, V.C., Fontan, F., Parseval, P.De, Leroy, G.The compositional evolution of apatite in the weathering profile of the Catalao 1 alkaline carbonatitic complex, Goias, Brazil.Canadian Mineralogist, Vol. 42, 4, August, pp. 1139-1158.South America, Brazil, GoiasCarbonatite, geomorphology
DS201610-1846
2016
Lenharo, S.L.R.Borges, M.P.A.C., Moura, M.A., Lenharo, S.L.R., Smith, C.B., Araujo, D.P.Mineralogical characaterization of diamonds from Roosevelt Indigenous Reserve, Brazil, using non-destructive methods. Lithos, in press available 17p.South America, Brazil, RondoniaDeposit - Igarape Lajes Diggings

Abstract: In this study, 660 diamonds from Igarapé Lajes Diggings (Roosevelt and Aripuanã Park indigenous areas), in Amazonian craton, Rondônia State, Brazil, were investigated. Their morphological, optical and surface characteristics were described using optical and scanning electron microscopy (SEM), cathodoluminescence (CL) and infrared spectroscopy (FTIR). The results demonstrated a predominance of resorbed crystals with many surface corrosion features, generally colorless, and led to the identification of four distinct groups: G1, G2, G3 and G4. Group G1 presents features of secondary sources while G2 and G4 show only primary features, some of which are not described in literature. Group G3 is similar to the other groups, however, is composed of less resorbed specimens with primary octahedral morphology relatively well preserved, indicating shorter time of exposure to dissolution effects. Cathodoluminescence in G2 is attributed to features of plastic deformation and to low contents of nitrogen (< 100 ppm, Type II) and high aggregation (IaB). G4 shows homogeneous blue CL, high contents of nitrogen (700 to 1000 ppm) and intermediate aggregation (IaAB). G1 presents luminescence influenced by radiation effects and populations with N contents and aggregation in the same ranges of G2 and G4, suggesting that the primary sources of the three groups can be the same. The relationship of nitrogen content versus aggregation state indicates higher temperatures of formation for G2 and lower for G4. The obtained data suggests that diamonds of G2 originated in sublithospheric mantle as has also been reported in nearby deposits (Machado River and Juína). The employed techniques were also effective in distinguishing diamonds from Roosevelt Reserve and from other localities, indicating that they could be used for improvement of certification procedures of diamonds of unknown origin.
DS2001-0675
2001
Lenne, I.Lenne, I.Dynamics of marine glacier termini read from moraine architectureGeology, Vol. 29, No. 3, Mar. pp.199-202.GlobalGeomorphology - glaciers, Allostratigraphic model - not specific to diamonds
DS200912-0805
2009
LennieWalter, M.J., Bulanova, G.P., Armstrong, L.S., Keshav, S., Blundy, Gudfinnsson, Lord, Lennie, Clark, GobboPrimary carbonatite melt from deeply subducted oceanic crust.Nature, Vol. 459, July 31, pp. 622-626.South America, Brazil, MantleMelting, geochemistry
DS201212-0025
2012
Lennie, A.R.Armstrong, L.S., Walter, M.J., Tuff, J.R., Lord, O.T., Lennie, A.R., Kleppe, A.K., Clark, S.M.Perovskite phase relations in the system CaO-MgO-TiO2-Si02 and implications for deep mantle lithologies.Journal of Petrology, Vol. 53, 3, pp. 611-635.MantlePerovskite
DS201012-0550
2010
Lennikov, A.A.Oktaybrskii, N.V., Vladykin, A.M., Lennikov, A.A., Vrzhosek, T.A., Yasnygina, et al.Chemical composition and geochemical characteristics of the Koksharovka alkaline ultrabasic massif with carbonatites.Geochimica et Cosmochimica Acta, Vol.74, 19, pp. 778-791.Asia, RussiaCarbonatite
DS1983-0401
1983
Lennikov, A.M.Lennikov, A.M., Romanenko, I.M.Unusual Lherzolite Inclusions in Alkali Basaltoids of the Stanovoi Ridge.Doklady Academy of Sciences AKAD. NAUK SSSR., Vol. 269, No. 4, PP. 915-919.RussiaPetrology
DS200812-0646
2008
Lennikov, A.M.Lennikov, A.M., Zalisjchak, B.L., Oktyabrsky, R.A., Ivanov, V.V.Variations of chemical composition in platinum group minerals and gold of the Konder alkali ultrabasic massif, Aldan Shield, Russia.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., 2008 pp. 181-208.RussiaKonder alkaline massif
DS1995-1143
1995
Lennox, P.Mah, A., Taylor, G.R., Lennox, P., Balia, L.Lineament analyses of Land sat thematic mapper images, Northern TerritoryPhotogr. Eng. and Remote Sensing, Vol. LXI, No. 6, June pp. 761-773AustraliaRemote sensing, Structure - lineaments
DS1996-0834
1996
Lennykh, V.I.Lennykh, V.I., Valizer, P.M., Beane, R., et al.Petrotectonic evolution of the Maksyutov Complex, southern Urals, Russia:implications for metamorphismInternational Geology Review, Vol. 37, pp. 584-600.Russia, UralsPlate tectonics, Metamorphism -ultra high pressure
DS1950-0409
1958
Lenoff, J.Lenoff, J.Oroville's Mystery DiamondsThe Feather River Territorial, Summer 1958, PP. 4-9.United States, California, West Coast, MontanaBlank
DS2003-0136
2003
Lenoir, D.Boschen, S., Lenoir, D., Scheringer, M.Sustainable chemistry: starting points and prospectsNaturwissenschaftern, Vol. 90, pp. 93-102.GlobalChemistry - review not specific to diamonds
DS2000-0567
2000
Lenoir, X.Lenoir, X., Garrido, C.J., Bodinier, J.L., Dautria, J-M.Contrasting lithospheric mantle domains beneath the Massif Central revealed by geochemistry peridotite...Earth and Planetary Science Letters, Vol.181, No.3, Sept.15, pp.359-75.FranceXenoliths - geochemistry
DS1950-0109
1952
Lenormand, J.Lenormand, J., Lenormand, J.P.L'or et le DiamantParis: S.e.f., 602P. PT. 3, PP. 325-376.GlobalDiamond, Gold, Statistics, Production
DS1950-0109
1952
Lenormand, J.P.Lenormand, J., Lenormand, J.P.L'or et le DiamantParis: S.e.f., 602P. PT. 3, PP. 325-376.GlobalDiamond, Gold, Statistics, Production
DS2003-0794
2003
Lensky, N.G.Lensky, N.G., Niebo, R.W., Holloway, J.R., Lyakhovsky, V., Navon, O.Bubble nucleation as a trigger for xenolith entrapment in mantle melts8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractGlobalKimberlite geology and economics
DS200612-0800
2006
Lensky, N.G.Lensky, N.G., Nicho, R.W., Holloway, J.R., Lyakhovsky, V., Navon, O.Bubble nucleation as a trigger for xenolith entrapment in mantle melts.Earth and Planetary Science Letters, Vol. 245, 1-2, pp. 278-288.MantleMelting
DS200512-0101
2005
LentonBohm, C.O., Corrigan, D., Corkery, T.M., Zwanzig, Lenton, Coyyle, ThomasRe-mapping the northern Superior Trans Hudson boundary by using newly acquired high resolution aeromagnetic data.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Manitoba, Saskatchewan, OntarioGeophysics - magnetics
DS2001-0883
2001
Lenton, Bailes et al.Panagapko, D.A., Chackowsky, Lenton, Bailes et al.Geoscience dat a compilation for southeastern ManitobaGeological Survey of Canada (GSC) Open File, No. 4159, CD $ 130.00 eachManitoba, southeastCompilation
DS1999-0210
1999
Lenton, P.G.Fedikow, M.A.F., Nielsen, E., Conley, G.G., Lenton, P.G.Operation Superior: multimedia geochemical surveys Webber, Knife, Goose lakes and Echimamish greenstoneMan. Geological Survey Open File, No. 99-8, 400p.ManitobaGeochemistry - exploration
DS2000-0287
2000
Lenton, P.G.Fedikow, M.A.F., Nielsen, E., Conley, G.G., Lenton, P.G.Operation Superior: multimedia geochemical surveys Knee Lake greenstone belMan. Geological Survey Open File, No. 2000-2, CD ROM $ 10.00ManitobaGeochemistry - exploration
DS2001-0317
2001
lenton, P.G.Fedikow, M.A.F., Nielsen, E., Conley, G.G., lenton, P.G.Operation Superior kimberlite indicator mineral survey results (2000) for the northern Knee Lake greenstone belt, northern Superior Province.Manitoba Report of Activities, 59p.ManitobaGeochemistry
DS2001-0318
2001
lenton, P.G.Fedikow, M.A.F., Nielsen, E., Conley, G.G., lenton, P.G.Operation Superior: compilation of kimberlite indicator mineral survey resultsManitoba Report of Activities, Open File, 60p.ManitobaGeochemistry
DS200412-0178
2004
Lenton, P.G.Bohm, C.O., Kasycki, C.A., Lenton, P.G., Syme, E.C., Keller, G.R., Matile, G.L.Revealing Manitoba's hidden kimberlites.Geological Association of Canada Abstract Volume, May 12-14, SS14-01 p. 260.abstractCanada, ManitobaBrief overview of structure, stratigraphy
DS201710-2256
2017
Lenton, T.M.Pogge von Strandmann, P.A.E., Desrochers, A., Murphy, M.J., Finlay, A.J., Selby, D., Lenton, T.M.Global climate stabilisation by chemical weathering during the Hirnantian glaciation.Geochemical Perspectives Letters, Vol. 3, pp. 230-237.Canada, Quebec, Anticosti Islandcarbon cycle

Abstract: Chemical weathering of silicate rocks is a primary drawdown mechanism of atmospheric carbon dioxide. The processes that affect weathering are therefore central in controlling global climate. A temperature-controlled “weathering thermostat” has long been proposed in stabilising long-term climate, but without definitive evidence from the geologic record. Here we use lithium isotopes (?7Li) to assess the impact of silicate weathering across a significant climate-cooling period, the end-Ordovician Hirnantian glaciation (~445 Ma). We find a positive ?7Li excursion, suggestive of a silicate weathering decline. Using a coupled lithium-carbon model, we show that initiation of the glaciation was likely caused by declining CO2 degassing, which triggered abrupt global cooling, and much lower weathering rates. This lower CO2 drawdown during the glaciation allowed climatic recovery and deglaciation. Combined, the data and model provide support from the geological record for the operation of the weathering thermostat.
DS201903-0532
2019
Lenton, T.M.Mills, B.J.W., Krause, A.J., Scotese, C.R., Hill, D.J., Shields, G.A., Lenton, T.M.Modelling the long term carbon cycle, atmospheric CO2, and Earth surface temperature from late Neoproterozoic to present day.Gondwana Research, Vol. 67, pp. 172-186.Mantlecarbon

Abstract: Over geological timescales, CO2 levels are determined by the operation of the long term carbon cycle, and it is generally thought that changes in atmospheric CO2 concentration have controlled variations in Earth's surface temperature over the Phanerozoic Eon. Here we compile independent estimates for global average surface temperature and atmospheric CO2 concentration, and compare these to the predictions of box models of the long term carbon cycle COPSE and GEOCARBSULF. We find a strong relationship between CO2 forcing and temperature from the proxy data, for times where data is available, and we find that current published models reproduce many aspects of CO2 change, but compare poorly to temperature estimates. Models are then modified in line with recent advances in understanding the tectonic controls on carbon cycle source and sink processes, with these changes constrained by modelling 87Sr/86Sr ratios. We estimate CO2 degassing rates from the lengths of subduction zones and rifts, add differential effects of erosion rates on the weathering of silicates and carbonates, and revise the relationship between global average temperature changes and the temperature change in key weathering zones. Under these modifications, models produce combined records of CO2 and temperature change that are reasonably in line with geological and geochemical proxies (e.g. central model predictions are within the proxy windows for >~75% of the time covered by data). However, whilst broad long-term changes are reconstructed, the models still do not adequately predict the timing of glacial periods. We show that the 87Sr/86Sr record is largely influenced by the weathering contributions of different lithologies, and is strongly controlled by erosion rates, rather than being a good indicator of overall silicate chemical weathering rates. We also confirm that a combination of increasing erosion rates and decreasing degassing rates over the Neogene can cause the observed cooling and Sr isotope changes without requiring an overall increase in silicate weathering rates. On the question of a source or sink dominated carbon cycle, we find that neither alone can adequately reconstruct the combination of CO2, temperature and strontium isotope dynamics over Phanerozoic time, necessitating a combination of changes to sources and sinks. Further progress in this field relies on >108?year dynamic spatial reconstructions of ancient tectonics, paleogeography and hydrology. Whilst this is a significant challenge, the latest reconstruction techniques, proxy records and modelling advances make this an achievable target.
DS1999-0407
1999
Lentz, D.Lentz, D.Peralkalic magma carbonatite genesis:re-examination of syntectic reactions involving limestone -carbonatiticGeological Association of Canada (GAC) Geological Association of Canada (GAC)/Mineralogical Association of Canada (MAC)., Vol. 24, p. 69. abstractGlobalCarbonatite, Genesis
DS200712-1116
2007
Lentz, D.Veksler, I.V., Lentz, D.Parental magmas of plutonic carbonatites, carbonate silicate immiscibility and decarbonation reactions: evidence from melt and fluid inclusions.Mineralogical Association of Canada, Vol. 36, pp. 123-150.MantleCarbonatite
DS201906-1313
2019
Lentz, D.Lentz, D., Steele-MacInnis, M., Charlier, B.Carbonatitic to limestone syntectic decarbonation reactions in silicate magmas: CO2 oxidant enhancing IOA liquid immiscibility.GAC/MAC annual Meeting, 1p. Abstract p. 130.Mantlecarbonatites

Abstract: The formation of Iron Oxide-Apatite (IOA) systems has long been enigmatic. The compositions of both magnetite and apatite and the other component elements suggest derivation from high temperature (T) magmatic systems, with genetic models including iron oxide magmas or igneous magnetite and apatite flotation. Ideas related to the role of H2O and associated oxidative mechanisms have resurfaced from models of the late 1960s. As such, salt melts forming in open, differentially degassing systems could represent an end-member to the formation of IOA deposits. Another end-member involves autometasomatic decarbonation reactions involving ferroan carbonatites with co-genetic melts or host rocks generating CO2 capable of oxidizing carbonatites to enhance magnetite-apatite saturation. The syntectic decarbonation end-member presented here examines the reactions of carbonate melts of mantle origin or from syntectic reactions with limestone, with cogenetic silicate magmas. Although carbonate and silicate melts can coexist at magmatic pressure (P) and T, their compositions must be peralkalic. However, as P decreases, immiscibility or reactivity between these melts is such that CO2 is exsolved (decarbonation) to the point that at near surface conditions, decarbonation is complete. The addition of CO2 to silicate melt will drive the conversion of FeO to Fe2O3 in order to make carbon monoxide (CO), thus shifting the redox equilibria. For most silicate magmas, the amount of dissolved carbonate and CO2 is quite limited, and differential CO2 degassing results. These carbonate: silicate melt reactions then may result in oxidation of the silicate magma, to enhance immiscibility of IOA (liquation) and elemental partitioning associated with liquid-liquid immiscibility. This could be an oxidative mechanism for Fe-Ti tholeiites (ferrobasalts) and diorites to reach a two-liquid field and form IOA melts via liquation. Carbonates would typically be consumed in these reactions, although CO2 is an important degassing product that would substantially increase ?V of the reaction, which has implications during high-level emplacement.
DS1994-1027
1994
Lentz, D.R.Lentz, D.R.Alteration and alteration processes associated with ore-forming systemsGeological Association of Canada (GAC) Short Course, No. 11, 440p. $ 50.00CanadaTable of contents, Alteration short course notes
DS1998-0860
1998
Lentz, D.R.Lentz, D.R.Mineralized intrusion related skarn systemsMineralogical Association of Canada, Short course No. 26, 664pGlobalBook - table of contents, Skarn systems, composition, metallogeny, magmas
DS1998-0861
1998
Lentz, D.R.Lentz, D.R.A re-examination of carbonatite genesis: the role of intrusion related pneumatolytic skarn processes...Geological Society of America (GSA) Annual Meeting, abstract. only, p.A25-6.GlobalVolatile fluxing, Carbonatite - genesis
DS1999-0408
1999
Lentz, D.R.Lentz, D.R.Carbonatite genesis: a reexamination of the role of intrusion related pneumatolytic skarn processes ...Geology, Vol. 27, No. 4, Apr pp. 335-8.GlobalCarbonatite - skarn reactions, Model - limestone melting
DS200512-0002
2005
Lentz, D.R.Adams, M.G., Lentz, D.R., Shaw, C.S., Williams, P.F., Archibald, D.A., Cousens, B.Eocene shoshonitic mafic dykes intruding the Monashee Complex, British Columbia: a petrogenetic relationship with the Kam loops Group volcanic sequence.Canadian Journal of Earth Sciences, Vol. 42, 1, pp. 11-24.Canada, British ColumbiaShoshonite
DS200812-0775
2008
Lentz, D.R.Mumford, T.R., Shaw, C.S.J., Lentz, D.R.Magmatic history of the Ice River alkaline complex, British Columbia, Canada.Goldschmidt Conference 2008, Abstract p.A663.Canada, British ColumbiaAlkalic
DS201603-0390
2016
Lentz, D.R.Kanouo, N.S., Ekomane, E., Yongue, R.F., Njonfang, E., Zaw, K., Changian, M., Ghogomu, T.R., Lentz, D.R., Venkatesh, A.S.Trace elements in corundum, chrysoberyl, and zircon: application to mineral exploration and provenance study of the western Mamfe gem clastic deposits ( SW Cameroon, Central Africa).Journal of African Earth Sciences, Vol. 113, pp. 35-50.Africa, CameroonGeochemistry

Abstract: Trace element abundances in three indicator minerals (corundum, chrysoberyl, and zircon grains) from the western Mamfe gem placers, as determined by LA-ICP-MS analytical techniques, are shown to be sensitive to their crystallization conditions and source rock types. Corundum is dominantly composed of Al (standardized at 529,300 ppm), Fe (2496-12,899 ppm), and Ti (46-7070 ppm). Among element ratios, Fe/Mg (73-1107), Fe/Ti (0.5-245.0), Ti/Mg (1-175), and Ga/Mg (4-90) are generally higher whereas, Cr/Ga (<0.072) is low. The Fe (?12,899), Ga (?398), Mg (2-62), Cr (1.1-33.0), and V (3.0-93.0) contents (in ppm) mostly typify corundum grains formed in magmatic rocks, although some are metamorphic affiliated. A very higher Ti and significantly low Ga, Ta and Nb contents in some blue grains, suggest interesting concentrations of those high-tech metals in their source rocks. Chrysoberyl is dominantly composed of Al (standardized at 425,000 ppm) and Be (62701-64371 ppm). Iron (7605-9225 ppm), Sn (502-3394 ppm), and Ti (33-2251 ppm) contents are high, whereas Ga (333-608 ppm), Ta (<456.0 ppm), and Nb (<3.0 ppm) are significantly low. The high (Be and Sn) and significantly low Ga-Rb abundances, and Ta > Nb in the western Mamfe chrysoberyls show that they were crystallized in granitic pegmatites, with some of those source rocks being enriched in Ta and Sn. Zirconium oxide (ZrO2: standardized at 66.1 wt.%)) is the only major oxide in analysed coarse-grained zircons. Within the minor elementary suites: Hf (4576-12,565 ppm) and Y (48-2805 ppm) contents are significantly high. The trace element suites include: Th (7-1565 ppm), U (13-687 ppm), and ?REE (50-2161 ppm), whose values are significantly low. The (Yb/Sm)N, Ce/Ce*, and Eu/Eu* anomalies range from 1.0 to 227.0, 0 to 308, and 0.08 to 1.7 respectively. They are Hf-Y-HREE enriched and depleted zircons mainly crystallized in magmatic oxidized environments. They were mainly sorted from granitoids, syenites and kimberlites.
DS201112-0199
2010
Lenz, C.Conceicao, R.V., Green, D.H., Lenz, C., Gervasconi, F., Drago, S.Derivation of potassic magmas by decompression melting of phlogopite+pargasite lherzolite.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 74.MantleMetasomatism
DS201112-0200
2010
Lenz, C.Conceicao, R.V., Lenz, C., Gervasconi, F., Drago, S.Origin of the potassium in the Earth-Moon system and contribution for the K-rich rocks.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 73.MantleMelting
DS201112-0201
2011
Lenz, C.Conceicao, R.V., Lenz, C., Provenzano, C.A.S., Sander, A., Silveira, F.V.U Pb perovskite ages of kimberlites from the Rosario do Sul cluster Southern Brazil.Goldschmidt Conference 2011, abstract p.691.South America, Brazil, Rio Grande do SulGeochronology
DS200612-0801
2006
Lenz, D.Lenz, D., Lalonde, A., Salvi, S., Paquette, J.Alkaline igneous systems: dissecting magmatic to hydrothermal mineralizing processes.Mineralogical Association of Canada, www.gacmac2006.caCanada, QuebecTechnical meeting - volcanism, alkaline rocks
DS200712-0619
2007
Lenze, A.Lenze, A., Stockhert, B.Microfabrics of UHP metamorphic granites in the Dora Maira Massif, western Alps - no evidence of deformation at great depths.Journal of Metamorphic Geology, Vol. 25, pp. 461-475.EuropeUHP metamorphism
DS1960-0696
1966
Lenzen, G.Lenzen, G.Die Qualitatsmerkmale des Diamanten Geschichtliches Unsd Gegenwartiges.Hamburg: Lenzen And Stormer., 39P.IndiaDiamond Colour
DS1960-0697
1966
Lenzen, G.Lenzen, G.Produktion und Handelsgeschichte des DiamantenBerlin: Duncker And Humblot., 280P.India, Brazil, AfricaDiamond Production
DS1970-0121
1970
Lenzen, G.Lenzen, G.The History of Diamond Production and the Diamond TradeNew York: Praeger Publishing, 230P.South Africa, GlobalKimberley
DS1970-0339
1971
Lenzen, G.Lenzen, G.Kurzgefaszte DiamantenkundeWeiszenthurm:, GlobalKimberlite, Kimberley, Janlib, Gemology
DS1975-1115
1979
Lenzen, G.Lenzen, G.Kurzgefasite Diamanten kunde Fur Den Fachhanden une Erste Einfuhrung.Hamburg: Lenzen And Stormer., 149P.GlobalDiamonds, Kimberley
DS1975-1116
1979
Lenzen, G.Lenzen, G.Diamant kunde Mit Kritischer Darstellung der Diamantengraduierung.Kirschweiler: Verlag E. Lenzen, 3rd. Edition., GlobalKimberlite, Kimberley, Janlib, Gemology
DS2002-0935
2002
Leo, C.Leo, C.An a analysis of a remotely sensed circular feature near lake Spring, Missouri16th. International Conference On Basement Tectonics '02, Abstracts, 1p., 1p.MissouriBasement features - ring dykes, laccoliths, high mafic
DS1960-1229
1969
Leo, G.W.White, R.W., Leo, G.W.Geological Reconnaissance in Western LiberiaGeological Survey LIBERIA SPECIAL PAPER., No. 1GlobalGeology, Diamonds
DS1970-0214
1970
Leo, G.W.White, R.W., Leo, G.W.Geological Summary of Age Provinces of LiberiaLiberia Geol. Min. Met. Soc. Bulletin., No. 4, PP. 96-106.GlobalGeology, Geochronology
DS1970-0308
1971
Leo, G.W.Hurley, P.M., Leo, G.W., White, R.W., Fairbairn, H.W.Liberian Age Province ( About 2700ma) and Adjacent Provinces in Liberia and Sierra Leone.Geological Society of America (GSA) Bulletin., Vol. 82, PP. 3483-3490.Sierra Leone, Liberia, West AfricaGeochronology
DS1970-0309
1971
Leo, G.W.Hurley, P.M., Leo, G.W., White, R.W., Fairbairn, H.W.Liberian Age Province ( About 2, 700 M.y.) and Adjacent Provinces in Liberia and Sierra Leone.Geological Society of America (GSA) Bulletin., Vol. 82, PP. 3483-3490.West Africa, Liberia, Sierra Leone, GuineaStructure, Tectonics
DS201412-0510
2014
Leo, J.F.Li, Z-H., Leo, J.F., Ribe, N.M.Subduction induced mantle flow, finite strain, and seismic anisotropy: numerical modeling.Journal of Geophysical Research, Vol. 119, no. 6, pp. 5052-5076.MantleSubduction
DS201906-1327
2019
Leonard, J.Muller, R.D., Zahirovic, S., Williams, S.E., Cannon, J., Seton, M., Bower, D.J., Tetley, M., Heine, C., Le Breton, E., Liu, S., Russell, S.H.J., Yang, T., Leonard, J., Gurnis, M.A global plate model including lithospheric deformation along major rifts and orogens since the Triassic.Tectonics, May 5, 36p. Mantleplate tectonics

Abstract: Global deep?time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic?Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hotspot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 million km2 in the Late Jurassic (~160?155 Ma), driven by a vast network of rift systems. After a mid?Cretaceous drop in deformation it reaches a high of 48 million km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate?mantle system.
DS201907-1562
2019
Leonard, J.Muller, D., Zahirovic, S., Williams, S.E., Cannon, J., Seton, M., Bower, D.J., Tetley, M., Heine, C., Le Breton, E., Liu, S., Russell, S.H.J., Yang, T., Leonard, J., Gurnis, M.A global plate model including lithospheric deformation along major rifts and orogens since the Triassic.Tectonics, in press available, 37p.Africa, globalplate tectonics, rotation

Abstract: Global deep?time plate motion models have traditionally followed a classical rigid plate approach, even though plate deformation is known to be significant. Here we present a global Mesozoic-Cenozoic deforming plate motion model that captures the progressive extension of all continental margins since the initiation of rifting within Pangea at ~240 Ma. The model also includes major failed continental rifts and compressional deformation along collision zones. The outlines and timing of regional deformation episodes are reconstructed from a wealth of published regional tectonic models and associated geological and geophysical data. We reconstruct absolute plate motions in a mantle reference frame with a joint global inversion using hot spot tracks for the last 80 million years and minimizing global trench migration velocities and net lithospheric rotation. In our optimized model, net rotation is consistently below 0.2°/Myr, and trench migration scatter is substantially reduced. Distributed plate deformation reaches a Mesozoic peak of 30 × 106 km2 in the Late Jurassic (~160-155 Ma), driven by a vast network of rift systems. After a mid?Cretaceous drop in deformation, it reaches a high of 48 x 106 km2 in the Late Eocene (~35 Ma), driven by the progressive growth of plate collisions and the formation of new rift systems. About a third of the continental crustal area has been deformed since 240 Ma, partitioned roughly into 65% extension and 35% compression. This community plate model provides a framework for building detailed regional deforming plate networks and form a constraint for models of basin evolution and the plate?mantle system.
DS1990-0777
1990
Leonard, J.E.Jones, T.A., Leonard, J.E.Why 3-D modeling?Nine articles on the subject - three dimensions. mostly applicable to petroleuM.Geobyte, Vol. 5, No. 1, pp. 25-49GlobalComputer -modeling, Graphics - 3 D.
DS200612-0615
2006
Leonard, L.Hyndman, R.D., Fluck, P., Mazzotti, S., Lewis, T.J., Ristau, J., Leonard, L.Current tectonics of the northern Canadian Cordillera.Canadian Journal of Earth Sciences, Vol. 42, 6, pp. 1117-1136.Canada, British ColumbiaTectonics
DS200412-0332
2004
Leonard, M.Clark, D., Leonard, M.Principal stress orientations from multiple focal plane solutions: new insight into the Australian intraplate stress field.Hillis, R.R., Muller, R.D. Evolution and dynamics of the Australian Plate, Geological Society America Memoir, No. 372, pp. 71-90.AustraliaTectonics
DS1994-0619
1994
Leonardo, O.H.Gibson, S.A., Thompson, R.N., Leonardo, O.H., Turner, S.The Serra do Bueno potassic diatreme - a possible hypabyssal equiv. of ultramafic alkaline volcanics.Mineralogical Magazine, Vol. 58, No. 392, Sept. 357-373.BrazilAlkaline rocks, Diatremes
DS2000-0336
2000
LeonardosGibson, S.A., Thompson, Dickin, LeonardosCarbonatite and kimberlite magmatism asssociated wiht the impact of the Proto-Tristan plume.Igc 30th. Brasil, Aug. abstract only 1p.BrazilParan-Etendeka igneous
DS1995-0630
1995
Leonardos, G.H.Gibson, S.A., Thompson, R.N., Leonardos, G.H., DickinThe late Cretaceous impact of the Trindade mantle plume; evidence from large volume, mafic potassic MagazineJournal of Petrology, Vol. 36, No. 1, February, pp. 189-229.BrazilMagmatism -potassic, Alkaline rocks
DS1996-0522
1996
Leonardos, O.Gibson, S.A., Thompson, R.N., Dickin, A.P., Leonardos, O.Erratum to High Ti and low Ti mafic potassic magmas: Key to plume lithosphere interactions and flood genesisEarth and Planetary Science Letters, Vol. 141, pp. 325-341Brazil, ParaguayMagmas, Lithosphere
DS1930-0254
1937
Leonardos, O.H.Leonardos, O.H.Diamante E Carbonado No Estado Da BahiaRio De Janeiro: D N P M, Avulso, No. 19, 25P.BrazilKimberlite, Kimberley, Janlib, Mineralogy
DS1986-0288
1986
Leonardos, O.H.Gierth, E., Goldman, D., Leonardos, O.H., Baecker, M.L.Main features of the paragenetic evolution of the Carbonatite complex of Catalao 1, GoiasBrasilIn: Symposium on Latin American Sciences, Vol. 1985 No. 9-10, pp. 1469-1475BrazilBlank
DS1987-0405
1987
Leonardos, O.H.Leonardos, O.H., Ulbrich, M.N.C.Lamproitos de Presidente Olegano, Minas Gerais.(in Portugese)39th. Annual Meeting Brazilian Soc. For Advancement Of Science, Abstract (ref. from Mitchell)GlobalBlank
DS1989-0510
1989
Leonardos, O.H.Gierth, E., Leonardos, O.H.Some characteristics of the niobium ores in the unweathered sections Of the carbonatite complexes Catalao I and II, Goias, Brasil79th. Annual Meeting Of The Geologische Vereinigung, Mineral, p. 1-2. (abstract.)BrazilCarbonatite
DS1991-0974
1991
Leonardos, O.H.Leonardos, O.H., Meyer, H.O.A.Cretaceous intrusions in western Minas GeraisFifth International Kimberlite Conferences Field Excursion Guidebook, Servico Geologico do Brasil (CPRM) Special, pp. 17-24BrazilGeology, Diamond areas
DS1991-0975
1991
Leonardos, O.H.Leonardos, O.H., Meyer, H.O.A., Gaspar, J.C.Proceedings of Fifth International Kimberlite Conference GuidebookServico Geologico do Brasil (CPRM) Special Publication 3/91, Brasilia, 100pBrazilGuidebook, Diamond areas
DS1991-0976
1991
Leonardos, O.H.Leonardos, O.H., Ulbrich, M.N., Gaspar, J.C.The Mat a da Corda volcanic rocksFifth International Kimberlite Conferences Field Excursion Guidebook, Servico Geologico do Brasil (CPRM) Special, pp. 65-74BrazilGeology, Volcanics
DS1991-1688
1991
Leonardos, O.H.Tallarico, F.H.B., Souza, J.C.F., Leonardos, O.H., Meyer, H.O.A.The Mat a Do Lenco mica-rich kimberlite, western Minas GeraisProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 408-409BrazilMacrocrysts, Mineral chemistry
DS1991-1761
1991
Leonardos, O.H.Ulbrich, M.N.C., Leonardos, O.H.The ultrabasic potassic rocks of Presidente Olegario, Serra da Mat a daCorda, Minas Gerais, BrasilProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 437-439BrazilMineral chemistry, analyses, Wadeite, Kamafugite, lamproite
DS1993-0540
1993
Leonardos, O.H.Gibson, S.A., Leonardos, O.H., Thompson, R.N., Turner, S.E.O diatrema alcalino-ultrafico da Serra do Bueno, Alto Paranaiba MinasGerais. (in Portugese).Brasiliao Geologi do Diamante UFMT., Esp. 2/93, Cuabe, pp. 57-78.BrazilKimberlites, mafic ultrapotassic rocks, alkaline rocks, Serra do Bueno
DS1993-0905
1993
Leonardos, O.H.Leonardos, O.H., Carvalho, J.B., et al.O xenolito de Granada lherzolito de Tres Ranchos 4: uma rocha matriz dodiamante na provincia magmatica Cretacea do Alto Paranaiba, Goias. (in Portugese).Brasiliao Geologi do Diamante UFMT., Esp. 2/93, Cuabe, pp. 3-16.BrazilXenoliths, Tres Ranchos 4
DS1993-1569
1993
Leonardos, O.H.Tallarico, F.H.B., Leonardos, O.H., Gibson, S.A., Meyer, H.O.A.Quimica mineral da intrusa o da mat a do lenco, Abadia dos Dourados, MinasGerais.(in Portugese).Brasiliao Geologi do Diamante UFMT., Esp. 2/93, Cuabe, pp. 114-128.BrazilDa Mata do Lenco, Kimberlitic intrusive
DS1994-0620
1994
Leonardos, O.H.Gibson, S.A., Thompson, R.N., Leonardos, O.H., Dickin, A.The late Cretaceous impact of the Trindade plume: evidence from large volume mafic potassic magmatism.International Symposium Upper Mantle, Aug. 14-19, 1994, Extended abstracts pp. 56-58.BrazilMantle plume, Alkaline rocks
DS1995-0281
1995
Leonardos, O.H.Carvalho, J.B., Leonardos, O.H.Preliminary geothermobarometric and metasomatism studies mantle xenoliths-Alto Parananaiba kimberlitesProceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 101-103.BrazilGeothermometry, lamproites, Kimberlites, Tres Ranchos, Indaia Pantano, Serro do Buen
DS1995-0631
1995
Leonardos, O.H.Gibson, S.A., Thompson, R.N., Leonardos, O.H., Dickin, A.P.The Late Cretaceous impact of the Trindada mantle plume: evidence large volume mafic potassic magmatismJournal of Petrology, Vol. 36, No. 1, Feb. pp. 189-230.BrazilMagmatism -potassic, Alkaline rocks
DS1995-1085
1995
Leonardos, O.H.Leonardos, O.H., Carvalho, J.B., Gibson, S.A., ThompsonThe diamond potential of the late Cretaceous Alto Paranaiba igneousprovince, Brasil.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 320-322.BrazilAlluvials, Deposit -Alto Paranaiba
DS1995-1086
1995
Leonardos, O.H.Leonardos, O.H., Teixeira, N.A., Dino, R.Geology and palinology of the Santa Clara kimberlite Maar, Coromandel, Brasil.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 323-325.BrazilMaar, Deposit -Santa Clara
DS1995-1867
1995
Leonardos, O.H.Tallarico, F.H.B., Leonardos, O.H.Glimeritic and peridotitic xenoliths from the Mat a do Lenco micaceous kimberlite -Alto Paranaiba-MetasomatismProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 600-602.Brazil, Alto ParanaibaXenoliths, Deposit -Mato do Lenco
DS1996-0523
1996
Leonardos, O.H.Gibson, S.A., Thomspon, R.N., Leonardos, O.H.Erratun to high Ti and low Ti mafic potassic magmas: key to plume lithosphere interactions ...Earth and Planetary Science Letters, Vol. 141, No. 1-4, June 1, pp. 325-MantleAlkaline rocks, Plumes
DS1996-0835
1996
Leonardos, O.H.Leonardos, O.H., Thompson, R.N., Fleicher, R., Gibson, S.The origin of diamonds in western Minas Gerais, Brasil. Comment andreply., ,by Gonzaga, Teixeira and Gaspar.Mineral Deposits, Vol. 31, No. 4, May pp. 343-347.BrazilDiamond genesis
DS1998-1144
1998
Leondaros, O. Brito-.Pedrosa-Soares, A.C., Vidal, P., Leondaros, O. Brito-.Neoproterozoic oceanic remnants in eastern Brasil: further evidence and refutation of exclusively ensialicGeology, Vol. 26, No. 6, June pp. 519-522.BrazilAracuai West Congo orogen, Craton - Sa Francisco, Congo
DS202108-1308
2021
Leone, F.Rey, T., Leone, F., Defossez, S., Gherardi, M., Parat, F.Volcanic hazards assessment of Oldoinyo Lengai in a data scarcity context.Territorium, Vol. 28, (II) pp. 69-81. pdfAfrica, Tanzaniadeposit - Oldoinyo Lengai

Abstract: The objective of our study is to establish an assessment of four volcanic hazards in a country threatened by the eruption of the OlDoinyo Lengai volcano. The last major eruption dates back to 2007-2008 but stronger activity in 2019 has revived the memory of volcanic threats to the Maasai and Bantu communities and human activities (agro-pastoral and tourism). The methods chosen have had to be adapted to the scarce and incomplete data. The volcanic hazards and their probability of occurrence were analysed on the basis of data available in the scientific literature and were supplemented by two field missions combining geography and hydro-geomorphology. Our study enabled us to map the hazards of ash fall, lava flows, lahars and avalanches of debris. Each hazard was spatialised by being ascribed an intensity. They are sometimes synchronous with the eruption sometimes they occur several months or years after a volcanic eruption. The results are the first step towards developing a volcanic risk management strategy, especially for the pastoral communities living around Lengai and for the growing tourist activities in this area.
DS202002-0183
2019
Leonhardi, T.C.First, E.C., Leonhardi, T.C., Hammer, J.E.Effects of superheating magnitude on olivine growth.Contributions to Mineralogy and Petrology, Vol. 175, 13p. pdfMantlemagmatism

Abstract: Magmatic superheating is a condition with relevance to natural systems as well as experimental studies of crystallization kinetics. Magmas on Earth and other planetary bodies may become superheated during adiabatic ascent from the mantle or as a consequence of meteorite impact-generated crustal melting. Experimental studies of igneous processes commonly employ superheating in the homogenization of synthetic starting materials. We performed 1-atmosphere dynamic crystallization experiments to study the effects of superliquidus thermal history on the morphologies and compositions of subsequently grown olivine crystals. An ultramafic volcanic rock with abundant olivine was fused above the experimentally determined liquidus temperature (1395 °C), held for 0, 3, or 12 h, cooled at 25 °C h?1, and quenched from 200 °C below the liquidus, all at constant fO2, corresponding to FMQ-2?±?0.2 log units. An increase in olivine morphologic instability is correlated with superheating magnitude, parameterized as the integrated time the sample is held above the liquidus (“TtL”; °C h). We infer that a delay in nucleation, which intensifies monotonically with increasing TtL, causes crystal growth to be increasingly rapid. This result indicates that the structural relaxation time scale controlling the formation of crystal nuclei is (a) far longer than the time scale associated with viscous flow and (b) exceeds the liquidus dwell times typically imposed in crystallization experiments. The influence of magmatic superheating on crystal morphology is similar in sense and magnitude to that of subliquidus cooling rate and thus, both factors should be considered when interpreting the thermal history of a volcanic rock containing anhedral olivine.
DS1984-0450
1984
Leonhardt, F.H.Leonhardt, F.H., Aikem, C.L.V.Gravity Study of Some Shallow and Deep Structures in the Ouachita Tectonic Belt, Oklahoma.Geophysics, Vol. 49, No. 5, MAY P. 618. (abstract.).OklahomaMid-continent
DS1982-0383
1982
Leonov, A.V.Lyalin, YU.I., Shuzhanov, V.M., Leonov, A.V.Basaltic volcanism of epochs of molasse formation in central Kazakhstan and northern Tien Shan.(Russian)Magmat. Molasse Form. Epoch. Symposium, (Russian), Publishing Stav. Dionyza Stura Bratislava Czech., 480 100 pRussiaBlank
DS1960-0265
1962
Leonov, B.N.Leonov, B.N., Prokopchuk, B.I.Problem of the Age of the Kimberlites in Northeastern Siberian PlatformIn: Data of Regional Geology of The Siberian Platform And It, TRUDY VSES AEROGEOL. TRESTA, No. 8, PP. 80-84.RussiaBlank
DS1960-0698
1966
Leonov, B.N.Leonov, B.N., Prokopchuk, B.I., Orlov, I.L.Almazy-prilenskoy OblastiMoscow: Nauka., 278P.RussiaDiamonds, Kimberley
DS1994-1028
1994
Leonov, M.G.Leonov, M.G.Interior mobility of the basement and Tectonogenesis of activatedplatforms.Geotectonics, Vol. 27, No. 5, April, pp. 369-379.MantleTectonics, Stratigraphy -platform evolution
DS201112-0727
2010
Leonov, V.L.Naumov, V.B., Tolstykh, M.L., Grib, E.N., Leonov, V.L., Kononkova, N.N.Chemical composition, volatile components, and trace elements in melts of the Karymskii volcanic centre, Kamchatka and Golovnin a volcano, Kunashir Island....Vladykin, N.V., Deep Seated Magmatism: its sources and plumes, pp. 104-127.RussiaMineral inclusions
DS2001-0676
2001
Leonov, Y.G.Leonov, Y.G.Continental rifting: modern views, problems and solutionsGeotectonics, Vol. 35, No. 2, pp. 81-92.GlobalGeophysics - seismics, Tectonics
DS1994-1029
1994
Leonov, Yu.G.Leonov, Yu.G.Tectonic criteria for interpretation of seismic reflectors in the lower crust of continents.Geotectonics, Vol. 27, No. 5, April, pp. 358-368.MantleTectonics, Geophysics -seismics
DS1950-0335
1957
Leont'ev, L.N.Leont'ev, L.N., Kadensky, A.A.The Nature of the Yakutian Kimberlite PipesDoklady Academy of Sciences Nauk SSSR., Vol. 115, No. 2, PP. 368-37L.RussiaBlank
DS2002-0674
2002
Leonyuk, N.I.Hatchaturov, S., Aksionov, N., Leonyuk, N.I.BHT processing of natural diamonds: new intense fancy green18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.148.GlobalDiamond - colouration
DS2003-0795
2003
Leost, I.Leost, I., Stachel, T., Brey, G.P., Harris, J.W., Ryabchikov, I.D.Diamond formation and source carbonation: mineral associations in diamonds fromContributions to Mineralogy and Petrology, Vol. 145, 1, pp. 15-24.NamibiaDiamond genesis
DS2003-0796
2003
Leost, I.Leost, I., Tachel, T., Brey, G.P., Harris, J.W.An unusual suite of inclusions in diamonds from Namibia8 Ikc Www.venuewest.com/8ikc/program.htm, Session 3, AbstractNamibiaDiamonds, Diamond - inclusions
DS2003-1324
2003
Leost, I.Stachel, T., Aulbavh, S., Brey, G.P., Harris, J.W., Leost, I., Tappert, R., ViljoenDiamond formation and mantle metasomatism: a trace element perspective8 Ikc Www.venuewest.com/8ikc/program.htm, Session 3, AbstractGlobalDiamonds, database REE 135 peridotite garnet inclusions, Review - genesis
DS200412-0798
2004
Leost, I.Harris, J.W., Stachel, T., Leost, I., Brey, G.P.Peridotitic diamonds from Namibia: constraints on the composition and evolution of their mantle source.Lithos, Vol. 77, 1-4, Sept. pp. 209-223.Africa, NamibiaPlacer, alluvials, diamond inclusions, metasomatism,REE
DS200412-1116
2003
Leost, I.Leost, I., Stachel, T., Brey, G.P., Harris, J.W., Ryabchikov, I.D.Diamond formation and source carbonation: mineral associations in diamonds from Namibia.Contributions to Mineralogy and Petrology, Vol. 145, 1, pp. 15-24.Africa, NamibiaDiamond genesis
DS200412-1117
2003
Leost, I.Leost, I., Tachel, T., Brey, G.P., Harris, J.W.An unusual suite of inclusions in diamonds from Namibia.8 IKC Program, Session 3, AbstractAfrica, NamibiaDiamonds Diamond - inclusions
DS200412-1905
2004
Leost, I.Stachel, T., Aulbach, S., Brey, G.P., Harris, J.W., Leost, I., Tappert, R., Vijoen, K.S.The trace element composition of silicate inclusions in diamonds: a review.Lithos, Vol. 77, 1-4, Sept. pp. 1-19.MantleDiamond inclusion, REE, metasomatism, lithosphere, garn
DS200412-1906
2003
Leost, I.Stachel, T., Aulbavh, S., Brey, G.P., Harris, J.W., Leost, I., Tappert, R., Viljoen, K.S.Diamond formation and mantle metasomatism: a trace element perspective.8 IKC Program, Session 3, AbstractTechnologyDiamonds, database REE 135 peridotite garnet inclusions Review - genesis
DS2003-0797
2003
Leost, J.Leost, J., Stachel, T., Brey, G.P., Harris, J.W., Ryabichikov, I.D.Diamond formation and source carbonation: mineral associations in diamonds fromContribution to Mineralogy and Petrology, NamibiaDiamond mineralogy, morphology, genesis
DS2003-0798
2003
LePage, L.D.LePage, L.D.ILMAT: an excel worksheet for ilmenite magnetite geothermometry and geobarometryComputers and Geosciences, Vol. 29, 5, pp. 673-8.GlobalComputer - program
DS200412-1118
2003
LePage, L.D.LePage, L.D.ILMAT: an excel worksheet for ilmenite magnetite geothermometry and geobarometry.Computers & Geosciences, Vol. 29, 5, pp. 673-8.TechnologyComputer - program
DS1995-1087
1995
Lepard, D.W.Lepard, D.W.Industry standard (CALCOMP) graphics library for DXF output and relatedutilitiesGeological Survey of Canada Open File, No. 3106, $ 20.00GlobalComputer, Program -DXFLIB.
DS200612-0802
2006
Lepard, D.W.Lepard, D.W.Geographic location conversion tool. Version 3.Geological Survey of Canada, Open file 3939, 1CD $20.00TechnologyComputer - program
DS200612-0803
2006
Lepard, D.W.Lepard, D.W.Geographic location conversion tool. Version 4.21).Geological Survey of Canada, No. 3939, 1 CD $ 9.10GlobalTechnology
DS201412-0505
2014
Leparmentier, F.Leprtre, R., Barbarand, J., Missenard, Y., Leparmentier, F., Frizon de lamotte, D.Reguibat shield and adjacent basins.Geological Magazine, Vol. 151, 5, pp. 885-898.Africa, MauritaniaGeology
DS201506-0268
2015
Leparmentier, F.Frizon de Lamotte, D., Fourdan, B., Leleu, S., Leparmentier, F., de Clarens, P.Style of rifting and the stages of Pangea break up.Tectonics, Vol. 34, 5, pp. 1009-1029.Global, RussiaPangea
DS201805-0989
2018
Leparmentier, F.Vincente de Gouveia, S., Besse, J., Frizon de Lamotte, D., Greff-Lefftz, M., Lescanne, M., Gueydan, F., Leparmentier, F.Evidence of hot spot paths below Arabia and the Horn of Africa and consequences on the Red Sea opening.Earth Planetary Science Letters, Vol. 487, pp. 210-220.Africatectonics

Abstract: Rifts are often associated with ancient traces of hotspots, which are supposed to participate to the weakening of the lithosphere. We investigated the expected past trajectories followed by three hotspots (Afar, East-Africa and Lake-Victoria) located around the Red Sea. We used a hotspot reference frame to compute their location with respect to time, which is then compared to mantle tomography interpretations and geological features. Their tracks are frequently situated under continental crust, which is known to strongly filter plume activity. We looked for surface markers of their putative ancient existence, such as volcanism typology, doming, and heat-flow data from petroleum wells. Surface activity of the East-Africa hotspot is supported at 110 Ma, 90 Ma and 30 Ma by uplift, volcanic activity and rare gas isotopic signatures, reminiscent of a deep plume origin. The analysis of heat-flow data from petroleum wells under the Arabian plate shows a thermal anomaly that may correspond to the past impact of the Afar hotspot. According to derived hotspot trajectories, the Afar hotspot, situated (at 32 Ma) 1000 km north-east of the Ethiopian-Yemen traps, was probably too far away to be accountable for them. The trigger of the flood basalts would likely be linked to the East-Africa hotspot. The Lake-Victoria hotspot activity appears to have been more recent, attested only by Cenozoic volcanism in an uplifted area. Structural and thermal weakening of the lithosphere may have played a major role in the location of the rift systems. The Gulf of Aden is located on inherited Mesozoic extensional basins between two weak zones, the extremity of the Carlsberg Ridge and the present Afar triangle, previously impacted by the East-Africa hotspot. The Red Sea may have opened in the context of extension linked to Neo-Tethys slab-pull, along the track followed by the East Africa hotspot, suggesting an inherited thermal weakening.
DS201512-1909
2015
Leparmentier, S.De Lamotte, F., Fourdan, D., Leleu, B., Leparmentier, S., Clarens, F.Style of rifting and the stages of Pangea.Tectonics, Vol. 34, 5, pp. 1009-1029.MantlePangea

Abstract: Pangea results from the progressive amalgamation of continental blocks achieved at 320?Ma. Assuming that the ancient concept of “active” versus “passive” rifting remains pertinent as end-members of more complex processes, we show that the progressive Pangea breakup occurred through a succession of rifting episodes characterized by different tectonic evolutions. A first episode of passive continental rifting during the Upper Carboniferous and Permian led to the formation of the Neo-Tethys Ocean. Then at the beginning of Triassic times, two short episodes of active rifting associated to the Siberian and Emeishan large igneous provinces (LIPs) failed. The true disintegration of Pangea resulted from (1) a Triassic passive rifting leading to the emplacement of the central Atlantic magmatic province (200?Ma) LIP and the subsequent opening of the central Atlantic Ocean during the lowermost Jurassic and from (2) a Lower Jurassic active rifting triggered by the Karoo-Ferrar LIP (183?Ma), which led to the opening of the West Indian Ocean. The same sequence of passive then active rifting is observed during the Lower Cretaceous with, in between, the Parana-Etendeka LIP at 135?Ma. We show that the relationships between the style of rifts and their breakdown or with the type of resulting margins (as magma poor or magma dominated) are not straightforward. Finally, we discuss the respective role of mantle global warming promoted by continental agglomeration and mantle plumes in the weakening of the continental lithosphere and their roles as rifting triggers.
DS201312-0334
2013
Lepehina, E.N.Griban, J.G., Samsonov, A.V., Salnikov, E.B., Lepehina, E.N.Kimberlitic zircons from the Paleoproterozoic Kimzero kimberlites ( Karelia): mineralogy, geochemistry and U-Pb geochronology.Goldschmidt 2013, AbstractRussia, KareliaDeposit - Kimozero
DS2000-0048
2000
LepekhinaBabushkina, M.S., Lepekhina, Nikitina, et al.Structural distortion of micas from lamproites: evidence from Mossbauer and IR spectroscopy.Doklady Academy of Sciences, Vol. 371a, No. 3, Mar-Apr. pp. 575-8.RussiaLamproites, Mineralogy - micas
DS201112-0160
2011
LepekhinaChakmouradian, A.R., Bohm, Coeslan, Mumin, Reguir, Demeny, Simonetti, Kressall, Martins, Kamenov, Creaser, LepekhinaPostorogenic carbonatites: more abundant than we realize and more important than given credit for.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.17-19.Canada, ManitobaCinder Lake, Eden Lake, Paint Lake
DS201112-0161
2011
LepekhinaChakmouradian, A.R., Bohm, Coeslan, Mumin, Reguir, Demeny, Simonetti, Kressall, Martins, Kamenov, Creaser, LepekhinaPostorogenic carbonatites: more abundant than we realize and more important than given credit for.Peralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.17-19.Canada, ManitobaCinder Lake, Eden Lake, Paint Lake
DS200912-0797
2009
Lepekhina, E.A.N.A.Vetrin, V.A.R.A., Lepekhina, E.A.N.A., Paderin, I.A.P.A., Rodionov, N.A.V.A.Stages of the lower crust formation of the Belomorian mobile belt, Kola Peninsula.Doklady Earth Sciences, Vol. 425, 2, pp. 269-273.Russia, Kola PeninsulaCraton
DS200712-1119
2007
Lepekhina, E.N.Vetrin, V.R., Lepekhina, E.N., Larionov, A.N., Presnyakov, S.L., Serov, P.A.Initial subalkaline magmatism of the Neoarchean alkaline province of the Kola Peninsula.Doklady Earth Sciences, Vol. 415, No. 5, June-July pp. 714-717.Russia, Kola PeninsulaAlkalic
DS200812-0647
2008
Lepekhina, E.N.Lepekhina, E.N., Rotman, AS.Ya., Antonov, A.V., Sergeev, S.A.SHRIMP U Pb dating of perovskite from kimberlites of the Siberian platform ( Verhnemunskoe and Alakite Marhinskoe fields.9IKC.com, 2p. extended abstractRussia, SiberiaEmplacement
DS200812-0648
2008
Lepekhina, E.N.Lepekhina, E.N., Rotman, AS.Ya., Antonov, A.V., Sergeev, S.A.SHRIMP U Pb zircon ages of Yakutian kimberlite pipes.9IKC.com, 3p. extended abstractRussia, SiberiaGeochronology
DS201012-0435
2010
Lepekhina, E.N.Lepekhina, E.N., Antonov, A.V., Belyatsky, B.V., Sergeev, S.A.Perovskite from the Proterozoic Tiksheozero carbonatite ( Russia): age and genesis.International Mineralogical Association meeting August Budapest, abstract p. 445.RussiaCarbonatite
DS201212-0016
2012
Lepekhina, E.N.Antonov, A.V., Lepekhina, E.N., Belyatsky, B.V., Lehmann, B.Kimberlitic zircon: results of magma interaction.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractIndiaDeposit - Bastar
DS201212-0418
2012
Lepekhina, E.N.Lokhov, K., Lukyanova, L., Kapitonov, I.N., Lepekhina, E.N., Antonov, A.V.,Sergeev, S.A.,Shokalsky, S.P.U-Pb and LU-HF isotopic systems in zircons from some kimberlites of the Siberian platform and from Ebeliakh alluvial deposit: age and geochemical pecularities of the source rocks.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussiaDeposit - Ebeliakh
DS201212-0620
2012
Lepekhina, E.N.Samsonov, A.V., Tretyachenko, W., Nosova, A.A., Larionova, Yu.O., Lepekhina, E.N., Larionov, A.N., Ipatieva, I.S.Sutures in the early Precambrian crust as a factor responsible for localization of Diamondiferous kimberlites in the northern east European platform.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractRussia, Kola PeninsulaStructure
DS201709-2049
2017
Lepekhina, E.N.Rodionov, N.V. , Lepekhina, E.N., Antonov, A.V., Petrov, O.V., Belyatsky, B.V., Shevchenko, S.S., Sergeev, S.A.Pyrochlore and baddeleyite from carbonatites of the Paleozoic polyphase Kovdor Massif ( N. Karelia).Goldschmidt Conference, abstract 1p.Russia, Kareliacarbonatite. Kovdor

Abstract: Pyrochlore is the main host of rare-metal elements of carbonatite rocks, including phoscorites, typical for prolonged history of alkaline magma crystallization at the mafic-ultramafic polyphase Kovdor massif. Pyrochlore associated with baddeleyite, zircon, zirkelite, zirkonolite and forms octahedral and cube-octahedral poikilitic crystals up to 2-5 cm, and represented by U, Ba-Sr and REE species of pyrochlore subgroup. The studied Kovdor pyrochlores are characterized by increased up to 6.5% U and an extremely high Th – up to 40%, with Th/U up to 500. Pyrochlore U-Pb SHRIMP ages of 290-364 Ma correlate with variations in U of different samples, whereas the Th and common Pb have a minor effect on this value. Obtained ages are significantly underestimated and may reflect the influence of the matrix effect or later low-temperature closing of the U-Pb pyrochlore system, as well as the actual transformations of pyrochlore crystal matrix due to the interaction with the late carbonate fluids. Thus the early pyrochlores and U-pyrochlores crystallized at 364 Ma within phoscorites and early calcite carbonatites, whereas Sr-Ba pyrochlores of late calcitedolomite carbonatite formed at 340 Ma, and Th-pyrochlore rims occured at the later stages of the interaction with metasomatizing fluids 290 m.y. ago. Kovdor baddeleyite is also charecterized by high composition heterogeneity determined by the difference in its origin from olivinites to ore-bearing foscorites and postmagmatic syenites. But baddeleyite from calcitemagnetite mineral association have uniform U: 184 ±40, Th: 6.4 ±1.7, ¦REE: 34 ±6, Hf: 7629 ± 599, Nb: 3595 ±840, Ti: 56 ±14, Y: 22 ±4 ppm, and HHf: +6.5 ±1.7 at the age of 379 ±6 Ma. The U-Pb SHRIMP age data demonstrate the concordance of all studied baddeleyite samples and the absence of a significant age difference between baddeleyites of the carbonatite phase: 379 ±3 and foscorites: 379 ±4 Ma. The weighted average age for all the studied baddeleyite samples (n = 8) is 379 ±2.4 Ma at MSWD of 0.6. This can also indicate a relatively short time-interval of magmatism in the formation of Kovdor polyphase massif which did not exceed 5 m.y. and could be related to the Devonian mantleplume activity.
DS201012-0823
2010
Lepekina, E.A.Vladykin, N.V., Lepekina, E.A.The age of unusual xenogenic zircons from Yakutian kimberlites.Doklady Earth Sciences, Vol. 429, 2, pp. 1451-1456.Russia, YakutiaGeochronology
DS1940-0212
1949
Lepersonne, J.Lepersonne, J.Les Grandes Traits de la Geologie du Kasai Occidental et l'origine du Diamant.Soc. Geol. Belge Bulletin., Vol. 58, No. 2, PP. 284-291.Democratic Republic of Congo, Central AfricaGeology, Diamond
DS1950-0018
1950
Lepersonne, J.Cahen, L., Lepersonne, J.Exquisse de la Geologie du Congo BelgeInternational Geological Congress 18TH., PT. 14, PP. 61-83.Democratic Republic of Congo, Central AfricaGeology
DS202006-0939
2020
Lepetre, A.Moulin, M., Aslainian, D., Evain, M., Lepetre, A., Schnurle, P., Verrier, F., Thompson, J., De Clarens, P., Leroy, S., Dias, N.Gondwana breakup: messages from the north Natal Valley.Terra Nova, Vol. 32, 3, pp. 205-210.Africa, Mozambiquegeophysics - seismics

Abstract: The Natal Valley, offshore Mozambique, is a key area for understanding the evolution of East Gondwana. Within the scope of the integrated multidisciplinary PAMELA project, we present new wide?angle seismic data and interpretations, which considerably alter Geoscience paradigms. These data reveal the presence of a 30?km?thick crust that we argue to be of continental nature. This falsifies all the most recent palaeo?reconstructions of the Gondwana. This 30?km?thick continental crust 1,000 m below sea level implies a complex history with probable intrusions of mantle?derived melts in the lower crust, connected to several occurrences of magmatism, which seems to evidence the crucial role of the lower continental crust in passive margin genesis.
DS1993-1301
1993
Lepetukha, V.V.Reverdatto, V.V., Lepetukha, V.V., Kolobov, V.Yu.Contact effect of the Zerenda granites on the Berlyk suite of rocks in the Kokchetav anticlinorium.Russian Geology and Geophysics, Vol. 34, No. 12, pp. 117-124.RussiaMetasomatism
DS2001-1207
2001
LepezinVolkova, N.I., Frenkel, Budanov, Kholodova, LepezinEclogites of the Maksyutov Complex, southern Urals: geochemistry and the nature of the Protolith.Geochemistry International, Vol. 39, No. 10, pp. 935-46.Russia, UralsEclogites
DS1994-1567
1994
Lepin, V.S.Sekerin, A.P., Menshagin, Yu.V., Lepin, V.S., Revenko, A.high pressureotassium picritic basalts of the Sayan region, near IrkutskDoklady Academy of Sciences USSR, Vol. 326, Oct. pp. 127-130.Russia, SiberiaCraton, Alkaline rocks
DS1985-0770
1985
Lepina, S.V.Zorin, YU.A., Lepina, S.V.Geothermal Aspects of Development of Asthenospheric Upwellings Beneath Continental Rift Zones.Journal of GEODYNAMICS, Vol. 3, No. 1-2, JULY PP. 1-22.GlobalBlank
DS1991-1366
1991
Lepina, S.V.Popov, A.M., Kiselev, A.I., Lepina, S.V.Magnetotelluric investigations in the Baikal region: deep structureSoviet Geology and Geophysics, Vol. 32, No. 4, pp. 93-100Russia, Lake BaikalTectonics, Structure
DS200912-0222
2009
Lepine, I.Fitzgerald, C.E., Hetman, C.M., Lepine,I., Skelton, D.S., McCandless, T.E.The internal geology and emplacement history of the Renard 2 kimberlite, Superior Province, Quebec, Canada.Lithos, In press - available 29p.Canada, QuebecDeposit - Renard
DS201212-0202
2012
Lepine, I.Fitzgerald, C.E., Lepine, I., Armstrong, J.Geology of the kimberlite pipes of the Renard cluster, Quebec, Canada.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractCanada, QuebecDeposit - Renard
DS201708-1703
2017
Lepine, I.Lepine, I.Geochemistry and geology of the Renard 2 coherent kimberlitic phases, Quebec, Canada - spatial distribution and diamond content.11th. International Kimberlite Conference, PosterCanada, Quebecdeposit - Renard 2
DS201708-1704
2017
Lepine, I.Lepine, I.3D geological modeling of the Renard 2 pipe, Quebec, Canada: from exploration to extraction.11th. International Kimberlite Conference, PosterCanada, Quebecdeposit - Renard
DS201805-0957
2018
Lepine, I.Lepine, I., Farrow, D.3D geological modelling of the Renard 2 kimberlite pipe, Quebec, Canada: from exploration to extraction.Mineralogy and Petrology, doi.org/10.1007/s00710-018-0567-y 9p.Canada, Quebecdeposit - Renard

Abstract: The Renard 2 kimberlite pipe is one of nine diamondiferous kimberlite pipes that form a cluster in the south-eastern portion of the Superior Province, Québec, Canada and is presently being extracted at the Renard Mine. It is interpreted as a diatreme-zone kimberlite consisting of two Kimberley-type pyroclastic units and related country rock breccias, all cross-cut by coherent kimberlite dykes and irregular intrusives. Renard 2 has been the subject of numerous diamond drilling campaigns since its discovery in 2001. The first two geological models modelled kimberlite and country rock breccia units separately. A change in modelling philosophy in 2009, which incorporated the emplacement envelope and history, modelled the entire intrusive event and projected the pipe shape to depth allowing for more targeted deep drilling where kimberlite had not yet been discovered. This targeted 2009 drilling resulted in a?>?400% increase in the volume of the Indicated Resource. Modelling only the kimberlite units resulted in a significant underestimation of the pipe shape. Current open pit and underground mapping of the pipe shape corresponds well to the final 2015 geological model and contact changes observed are within the expected level of confidence for an Indicated Resource. This study demonstrates that a sound understanding of the geological emplacement is key to developing a reliable 3D geological and resource model that can be used for targeted delineation drilling, feasibility studies and during the initial stages of mining.
DS201801-0067
2017
Lepkhina, E.N.Sorokhtina, N.V., Belyatsky, B.V., Kononkova, N.N., Rodionov, N.V., Lepkhina, E.N., Antonov, A.V., Sergeev, S.A.Pyrochlore group minerals from Paleozoic carbonatite massifs of the Kola Peninsula: composition and evolution.Carbonatite-alkaline rocks and associated mineral deposits , Dec. 8-11, abstract p. 20-21.Russia, Kola Peninsulacarbonatites

Abstract: Chemical composition and evolution of pyrochlore-group minerals (Nb?Ta?Ti) from the early phoscorites and calcite carbonatites, and late rare-earth dolomite carbonatites from Seblyavr and Vuorijarvi Paleozoic massifs have been studied. There are two trends in pyrochlore composition evolution: the change of U, Ti, and Ta enriched varieties by calcium high-Nb, and the change of early calcium varieties by barium-strontium pyrochlores. The substitutions are described by the typical reactions: 2Ti4+ + U4+ ? 2Nb5+ + Ca2+; Ta5+ ? Nb5+; U4+ + v (vacancy) ? 2Ca2+. The Ca ranges in pyrochlores are explained by isomorphic occupation of the cation position A with Ba, Sr, and REE, the total concentration of which increases as the carbonatite melt evolved and reaches a maximum in rare-earth dolomite carbonatites. The formation of barium pyrochlore is mainly due to successive crystallization from the Ba and Sr enriched melt (oscillatory zoning crystals), or with the secondary replacement of grain margins of the calcium pyrochlore, as an additional mechanism of formation. High enrichments in LREE2O3 (up to 6 wt.%) are identified. The fluorine content in pyrochlore group minerals varies widely. A high concentration (up to 8 wt.%) is found in central and marginal zones of crystals from calcite carbonatites, while it decreases in the pyrochlore from dolomite carbonatites. Fluorine in the crystal lattice has sufficient stability during cation-exchange processes and it is not lost in the case of developing of late carbonatites over the earlier ones. In the late mineral populations the relics enriched by this component are observed. There is a positive correlation of fluorine with sodium. The marginal and fractured zones of pyrochlore crystals from all rock types are represented by phases with a cation deficiency in position A and an increased Si. The evolution of mineral composition depends on the alkaline-ultramafic melt crystallization differentiation, enrichment of the late melts by alkalis and alkaline earth metals at the high fluorine activity. It is determined that the fluorine sharply increases from the early pyroxenites to the carbonatite rocks of the massif. The foscorites and carbonatites of the early stages of crystallization are the most enriched in fluorine, while the late dolomite carbonatites are depleted by this component and enriched in chlorine and water. The fluorine saturation of the early stages of carbonatite melting leads to the formation of fluorapatite and pyrochlore minerals which are the main mineralsconcentrators of fluorine. Pyrochlore group minerals from the Paleozoic carbonatite complexes of the Kola Peninsula are characterized by decreasing Pb, Th and U, and Th/U ratios in the transition from the early foscorites to later calcite carbonatites and hydrothermal dolomite carbonatites. The pyrochlore age varies within the 420-320 m.y. interval (U-Pb SHRIMPII data), while the rocks of the earliest magmatic stages has an individual grain age of 423 ± 15 Ma, but pyrochlore ages for calcite and dolomite carbonatites are younger: 351 ± 8.0 Ma and 324 ± 6.1 Ma, respectively. Such a dispersion of the age data is apparently associated with a disturbed Th/U ratio due to high ability for cation-exchange processes of pyrochlore crystalline matrix including secondary transformations. The research was done within the framework of the scientific program of Russian Academy of Sciences and state contract K41.2014.014 with Sevzapnedra.
DS201707-1346
2017
Lepore, G.O.Lepore, G.O., Bindi, L., Pedrazzi, G., Conticelli, S., Bonazzi, P.Structural and chemical variations in phlogopite from lamproitic rocks of the central Mediterranean region.Lithos, in press available, 69p.Europe, Italylamproite

Abstract: Micas from mafic ultrapotassic rocks with lamproitic affinity from several localities of the Central Mediterranean region were studied through single-crystal X-ray diffraction (SC-XRD), electron microprobe analysis (EMPA) and Secondary Ion Mass Spectrometry (SIMS); Mössbauer Spectroscopy (MöS), when feasible, was also applied to minimise the number of unknown variables and uncertainties. Lamproitic samples analysed cover the most important Central Mediterranean type localities, from Plan d'Albard (Western Alps) to Sisco (Corsica), Montecatini Val di Cecina and Orciatico (Tuscany, Italy) and Torre Alfina (Northern Latium, Italy). The studied crystals show distinctive chemical and structural features; all of them belong to the phlogopite-annite join and crystallise in the 1 M polytype, except for micas from Torre Alfina, where both 1 M and 2 M1 polytypes were found. Studied micas have variable but generally high F and Ti contents, with Mg/(Mg + Fe) ranging from ~ 0.5 to ~ 0.9; 2M1 crystals from Torre Alfina radically differ in chemical composition, showing high contents of Ti and Fe as well as of Al in both tetrahedra and octahedra, leading to distinctive structural distortions, especially in tetrahedral sites. SIMS data indicate that studied micas are generally dehydrogenated with OH contents ranging from ~ 0.2 apfu (atoms per formula unit) for Orciatico and Torre Alfina to ~ 1.4 for Plan d'Albard crystals; this feature is also testified by the length of the c parameter, which decreases with the loss of hydrogen and/or the increase of the F ? OH substitution. Chemical and structural data suggest that the entry of high charge octahedral cations is mainly balanced by an oxy mechanism and, to a lesser extent, by a M3 +,4 +-Tschermak substitution. Our data confirm that Ti preferentially partitions into the M2 site and that different Ti and F contents, as well as different K/Al values, are both dependant upon fH2O and the composition of magma rather than controlled by P and T crystallisation conditions. The obtained data help to discriminate among lamproite-like rocks formed within a complex geodynamic framework but still related to a destructive tectonic margin and evidence different trends for micas from the youngest Torre Alfina (Northern Latium) lamproites, referred to the Apennine orogeny and those of the older lamproites from Orciatico, Montecatini Val di Cecina (Tuscany), Western Alps, and Corsica, the latter referred to the Alpine orogeny. Phlogopite crystals from the older lamproites fall within the compositional and structural field of worldwide phlogopites from both within-plate and subduction-related settings. Phlogopite from the Plio-Pleistocene lamproite-like occurrence in Tuscany and Northern Latium, despite crystals with low Mg# of the Torre Alfina rock plot well within the general field of the other crystals in less evolved samples, follows a different evolution trend similar to that of shoshonites from Tuscany and Northern Latium. On this basis, we argue that the observed differences are inherited by slight differences in the magma compositions that are related with different genetic and evolution pathways.
DS2001-0151
2001
LePourhiet, L.Burov, E., Jolivet, L., LePourhiet, L., Poliakov, A.A thermomechanical model of exhumation of high pressure HP and ultra high pressure UHP metamorphic rocks...Tectonophysics, Vol. 342, No. 2, pp. 113-36.GlobalAlpine type collision belts, UHP
DS1993-0906
1993
Lepper, J.Lepper, J.The Lower Karoo in the mid-Zambesi Basin ( Zimbabwe)Geologische Jahrbuch Reihe B., Hefte 82, 38pZimbabweStratigraphy, Sedimentology
DS202202-0223
2021
Lepretre, A.Watremez, L., Leroy, S., d'Acremont, E., Roche, V., Evain, M., Lepretre, A., Verrier, F., Aslanian, D., Dias, N., Afilhado, A., Schnurle, P., Castilla, R., Despinois, F., Moulin, M. The Limpopo magma-rich transform margin, south Mozambique - pt. 1 Insights from deep-structure seismic imaging.Tectonics, e2021TC006915Africa, Mozambiquegeophysics -seismics

Abstract: A variety of structures results from the interplay of evolving far-field forces, plate kinematics, and magmatic activity during continental break-up. The east Limpopo transform margin, offshore northern Mozambique, formed as Africa and Antarctica separated during the mid-Jurassic period break-up of the Gondwana supercontinent. The nature of the crust onshore has been discussed for decades in an effort to resolve issues with plate kinematic models. Two seismic refraction profiles with coincident multichannel seismic reflection profiles allow us to interpret the seismic velocity structures across the margin, both onshore and offshore. These seismic profiles allow us to (a) delineate the major regional crustal domains; (b) identify widespread indications of magmatic activity; and (c) map crustal structure and geometry of this magma-rich transform margin. Careful examination of the profiles allows us to make the following observations and interpretations: (a) on land, continental crust is overlain by a >10-km thick volcano-sedimentary wedge related to an early rifting stage, (b) offshore, thick oceanic crust formed due to intense magmatic activity, and between the two (c) a 50-60-km wide transform zone where the crustal structures are affected by intense magmatic activity and faulting. The prominent presence of intrusive and extrusive igneous units may be attributed to the combination of a deep-seated melting anomaly and a trans-tensional fault zone running through thinned lithosphere that allowed melt to reach the surface. A comparison of the crustal thinning along other transform margins shows a probable dependence with the thermal and/or tectonic history of the lithosphere.
DS201412-0505
2014
Leprtre, R.Leprtre, R., Barbarand, J., Missenard, Y., Leparmentier, F., Frizon de lamotte, D.Reguibat shield and adjacent basins.Geological Magazine, Vol. 151, 5, pp. 885-898.Africa, MauritaniaGeology
DS201809-2005
2017
Lepy, M-C.Cassette, P., Notari, F., Lepy, M-C., Caplan, C., Pierre, S., Hainschwang, T., Fritsch, E.Residual radioactivity of treated green diamonds.Applied Radiation and Isotopes, Vol. 126, 1, pp. 66-72.Globaldiamond - green

Abstract: Treated green diamonds can show residual radioactivity, generally due to immersion in radium salts. We report various activity measurements on two radioactive diamonds. The activity was characterized by alpha and gamma ray spectrometry, and the radon emanation was measured by alpha counting of a frozen source. Even when no residual radium contamination can be identified, measurable alpha and high-energy beta emissions could be detected. The potential health impact of radioactive diamonds and their status with regard to the regulatory policy for radioactive products are discussed.
DS1989-0876
1989
LeQuentrec, M.F.LeQuentrec, M.F., Mareschal, J.C., Parphenuk, O.A finite element model of the thermal evolution of theKapuskasingstructureGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A103. (abstract.)OntarioTectonics, Kapuskasing Lithoprobe
DS1960-0472
1964
Lerbekmo, J.F.Lerbekmo, J.F.Heavy Minerals and the Cretaceous Tertiary Boundary in Alberta, CanadaGeological Survey of Canada, pp. 137-143.AlbertaGeochemistry - Heavy Minerals
DS1991-0977
1991
Lerche, I.Lerche, I.Inversion of dynamical indicators in quantitative basin analysis models: I.theoretical considerationsMath. Geol, Vol. 23, No. 6, August pp. 817-832GlobalGeostatistics, Basin - quantitative data
DS200812-0649
2007
Lerche, I.Lerche, I., Reicherter, K.Uplift and mantle thickness: a sensitivity study.Energy Exploration Exploitation, Multi-Science Publishing Co., Vol. 25, 4, August pp. 273-299. IngentaMantleGeophysics - seismics
DS200712-0474
2007
Lerche, M.Jackson, J.M., Sturhahn, W., Lerche, M., Li, J.Electronic structure of iron in aluminous ferromagnesium silicate perovskite under lower mantle conditions.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.146.MantlePerovskite
DS200712-0475
2007
Lerche, M.Jackson, J.M., Sturhahn, W., Lerche, M., Li, J.Electronic structure of iron in aluminous ferromagnesium silicate perovskite under lower mantle conditions.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p.146.MantlePerovskite
DS200412-1468
2004
Lernardic, A.O'Neill, C., Moresi, L., Lernardic, A., Cooper, C.M.Inferences on Australia's heat flow and thermal structure from mantle convection modelling results.Hillis, R.R., Muller, R.D. Evolution and dynamics of the Australian Plate, Geological Society America Memoir, No. 372, pp. 169-184.AustraliaGeothermometry
DS1991-0123
1991
Lerner, D.N.Bishop, P.K., Burston, M.W., Tong Chen, Lerner, D.N.A low cost dedicated multi-level groundwater sampling systemQuart. Journal of Engineering Geology, Vol. 24, pp. 311-324GlobalGroundwater, Sampling
DS1998-0862
1998
Lerner, D.N.Lerner, D.N., Walton, N.R.G.Contaminated land and groundwater: future directionsGeological Society of London Special Publication, No. 14, 248p. $ 107GlobalBook - ad, Engineering - groundwater management
DS1991-1548
1991
Lerner-Lam, A.Shalev, E., Park, J., Lerner-Lam, A.Crustal veolocity and Moho topography in central New HampshireJournal of Geophysical Research, Vol. 96, No. B 10, September 10, pp. 16, 415-427GlobalCrust, Tectonics
DS1991-1549
1991
Lerner-Lam, A.Shalev, E., Park, J., Lerner-Lam, A.Crustal velocity and Moho topography in central New HampshireJournal of Geophysical Research, Vol. 96, No. B 10, September 10, pp.16, 415-16, 427New HampshireGeophysics -seismics, White Mountain area
DS2002-0764
2002
LeRoex, A.P.Janney, P.E., LeRoex, A.P., Carlson, R.W., Viljoen, K.S.A chemical and multi isotope study of the western Cape olivine melilitite province SouthJournal of Petrology, Vol. 43, 12, pp. 2339-70.South AfricaGeochemistry - HIMU signature, Geochronology
DS2003-0500
2003
LeRoex, A.P.Gregoire, M., Bell, D.R., LeRoex, A.P.Garnet lherzolites from the Kaapvaal Craton ( South Africa): trace element evidence forJournal of Petrology, Vol. 44, 4, pp. 629-58.South AfricaMineralogy, Metasomatism
DS200412-0717
2003
LeRoex, A.P.Gregoire, M., Bell, D.R., LeRoex, A.P.Garnet lherzolites from the Kaapvaal Craton ( South Africa): trace element evidence for a metasomatic history.Journal of Petrology, Vol. 44,4,pp. 629-58.Africa, South AfricaMineralogy Metasomatism
DS200912-0763
2008
LeRoex, A.P.Tinguely, C.E., Gregoire, M., LeRoex, A.P.Eclogite and pyroxenite xenoliths from off craton kimberlites near the Kaapvaal Craton, South Africa.Comptes Rendus Geoscience, Vol. 340, 12, pp. 811-812.Africa, South AfricaMineral chemistry
DS1975-0718
1978
Leroex, H.D.Cole, M.M., Leroex, H.D.The Role of Geobotany, Biogeochemistry and Geochemistry in Mineral Exploration in Southwest Africa and Botswana. a Case History.Geological Society of South Africa Transactions, Vol. 81, No. 3, PP. 277-317.Southwest Africa, Namibia, BotswanaDiamond, Sampling
DS201412-0506
2013
Leroux, D.C.Leroux, D.C.Geology, mineral chemistry and diamond potential of the "K" property, Knicely Township Northwestern Ontario - prospectivity for diamonds in an Archean geological environment.Thesis: Msc. Lakehead University, 102p. Available as pdf from authorCanada, OntarioThesis
DS1989-0877
1989
LeRoux, J.P.LeRoux, J.P., Rust, I.C.Composite facies maps: a new aid to paleoenvironmental reconstructionSouth African Journal of Geology, Vol. 92, No. 4, pp; 436-443South AfricaStratigraphic/lithofacies, Mapping
DS1991-0978
1991
Leroux, J.S.Leroux, J.S.Is the pediplanation cycle a useful model- evaluation in the Orange Free State (and elsewhere) in South AfricaZeitschrift fur Geomorphologie, Vol. 35, No. 2, June pp. 175-186South AfricaLaterites, Weathering -alluvials -general
DS200512-0619
2005
Leroux, M.Leroux, M., Comby, J.Global warming.. myth or reality.Springer, 540p. $ 129. ISBN 3-540-23909-XBook - climate
DS2002-0608
2002
LeroyGrancea, L., Bailly, L., Leroy, Banks, Marcoux, MilisiFluid evolution in the Baia Mare epithermal gold/polymetallic district, Inner CarpathiansMineralium deposita, RomaniaGold, copper, zinc, Deposit - Baia Mare
DS201612-2282
2016
Leroy, C.Bureau, H., Frost, D.J., Bolfan-Casanova, N., Leroy, C.Diamond growth in mantle fluids.Lithos, Vol. 265, pp. 4-15.MantleDiamond morphology

Abstract: In the upper mantle, diamonds can potentially grow from various forms of media (solid, gas, fluid) with a range of compositions (e.g. graphite, C-O-H fluids, silicate or carbonate melts). Inclusions trapped in diamonds are one of the few diagnostic tools that can constrain diamond growth conditions in the Earth's mantle. In this study, inclusion-bearing diamonds have been synthesized to understand the growth conditions of natural diamonds in the upper mantle. Diamonds containing syngenetic inclusions were synthesized in multi-anvil presses employing starting mixtures of carbonates, and silicate compositions in the presence of pure water and saline fluids (H2O-NaCl). Experiments were performed at conditions compatible with the Earth's geotherm (7 GPa, 1300-1400 °C). Results show that within the timescale of the experiments (6 to 30 h) diamond growth occurs if water and carbonates are present in the fluid phase. Water promotes faster diamond growth (up to 14 mm/year at 1400 °C, 7 GPa, 10 g/l NaCl), which is favorable to the inclusion trapping process. At 7 GPa, temperature and fluid composition are the main factors controlling diamond growth. In these experiments, diamonds grew in the presence of two fluids: an aqueous fluid and a hydrous silicate melt. The carbon source for diamond growth must be carbonate (CO32) dissolved in the melt or carbon dioxide species in the aqueous fluid (CO2aq). The presence of NaCl affects the growth kinetics but is not a prerequisite for inclusion-bearing diamond formation. The presence of small discrete or isolated volumes of water-rich fluids is necessary to grow inclusion-bearing peridotitic, eclogitic, fibrous, cloudy and coated diamonds, and may also be involved in the growth of ultradeep, ultrahigh-pressure metamorphic diamonds.
DS200412-0427
2004
Leroy, G.De Toledo, M.C.M., Lenharo, S.L.R., Ferrari, V.C., Fontan, F., Parseval, P.De, Leroy, G.The compositional evolution of apatite in the weathering profile of the Catalao 1 alkaline carbonatitic complex, Goias, Brazil.Canadian Mineralogist, Vol. 42, 4, August, pp. 1139-1158.South America, Brazil, GoiasCarbonatite, geomorphology
DS1991-1282
1991
Leroy, J.L.Pagel, M., Leroy, J.L.Source, transport and deposition of metalsA.a. Balkema, 850p. approx. $ 95.00GlobalBook -table of contents -metallogeny, transport, deposits, Ore deposition, PTXt, source of metals, dating, structur
DS1994-1030
1994
LeRoy, L.W.LeRoy, L.W., Hutchinson, R.M.Basic geologic guidelines in placer miningColorado School of Mines Quarterly review, Vol. 94, No. 4, pp. 1-18.GlobalPlacer mining, Classification, history development
DS2003-0305
2003
Leroy, S.D'Acremont, E., Leroy, S., Burov, E.B.Numerical modelling of a mantle plume: the plume head lithosphere interaction in theEarth and Planetary Science Letters, Vol. 206, No. 3-4, pp. 379-396.MantleModel - plume
DS201506-0282
2015
Leroy, S.Koptev, A., Calais, E., Burov, E., Leroy, S., Gerya, T.Dual continental rift systems generated by plume-lithosphere interaction. Central East African RiftNature Geoscience, Vol. 8, pp. 388-392.AfricaMagmatism
DS201804-0713
2017
Leroy, S.Koptev, A., Cloetingh, S., Gerya, T., Calais, E., Leroy, S.Non-uniform splitting of a single mantle plume by double cratonic roots: insights into the origin of the central and southern East African Rift System.Terra Nova, pp. 125-134.Africa, Tanzaniacraton

Abstract: Using numerical thermo?mechanical experiments we analyse the role of an active mantle plume and pre?existing lithospheric thickness differences in the structural development of the central and southern East African Rift system. The plume?lithosphere interaction model setup captures the essential features of the studied area: two cratonic bodies embedded into surrounding lithosphere of normal thickness. The results of the numerical experiments suggest that localization of rift branches in the crust is mainly defined by the initial position of the mantle plume relative to the cratons. We demonstrate that development of the Eastern branch, the Western branch and the Malawi rift can be the result of non?uniform splitting of the Kenyan plume, which has been rising underneath the southern part of the Tanzanian craton. Major features associated with Cenozoic rifting can thus be reproduced in a relatively simple model of the interaction between a single mantle plume and pre?stressed continental lithosphere with double cratonic roots.
DS201905-1051
2019
Leroy, S.Koptev, A., Beniest, A., Gerya, T., Ehlers, T.A., Jolivet, L., Leroy, S.Plume induced breakup of a subducting plate: microcontinent formation without cessation of the subduction process.Geophysical Research Letters, Vol. 46, 7, pp. 3663-3675.Mantlesubduction

Abstract: Separation of microcontinental blocks from their parent continent is usually attributed to abrupt relocation of concentrated extension from the mid?oceanic ridge to the adjacent continental margin. In the context of extensional passive margin evolution, previous extensive numerical and analog studies have revealed that hot upwelling mantle flow plays a key role in the mechanical weakening of the passive margin lithosphere needed to initiate a ridge jump. This, in turn, results in continental breakup and subsequent microcontinent isolation. However, the consequences of mantle plume impingement on the base of a moving lithospheric plate that is already involved into subduction are still unexplored quantitatively. Here we present the results of 3?D thermo?mechanical models showing that even in the context of induced plate motion (contractional boundary conditions), which are necessary to sustain continuous convergence, thermal and buoyancy effects of the mantle plume emplaced at the bottom of the continental part of the subducting plate are sufficient to initiate continental breakup and the subsequent opening of a new oceanic basin that separates the microcontinental block from the main body of the continent. With these models, we show that it is physically possible to form microcontinents in a convergent setting without the cessation of subduction.
DS202006-0939
2020
Leroy, S.Moulin, M., Aslainian, D., Evain, M., Lepetre, A., Schnurle, P., Verrier, F., Thompson, J., De Clarens, P., Leroy, S., Dias, N.Gondwana breakup: messages from the north Natal Valley.Terra Nova, Vol. 32, 3, pp. 205-210.Africa, Mozambiquegeophysics - seismics

Abstract: The Natal Valley, offshore Mozambique, is a key area for understanding the evolution of East Gondwana. Within the scope of the integrated multidisciplinary PAMELA project, we present new wide?angle seismic data and interpretations, which considerably alter Geoscience paradigms. These data reveal the presence of a 30?km?thick crust that we argue to be of continental nature. This falsifies all the most recent palaeo?reconstructions of the Gondwana. This 30?km?thick continental crust 1,000 m below sea level implies a complex history with probable intrusions of mantle?derived melts in the lower crust, connected to several occurrences of magmatism, which seems to evidence the crucial role of the lower continental crust in passive margin genesis.
DS202202-0212
2021
Leroy, S.Roche, V., Leroy, S., Guillocheau, F., Revillon, S., Ruffet, G., Watremez, L., d'Acremont, E., Nonn, C., Vetel, W., Despinois, F.The Limpopo magma-rich transform margin, south Mozambique - pt. 2. Implications for the Gondwana breakup.Tectonics, e2021TC006914 Africa, Mozambiquegeophysics - seismics

Abstract: The rifted continental margins of Mozambique provide excellent examples of continental passive margins with a significant structural variability associated with magmatism and inheritance. Despite accumulated knowledge, the tectonic structure and nature of the crust beneath the South Mozambique Coastal Plain (SMCP) are still poorly known. This study interprets high-resolution seismic reflection data paired with data from industry-drilled wells and proposes a structural model of the Limpopo transform margin in a magma-rich context. Results indicate that the Limpopo transform margin is characterized by an ocean-continent transition that links the Beira-High and Natal valley margin segments and represents the western limit of the continental crust, separating continental volcano-sedimentary infilled grabens from the oceanic crust domain. These basins result from the emplacement of the Karoo Supergroup during a Permo-Triassic tectonic event, followed by an Early Jurassic tectonic and magmatic event. This latter led to the establishment of steady-state seafloor spreading at ca.156 Ma along the SMCP. A Late Jurassic to Early Cretaceous event corresponds to formation of the Limpopo transform fault zone. Which accommodated the SSE-ward displacement of Antarctica with respect to Africa. We define a new type of margin: the magma-rich transform margin, characterized by the presence of voluminous magmatic extrusion and intrusion coincident with the formation and evolution of the transform margin. The Limpopo transform fault zone consists of several syn-transfer and -transform faults rather than a single transform fault. The intense magmatic activity was associated primarily with mantle dynamics, which controlled the large-scale differential subsidence along the transform margin.
DS202202-0223
2021
Leroy, S.Watremez, L., Leroy, S., d'Acremont, E., Roche, V., Evain, M., Lepretre, A., Verrier, F., Aslanian, D., Dias, N., Afilhado, A., Schnurle, P., Castilla, R., Despinois, F., Moulin, M. The Limpopo magma-rich transform margin, south Mozambique - pt. 1 Insights from deep-structure seismic imaging.Tectonics, e2021TC006915Africa, Mozambiquegeophysics -seismics

Abstract: A variety of structures results from the interplay of evolving far-field forces, plate kinematics, and magmatic activity during continental break-up. The east Limpopo transform margin, offshore northern Mozambique, formed as Africa and Antarctica separated during the mid-Jurassic period break-up of the Gondwana supercontinent. The nature of the crust onshore has been discussed for decades in an effort to resolve issues with plate kinematic models. Two seismic refraction profiles with coincident multichannel seismic reflection profiles allow us to interpret the seismic velocity structures across the margin, both onshore and offshore. These seismic profiles allow us to (a) delineate the major regional crustal domains; (b) identify widespread indications of magmatic activity; and (c) map crustal structure and geometry of this magma-rich transform margin. Careful examination of the profiles allows us to make the following observations and interpretations: (a) on land, continental crust is overlain by a >10-km thick volcano-sedimentary wedge related to an early rifting stage, (b) offshore, thick oceanic crust formed due to intense magmatic activity, and between the two (c) a 50-60-km wide transform zone where the crustal structures are affected by intense magmatic activity and faulting. The prominent presence of intrusive and extrusive igneous units may be attributed to the combination of a deep-seated melting anomaly and a trans-tensional fault zone running through thinned lithosphere that allowed melt to reach the surface. A comparison of the crustal thinning along other transform margins shows a probable dependence with the thermal and/or tectonic history of the lithosphere.
DS200512-0485
2005
Leroy, Y.Jolivet, L., Raimbourg, H., Labrousse, L., Avigad, D., Leroy, Y., Austrheim, H., Andersen, T.B.Softening triggered by eclogitization, the first step toward exhumation during continental subduction.Earth and Planetary Science Letters, Vol. 237, 3-4, Sept. 15, pp. 532-547.Europe, NorwayEclogite, subduction
DS200712-0865
2006
Leroy, Y.Raimbourg, H., Jolivet, L., Leroy, Y.Consequences of progressive eclogization on crustal exhumation, a mechanical study.Geophysical Journal International, Vol. 168, 1, pp. 379-401.TechnologyEclogite
DS201805-0989
2018
Lescanne, M.Vincente de Gouveia, S., Besse, J., Frizon de Lamotte, D., Greff-Lefftz, M., Lescanne, M., Gueydan, F., Leparmentier, F.Evidence of hot spot paths below Arabia and the Horn of Africa and consequences on the Red Sea opening.Earth Planetary Science Letters, Vol. 487, pp. 210-220.Africatectonics

Abstract: Rifts are often associated with ancient traces of hotspots, which are supposed to participate to the weakening of the lithosphere. We investigated the expected past trajectories followed by three hotspots (Afar, East-Africa and Lake-Victoria) located around the Red Sea. We used a hotspot reference frame to compute their location with respect to time, which is then compared to mantle tomography interpretations and geological features. Their tracks are frequently situated under continental crust, which is known to strongly filter plume activity. We looked for surface markers of their putative ancient existence, such as volcanism typology, doming, and heat-flow data from petroleum wells. Surface activity of the East-Africa hotspot is supported at 110 Ma, 90 Ma and 30 Ma by uplift, volcanic activity and rare gas isotopic signatures, reminiscent of a deep plume origin. The analysis of heat-flow data from petroleum wells under the Arabian plate shows a thermal anomaly that may correspond to the past impact of the Afar hotspot. According to derived hotspot trajectories, the Afar hotspot, situated (at 32 Ma) 1000 km north-east of the Ethiopian-Yemen traps, was probably too far away to be accountable for them. The trigger of the flood basalts would likely be linked to the East-Africa hotspot. The Lake-Victoria hotspot activity appears to have been more recent, attested only by Cenozoic volcanism in an uplifted area. Structural and thermal weakening of the lithosphere may have played a major role in the location of the rift systems. The Gulf of Aden is located on inherited Mesozoic extensional basins between two weak zones, the extremity of the Carlsberg Ridge and the present Afar triangle, previously impacted by the East-Africa hotspot. The Red Sea may have opened in the context of extension linked to Neo-Tethys slab-pull, along the track followed by the East Africa hotspot, suggesting an inherited thermal weakening.
DS201112-0224
2011
Lesemann, J.Cummings, D.I., Broscoe, D., Kjarsgaard, B.A., Lesemann, J., Russell, H.A.J., Sharpe, D.R.Eskers as mineral exploration tools: how to sample eskers and interpret data.Yellowknife Geoscience Forum Abstracts for 2011, Poster abstract p. 95-96.Canada, Northwest TerritoriesEsker related literature
DS201312-0762
2013
Lesemann, J-E.Russell, H.A.J., Kjarsgaard, B.A., Lesemann, J-E., Sharpe, D.R.Developing an improved knowledge framework for indicator mineral interpretation.Geoscience Forum 40 NWT, Poster abstract only p. 68.Canada, Nunavut, Baffin IslandDeposit - Chidliak
DS201312-0488
2013
Lesenabb, J-E.Kjarsgaard, B.A., Knight, R., Sharpe, D., Cummings, D., Lesenabb, J-E., Russell, H., Plourde, A., Kerr, D.Diverse indicator mineral and geochemical dispersal plumes in till and esker samples: East arm of Great Slave Lake to the The lon River, NT.2013 Yellowknife Geoscience Forum Abstracts, p. 33-34.Canada, Northwest TerritoriesGeochemistry - mentions kimberlites
DS2003-0799
2003
Lesher, C.ELesher, C.E, Pickering Witter, J., Baxterm G., Walter, M.Melting of garnet peridotite: effects of capsules and thermocouples, and implications forAmerican Mineralogist, Vol. 88, 8-9, pp. 1181-89.MantleGeothermometry, UHP
DS200412-1119
2003
Lesher, C.ELesher, C.E, Pickering Witter, J., Baxter, G., Walter, M.Melting of garnet peridotite: effects of capsules and thermocouples, and implications for the high pressure mantle solidus.American Mineralogist, Vol. 88, 8-9, pp. 1181-89.MantleGeothermometry, UHP
DS1990-0918
1990
Lesher, C.E.Lesher, C.E.Decoupling of chemical and isotopic exchange during magma mixingNature, Vol. 344, No. 6263, March 15, pp. 235-237GlobalMagma, Geochemistry
DS1991-0979
1991
Lesher, C.E.Lesher, C.E., Baker, M.B.Recent developments in igneous petrology #1 (1991)International Union of Geodesy and Geophysics, 20th. meeting held Vienna, pp. 471-485GlobalIgneous petrology, Overview -review paper
DS1991-0980
1991
Lesher, C.E.Lesher, C.E., Baker, M.B.Recent developments in igneous petrologyá#2 (1991)Iugg Contributions In Volcanology, Geochemistry And Petrology, National, pp. 471-485GlobalReview -Petrology, Igneous rocks
DS1993-0458
1993
Lesher, C.E.Fram, M.S., Lesher, C.E.Geochemical constraints on mantle melting during creation of the North Atlantic basinNature, Vol. 363, No. 6431, June 24, pp. 712-715MantleCraton, Geochemistry
DS1993-0459
1993
Lesher, C.E.Fram, M.S., Lesher, C.E.Geochemical constraints on mantle melting during creation of the North-Atlantic BasinNature, Vol. 363, No. 6431, June 24, pp. 712-714MantleGeochemistry, Basin
DS2000-0636
2000
Lesher, C.E.Mayborn, K.R., Lesher, C.E.Trace element constraints on the tectonic setting during emplacement of 2.04 Ga Kangamiut dike swarm.Geological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-376.GreenlandTectonic - history Paleoproterozoic, Laurentia
DS200412-1252
2004
Lesher, C.E.Mayborn, K.R., Lesher, C.E.Paleoproterozoic mafic dike swarms of northeast Laurentia: products of plumes or ambient mantle?Earth and Planetary Science Letters, Vol. 225, 3-4, Sept. 15, pp. 305-317.Europe, GreenlandKangamiut swarm, REE chemistry
DS200512-0419
2005
Lesher, C.E.Heister, L.E., Lesher, C.E.Mantle redox conditions in LIPs: constraints from the North Atlantic igneous province.Chapman Conference held in Scotland August 28-Sept. 1 2005, 1p. abstractMantleMantle plume, tectonics, rifting
DS200512-0620
2005
Lesher, C.E.Lesher, C.E., Brown, E.L., Heister, L.E.Paleogene North Atlantic Igneous Province and the Iapetus connection.Chapman Conference held in Scotland August 28-Sept. 1 2005, 1p. abstractMantle, Europe, Iceland, GreenlandMantle plume
DS200612-1250
2006
Lesher, C.E.Schutt, D.L., Lesher, C.E.Effects of melt depletion on the density and seismic velocity of garnet and spinel lherzolite.Journal of Geophysical Research, Vol. 111,B5 B05401.MantleGeophysics - seismices
DS200612-1251
2006
Lesher, C.E.Schutt, D.L., Lesher, C.E.Effects of melt depletion on the density and seismic velocity of garnet and spinel lherzolite.Journal of Geophysical Research, Vol. 111, B5, B05401.MantleGeophysics - seismics
DS201112-0933
2010
Lesher, C.E.Schutt, D.L., Lesher, C.E.Compositional trends among Kaavaal Craton garnet peridotite xenoliths and their effects on seismic velocity and density.Earth and Planetary Science Letters, Vol. 300, 3-4, pp. 367-373.Africa, South AfricaGeophysics - seismics
DS201612-2281
2016
Lesher, C.E.Brown, E.L., Lesher, C.E.REEBOX PRO: a forward model simulating melting of thermally and lithologically variable upwelling mantle.Geochemistry, Geophysics, Geosystems: G3, Vol. 17, 10, pp. 3929-3968.MantleMelting
DS1992-0044
1992
Lesher, C.M.Arndt, N.T., Lesher, C.M.Fractionation of rare earth elements (REE)'s by olivine and the origin of Kambalda western AustraliaGeochimica et Cosmochimica Acta, Vol. 56, pp. 4191-4204AustraliaGeochemistry, Komatiites
DS1997-1112
1997
Lesher, C.M.Stone, W.E., Deloule, E., Larson, M.S., Lesher, C.M.Evidence for hydrous high MgO melts in the PrecambrianGeology, Vol. 25, No. 2, Feb. pp. 143-146Ontario, QuebecKomatiites, Abitibi belt
DS200512-0621
2005
Lesher, C.M.Lesher, C.M.High Mg magmatism through time: implications for mantle plumes.Chapman Conference held in Scotland August 28-Sept. 1 2005, 1p. abstractMantle, Canada, Nunavut, Baffin IslandMantle plume
DS1997-0674
1997
Leshin, L.A.Leshin, L.A., et al.The oxygen isotopic compositon of olivine and pyroxene from CI chronditesGeochimica Et Cosmochimica Acta, Vol. 61, No. 4, pp. 835-45.GlobalChondrites
DS1990-1605
1990
Leskina, L.M.Yakovleva, T.P., Leskina, L.M., Matyukhin, V.V., Yampolskaya, E.G.Functional state and sickness rate of diamond processing workers. (Russian)Gig Tr Prof. Zabol., (russian), No. 8, pp. 38-42RussiaDiamond processing, Workers
DS1980-0079
1980
Leskova, N.V.Bulanova, G.P., Shestakova, O.E., Leskova, N.V.Djerfisherite in Sulfide Inclusions from DiamondDoklady Academy of Science USSR, Earth Science Section., Vol. 255, No. 1-6, PP. 158-161.Russia, YakutiaMineralogy
DS1983-0434
1983
Leskova, N.V.Marshintsev, V.K., Zayakina, N.V., Leskova, N.V.New Find of Cubic Silicon Carbide, As Inclusions in Moissanite from Kimberlitic Rocks.Doklady Academy of Science USSR, Earth Science Section., Vol. 262, No. 1-6, PP. 163-166.RussiaMineralogy
DS1987-0083
1987
Leskova, N.V.Bulanova, G.P., Varshavskii, A.V., Leskova, N.V., Nikishova, L.V.Central inclusions as indicators of growth conditions of natural diamond.(Russian)Fiz. Svoistva I Mineral. Prirod. Almaza Yakutsk, (Russian), 1986 pp. 29-45RussiaDiamond inclusions
DS1988-0661
1988
Leskova, N.V.Spetsius, Z.V., Bulanova, G.P., Leskova, N.V.Djerfisherite and its genesis in kimberlitic rocksDoklady Academy of Science USSR, Earth Science Section, Vol. 293, No. 1-6, September pp. 133-136RussiaDjerfisherite
DS1989-0540
1989
Leslett, G.M.Green, P.F., Duddy, I.R., Leslett, G.M., Hegarty, K.A., GleadowThermal annealing of fission tracks in apatite, 4. Quantitative modelling techniques and extension to geological timescalesChemical Geology, Vol. 79, No. 2, August 1, pp. 155-GlobalGeochronology, Timescales
DS2000-0085
2000
Leslie, A.G.Bernstein, S., Leslie, A.G., Brooks, C.K.Tertiary alkaline volcanics in the Nunatak region: new observations and comparison with Siberian meymechites.Lithos, Vol. 53, No.1, July pp. 1-20.Greenland, Russia, SiberiaAlkaline rocks, Meymechites
DS200812-0650
2007
Leslie, C.D.Leslie, C.D., Sandeman, H.A., Mortensen, J.K.Diatremes and related volcanic rocks of the lower Palezoic Misty Creek Embayment, Mackenzie Mountains, NT.35th. Yellowknife Geoscience Forum, Abstracts only p. 34-35.Canada, Northwest TerritoriesMountain Diatreme - geology
DS200812-0651
2008
Leslie, C.D.Leslie, C.D., Sandeman, H.A., Mortensen, J.K.Lower Paleozoic rift related alkaline volcanic rocks, Mackenzie Mountains, NWT.Northwest Territories Geoscience Office, p. 40. abstractCanada, Northwest TerritoriesBrief overview - Mountain diatreme
DS200512-0207
2004
Leslie, R.A.J.Danyushevsky, L.V., Leslie, R.A.J., Crawford, A.J., Durance, P.Melt inclusions in primitive olivine phenocrysts: the role of localized reaction processes in the origin of anomalous compositions.Journal of Petrology, Vol. 45, 12, pp. 2531-2553.Petrology - not specific to diamonds
DS2000-1040
2000
LesnovYatsenko, G.M., Panov, Belousoba, Lesnov, GriffinThe rare earth elements (REE) distribution in zircon from minettes of the Kirovograd Ukraine.Doklady Academy of Sciences, Vol. 370, No. 1, Jan-Feb pp.196-200.Russia, UkraineGeochronology, Minettes
DS1995-1088
1995
Lesnov, F.P.Lesnov, F.P., Lomonosova, E.I., et al.Partitioning of rare earth elements in olivines from ultramafic ophioliteassociations.Russian Geology and Geophysics, Vol. 36, No. 2, pp. 42-51.RussiaHarzburgite, lherzolite, wehrlite, Massif -Shaman, Naran, Dovyren
DS201112-0583
2011
Lesnov, F.P.Lesnov, F.P., Khlestov, V.V., Selyatitskii, A.Yu.Multiparametric discrimination of ultramafic rocks by rare earth elements in clinopyroxenes.Doklady Earth Sciences, Vol. 438, 2, pp. 825-829.MantleREE chemistry
DS2002-0105
2002
Lesourd, M.Barrat, J.A., Jambon, A., Bohn, M., Gillet, P., Sautter, V., Gopei, C., Lesourd, M.Petrology and chemistry of the picritic shergottite north west AfricaGeochimica et Cosmochimica Acta, Vol.66, 19, pp.3505-18.West AfricaPicrites
DS1982-0369
1982
Lesquer, A.Lesquer, A., Louis, P.Anomalies Grammetrique et Collision Continentale au Precambrian.Geoexploration., Vol. 20, No. 3-4, PP. 275-293.West Africa, Mali, GuineaStructure, Tectonics
DS1982-0503
1982
Lesquer, A.Ponsard, J.F., Lesquer, A., Villeneuve, M.Une Suture Panafricaine sur la Bordure Occidentale du Craton Ouest Africain.Comptes Rendus Seances Academy of Science Ser. 2, Mec. Phys. Chim. S, Vol. 295, No. 13, PP. 1161-1164.West Africa, Guinea, Sierra Leone, Mali, GermanyTectonics
DS1984-0451
1984
Lesquer, A.Lesquer, A., Beltrao, J.F., De abreu, F.A.M.Proterozoic Links between Northeastern Brasil and West Africa: a Plate Tectonic Model Based on Gravity Data.Tectonophysics, Vol. 110, PP. 9-26.Brazil, South AfricaTectonics
DS1990-0919
1990
Lesquer, A.Lesquer, A., Takheris, D., Dauteria, J.M.Geophysical and petrological evidence for the presence of an anomalous upper mantle beneath the Sahara BasinsEarth Planetary Sci. Letters, Vol. 96, No. 3-4, January pp. 407-418AlgeriaGeophysics, Mantle
DS1991-0981
1991
Lesquer, A.Lesquer, A., Villeneuve, J.C., Bronner, G.Heat flow dat a from the western margin of the West African craton(Mauritania)Physics of the Earth and Planetary Interiors, Vol. 66, pp. 320-329GlobalHeat flow, Craton
DS1991-1019
1991
Lesquer, A.Lucazeau, F., Lesquer, A., Vasseur, G.Trends of heat flow density from West AfricaTerrestrial Heat Flow and the Lithosphere Structure, editors Cermak, V. and, Springer Verlag, pp. 417-425West AfricaHeat flow, Geophysics
DS1859-0008
1735
Lesser, F.C.Lesser, F.C.Naturliche Historie und Gestliche Betrachtung derer Steine....Nine Books For A Total of 1300p., Fifth Book: Precious And N, PP. 343-366.GlobalDiamond Occurrence
DS1989-0359
1989
Leta, D.P.Dismukes, J.P., Gaines, P.R., Witzke, H., Leta, D.P., Kear, B.H.Demineralization and microstructure of carbonadoMater. Sci. Eng. Proceedings 'A struct. mater. prop. microstruct. Proceedings', Vol. 105-106, Dec.3rd International Sci Conference Hard Mat.pp. 555-63GlobalCarbonado
DS1910-0294
1912
Letcher, O.Letcher, O.The Great Mines of Africa. de Beers Con. IvMining Engineering WORLD., Vol. 37, NOVEMBER 23RD. PP. 955-956.South AfricaDe Beers, History
DS1930-0113
1932
Letcher, O.Letcher, O.Namaqualand: a Cradle of Mineral Development in Southern AfrJohannesburg: Mineral And Industry Magazine., 56P.Southwest Africa, NamibiaHistory, Diamonds, Kimberley
DS1998-0863
1998
Letendre, J.Letendre, J., McCandless, T.E., Eastoe, C.J.Morphology and carbon isotope composition of microdiamonds from Dachine, French Guiana.7th International Kimberlite Conference Abstract, pp. 500-2.French GuianaDiamond morphology, resorption, Deposit - Dachine
DS1999-0453
1999
Letendre, J.McCandless, T.E., Letendre, J., Eastoe, C.J.Morphology and carbon isotope composition of microdiamonds from Dachine, French Guiana.7th International Kimberlite Conference Nixon, Vol. 2, pp. 550-56.French GuianaMicro diamonds, diamond morphology, eclogite, Deposit - Dachine
DS2001-0677
2001
Letendre, J.Letendre, J.Diamond potential of northern QuebecNw Mining Association Meet., Dec. 7, 1p. abstr.QuebecNews item
DS2002-0936
2002
Letendre, J.Letendre, J.Exploring for diamonds in northern QuebecUniversity of Western Ontario, SEG Student Chapter, March 8, pp. 29-30. abstractQuebecOverview - brief
DS200412-0312
2004
Letendre, J.Charbonneau, R.,Letendre, J.Wemindji: of dispersion trains and drilling.Quebec Exploration Conference, abstractCanada, QuebecGeochemistry, geomorphology
DS200512-0842
2004
Letendre, J.Pereira, P., Wyatt, B., Scott Smith, B., Letendre, J.Retrospective of diamond exploration at the Hardy Lake property, Lac de Gras region, Northwest Territories, Canada.32nd Yellowknife Geoscience Forum, Nov. 16-18, p.60-61. (talk)Canada, Northwest TerritoriesGeochemistry, geophysics, petrology
DS201512-1943
1999
Letendre, J.McCandless, T.E., Letendre, J., Eastoe, C.J.The morphology and carbon isotope chemistry of microdiamonds from the Dachine Diamondiferous body, French Guiana.Proceedings of rhe 7th International Kimberlite Conference, Vol. 2, pp. 550-556.South America, French GuianaMicrodiamonds
DS2003-0800
2003
Letendre, J.P.J.Letendre, J.P.J., L'Heureux, M., Nowicki, T.E., Creaser, R.The Wemindji kimberlites: exploration and geology8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractQuebecKimberlite geology and economics, Deposit - Wemindji
DS1996-1209
1996
Letian, D.Rong, J., Letian, D.Godizition of enstatite in mantle xenolithsInternational Geological Congress 30th Session Beijing, Abstracts, Vol. 1, p. 104.ChinaAlkaline rocks, xenoliths
DS201607-1359
2016
Letlole, P.T.Letlole, P.T.The Precambrian geology of Botswana: an update from magnetic and gravity data.IGC 35th., Session A Dynamic Earth 1p. AbstractAfrica, BotswanaGeophysics
DS1984-0452
1984
Letnikov, F.A.Letnikov, F.A.The Formation of Diamond in Deep Tectonic ZonesDoklady Academy of Science USSR, Earth Science Section., Vol. 271, No. 1-6, PP. 170-171.West Africa, LiberiaGenesis, Diamond Content, Evaluation
DS1985-0389
1985
Letnikov, F.A.Letnikov, F.A.Formation of Diamonds in Deep Tectonic ZonesDoklady Academy of Science USSR, Earth Science Section, Vol. 271, No. 1-6, pp. 170-172RussiaDiamond Genesis, Diamond Morphology
DS1993-0907
1993
Letnikov, F.A.Letnikov, F.A.The problem of synergetics of geological systemsRussian Geology and Geophysics, Vol. 34, No. 1, pp. 28-43RussiaGenesis
DS1995-1089
1995
Letnikov, F.A.Letnikov, F.A.To the problem of diamond genesis in the Kumdy Kul depositProceedings of the Sixth International Kimberlite Conference Abstracts, pp. 326-327.Russia, KazakhstanMetamorphic, Deposit -Kumdy-Kul
DS1999-0409
1999
Letnikov, F.A.Letnikov, F.A., Zvobkova, Sizykh, DanilovAccessory minerals from eclogites and diamond bearing rocks of the Kumdykul deposit.in RUSSIAN.Proceedings Russ. Min. Soc. *RUSS, Vol. 128, 6, pp. 16-27.RussiaEclogites, Deposit - Kumdykul
DS2001-0678
2001
Letnikov, F.A.Letnikov, F.A.Ultra deep fluid systems of the Earth and problems of ore genesisGeology of Ore Deposits, Vol. 43, No. 4, pp. 259-73.MantleGeodynamics
DS2001-0679
2001
Letnikov, F.A.Letnikov, F.A., Watanabe, Kotov, Yokayama, Zyryanov..Problem of the age of metamorphic rocks of the Kokchetav Block, northern Kazakhstan.Doklady, Vol. 381A, Nov-Dec. pp. 1025-7.Russia, KazakhstanGeochronology
DS2003-0801
2003
Letnikov, F.A.Letnikov, F.A.Nature of Vp variations in the mantle related to the action of plumesDoklady Earth Sciences, Vol. 391, 5, pp.697-8.MantleGeophysics
DS200412-1120
2003
Letnikov, F.A.Letnikov, F.A.Nature of Vp variations in the mantle related to the action of plumes.Doklady Earth Sciences, Vol. 391, 5, pp.697-8.MantleGeophysics
DS200512-0622
2004
Letnikov, F.A.Letnikov, F.A., Kostitsyn, Yu.A., Vladykin, N.V., Zayachkovski, A.A., Mishina, E.I.Isotopic characteristics of the Krasnyi Mai ultramafic alkaline rock complex.Doklady Earth Sciences, Vol. 399A, 9, Nov-Dec. pp. 1315-1319.RussiaAlkalic
DS201112-0584
2011
Letnikov, F.A.Letnikov, F.A.Successful attempt to provide insights into the Earth's interior.Geotectonics, Vol. 45, 3, pp. 83-88.MantleGeothermometry
DS201802-0248
2017
Letnikov, F.A.Letnikov, F.A., Los, V.L., Narseev, V.F.Technical diamond deposit Kumdy-Kul ( northern Kazakhstan). ***IN RUSStarosin, V.I. (ed) Problems of the mineralogy, economic geology and mineral resources. MAKS Press, Moscow *** IN RUS, pp. 197-206.Russia, Kazakhstandeposit - Kumdy-Kul
DS202104-0586
2021
Letnikov, F.A.Letnikova, E.F., Izokh, A.E., Kosticin, Y.A., Letnikov, F.A., Ershova, V.B., Federyagina, E.N., Ivanov, A.V., Nojkin, A.D., Shkolnik, S.I., Brodnikova, E.A.High-potassium volcanism approximately 640 Ma in the southwestern Siberian platform ( Biryusa uplift Sayan region).Doklady Earth Sciences, Vol. 496, 1, pp. 53-59.Russia, Siberiaalkaline rocks

Abstract: On the basis of petrographic and mineralogical studies, we have established the presence of clastic rocks with a strong predominance of K-feldspar among the rock-forming fragments within the Late Precambrian sedimentary sequence in the southwestern part of the Siberian Platform. Two types of mineralogical occurrence of K-feldspars are determined: (1) huge zonal crystal clasts with increased Ba concentrations in the central parts of the grains and (2) the main mineral phase in the form of a decrystallized glassy mass. In both cases, low concentrations of Na (lower than 0.1 wt %) are detected. K-feldspars of the second type contain intergrowths of idiomorphic rhombic dolomite with a high ankerite component. Dolomite grains contain inclusions of K-feldspar. The prevailing accessory minerals are F-apatite (with high concentrations of REEs), zircon (with high concentrations of Th), magnetite, rutile, monacite, and sinchizite. Encasement minerals with an idiomorphic shape are identified, with K-feldspar being located in the center, while the middle shell is formed by apatite with a high REE content, and the outer shell is formed by apatite without rare earth elements. These rocks are products of high-potassium volcanic activity. The age of this event has been established on the basis of U-Pb zircon dating to about 640 Ma. The Lu-Hf zircon systematics for these rocks indicates the connection of volcanism with igneous events of mantle genesis within its range. The products of explosive eruption, which are widespread within the Biryusa uplift of the Siberian Platform, were erroneously considered earlier as Riphean sedimentary rocks of the Karagas Series.
DS201112-0586
2010
Letnikova, A.F.Levin, A.V., Letnikova, A.F.Tourmaline granite of the Kumdykol graphite diamond deposit.Doklady Earth Sciences, Vol. 435, 2, pp. 1637-1640.RussiaPetrology
DS201312-0534
2013
Letnikova, E.F.Letnikova, E.F., Lobanov, S.S., Pokhilenko, N.P., Izokh, A.E., Nikolenko, E.I.Sources of clastic material in the Carnian diamond bearing horizon of the northeastern part of the Siberian Platform.Doklady Earth Sciences, Vol. 451, 1, pp. 702-705.Russia, SiberiaCarnion
DS202104-0586
2021
Letnikova, E.F.Letnikova, E.F., Izokh, A.E., Kosticin, Y.A., Letnikov, F.A., Ershova, V.B., Federyagina, E.N., Ivanov, A.V., Nojkin, A.D., Shkolnik, S.I., Brodnikova, E.A.High-potassium volcanism approximately 640 Ma in the southwestern Siberian platform ( Biryusa uplift Sayan region).Doklady Earth Sciences, Vol. 496, 1, pp. 53-59.Russia, Siberiaalkaline rocks

Abstract: On the basis of petrographic and mineralogical studies, we have established the presence of clastic rocks with a strong predominance of K-feldspar among the rock-forming fragments within the Late Precambrian sedimentary sequence in the southwestern part of the Siberian Platform. Two types of mineralogical occurrence of K-feldspars are determined: (1) huge zonal crystal clasts with increased Ba concentrations in the central parts of the grains and (2) the main mineral phase in the form of a decrystallized glassy mass. In both cases, low concentrations of Na (lower than 0.1 wt %) are detected. K-feldspars of the second type contain intergrowths of idiomorphic rhombic dolomite with a high ankerite component. Dolomite grains contain inclusions of K-feldspar. The prevailing accessory minerals are F-apatite (with high concentrations of REEs), zircon (with high concentrations of Th), magnetite, rutile, monacite, and sinchizite. Encasement minerals with an idiomorphic shape are identified, with K-feldspar being located in the center, while the middle shell is formed by apatite with a high REE content, and the outer shell is formed by apatite without rare earth elements. These rocks are products of high-potassium volcanic activity. The age of this event has been established on the basis of U-Pb zircon dating to about 640 Ma. The Lu-Hf zircon systematics for these rocks indicates the connection of volcanism with igneous events of mantle genesis within its range. The products of explosive eruption, which are widespread within the Biryusa uplift of the Siberian Platform, were erroneously considered earlier as Riphean sedimentary rocks of the Karagas Series.
DS2003-1026
2003
LeToullec, R.Occelli, F., Loubeyre, P., LeToullec, R.Properties of diamond under hydrostatic pressures up to 140 GPaNature Materials, Vol. 2,3,pp. 151-54.GlobalDiamond morphology
DS1987-0399
1987
Letov, S.V.Lavrentev, Yu.G., Usova, L.V., Kuznetsova, A.I., Letov, S.V.Quantiometric x-ray spectral microanalysis of the major minerals ofkimberlites.(Russian)Geologii i Geofiziki, (Russian), No. 5, pp. 75-81RussiaBlank
DS201803-0460
2017
Letsch, D.Letsch, D.A pioneer of Precambrian geology: Boris Choubert's fit of the continents across the Atlantic ( 1935) and his insights into the Proterozoic tectonic structure of the west African craton and adjacent areas.Precambrian Research, Vol. 294, pp. 230-243.Gondwanadiamonds

Abstract: Plate tectonics revolutionized the Earth Sciences during the 1960s and led to a fundamentally new view of tectonic processes inside mountain belts. Application of the new theory to pre-Permian and especially Precambrian orogenic belts developed somewhat reluctantly during the 1970s and 1980s. The present article presents and discusses the ideas of Boris Choubert (1906-1983), a French colonial geologist of Russian origin, which he first developed in 1935. He tried to test Wegener’s theory of continental displacement (a forerunner of plate tectonics) by applying it to Paleozoic and Precambrian orogenic belts around the Atlantic (a topic altogether neglected by Wegener). To achieve this, he produced a fit of the continents across the Atlantic which is almost identical to the famous 1965 fit of Bullard et al. Starting from this Paleozoic continental configuration, he presented an inter-continental synthesis of Precambrian geology and discussed problems from a wide array of topics, ranging from regional tectonics of the West African Craton, questionable Precambrian fossils, tillites (and cap carbonates) to the supposed origin of detrital diamonds in Gabon and Brazil. He also provided probably the first Precambrian plate reconstruction avant la lettre. After his 1935 paper, Choubert worked for decades in Africa and South America and had opportunity to test and refine his synthesis. His example is a call, addressed to present-day geologists working on Precambrian geology in Africa and other regions, to consult the old colonial literature which contains a wealth of factual information and theoretical inspiration which is still of interest today.
DS2000-0282
2000
Letser, A.C.Farmer, G.L., Letser, A.C., Bowring, S., Matzel, J.Composition of the lower continental crust beneath the Cheyenne Belt S. WyoGeological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-386.Wyoming, ColoradoGeochronology - isotopic evidence, Xenoliths - mafic
DS200712-0620
2006
Lett, C.T.A.Lett, C.T.A.Chemical modification of lithosphere and the origin of intracontinental magmatism and deformation.Geochimica et Cosmochimica Acta, In press availableMantleMagmatism
DS201911-2507
2019
Lett, R.Akam, C., Simandl, G.J., Lett, R., Paradis, S., Hoshino, M., Kon, Y., Araoka, D., Green, C., Kodama, S., Takagi, T., Chaudhry, M.Comparison of methods for the geochemical determination of rare earth elements: Rock Canyon Creek REE-F-Ba deposit case study, SE British Columbia, Canada.Geochemistry: Exploration, Environment, Analysis, Vol. 19, pp. 414-430.Canada, British Columbiageochemistry

Abstract: Using Rock Canyon Creek REE-F-Ba deposit as an example, we demonstrate the need for verifying inherited geochemical data. Inherited La, Ce, Nd, and Sm data obtained by pressed pellet XRF, and La and Y data obtained by aqua regia digestion ICP-AES for 300 drill-core samples analysed in 2009 were compared to sample subsets reanalysed using lithium metaborate-tetraborate (LMB) fusion ICP-MS, Na2O2 fusion ICP-MS, and LMB fusion-XRF. We determine that LMB ICP-MS and Na2O2 ICP-MS accurately determined REE concentrations in SY-2 and SY-4, and provided precision within 10%. Fusion-XRF was precise for La and Nd at concentrations exceeding ten times the lower detection limit; however, accuracy was not established because REE concentrations in SY-4 were below the lower detection limit. Analysis of the sample subset revealed substantial discrepancies for Ce concentrations determined by pressed pellet XRF in comparison to other methods due to Ba interference. Samarium, present in lower concentrations than other REE compared, was underestimated by XRF methods relative to ICP-MS methods. This may be due to Sm concentrations approaching the lower detection limits of XRF methods, elemental interference, or inadequate background corrections. Aqua regia dissolution ICP-AES results, reporting for La and Y, are underestimated relative to other methods.
DS201012-0436
2009
Lett, R.E.Lett, R.E.Regional geochemical surveys in British Columbia.Geological Association of Canada Short Course, No. 18, pp. 97-110.Canada, British ColumbiaGeochemistry, technology
DS1997-1267
1997
LettenmaierWood, E.F., Lettenmaier, Xu Liang, Njssen, B., Wetzel, S.Hydrological modeling of continental scale basinsAnnual Review of Earth and Planetary Sciences, Vol. 25, pp. 279-300GlobalReview - basin stratigraphy
DS1999-0432
1999
Lettley, C.Macek, J.J., Ducharme, E.B., Lettley, C., McGregor, C.R.Thompson nickel belt project: retrieval of core from Falcon bridge Bucko exploration site near Wabowden.Man. Geological Survey Report Activities, pp. 15-17.ManitobaExploration - drilling, Bucko project, Falconbridge Ltd.
DS201112-0585
2011
Letts, S.Letts, S., Torsvik, T.H., Webb, S.J., Ashwal, L.D.New Paleoproterozoic palaeomagnetic dat a from the Kaapvaal Craton, South Africa.The Formation and Evolution of Africa: A synopsis of 3.8 Ga of Earth History, Geol. Soc. London Special Publ., 357, pp. 9-26.Africa, South AfricaMagnetics
DS201412-0956
2014
Letts, S.Vorster, A., Letts, S., Brovko, O.New advances in kimberlite exploration geophysics.PDAC 2014, March 3, 1p. AbstractTechnologyGeophysics
DS200612-1257
2006
Leturmy, P.Sebrier, M., Siame, L., Zouine, E.M., Winter, T., Missenard, Y., Leturmy, P.Active tectonics in the Moroccan High Atlas.Comptes Rendus Geoscience, Vol. 338, 1-2, pp. 65-79.Africa, MoroccoTectonics
DS200512-1147
2002
Letyukh, M.I.Vladykin, N.V., Letyukh, M.I.Lamproite rocks of the eastern Anabar region.Deep Seated Magmatism, magmatism sources and the problem of plumes., pp. 80-94.RussiaLamproite
DS201810-2313
2018
Leu, B.M.Finkelstein, G.J., Jackson, J.M., Said, A., Alatas, A., Leu, B.M., Sturhahn, W., Toellner, T.S.Strongly anisotropic magnesiowustite in Earth's lower mantle. Journal of Geophysical Research Solid Earth, doi.org/10.1029/ 2017JB015349Mantlecore mantle boundary

Abstract: The juxtaposition of a liquid iron?dominant alloy against a mixture of silicate and oxide minerals at Earth's core?mantle boundary is associated with a wide range of complex seismological features. One category of observed structures is ultralow?velocity zones, which are thought to correspond to either aggregates of partially molten material or solid, iron?enriched assemblages. We measured the phonon dispersion relations of (Mg,Fe) O magnesiowüstite containing 76 mol % FeO, a candidate ultralow?velocity zone phase, at high pressures using high?energy resolution inelastic X?ray scattering. From these measurements, we find that magnesiowüstite becomes strongly elastically anisotropic with increasing pressure, potentially contributing to a significant proportion of seismic anisotropy detected near the base of the mantle.
DS200912-0283
2009
Leuangthong, O.Harrison, S., Leuangthong, O., Crawford, B., Oshust, P.Uncertainty based grade modeling of kimberlite: a case study of the Jay kimberlite pipe, Ekati diamond mine, Canada.Lithos, In press available, 25p.Canada, Northwest TerritoriesSequential Gaussian Simulation - evaluation
DS1992-1525
1992
Leube, A.Taylor, P.N., Moorbath, S., Leube, A., Hirdes, W.Early Proterozoic crustal evolution in the Birimian of Ghana: constraints from geochronology and isotope geochemistryPrecambrian Research, Vol. 56, No. 1/2, April pp. 97-112GhanaProterozoic, Geochronology
DS200512-0623
2005
Leung, C.Leung, C.Diamonds in the rough Shore Gold digs for fortune in Saskatchewan.Canadian Business, Vol. 78, No. 5, pp. 65-68.Canada, SaskatchewanNews item - Shore Gold
DS1983-0402
1983
Leung, C.S.Leung, C.S., Merigoux, H., Poirot, J.P., Zecchini, P.Identification of precious stones and synthesis by infraredspectroscopy.(in French)Revue de Gemmologie, (in French), Vol. 75, pp. 14-15GlobalSpectroscopy
DS1996-0836
1996
Leung, I.Leung, I.Inclusions of pyrite in diamond from Fuxian, ChinaGeological Society of America, Abstracts, Vol. 28, No. 7, p. A-47.ChinaDiamond inclusions
DS1998-0864
1998
Leung, I.Leung, I.Diamonds from Shandong contain kimberlitic inclusionsGeological Society of America (GSA) Annual Meeting, abstract. only, p.A378.ChinaDiamond inclusions, Deposit - Shengli
DS1989-0878
1989
Leung, I. S.Leung, I. S.Ordered silicon carbide polytypes in Chinese kimberlitesGeological Society of America (GSA) Annual Meeting Abstracts, Vol. 21, No. 6, p. A118. AbstractChinaCrystallography, SIC.
DS1984-0453
1984
Leung, I.S.Leung, I.S.The Discovery of Calcite Inclusion in Natural Diamond and Its Implications on the Genesis of Diamond.Geological Society of America (GSA), Vol. 16, No. 6, P. 574. (abstract.).GlobalMineral Chemistry
DS1985-0390
1985
Leung, I.S.Leung, I.S.Unusual Inclusions Found in a Natural DiamondGeological Society of America (GSA), Vol. 17, No. 7, P. 642-3. (abstract.).GlobalDiamond Genesis, Garnet, Coesite, Biotite, Apatite
DS1987-0406
1987
Leung, I.S.Leung, I.S.Moissanite sanidine intergrowth occurs in diamond containing griquaiticinclusionsEos, abstractRussia, ChinaPetrology, Moissanite
DS1987-0407
1987
Leung, I.S.Leung, I.S., Pneg MingshengMoissanite from diamond bearing kimberlite in Shandong, ChinaGeological Society of America, Vol. 19, No. 7 annual meeting abstracts, p.744. abstracChinaKimberlite
DS1987-0408
1987
Leung, I.S.Leung, I.S., Xiang, K.W.chromium diopside macrocrysts from the Mengyin kimberlite pipe, ChinaEos, Vol. 68, No. 44, November 3, p. 1537. abstract onlyChinaBlank
DS1989-0879
1989
Leung, I.S.Leung, I.S.Multi coloured silicon carbide occurs in two diamond Mines in ChinaEos, Vol. 70, No. 15, April 11, p. 511. (abstract.)ChinaDiamond morphology
DS1990-0920
1990
Leung, I.S.Leung, I.S.Silicon carbide cluster entrapped in a diamond from Fuxian, ChinaAmerican Mineralogist, Vol. 75, No. 9-10. Sept.-Oct. pp. 1110-1119ChinaDiamond inclusions, Silicon carbide
DS1990-0921
1990
Leung, I.S.Leung, I.S. , Guo, WX, Friedman, I., Gleason, J.Natural occurrence of silicon-carbide in a Diamondiferous kimberlite fromFuxianNature, Vol. 346, No. 6282, July 26, pp. 352-354ChinaDiamond genesis -Silicon carbide, Mineralogy -kimberlite
DS1990-0922
1990
Leung, I.S.Leung, I.S., Friedman, I., Gleason, J.Evidence of silicon carbide diamond paragenesis:implications for carbon isotopic composition of themantleEos, Vol. 71, No. 17, April 24, p. 644 Abstract onlyChinaDiamond genesis, Geochronology -carbon
DS1992-0937
1992
Leung, I.S.Leung, I.S., Wang, M., Xie, JiuwuSIC microphenocrysts found in newly discovered lamproites in Sichuan, ChinaGeological Society of America (GSA) Abstracts with programs, 1992 Annual, Vol. 24, No. 7, abstract p. A258ChinaLamproites
DS1994-1031
1994
Leung, I.S.Leung, I.S., et al.Metasomatized olivine: garnet and diopside entrapped in diamonds fromFuxian.Eos, Vol. 75, No. 16, April 19, p. 192.ChinaDiamond morphology
DS1995-1090
1995
Leung, I.S.Leung, I.S., Tsao, C.S., et al.Inclusions of immiscible melts and quartz trapped in diamonds from FuxianChina.Geological Society of America (GSA) Abstracts, Vol. 27, No. 6, abstract p. A 365.ChinaDiamond inclusions, Quartz
DS1996-0837
1996
Leung, I.S.Leung, I.S., Taylor, L.A., Han, Z.SIC in diamond and kimberlites: implications for nucleation and growth ofdiamond.International Geology Review, Vol. 3, No. 7, July 1, pp. 595-606.GlobalDiamond morphology, SIC.
DS1995-1091
1995
Leung, S.Leung, S., Han, Z.G.A comparative study of SIC crystals from Kimberley and FuxianEos, Abstracts, Vol. 76, No. 17, Apr 25, p. S 155.South Africa, ChinaSIC mineralogy, Deposit -Kimberley, Fuxian
DS1997-0701
1997
Leung, S.H.F.Lumpkin, G.R., Leung, S.H.F., Mariano, A.N.Paragenesis and composition of columbite and pyrochlore from the Blue Rivercarbonatite, British Columbia.Geological Association of Canada (GAC) Abstracts, British ColumbiaCarbonatite
DS1997-0702
1997
Leung, S.H.F.Lumpkin, G.R., Mariano, A.N., Leung, S.H.F.Ideal defect pyrochlores from the Arax carbonatite complex and laterite Alto Paranaba Province, Brasil.Geological Association of Canada (GAC) Abstracts, POSTER.BrazilCarbonatite, Deposit - Arax
DS2003-0850
2003
Leung, Y.Luo, J.C., Zheng, J., Leung, Y., Zhou, C.H.A knowledge integrated stepwise optimization model for feature mining in remotelyInternational Journal of Remote Sensing, Vol. 24, 23, pp. 4661-80.GlobalGIS
DS200412-1184
2003
Leung, Y.Luo, J.C., Zheng, J., Leung, Y., Zhou, C.H.A knowledge integrated stepwise optimization model for feature mining in remotely sensed images.International Journal of Remote Sensing, Vol. 24, no. 23, Dec.pp. 4661-80.TechnologyGIS
DS1960-0699
1966
Leuria, B.Leuria, B.Diamond Prospecting in Lofa CountyLiberia Geol. Min. Met. Soc. Bulletin., Vol. 1, No. 1, PP. 27-35.GlobalGeology
DS1960-0700
1966
Leuria, B.Leuria, B.Diamond Prospects in Lofa County, LiberiaLiberia Geol. Min. Met. Soc. Bulletin., No. 1, PP. 27-35.GlobalBlank
DS1960-0701
1966
Leuria, B.Leuria, B., Stracke, K.J.Diamonds and their Occurence in LiberiaLiberia Geol. Min. Met. Soc. Bulletin., Vol. 1, No. 1, PP. 5-12.GlobalDiamond Genesis
DS1960-0859
1967
Leuria, B.Leuria, B.Notes on the Geology of the Lofa River South of Wea Sua With a Comment on Diamond Dispersal and Recovery.Liberia Geol. Min. Met. Soc. Bulletin., Vol. 2, PP. 4-8.GlobalDiamond Mining Recovery
DS1910-0378
1913
Leutwein, P.Schwabe, K., Leutwein, P.Deutsch Suedwestafrika. #2Die Deutschen Kolonien (nationalausgabe), BERLIN: I.K. WELLER, PP. 105-168.Southwest Africa, NamibiaDiamonds, Occurrences, Kimberley
DS1859-0022
1809
Leuwenhoeck, A. Van.Leuwenhoeck, A. Van.Microscopical Observation on the Configuration of DiamondsPhilosphical Transactions Royal Soc. London., Vol. 5, No. 324, P. 479; No. 324, PP. 537-539.GlobalDiamond morphology
DS1998-1364
1998
LevanderSnelson, C.M., Henstock, T.J., Keller, Miller, LevanderCrustal and uppermost mantle structure along the Deep Probe seismic profileRocky Mountain Geol., Vol. 33, No. 2, pp. 181-98.Alberta, Western CanadaGeophysics - seismics, Lithoprobe
DS1999-0356
1999
LevanderKeller, G.R., Miller, Snelson, Sheehan, Levander, GrauchCrustal structure of the Rocky Mountain region, review and recent resultsGeological Society of America (GSA), Vol. 31, No. 7, p. 186. abstract.Alberta, WyomingTectonics
DS1994-0784
1994
Levander, A.Holliger, K., Levander, A.Lower crustal reflectivity modeled by rheological controls on maficintrusionsGeology, Vol. 22, No. 4, April pp. 367-370Basin and RangeLithosphere, Phanerozoic
DS1997-0650
1997
Levander, A.Larkin, S.P., Levander, A. , Henstock, T.J.Is the MOHO flat? Seismic evidence for a rough crust-mantle interface beneath the north Basin -RangeGeology, Vol. 25, No. 5, May pp. 451-454United States, Basin and RangeGeophysics - seismics, Crust - mantle
DS1998-0865
1998
Levander, A.Levander, A., Henstock, T.J., Snelson, C.M., KellerThe Deep Probe experiment; what is the role of inherited structure in the continents?Geological Society AmericanAnn.Meet., Vol. 30, No. 7, p. 161. abstract.Alberta, Western CanadaLithoprobe
DS1998-0866
1998
Levander, A.Levander, A., Henstock, T.J., Snelson, Keller, GormanThe deep probe experiment: what is the role of inherited structure in thecontinents?Geological Society of America (GSA) Annual Meeting, abstract. only, p.A161.Northwest TerritoriesTectonics, Lithoprobe
DS2003-0802
2003
Levander, A.Levander, A.USarray design implications for wavefield imaging in the lithosphere and upper mantleLeading Edge, Vol. 22, 3, pp. 250-55.MantleGeophysics - seismics
DS200412-1121
2003
Levander, A.Levander, A.USarray design implications for wavefield imaging in the lithosphere and upper mantle.Leading Edge, Vol. 22, 3, pp. 250-55.MantleGeophysics - seismics
DS200412-1439
2004
Levander, A.Niu, F., Levander, A., Cooper, C.M., Lee, C.T., Lenardic, A., James, D.E.Seismic constraints on the depth and composition of the mantle keel beneath the Kaapvaal craton.Earth and Planetary Science Letters, Vol. 224, 3-4, pp. 337-346.Africa, South AfricaGeophysics - seismics, boundary
DS200512-0613
2004
Levander, A.Lee, C-T., Lenardic, A., Cooper, C., Niu, F., Levander, A.The role of chemical boundary layers in regulating the thermal thickness of continents and oceans.Geological Society of America Annual Meeting ABSTRACTS, Nov. 7-10, Paper 17-1, Vol. 36, 5, p. 46.MantleGeothermometry, xenoliths
DS200512-0624
2005
Levander, A.Levander, A., Zelt, C., Magnani, M.B.Crust and upper mantle velocity structure of the Southern Rocky Mountains from the Jemez Lineament to the Cheyenne Belt.American Geophysical Union, Geophysical Monograph, No. 154, pp. 293-308.United States,Wyoming, Colorado PlateauGeophysics - seismics, tectonics
DS200612-0274
2005
Levander, A.Cooper, C.M., Lenardic, A., Levander, A., Moresi, L.Creation and preservation of cratonic lithosphere: seismic constraints and geodynamic models.Benn, K., Mareschal, J-C., Condie, K.C. Archean Geodynamics and Environments, AGU Geophysical Monograph, No. 164, pp. 75-88.MantleGeophysics - seismics, tectonics
DS200612-0797
2006
Levander, A.Lenardic, A., Cooper, C.M., Moresi, L., Levander, A.Making, keeping and may be even losing ancient continental lithosphere.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 13. abstract only.MantleAccretion
DS200612-0804
2006
Levander, A.Levander, A., Lenardic, A., Karlstrom, K.E.Structure of the continental lithosphere.Brown, M., Rushmer, T., Evolution and differentiation of the continental crust, Cambridge Publ., Chapter 2,MantleStructure
DS200612-0805
2006
Levander, A.Levander, A., Lenardic, A., Karstrom, K.Structure of the continental lithosphere.Evolution and differentiation of Continental Crust, ed. Brown, M., Rushmer, T., Cambridge Univ. Press, Chapter 2, pp. 21-66.MantleTectonics
DS200612-0806
2006
Levander, A.Levander, A., Niu, F., Lee, C-T.A., Cheng, X.Imag(in)ing the continental lithosphere.Tectonophysics, Vol. 416, 1-4, April 5, pp. 167-185.MantleGeophysics - seismics
DS201112-0652
2011
Levander, A.Masy, J., Niu, F., Levander, A., Schmitz, M.Mantle flow beneath northwestern Venezuela: seismic evidence for a deep origin of the Merida Andes.Earth and Planetary Science Letters, Vol. 305, 3-4, pp. 396-404.South America, VenezuelaGeophysics - seismics
DS201112-0653
2011
Levander, A.Masy, J., Niu, F., Levander, A., Schmitz, M.Mantle flow beneath northwestern Venezuela: seismic evidence for a deep orogin of the Merida Andes.Earth and Planetary Science Letters, In press, availableSouth America, VenezuelaGeophysics - seismics
DS201212-0049
2012
Levander, A.Bailey, I.W., Miller, M.S., Liu, K., Levander, A.V(S) and density structure beneath the Colorado Plateau constrained by gravity anomalies and joint inversions of receiver function and phase velocity data.Journal of Geophysical Research, Vol. 117, B2, B02313.United States, Colorado PlateauGeophysics - gravity
DS201212-0402
2012
Levander, A.Levander, A., Miller, M.S.Evolutionary aspects of lithosphere discontinuity structure in the Western USA.Geochemical, Geophysics, Geosystems: G3, Vol. 10, in pressUnited StatesTomography
DS201212-0581
2012
Levander, A.Reid, M.R., Boucher, R.A., Ichert-Toft, J., Levander, A., Liu, K., Miller, M.S., Ramos, F.C.Melting under the Colorado Plateau, USA.Geology, Vol. 40, 5, pp. 387-390.United States, Colorado PlateauMelting
DS201412-0054
2014
Levander, A.Bezada, M.J., Humphreys, E.D., Davila, J.M., Carbonell, R., Harnafi, M., Palomeras, I., Levander, A.Piecewise delamination of Moroccan lithosphere from beneath the Atlas Mountains.Geochemistry, Geophysics, Geosystems: G3, Vol. 15, 4, pp. 975-985.Africa, MoroccoGeophysics
DS201501-0019
2015
Levander, A.Masy, J., Niu, F., Levander, A., Schmitz, M.Lithospheric expression of cenozoic subduction, mesozoic rifting and the Precambrian shield in Venezuela.Earth and Planetary Science Letters, Vol. 410, pp. 12-24.South America, VenezuelaSubduction
DS202002-0205
2019
Levander, A.Mazuera, F., Schmitz, M., Escalona, A., Zelt, C., Levander, A.Lithospheric structure of northwestern Venezuela from wide angle seismic data: implications for the understanding of continental margin evolution.Journal of Geophysical Research: Solid Earth, Vol. 124, 12, pp. 13124-131249. ( open access)South America, Venezuelageophysics - seismic

Abstract: Northwestern Venezuela is located in the complex deformation zone between the Caribbean and South American plates. Several models regarding the lithospheric structure of the Mérida Andes have been proposed. Nevertheless, they lack relevant structural information in order to support the interpretation of deeper structures. Therefore, a 560?km?long refraction profile across the northern part of Mérida Andes, oriented in a NNW direction, covering areas from the Proterozoic basement in the south, to both Paleozoic and Meso?Cenozoic terranes of northwestern Venezuela to the north, is analyzed in this contribution. Thirteen land shots were recorded by 545 short?deployment seismometers, constraining P wave velocity models from first?arrival seismic tomography and layer?based inversion covering the whole crust in detail, with some hints to upper mantle structures. The most prominent features imaged are absence of a crustal root associated to the Mérida Andes, as the Northern Andes profile is located marginal to the Andean crustal domain, and low?angle subduction of the Caribbean oceanic slab (~10-20°) beneath northwestern South America. Further crustal structures identified in the profile are (a) crustal thinning beneath the Falcón Basin along the western extension of the Oca?Ancón fault system interpreted as a back?arc basin; (b) suture zones between both the Proterozoic and Paleozoic provinces (Ouachita?Marathon?related suture?), and Paleozoic and Meso?Cenozoic terranes (peri?Caribbean suture) interpreted from lateral changes in seismic velocity; and (c) evidence of a deep Paleozoic(?) extensional basin, underlying thick Mesozoic and Cenozoic sequences (beneath the Guárico area).
DS202103-0405
2021
Levander, A.Schmitz, M., Ramirez, K., Mazuera, F., Avila, J., Yegres, L., Bezada, M., Levander, A.Moho depth map of northern Venezuela on wide-angle seismic studies.Journal of South American Earth Sciences, Vol. 107, 103088, 17p. PdfSouth America, VenezuelaGeophysics - seismics

Abstract: As part of the lithosphere, the crust represents Earth's rigid outer layer. Some of the tools to study the crust and its thickness are wide-angle seismic studies. To date, a series of seismic studies have been carried out in Venezuela to determine in detail the crustal thickness in the southern Caribbean, in the region of the Caribbean Mountain System in northern Venezuela, as well as along the Mérida Andes and surrounding regions. In this study, a review of the wide-angle seismic data is given, incorporating new data from the GIAME project for western Venezuela, resulting in a map of Moho depth north of the Orinoco River, which serves as the basis for future integrated models. Differences in Moho depths from seismic data and receiver function analysis are discussed. From the Caribbean plate, Moho depth increases from 20 to 25 km in the Venezuela Basin to about 35 km along the coast (except for the Falcón area where a thinning to less than 30 km is observed) and 40-45 km in Barinas - Apure and Guárico Basins, and Guayana Shield, respectively. Values of more than 50 km are observed in the Maturín Basin and in the southern part of the Mérida Andes.
DS1998-0575
1998
Levander, A.R.Hanstock, T.J., Levander, A.R., Snelson, C.M., et al.The deep probe experiments: continent scale active source seismic profilingAmerican Geophysical Union (AGU) Annual Meeting, Vol 79, No. 17, p. 229. abstract.Alberta, Montana, Colorado PlateauGeophysics - seismics
DS200512-0503
2005
Levander, A.R.Keller, G.R., Karlstrom, K.E., Williams, M.L., Miller, K.C., Andronicos, C., Levander, A.R., Snelson, ProdehlThe dynamic nature of the continental crust-mantle boundary: crustal evolution in the southern Rocky Mountain region as an example.American Geophysical Union, Geophysical Monograph, No. 154, pp. 403-420.United States,Wyoming, Colorado PlateauTectonics
DS201807-1507
2018
Levandowski, W.Levandowski, W., Herrmann, R.B., Briggs, R., Boyd, O., Gold, R.An updated stress map of the continental United States reveals heterogeneous intraplate stress. TectonicsNature Geoscience, Vol. 11, 6, pp. 433-437.United Statesgeodynamics

Abstract: Knowledge of the state of stress in Earth’s crust is key to understanding the forces and processes responsible for earthquakes. Historically, low rates of natural seismicity in the central and eastern United States have complicated efforts to understand intraplate stress, but recent improvements in seismic networks and the spread of human-induced seismicity have greatly improved data coverage. Here, we compile a nationwide stress map based on formal inversions of focal mechanisms that challenges the idea that deformation in continental interiors is driven primarily by broad, uniform stress fields derived from distant plate boundaries. Despite plate-boundary compression, extension dominates roughly half of the continent, and second-order forces related to lithospheric structure appear to control extension directions. We also show that the states of stress in several active eastern United States seismic zones differ significantly from those of surrounding areas and that these anomalies cannot be explained by transient processes, suggesting that earthquakes are focused by persistent, locally derived sources of stress. Such spatially variable intraplate stress appears to justify the current, spatially variable estimates of seismic hazard. Future work to quantify sources of stress, stressing-rate magnitudes and their relationship with strain and earthquake rates could allow prospective mapping of intraplate hazard.
DS1970-0122
1970
Levashov, K.K.Levashov, K.K.The Diamond Potential of the Sette Daban RangeDoklady Academy of Science USSR, Earth Science Section., Vol. 195, No. 1-6, PP. 42-43.RussiaKimberlite
DS201906-1348
2019
Levashova, E.V.Skublov, S.G., Tolstov, A.V., Baranov, L.N., Melnik, A.E., Levashova, E.V.First data on the geochemistry and U-Pb age of zircons from the kamaphorites of the Tomtor alkaline ultrabasic massif, Arctic Yakutia. ( carbonatite)Geochemistry, in press available 11p.Russia, Yakutiadeposit - Tomtor

Abstract: Zircon from Tomtor syenites and kamaphorites was dated following the U-Pb method (SHRIMP-II), and the distribution of trace and rare-earth elements (REE) was studied at the same zircon point using an ion microprobe. The main zircon population from syenites was dated at 402?±?7 Ma, while the age range of single zircon grains was 700-660 M?. Different-aged zircon groups from syenites exhibited the characteristics of magmatic zircon, but their concentrations of REE and other trace elements differed markedly. The REE distribution in 700-660-M? zircon is consistent with that of the typical zircon from syenites (Belousova et al., 2002), while the heavy rare-earth elements (HREE), P, Ti, and Y concentrations of ca. 400-Ma zircon differ from those of older zircon. This is the first isotope-geochemical study of zircon from kamaphorites, and the U-Pb age of ca. 400 M? is within the error limits with of the main zircon population from syenites. The considerable enrichment of REE, C?, Ti, Sr, Y, Nb, and Ba in zircon from kamaphorites may be partly due to the presence of burbankite microinclusions. The trace-element distribution pattern of zircon from kamaphorites is very similar to the geochemical characteristics of zircon from Tiksheozero carbonatites (Tichomirowa et al., 2013). The new age dates for Tomtor syenites and kamaphorites, consistent with 700-660 M? and ca. 400 M? events, support the zircon (Vladykin et al., 2014) and pyrochlore (Antonov et al., 2017) age dates determined following the U-Pb method and those of biotite obtained following the 40Ar-39Ar method (Vladykin et al., 2014).
DS202012-2251
2020
Levashova, E.V.Skublov, S.G., Tolstov, A.V., Baranov, L.N., Melnik, A.E., Levashova, E.V.First data on the geochemistry and U-Pb age of zircons from the kamaphorites of the Tomtor alkaline-ultrabasic massif, Arctic Yakutia.Geochemistry , in press available, 11p. PdfRussia, Yakutiadeposit - Tomtor

Abstract: Zircon from Tomtor syenites and kamaphorites was dated following the U-Pb method (SHRIMP-II), and the distribution of trace and rare-earth elements (REE) was studied at the same zircon point using an ion microprobe. The main zircon population from syenites was dated at 402?±?7 Ma, while the age range of single zircon grains was 700-660 M?. Different-aged zircon groups from syenites exhibited the characteristics of magmatic zircon, but their concentrations of REE and other trace elements differed markedly. The REE distribution in 700-660-M? zircon is consistent with that of the typical zircon from syenites (Belousova et al., 2002), while the heavy rare-earth elements (HREE), P, Ti, and Y concentrations of ca. 400-Ma zircon differ from those of older zircon. This is the first isotope-geochemical study of zircon from kamaphorites, and the U-Pb age of ca. 400 M? is within the error limits with of the main zircon population from syenites. The considerable enrichment of REE, C?, Ti, Sr, Y, Nb, and Ba in zircon from kamaphorites may be partly due to the presence of burbankite microinclusions. The trace-element distribution pattern of zircon from kamaphorites is very similar to the geochemical characteristics of zircon from Tiksheozero carbonatites (Tichomirowa et al., 2013). The new age dates for Tomtor syenites and kamaphorites, consistent with 700-660 M? and ca. 400 M? events, support the zircon (Vladykin et al., 2014) and pyrochlore (Antonov et al., 2017) age dates determined following the U-Pb method and those of biotite obtained following the 40Ar-39Ar method (Vladykin et al., 2014).
DS202102-0223
2020
Levashova, E.V.Skublov, S.G., Tolstov, A.V., Baranov, L.N., Melnik, A.E., Levashova, E.V.First data on the geochemistry and U-Pb age of zircons from the kamaphorites of the Tomtor alkaline-ultrabasic massif, Arctic Yakutia.Geochemistry, Vol. 80, doi.org/10.1016 /j.chemer. 2019.04.001 11p. PdfRussiadeposit - Tomtor

Abstract: Zircon from Tomtor syenites and kamaphorites was dated following the U-Pb method (SHRIMP-II), and the distribution of trace and rare-earth elements (REE) was studied at the same zircon point using an ion microprobe. The main zircon population from syenites was dated at 402?±?7 Ma, while the age range of single zircon grains was 700-660 M?. Different-aged zircon groups from syenites exhibited the characteristics of magmatic zircon, but their concentrations of REE and other trace elements differed markedly. The REE distribution in 700-660-M? zircon is consistent with that of the typical zircon from syenites (Belousova et al., 2002), while the heavy rare-earth elements (HREE), P, Ti, and Y concentrations of ca. 400-Ma zircon differ from those of older zircon. This is the first isotope-geochemical study of zircon from kamaphorites, and the U-Pb age of ca. 400 M? is within the error limits with of the main zircon population from syenites. The considerable enrichment of REE, C?, Ti, Sr, Y, Nb, and Ba in zircon from kamaphorites may be partly due to the presence of burbankite microinclusions. The trace-element distribution pattern of zircon from kamaphorites is very similar to the geochemical characteristics of zircon from Tiksheozero carbonatites (Tichomirowa et al., 2013).The new age dates for Tomtor syenites and kamaphorites, consistent with 700-660 M? and ca. 400 M? events, support the zircon (Vladykin et al., 2014) and pyrochlore (Antonov et al., 2017) age dates determined following the U-Pb method and those of biotite obtained following the 40Ar-39Ar method (Vladykin et al., 2014).
DS200412-2118
2004
LevasseurWilliams, H.M., McCammon, C.A., Peslier, Halliday, Teutsch, Levasseur, BurgIron isotope fractionation and the oxygen fugacity of the mantle.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A563.MantleMelting
DS200412-2117
2004
Levasseur, S.Williams, H.M., McCammon, C.A., Peslier, A.H., Halliday, A.N., Teutsch, N., Levasseur, S., Burg, J-P.Iron isotope fractionation and the oxygen fugacity of the mantle.Science, Vol. 304, 5677, June 11, p. 1656.MantleGeothermobarometry
DS200512-1179
2005
Levasseur, S.Williams, H.M., Peslier, A.H., McCammon, C., Halliday, A.N., Levasseur, S., Teutsch, N., Burg, J.P.Systematic iron isotope variations in mantle rocks and minerals: the effects of partial melting and oxygen fugacity.Earth and Planetary Science Letters, Advanced in press,MantleMelting
DS200512-1180
2005
Levasseur, S.Williams, H.M., Peslier, A.H., McCammon, C., Halliday, A.N., Levasseur, S., Teutsch, N., Burg, J.P.Systematic iron isotope variations in mantle rocks and minerals. The effects of partial melting and oxygen fugacity.Earth and Planetary Science Letters, Vol. 235, 1-2, pp. 435-452.MantleGeochronology, melting
DS201512-1907
2015
Levato, F.D'Arpizio, C., Levato, F., Zito, D., De Montgolfier, J.Luxury goods worldwide market study Fall-Winter 2014.Bain & Company, Nov. 5, 38p. PdfGlobalDiamond market
DS1975-0796
1978
Levchenko, S.V.Levchenko, S.V., Mozeson, D.L.Za Rudami V SibirMoskova: Izdatelstvo Nauka., 141P.RussiaDiamonds, Exploration, Kimberley
DS1975-0797
1978
Levchenko, S.V.Levchenko, S.V., Mozeson, D.L.Za Rudani V SibirMoscow: Izdat Nauka., 142P.Russia, YakutiaKimberlite, Diamond, Kimberley
DS2002-0580
2002
Levchenkov, O.A.Glebovitskii, V.A., Baltybaev, S.K., Levchenkov, O.A., Berezhnaya, LevskiiAge, duration and Pt parameters of the multistage metamorphism of Svecofennides ofDoklady, Vol.385,June-July, pp. 483-7.Europe, Baltic shieldGeochronology - U Pb
DS200412-0016
2004
Levchenkov, O.A.Alekseev, N.L., Balagansky, V.V., Zinger, T.F., Levchenkov, O.A.Late Archean evolution of the junction between the Belomorian mobile belt and Karelian craton, Baltic Shield: evidence from newDoklady Earth Sciences, Vol. 397, 6, July-August pp. 743-746.Russia, Baltic ShieldGeochronology, tectonics
DS200512-0625
2005
Levchenkov, O.A.Levchenkov, O.A., Gaidamako, I.M., Levskii, L.K., Komarov, Yakovleva, Rizvanova, MakeevU Pb age of zircon from the Mir and 325 Let Yakutii pipes.Doklady Earth Sciences, Vol. 400, 1, pp. 99-101.Russia, YakutiaGeochronology
DS2001-0241
2001
Levchuk, M.A.Deev, E.V., Votakh, O.A., Belyaev, S.Y., Zinovev, S.V., Levchuk, M.A.Tectonics of the basement of the mid-Ob plate complex ( West Siberia)Russian Geology and Geophysics, Vol. 42, 6, pp. 920-9.Russia, SiberiaTectonics
DS2000-0568
2000
Levecchia, G.Levecchia, G., Bonco, P.Tectonic setting of the carbonatite melilitite association of ItalyMineralogical Magazine, Vol. 64, No. 4, Aug. pp. 583-92.ItalyCarbonatite, Tectonics
DS1995-1092
1995
Leventhal, J.A.Leventhal, J.A., Reid, M.R., Montana, A., Holden, P.Mesozoic invasion of crust by Mid Ocean Ridge Basalt (MORB) source asthenopheric magmas. U.S.Cordilleran interiorGeology, Vol. 23, No. 5, May pp. 399-402California, Basin and Range, CordilleraMantle lithosphere, Mid Ocean Ridge Basalt (MORB).
DS200812-0761
2007
LevequeMontagner, J.P., Marty, B., Stutzmann, E., Sicilia, D., Cara, M., Pik, R., Leveque, Roult, Beucier, DeBayleMantle upwellings and convective instabilities revealed by seismic tomography and helium isotope geochemistry beneath eastern Africa.Geophysical Research Letters, Vol. 34, 21, Nov. 16, ppp. L21303.AfricaConvection
DS1984-0323
1984
Leveque, B.Gruau, G., Martin, H., Leveque, B., Capdevila, R., Marot, A.Rubidium-strontium and Samarium-neodymium (sm-nd) Geochronology of Lower proterozoic Granite Greenstone Terrains in French Guiana, South America.B.r.g.m., IN PRESSSouth America, French GuianaBlank
DS1984-0482
1984
Leveque, B.Marot, A., Capdevila, R., Leveque, B., Gruau, G., Martin, G., Cha.Le Synclinorium du Sud de Guyane Francaise: une Ceinture Deroches Vertes D'age Proterozoic Inferieur.Annual DES SCIENCES DE la TERRE, 10TH. SESSION HELD BORDEAU, South America, GuyanaBlank
DS2001-0240
2001
Leveque, J.J.DeBayle, E., Leveque, J.J., Cara, M.Seismic evidence for deeply rooted low velocity anomaly in upper mantle beneath NE Afro Arabian continent.Earth and Planetary Science Letters, Vol. 193, No. 3-4, pp. 423-36.Mantle, ArabiaGeophysics - seismics, Plume - tomography, Afar Depression
DS2002-0155
2002
Leveque, J.J.Billien, M., Leveque, J.J., Artemieva, I.M., Mooney, W.D.Shear wave velocity, seismic attenuation and thermal structure of the continental lithosphere.Geological Society of America Annual Meeting Oct. 27-30, Abstract p. 263.South Africa, Russia, West AfricaGeophysics - seismics, Tectonics
DS2003-0039
2003
Leveque, J.J.Artemieva, I.M., Billen, M., Leveque, J.J.Shear wave velocity seismic attenuation and thermal structure of the continentalGeological Society of America, Annual Meeting Nov. 2-5, Abstracts p.14.North AmericaGeophysics - seismics, lithosphere
DS200412-0058
2003
Leveque, J.J.Artemieva, I.M., Billen, M., Leveque, J.J.Shear wave velocity seismic attenuation and thermal structure of the continental lithosphere.Geological Society of America, Annual Meeting Nov. 2-5, Abstracts p.14.United States, CanadaGeophysics - seismics, lithosphere
DS200412-0059
2004
Leveque, J.J.Artemieva, I.M., Billien, M., Leveque, J.J., Mooney, W.D.Shear wave velocity, seismic attenuation and thermal structure of the continental upper mantle.Geophysical Journal International, Vol. 157, 2, pp. 607-628.MantleGeophysics - seismics
DS1990-0923
1990
Lever, P.J.A.Lever, P.J.A., King, R.H., Cameron, R.E.Adapting the intelligent decision support system to variable miningconditionsAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, No. 90-69, 8pGlobalGeostatistics, Program -IDDS
DS1910-0468
1915
Leverett, F.Leverett, F., Taylor, F.B.The Pleistocene of Indiana and Michigan and the History of The Great Lakes.United States Geological Survey (USGS) MONOGRAPH, No. 53, 529P.United States, Great LakesBlank
DS1970-0098
1970
Leveshev, P.P.Ilupin, I.P., Leveshev, P.P.Application of X-ray Analysis in the Study of the Groundmass of Kimberlite.In: Geology, Petrography And Mineralogy of Magmatic Formatio, PP. 301-307.RussiaBlank
DS200812-0662
2007
Levesque, C.Liber, K., Weber, L.P., Levesque, C.Sublethal toxicity of two wastewater treatment polymers used at Ekati diamond mine to lake trout fry.Canadian Technical Report of Fisheries and Aquatic Sciences, No. 2746, p.25 Ingenta art1075288604Canada, Northwest TerritoriesDeposit - Ekati environmental
DS1991-1714
1991
Levi, B.Thiele, R., Beccar, I., Levi, B., Nystrom, J.O., Vergara, M.Tertiary Andean volcanism in a caldera-graben settingGeologische Rundschau, Vol. 80, No. 1, pp. 179-186Andes, Chile, CordilleraStructure, Graben
DS1984-0454
1984
Levi, J.Levi, J.Grenfell Joining Those Diamond DiggersEvening Standard., JUNE 4TH.Australia, Western AustraliaArgyle Region, Investment
DS1992-0429
1992
Leviant, N.Englund, E., Weber, D., Leviant, N.The effects of sampling design parameters on block selectionMath. Geol, Vol. 24, No. 3, pp. 329-343GlobalComputer, Program -Geostatistics, block selection
DS2002-0125
2002
LevinBea, F., Fershtater,Montero, Whitehouse, Levin, ScarrowRecycling of continental crust into the mantle as revealed by Kytlym dunite zircons, Ural Mountains.Terra Nova, Vol. 13, No. 6, pp. 407-12.RussiaSubduction
DS1984-0402
1984
Levin, A.A.Khakimov, Z.M., Pulatova, D.S., Makhumod, A.S., Levin, A.A., et al.Genealogy of Localized States in Diamond Like CrystalsDoklady Academy of Sciences AKAD. NAUK SSSR., Vol. 279, No. 1, PP. 153-156.RussiaDiamond Cystallography
DS201112-0586
2010
Levin, A.V.Levin, A.V., Letnikova, A.F.Tourmaline granite of the Kumdykol graphite diamond deposit.Doklady Earth Sciences, Vol. 435, 2, pp. 1637-1640.RussiaPetrology
DS1991-1413
1991
Levin, G.Reimold, W.U., Levin, G.The Vredefort structure, South Africa: a bibliography relating to its geology and evolutionEconomic Geology Research Unit, University of Witwatersrand, Info. Circular No. 242, 24pSouth AfricaBibliography, Vredefort Structure
DS1998-0867
1998
Levin, G.Levin, G.Appendix - South African land and mining unitsSouth Africa Council, Handbook # 16, pp. 686-8.South AfricaEconomic, Ore reserves, geostatistics, legal
DS1910-0362
1913
Levin, I.H.Levin, I.H.Synthesis of Precious StonesJournal of IND. ENG. CHEM., Vol. 5, No. 6, 12P.GlobalBlank
DS200612-0807
2006
Levin, L.E.Levin, L.E.Structure of the thermal lithosphere and asthenosphere beneath oceans and continents.Geotectonics, Vol. 40, 5, pp. 357-366.MantleGeothermometry
DS201212-0316
2012
Levin, N.Hugenholtiz, C.H., Levin, N., Barchyn, T.E., Baddock, M.C.Remote sensing and spatial analysis of aeolian sand dunes: a review and outlook.Earth Science Reviews, Vol. 111, 3-4, pp. 319-334.AfricaGeomorphology
DS201412-0220
2014
Levin, N.Eiler, J.M., Berquist, B., Bourg, I., Cartigny, P., Farquhar, J., Gagnon, A., Guo, W., Halevy, I., Hofman, A., larson, T.E., Levin, N., Schauble, E.A., Stolper, D.Frontiers of stable isotope geoscience.Chemical Geology, Vol. 372, pp. 119-143.TechnologyReview of isotopes
DS1983-0214
1983
Levin, P.Eisenburger, D., Hannak, W., Haut, R., Knabe, W., Levin, P., MullCircular Magnetic Structures in Upper Volta and Their Geological Significance for Prospecting.Journal of AFRICAN EARTH SCI., Vol. 1, No. 3-4, P. 358. (abstract.).West Africa, Upper VoltaGeotectonics
DS1984-0348
1984
Levin, P.Haut, F.R., Levin, P., Eisenburger, D.Diamantfuehrende Ultrabasite in ObervoltaGeol. Jahrb., Upper Volta, West AfricaKimberlite, Geophysics, Geology, Diamonds
DS1997-0675
1997
Levin, V.Levin, V., Park, J.Crustal anisotropy in the Ural Mountains foredeep from teleseismic receiverfunctions.Geophysical research Letters, Vol. 24, No. 11, June 1, pp. 1283-86.Russia, UralsGeophysics - seismics, Mantle, crust tectonics
DS2000-0569
2000
Levin, V.Levin, V., Park, J.Shear zones in the Proterozoic lithosphere of the Arabian Shield and nature of Hales discontinuity.Tectonophysics, Vol. 323, No.3-4, Aug, pp.131-48.GlobalGeophysics - discontinuity
DS2001-0914
2001
Levin, V.Peyton, V., Levin, V., Ozerov, A.Mantle flow at a slab edge: seismic anisotropy in the Kamchatka regionGeophysical Research Letters, Vol. 28, No. 2, Jan. 15, pp.379-82.RussiaSubduction
DS2002-0937
2002
Levin, V.Levin, V., Park, J., Brandon, M., Lees, J., Peyton, V., Gordeev, E., Ozerv, A.Crust and upper mantle of Kamchatka from teleseismic receiver functionsTectonophysics, Vol. 358, 1-4, pp. 233-265.MantleGeophysics - seismics
DS2002-1217
2002
Levin, V.Park, J., Levin, V.Seismic anisotropy - tracing plate dynamics in the mantleScience, No. 5567, April 19,pp.485-9., No. 5567, April 19,pp.485-9.MantleGeophysics - seismics, Geodynamics
DS2002-1218
2002
Levin, V.Park, J., Levin, V.Seismic anisotropy - tracing plate dynamics in the mantleScience, No. 5567, April 19,pp.485-9., No. 5567, April 19,pp.485-9.MantleGeophysics - seismics, Geodynamics
DS200612-0808
2000
Levin, V.Levin, V., Mormil, S.The Ilmeny Vishnevorgorsky complex of alkaline rocks and carbonatites.IUGS/UNESCO IGG RAS The eroded Uralian Paleozoic ocean to continent transition zone: Ed. Seltmann, R., et al., Excursion Guidebook Project 373, pp. 48-57.RussiaCarbonatite
DS201605-0859
2016
Levin, V.Levin, V., Van Tongeren, J.A., Servali, A.How sharp is the sharp Archean Moho? Example from eastern Superior Province.Geophysical Research Letters, Vol. 43, 5, pp. 1928-1933.Canada, OntarioGeophysics - seismics

Abstract: The Superior Province of North America has not experienced major internal deformation for nearly 2.8?Gyr, preserving the Archean crust in its likely original state. We present seismological evidence for a sharp (less than 1?km) crust-mantle boundary beneath three distinct Archean terranes and for a more vertically extensive boundary at sites likely affected by the 1.2-0.9?Ga Grenville orogeny. At all sites crustal thickness is smaller than expected for the primary crust produced by melting under higher mantle potential temperature conditions of Archean time. Reduced thickness and an abrupt contrast in seismic properties at the base of the undisturbed Archean crust are consistent with density sorting and loss of the residues through gravitational instability facilitated by higher temperatures in the upper mantle at the time of formation. Similar sharpness of crust-mantle boundary in disparate Archean terranes suggests that it is a universal feature of the Archean crustal evolution.
DS201609-1706
2016
Levin, V.Boyce, A., Bastow, I.D., Darbyshire, F.A., Ellwood, A.G., Gilligan, A., Levin, V., Menke, W.Subduction beneath Laurentia modifies the eastern North American cratonic edge: evidence from P wave and S wave tomography.Journal of Geophysical Research,, Vol. 121, 7, pp. 5013-5030.CanadaSubduction

Abstract: The cratonic cores of the continents are remarkably stable and long-lived features. Their ability to resist destructive tectonic processes is associated with their thick (?250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival-time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Québec. We also recover the NW-SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two-stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ?300 km SE of the Grenville Front, our tomographic models show a near-vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction-driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean-Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation.
DS201706-1090
2017
Levin, V.Levin, V., Servali, A., VanTongeren, J., Menke, W., Darbyshire, F.Crust-mantle boundary in eastern North America, from the (oldest) craton to the (youngest) rift.Geological Society of America, SPE 526 pp. 107-132.United Statescraton

Abstract: The North American continent consists of a set of Archean cratons, Proterozoic orogenic belts, and a sequence of Phanerozoic accreted terranes. We present an ~1250-km-long seismological profile that crosses the Superior craton, Grenville Province, and Appalachian domains, with the goal of documenting the thickness, internal properties, and the nature of the lower boundary of the North American crust using uniform procedures for data selection, preparation, and analysis to ensure compatibility of the constraints we derive. Crustal properties show systematic differences between the three major tectonic domains. The Archean Superior Province is characterized by thin crust, sharp Moho, and low values of Vp/Vs ratio. The Proterozoic Grenville Province has some crustal thickness variation, near-uniform values of Vp/Vs, and consistently small values of Moho thickness. Of the three tectonic domains in the region, the Grenville Province has the thickest crust. Vp/Vs ratios are systematically higher than in the Superior Province. Within the Paleozoic Appalachian orogen, all parameters (crustal thickness, Moho thickness, Vp/Vs ratio) vary broadly over distances of 100 km or less, both across the strike and along it. Internal tectonic boundaries of the Appalachians do not appear to have clear signatures in crustal properties. Of the three major tectonic boundaries crossed by our transect, two have clear manifestations in the crustal structure. The Grenville front is associated with a change in crustal thickness and crustal composition (as reflected in Vp/Vs ratios). The Norumbega fault zone is at the apex of the regional thinning of the Appalachian crust. The Appalachian front is not associated with a major change in crustal properties; rather, it coincides with a zone of complex structure resulting from prior tectonic episodes, and thus presents a clear example of tectonic inheritance over successive Wilson cycles.
DS201708-1575
2017
Levin, V.Levin, V., Servali, A., VanTongeren, J., Menke, W., Darbyshire, F.Crust mantle boundary in eastern North America, from the (oldest) craton to the (youngest) rift.Geological Society of London, Chapter 6, pp. 107-132.United States, Canadatectonics

Abstract: The North American continent consists of a set of Archean cratons, Proterozoic orogenic belts, and a Sequence of Phanerozoic accreted terranes. We present an ~1250-km-long seismological profile that crosses the Superior craton, Grenville Province, and Appalachian domains, with the goal of documenting the thickness, internal properties, and the nature of the lower boundary of the North American crust using uniform procedures for data selection, preparation, and analysis to ensure compatibility of the constraints we derive. Crustal properties show systematic differences between the three major tectonic domains. The Archean Superior Province is characterized by thin crust, sharp Moho, and low values of Vp/Vs ratio. The Proterozoic Grenville Province has some crustal thickness variation, near-uniform values of Vp/Vs, and consistently small values of Moho thickness. Of the three tectonic domains in the region, the Grenville Province has the thickest crust. Vp/Vs ratios are systematically higher than in the Superior Province. Within the Paleozoic Appalachian orogen, all parameters (crustal thickness, Moho thickness, Vp/Vs ratio) vary broadly over distances of 100 km or less, both across the strike and along it. Internal tectonic boundaries of the Appalachians do not appear to have clear signatures in crustal properties. Of the three major tectonic boundaries crossed by our transect, two have clear manifestations in the crustal structure. The Grenville front is associated with a change in crustal thickness and crustal composition (as reflected in Vp/Vs ratios). The Norumbega fault zone is at the apex of the regional thinning of the Appalachian crust. The Appalachian front is not associated with a major change in crustal properties; rather, it coincides with a zone of complex structure resulting from prior tectonic episodes, and thus presents a clear example of tectonic inheritance over successive Wilson cycles.
DS202004-0529
2020
Levin, V.Petrescu, L., Bastow, I.D., Darbyshire, F.A., Gilligan, A., Bodin, T., Menke, W., Levin, V.Three billion years of crustal evolution in eastern Canada: constraints from receiver functions.Journal of Geophysical Research: Solid Earth, in press available, 24p. PdfCanadageophysics - seismics

Abstract: The geological record of SE Canada spans more than 2.5Ga, making it a natural laboratory for the study of crustal formation and evolution over time. We estimate the crustal thickness, Poisson's ratio, a proxy for bulk crustal composition, and shear velocity (Vs) structure from receiver functions at a network of seismograph stations recently deployed across the Archean Superior craton, the Proterozoic Grenville and the Phanerozoic Appalachian provinces. The bulk seismic crustal properties and shear velocity structure reveal a correlation with tectonic provinces of different ages: the post-Archean crust becomes thicker, faster, more heterogenous and more compositionally evolved. This secular variation pattern is consistent with a growing consensus that crustal growth efficiency increased at the end of the Archean. A lack of correlation among elevation, Moho topography, and gravity anomalies within the Proterozoic belt is better explained by buoyant mantle support rather than by compositional variations driven by lower crustal metamorphic reactions. A ubiquitous ?20km thick high-Vs lower-crustal layer is imaged beneath the Proterozoic belt. The strong discontinuity at 20km may represent the signature of extensional collapse of an orogenic plateau, accommodated by lateral crustal flow. Wide anorthosite massifs inferred to fractionate from a mafic mantle source are abundant in Proterozoic geology and are underlain by high Vs lower crust and a gradational Moho. Mafic underplating may have provided a source for these intrusions and could have been an important post-Archean process stimulating mafic crustal growth in a vertical sense.
DS202109-1478
2021
Levin, V.Li, Y., Levin, V., Nikulin, A., Chen, X.Systematic mapping of upper mantle seismic discontinuities beneath northeastern North America.Geochemistry, Geophysics, Geosystems, 10.1029/2021GC009710 20p. PdfUnited States, Canadageophysics- seismic

Abstract: We probe the properties of upper mantle rocks beneath northeastern North America using the observations of seismic waves from distant earthquakes. We examine signals of converted P-S waves that originate from locations of rapid vertical or directional changes in seismic velocities. These abrupt velocity boundaries are thought to originate from rock deformation, variations in composition, temperature, or melt content. The sharp transitions detectable by this method are compositionally more plausible within the cold tectonic plate than within the hot convecting asthenosphere. Previous studies in this region that analyzed the same type of seismic data report boundaries with sharp downward reduction in seismic velocities between the depths of 60 and 100 km. Their widespread distribution and local consistency with seismic velocity models was used as evidence of them marking the transition between the cold tectonic plate and the hot convecting asthenosphere. Here we expand our search to other types of boundaries and find numerous examples at much greater depths (down to ?185 km). These deeper boundaries primarily reflect changes in directional variation of seismic velocities (anisotropy). The distribution of our deep boundaries broadly agrees with lithospheric thickness estimates in global upper mantle models that consider seismic, gravity, and heat flow data.
DS1985-0750
1985
Levin, V. YA.Yefimov, A.F., Yeskova, YE.M., Lebedeva, S.I., Levin, V. YA.Type Compositions of Accessory Pyrochlore in a Ural Alkali ComplexGeochemistry International, Vol. 22, No. 1, pp. 68-75RussiaAlkaline Rocks
DS1975-0386
1976
Levin, V.I.Prokopchuk, B.I., Trofimov, V.S., Levin, V.I.The Main Types of Diamond Deposits of Foreign CountriesSovetskaya Geologiya., No. 6, PP. 134-143.Russia, GlobalClassification
DS1987-0596
1987
Levin, V.I.Prokopchuk, B.I., Levin, V.I., Kolodko, A.A.Detrital quartz from kimberlitic rocks. (Russian)Litol. Polezn. Iskop., (Russian), No. 3, pp. 141-144RussiaBlank
DS1987-0597
1987
Levin, V.I.Prokopchuk, B.I., Levin, V.I., Metelkina, M.P., Shofman, I.L.Prospecting for sources of diamond placers based onunconventionalindicators.(Russian)Soviet Geology, (Russian), No. 6, pp. 41-49RussiaBlank
DS1987-0598
1987
Levin, V.I.Prokopchuk, B.I., Levin, V.I., Metelkina, M.P., Shofman, I.L.Prediction of diamond placers through the use of unconventionalindicators.(Russian)Soviet.Geol., (Russian), No. 6, pp. 41-49RussiaBlank
DS1991-0912
1991
Levin, V.I.Kolodko, A.A., Levin, V.I., Frantcesson, E.V., Kisel, S.I.Genetic types of kimberlite pipe craters of a new diamond bearing province of the USSR and some aspects of their developmentProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 516-517RussiaEuropean part, Pipes
DS1992-0858
1992
Levin, V.I.Kharkiv, A.D., Levin, V.I., Mankenda, A., Safronov, A.F.The Camafuca-Camazambo kimberlite pipe of Angola, the largest in theworldInternational Geology Review, Vol. 34, No. 7, July pp. 710-719AngolaKimberlite, Deposit -Camafuca-Camazambo
DS1987-0409
1987
Levin, V.Ya.Levin, V.Ya., Levina, I.A., Glebova, Z.M., Dolzhanskaya, T.Yu.Mineralogy of carbonatites of the Buldym massif in the VishnevoeMountains.(Russian)Mineraly Mestorozhd. Urala, Sverd., (in Russian), pp. 117-123RussiaBlank
DS200612-0809
2006
Levin, Y.Levin, Y., Kalmanovich, E.Results of the preliminary geological and mineralogical investigations for the discovery of diamonds and precious stones in the Qishon basin area.Israel Geological Society, 2006 p. 75, abstract Ingenta 1064296808Europe, IsraelBrief - mention of diamonds
DS1987-0409
1987
Levina, I.A.Levin, V.Ya., Levina, I.A., Glebova, Z.M., Dolzhanskaya, T.Yu.Mineralogy of carbonatites of the Buldym massif in the VishnevoeMountains.(Russian)Mineraly Mestorozhd. Urala, Sverd., (in Russian), pp. 117-123RussiaBlank
DS201112-0587
2011
Levine, J.Levine, J.A beautiful mine ( after the horrors of the 90's, when bling was equated with blood, De Beers brings new meaning to diamond clarity. Story based on OrapaNew York Times Magazine, April 17, pp. 75-77.Africa, BotswanaNews item - history
DS1992-0142
1992
Levine, R.M.Bond, A.R., Levine, R.M., Austin, G.I.Russian diamond industry in state of fluxPost Soviet Geology, Vol. 33, No. 10, December pp. 635-644Russia, Commonwealth of Independent States (CIS)Markets, Diamonds
DS1981-0265
1981
Levingston, K.Levingston, K.Gem Diggings- Chudleigh ParkWahroongahn News, Nov., P. 18.AustraliaKimberlite
DS2003-0803
2003
Levington, D.W.Levington, D.W., Teller, J.T.Paleotopographic reconstructions of the eastern outlets of glacial Lake AgassizCanadian Journal of Earth Sciences, Vol. 40, 9,Sept. 1259-78.Manitoba, Alberta, SaskatchewanGeomorphology
DS200412-1122
2003
Levington, D.W.Levington, D.W., Teller, J.T.Paleotopographic reconstructions of the eastern outlets of glacial Lake Agassiz.Canadian Journal of Earth Sciences, Vol. 40, 9,Sept. 1259-78.Canada, Manitoba, Alberta, SaskatchewanGeomorphology
DS1987-0410
1987
Levinson, A.A.Levinson, A.A.Geochemistry in the search for diamonds, Southern Africa #2Practical Geochemistry, Applied Publishing, pp. 158-160; 262-264GlobalProspecting, Techniques
DS1991-0877
1991
Levinson, A.A.Kirkley, M.B., Gurney, J.J., Levinson, A.A.Age, origin, and emplacement of diamonds: scientific advances in the lastdecadeGems and Gemology, Vol. XXVII, Spring pp. 2-25GlobalDiamond genesis, Overview -review/update
DS1991-0878
1991
Levinson, A.A.Kirkley, M.B., Gurney, J.J., Levinson, A.A.Age, origin and emplacement of diamonds: a review of the scientific advances in the decade 1981-1990The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Session on Diamonds at The Canadian Institute of Mining, Metallurgy and Petroleum (CIM) Annual Meeting April, Vol. 84, No. 947, March p. 90. AbstractGlobalOrigin -source of carbon, Emplacement mechanisM.
DS1991-0982
1991
Levinson, A.A.Levinson, A.A.Geographic origins of world diamond sources now and in the future #1International Gemological Symposium, June 20-24, 1991 Los Angeles, Gems and Gemology, Vol. 27, Spring, Program p. 3GlobalDiamond production-sources
DS1991-0983
1991
Levinson, A.A.Levinson, A.A.Diamond exploration in western Canada #1Xiii International Gemmological Conference Held South Africa, Stellenbosch, 1p. abstractSaskatchewan, Alberta, Northwest TerritoriesGeomorphology, History
DS1992-0637
1992
Levinson, A.A.Gurney, J.J., Levinson, A.A., Smith, H.S.Marine mining of diamonds off the west coast of southern AfricaGems and Gemology, Vol. 27, No. 4, pp. 206-219Southwest Africa, Namibia, South AfricaMarine mining, Orange River, Alluvial diamonds
DS1992-0867
1992
Levinson, A.A.Kirkley, M.B., Gurney, J.J., Levinson, A.A.Age, origin and emplacement of diamonds: a review of scientific advances In the last decade.reprinted from Gems and Gemology with some revisionThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 85, No. 956, January pp. 48-57GlobalDiamond exploration - techniques, Diamond genesis
DS1992-0938
1992
Levinson, A.A.Levinson, A.A.Age, origin and emplacement of diamonds: application to explorationV.m. Goldschmidt Conference, Held May 9, 1992, 1 pg. overview of distinguished invited lectureGlobalDiamond genesis, Xenoliths
DS1992-0939
1992
Levinson, A.A.Levinson, A.A.Geographic origins of world diamond sources now and in the future #2Gemological Institute of America, Proceedings Volume ed. A. Keller, p. 54. (abstract)GlobalEconomics, Diamond production
DS1992-0940
1992
Levinson, A.A.Levinson, A.A., Gurney, J.J., Kirkley, M.B.Diamond sources and production: past, present and futureGems and Gemology, Vol. 28, No. 4, Winter pp. 234-254GlobalReview, Production, current activities
DS1993-0908
1993
Levinson, A.A.Levinson, A.A.Worldwide sources and production of diamondsThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin) , Annual Meeting Abstracts LESS than approximately 10, Vol. 86, No. 968, March ABSTRACT p. 75GlobalBrief overview, Economics
DS1994-1032
1994
Levinson, A.A.Levinson, A.A., Pattison, D.R.M.Formation of microdiamonds and a possible genetic link with resorbedmacrodiamonds.Preprint, 20p.South Africa, Northwest TerritoriesDiamond genesis, Microdiamonds, macrodiamonds
DS1995-1449
1995
Levinson, A.A.Pattison, D.R.M., Levinson, A.A.Are euhedral microdiamonds formed during ascent and decompression Of kimberlite magmas? Implications -useApplied Geochemistry, Vol. 10, No. 6, Nov. pp. 725-Northwest TerritoriesDiamond grade estimation, Microdiamonds
DS1998-1316
1998
Levinson, A.A.Sevdermich, M., Miciak, A.R., Levinson, A.A.The diamond pipeline into the Third Millennium: a multi channel system From the mine to the consumer.Geoscience Canada, Vol. 25, No. 2, June pp. 71-84.GlobalDiamond markets, De Beers, diamond pipeline
DS1998-1317
1998
Levinson, A.A.Sevdermish, M., Miciak, A.R., Levinson, A.A.The rise to prominence of the modern diamond cutting industry in IndiaGems and Gemology, Vol. 34, Spring, pp. 4-23.IndiaDiamond cutting, History, economics, values, markets
DS2001-0680
2001
Levinson, A.A.Levinson, A.A., Cook, F.A.The United States of America: a cornerstone of the world gem diamond industry in the 20th. century.Geoscience Canada, Vol. 28, No. 3, Sept. pp. 113-8.United StatesEconomics - diamond industry, supply, demand
DS2002-0860
2002
Levinson, A.A.Kjarsgaard, B.A., Levinson, A.A.Diamonds in CanadaGems and Gemology, Vol. 38, Fall,208-38.Canada, Northwest TerritoriesHistory, excellent paper!
DS2003-0722
2003
Levinson, A.A.Kjarsgaard, B.A., Levinson, A.A., Thorleifson, L.H.Exploration for diamonds in Canada 1899-1999Geological Association of Canada Annual Meeting, Abstract onlyCanadaHistory - exploration
DS200412-1011
2003
Levinson, A.A.Kjarsgaard, B.A., Levinson, A.A., Thorleifson, L.H.Exploration for diamonds in Canada 1899-1999.Geological Association of Canada Annual Meeting, Abstract onlyCanadaHistory - exploration
DS1983-0403
1983
Levinson, O.Levinson, O.Diamonds in the DesertCape Town: Tafelberg Publishing, 172P.Southwest Africa, Namibia, LuderitzKimberley, Janlib, History, Biography, Littoral Dimaond Placers
DS1900-0683
1908
Levitcus, F.Levitcus, F., Polak, H.Geillustreerde Encyclopaedie der DiamantnizverheidHaarlem: Erven F Bohn., 526P.GlobalDictionary, History, Kimberley
DS201903-0520
2019
Levitskii, I.V.Ivanov, A.V., Levitskii, I.V., Levitskii, V.I., Corfu, F., Demonterova, E.I., Reznitskii, L.Z., Pavlova, L.A., Kamenetsky, V.S., Savatenkov, V.M., Powerman, V.I.Shoshonitic magmatism in the Paleoproterozoic of the south-western Siberian Craton: an analogue of the modern post-collisiion setting.Lithos, Vol. 328-329, pp. 88-100.Russiadeposit - Sharyzhalgay

Abstract: The Siberian Craton was assembled in a Paleoproterozoic episode at about 1.88?Ga by the collision of older blocks, followed at about 1.86?Ga by post-collisional felsic magmatism. We have found a set of extremely fresh mica-bearing lamprophyre-looking rocks within the Sharyzhalgay metamorphic complex of the south-western Siberian Craton. Zircon from these rocks yields a UPb TIMS age of 1864.7?±?1.8?Ma, which coincides perfectly with the peak of the post-collisional granite ages and postdates by ~15?Ma the peak of ages obtained for metamorphism. The same ages were reported earlier for a mafic dyke with ocean island basalt (OIB) geochemical signatures and a Pt-bearing mafic-ultramafic intrusion found in the same region. Mineralogy, major and trace element geochemistry and Sr-Nd-Pb isotopes show that the studied rocks (1) have shoshonitic affinity, (2) are hybrid rocks with mineral assemblages which could not be in equilibrium, (3) where derived by recycling of an Archean crustal source and (4) resemble post-collision Tibetan shoshonitic series. The genesis of these rocks is considered to be due to melting of crustal lithologies and metasomatized lithospheric mantle within a subducted slab. Some of the resulting melts ascended through the lithospheric column and fractionated to low-Mg absarokites, whereas other melts were contaminated by orthopyroxenitic mantle material and attained unusual high-Mg mafic compositions. According to our model, the post-collisional magmatism (shoshonite- and OIB-type) occurred due to upwelling of hot asthenosphere through a slab window, when the active collision ceased as a result of the slab break off and loss of the slab pull force. Overall, our study shows that in the Paleoproterozoic shoshonitic melts were emplaced within a similar tectonic setting as seen today in modern orogenic systems.
DS200512-0626
2004
Levitskii, V.I.Levitskii, V.I., Salnikova, E.B., Kotov, A.B., Reznitskii, L.Z., Barash, I.G., et al.Age of formation of apocarbonate metasomites of the Sharyzhalgai Uplift of the Siberian Craton basement, southwestern Baikal region U - Pb baddeleyite, zirconDoklady Earth Sciences, Vol. 399A, 9, Nov-Dec. pp. 1204-1208.Russia, SiberiaGeochronology
DS201903-0520
2019
Levitskii, V.I.Ivanov, A.V., Levitskii, I.V., Levitskii, V.I., Corfu, F., Demonterova, E.I., Reznitskii, L.Z., Pavlova, L.A., Kamenetsky, V.S., Savatenkov, V.M., Powerman, V.I.Shoshonitic magmatism in the Paleoproterozoic of the south-western Siberian Craton: an analogue of the modern post-collisiion setting.Lithos, Vol. 328-329, pp. 88-100.Russiadeposit - Sharyzhalgay

Abstract: The Siberian Craton was assembled in a Paleoproterozoic episode at about 1.88?Ga by the collision of older blocks, followed at about 1.86?Ga by post-collisional felsic magmatism. We have found a set of extremely fresh mica-bearing lamprophyre-looking rocks within the Sharyzhalgay metamorphic complex of the south-western Siberian Craton. Zircon from these rocks yields a UPb TIMS age of 1864.7?±?1.8?Ma, which coincides perfectly with the peak of the post-collisional granite ages and postdates by ~15?Ma the peak of ages obtained for metamorphism. The same ages were reported earlier for a mafic dyke with ocean island basalt (OIB) geochemical signatures and a Pt-bearing mafic-ultramafic intrusion found in the same region. Mineralogy, major and trace element geochemistry and Sr-Nd-Pb isotopes show that the studied rocks (1) have shoshonitic affinity, (2) are hybrid rocks with mineral assemblages which could not be in equilibrium, (3) where derived by recycling of an Archean crustal source and (4) resemble post-collision Tibetan shoshonitic series. The genesis of these rocks is considered to be due to melting of crustal lithologies and metasomatized lithospheric mantle within a subducted slab. Some of the resulting melts ascended through the lithospheric column and fractionated to low-Mg absarokites, whereas other melts were contaminated by orthopyroxenitic mantle material and attained unusual high-Mg mafic compositions. According to our model, the post-collisional magmatism (shoshonite- and OIB-type) occurred due to upwelling of hot asthenosphere through a slab window, when the active collision ceased as a result of the slab break off and loss of the slab pull force. Overall, our study shows that in the Paleoproterozoic shoshonitic melts were emplaced within a similar tectonic setting as seen today in modern orogenic systems.
DS201012-0719
2009
Levitsky, V.I.Sklyarov, E.V., Fedorovsky, V.S., Kotov, A.B., Lavrenchuk, A.V., Mazukebzov, A.M., Levitsky, V.I., et al.Carbonatites in collisional settings and pseudo-carbonatites of the Early Paleozoic Olkhon collisional system.Russian Geology and Geophysics, Vol. 50, 12, pp. 1091-1106.RussiaTectonics
DS1998-1025
1998
LevkovichMitrofanov, F.P., Skufin, P.K., Bayanova, LevkovichLamprophyres in rocks of the Early Proterozoic Pechanga structure KolaPeninsula.Doklady Academy of Sciences, Vol. 359A, No. 3, Mar-Apr. pp. 352=5Russia, Kola PeninsulaLamprophyres
DS2000-0671
2000
LevkovichMitrofanov, F.P., Zozulya, Bayanova, LevkovichThe world's oldest anorogenic alkali granitic magmatism in Keivy structure on Baltic Shield.Doklady Academy of Sciences, Vol. 374, No. 7, Sept-Oct. pp. 1145-48.Russia, Baltic ShieldMagmatism
DS1997-0083
1997
Levkovich, N.V.Bayanova, T.B., Kirnarskii, Y.M., Levkovich, N.V.uranium-lead (U-Pb) dating of baddeleyite from rocks of the Kovdor MassifDoklady Academy of Sciences, Vol. 356, No. 7, Sept-Oct. pp. 1094-6.RussiaKovdor Massif, Geochronology
DS1999-0676
1999
Levkovich, N.V.Skufin, P.K., Bayanova, T.B., Levkovich, N.V.Lamprophyres in the Early Proterozoic volcanic complex of the Pechengastructure, Kola Peninsula.Petrology, Vol. 7, No. 3, pp. 289-304.Russia, Kola PeninsulaLamprophyres
DS200412-0678
2004
Levkovich, N.V.Glukhovskii, M.Z., Bayanova, T.B., Moralev, V.M., Levkovich, N.V.The problem of tectonic evolution of the ancient continental crust: evidence from new U Pb zircon datings of rocks from the SunnDoklady Earth Sciences, Vol. 395, 2, pp. 157-160.Russia, Aldan ShieldTectonics
DS200612-0430
2005
Levresse, G.Gasquet, D., Levresse, G., Cheilletz, A., Azizi Samir, M.R., Mouttaqi, A.Contribution to a geodynamic reconstruction of the Anti-Atlas (Morocco) during Pan-African times with the emphasis on inversion tectonics and metallogeny...Precambrian Research, Vol. 140, 3-4, pp. 157-182.Africa, MoroccoTectonics - Precambrian-Cambrian transition
DS2001-0980
2001
LevshinRitzwoller, M.H., Shapiro, N.M., Levshin, LeahyCrustal and upper mantle structure beneath Antarctica and surrounding oceansJournal of Geophysical Research, Vol. 106, No. 12, pp. 30,645-70.AntarcticaTectonics
DS200512-0627
2005
Levshin, A.L.Levshin, A.L., Barmin, M.P., Riotzwoller, M.H., Trampert, J.Minor arc and major arc global surface wave diffraction tomography.Physics of the Earth and Planetary Interiors, Vol. 149, 3-4, April 15, pp. 205-223.MantleGeophysics - seismics
DS200512-0628
2005
Levshin, A.L.Levshin, A.L., Ritzwoller, M.H., Shapiro, N.M.The use of crustal higher modes to constrain crustal structure across Central Asia.Geophysical Journal International, Vol. 160, 3, pp. 961-972.Asia, ChinaTectonics
DS2002-0580
2002
LevskiiGlebovitskii, V.A., Baltybaev, S.K., Levchenkov, O.A., Berezhnaya, LevskiiAge, duration and Pt parameters of the multistage metamorphism of Svecofennides ofDoklady, Vol.385,June-July, pp. 483-7.Europe, Baltic shieldGeochronology - U Pb
DS200612-1083
2006
LevskiiPervov, V.A., Larchenko, V.A., Minchenko, G.V., Stepanov, V.P., Bogomolov, E.S., Levskii, SergeevTiming and duration of kimberlitic magmatism in the Zimnii Bereg Diamondiferous province: evidence from Rb Sr age dat a on kimberlitic sills along the Mela River.Doklady Earth Sciences, Vol. 407, 2, Feb-Mar. pp. 304-307.RussiaGeochronology - Zimnii Bereg
DS1990-0872
1990
Levskii, L.K.Komarov, A.N., Sharkov, Y.V., Levskii, L.K.Fission track age of kimberlites and associated rocks from explosive pipes of western Syria. (Russian)Doklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 315, No. 5, pp. 683-686SyriaGeochronology, Kimberlites and pipes
DS1997-0089
1997
Levskii, L.K.Belyatskii, B.V., Nikitinia, L.P., Levskii, L.K.Isotopic signatures of lamproite dikes on the Eastern Baltic shieldGeochemistry International, Vol. 35, No. 6, June 1, pp. 575-579.Russia, Baltic shieldLamproites, Geochronology
DS1999-0509
1999
Levskii, L.K.Nikitina, L.P., Levskii, L.K., et al.Proterozoic alkaline ultramafic magmatism in the eastern part of the BalticShield.Petrology, Vol. 7, No. 3, pp. 246-66.Russia, Kola Peninsula, Baltic shieldAlkaline rocks, Magmatism
DS2001-0624
2001
Levskii, L.K.Koreshkova, M.Y., Levskii, L.K., Ivanikov, V.V.Petrology of a lower crustal xenolith suite from dikes and explosion pipes of the Kandalaksha Graben.Petrology, Vol. 9, No. 1, pp. 79-RussiaXenoliths
DS2001-0681
2001
Levskii, L.K.Levskii, L.K.Is there an ultradepleted mantle?Geochemistry International, Vol. 39, S1, pp. S39-42.South Africa, Russia, YakutiaGeochronology, Deposit - Roberts Victor
DS200412-0689
2004
Levskii, L.K.Golubeva, Yu.Yu., Ovchinnikova, G.V., Levskii, L.K.Pb Sr Nd isotopic characteristics of mantle sources of kimberlites from the Nakyn field, Yakutia.Doklady Earth Sciences, Vol. 394, 2, Feb-Mar. pp. 230-234.Russia, YakutiaGeochronology
DS200512-0625
2005
Levskii, L.K.Levchenkov, O.A., Gaidamako, I.M., Levskii, L.K., Komarov, Yakovleva, Rizvanova, MakeevU Pb age of zircon from the Mir and 325 Let Yakutii pipes.Doklady Earth Sciences, Vol. 400, 1, pp. 99-101.Russia, YakutiaGeochronology
DS200512-0845
2005
Levskii, L.K.Perov, V.A., Bogomolov, E.S., Larchenko, V.A., Levskii, L.K., Minchenko, G.V., Sablukov, S.M., SZergeev, S.A., Stepanov, V.P.Rb Sr age of kimberlites of the Pionerskaya pipe, Arkangelsk Diamondiferous province.Doklady Earth Sciences, Vol. 400, 1, pp. 67-71.Russia, Kola Peninsula, ArchangelGeochronology -
DS200512-0847
2005
Levskii, L.K.Pervov, V.A., Bogomolov, E.S., Larchenko, V.A., Levskii, L.K., Minchenko, Sabukov, Sergeev, StepanovRb Sr age of kimberlites of the Pionerskaya pipe, Arkangelsk Diamondiferous province.Doklady Earth Sciences, Vol. 400, 1, pp. 67-71.Russia, Archangel, Kola PeninsulaGeochronology
DS200512-1227
2005
Levskii, L.K.Yutkina, E.V., Kononova, V.A., Tsymbal, S.N., Levskii, L.K., Kiryanov, N.N.Isotopic geochemical specialization of mantle source of kimberlites from the Kirovograd complex, Ukrainian shield.Doklady Earth Sciences, Vol. 402, 4, pp. 551-555.Russia, UkraineGeochronology
DS201212-0666
2012
Levskii, L.K.Skublov, S.G., Nikitina, L.P., Marin, Yu.B., Levskii, L.K., Guseva, N.S.U Pb age and geochemistry of zircons from xenoliths of the V. Grib kimberlitic pipe, Arkhangelsk diamond province.Doklady Earth Sciences, Vol. 444, 1, pp. 595-600.Russia, Archangel, Kola PeninsulaDeposit - Grib
DS1987-0411
1987
Levskiy, L.K.Levskiy, L.K., Drubetskoy, Ye.R.Isotopic stratification of the mantle: a summary.(Russian)In: Geochronology and geochemistry of isotopes: a collection of scientific, pp. 110-127RussiaBlank
DS1994-1045
1994
Levskiy, L.K.Lokhov, K.I., Levskiy, L.K.Geochemical and cosmochemical consequences of carbon and primordial helium and argon isotopes in mantle.Geochemistry International, Vol. 31, No. 4, pp. 1-28.MantleGeochemistry, Carbon
DS200512-0100
2004
LevskyBogatikov, O.A., Kononova, V.A., Golubeva, Zinchuk, Ilupin, Rotman, Levsky, Ovchinnikova, KondrashovVariations in chemical and isotopic compositions of the Yakutian kimberlites and their causes.Geochemistry International, Vol. 42, 9, pp. 799-821.Russia, Siberia, YakutiaGeochemistry
DS200512-0560
2005
LevskyKononova, V.A., Golubeva, Y.Y., Bogatikov, O.A., Nosova, Levsky, OvchinnikovaGeochemical diversity of Yakutian kimberlites: origin and diamond potential (ICP-MS dat a and Sr, Nd and Pb isotropy).Petrology, Vol. 13, 3, pp. 205-228.RussiaMineral chemistry
DS200912-0409
2009
Levsky, L.Koreshkova, M., Downes, H., Levsky, L.Geochemistry and petrology of lower crustal xenoliths from Udachnaya and Komsomolskaya kimberlite pipes, Siberia.Goldschmidt Conference 2009, p. A683 Abstract.Russia, SiberiaDeposit - Udachnaya
DS201801-0030
2017
Levsky, L.Koreshkova, M., Downes, H., Millar, I., Levsky, L., Larionov, A., Sergeev, S.Geochronology of metamorphic events in the lower crust beneath NW Russia: a xenolith Hf isotope study.Journal of Petrology, Vol. 58, 8, pp. 1567-1589.Russia, Kola Peninsulageochronology

Abstract: Hf isotope data for zircons and whole-rocks from lower crustal mafic granulite and pyroxenite xenoliths from NW Russia are presented together with the results of U-Pb zircon dating, Sm-Nd and Rb-Sr isotopic compositions of bulk-rocks and minerals, and trace element compositions of minerals. Most zircons preserve a record of only the youngest metamorphic events, but a few Grt-granulite xenoliths retain Archean magmatic zircons from their protolith. Metamorphic zircons have highly variable ?Hf(t) values from -25 to -4. The least radiogenic zircons were formed by recrystallization of primary magmatic Archean zircons. Zircons with the most radiogenic ?Hf grew before garnet or were contemporaneous with its formation. Zircons with ?Hf(t) from -15 to -9 formed by various mechanisms, including recrystallization of pre-existing metamorphic zircons, subsolidus growth in the presence of garnet and exsolution from rutile. They inherited their Hf isotopic composition from clinopyroxene, pargasite, rutile and earlier-formed zircon that had equilibrated with garnet. Subsolidus zircons were formed in response to a major change in mineral association (i.e. garnet- and zircon-producing reactions including partial melting). Recrystallized zircons date the onset of high-temperature conditions without a major change in mineral association. Age data for metamorphic zircons fall into five groups: >1•91 Ga, 1•81-1•86 Ga, 1•74-1•77 Ga, 1•64-1•67 Ga and <1•6 Ga. Most ages correlate with metamorphic events in the regional upper crust superimposed onto rocks of the Belomorian belt during formation of the Lapland Granulite Belt. Zircon formation and resetting at 1•64-1•67 Ga significantly postdates Lapland-Kola orogenic events and may relate to the onset of Mesoproterozoic rifting. The youngest ages (1•6-1•3 Ga) correspond to an event that affected only a few grains in some samples and can be explained by interaction with a localized fluid. The observed garnet-granulite associations were formed at 1•83 Ga in Arkhangelsk xenoliths and 1•74-1•76 Ga in most Kola xenoliths. By the end of the Lapland-Kola orogeny, the rocks were already assembled in the lower crust. However, no addition of juvenile material has been detected and preservation of pre-Lapland-Kola metamorphic zircon indicates that some xenoliths represent an older lower crust. Granulites, pyroxenites and Phl-rich rocks have a common metamorphic history since at least c. 1•75 Ga. At about 1•64 Ga metasomatic introduction of phlogopite took place; however, this was only one of several phlogopite-forming events in the lower crust.
DS201802-0247
2017
Levsky, L.Koreshkova, M., Downes, H., Millar, I., Levsky, L., Larianov, A.Geochronology of metamorphic events in the lower crust of NW Russia: a xenolith Hf isotope study.Journal of Petrology, Vol. 58, 8, pp. 1567-1589.Russia, Kola Peninsulageochronology

Abstract: Hf isotope data for zircons and whole-rocks from lower crustal mafic granulite and pyroxenite xenoliths from NW Russia are presented together with the results of U-Pb zircon dating, Sm-Nd and Rb-Sr isotopic compositions of bulk-rocks and minerals, and trace element compositions of minerals. Most zircons preserve a record of only the youngest metamorphic events, but a few Grt-granulite xenoliths retain Archean magmatic zircons from their protolith. Metamorphic zircons have highly variable ?Hf(t) values from -25 to -4. The least radiogenic zircons were formed by recrystallization of primary magmatic Archean zircons. Zircons with the most radiogenic ?Hf grew before garnet or were contemporaneous with its formation. Zircons with ?Hf(t) from -15 to -9 formed by various mechanisms, including recrystallization of pre-existing metamorphic zircons, subsolidus growth in the presence of garnet and exsolution from rutile. They inherited their Hf isotopic composition from clinopyroxene, pargasite, rutile and earlier-formed zircon that had equilibrated with garnet. Subsolidus zircons were formed in response to a major change in mineral association (i.e. garnet- and zircon-producing reactions including partial melting). Recrystallized zircons date the onset of high-temperature conditions without a major change in mineral association. Age data for metamorphic zircons fall into five groups: >1•91 Ga, 1•81-1•86 Ga, 1•74-1•77 Ga, 1•64-1•67 Ga and <1•6 Ga. Most ages correlate with metamorphic events in the regional upper crust superimposed onto rocks of the Belomorian belt during formation of the Lapland Granulite Belt. Zircon formation and resetting at 1•64-1•67 Ga significantly postdates Lapland-Kola orogenic events and may relate to the onset of Mesoproterozoic rifting. The youngest ages (1•6-1•3 Ga) correspond to an event that affected only a few grains in some samples and can be explained by interaction with a localized fluid. The observed garnet-granulite associations were formed at 1•83 Ga in Arkhangelsk xenoliths and 1•74-1•76 Ga in most Kola xenoliths. By the end of the Lapland-Kola orogeny, the rocks were already assembled in the lower crust. However, no addition of juvenile material has been detected and preservation of pre-Lapland-Kola metamorphic zircon indicates that some xenoliths represent an older lower crust. Granulites, pyroxenites and Phl-rich rocks have a common metamorphic history since at least c. 1•75 Ga. At about 1•64 Ga metasomatic introduction of phlogopite took place; however, this was only one of several phlogopite-forming events in the lower crust.
DS1990-0945
1990
Levsky, L.K.Lochov, K.I., Levsky, L.K.Fluids in depleted mantle and origin of diamonds21st. Lunar And Planetary Science Conference, March 12-16, Houston, March 16 presentationGlobalMantle, Diamond genesis
DS1993-0922
1993
Levsky, L.K.Lokhov, K.I., Levsky, L.K.Carbon and primary helium and argon isotopes in the mantle rocks...geochemical and cosmochemical consequences.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 9, September pp. 1263-1283.RussiaGeochronology, Geochemistry
DS2002-0876
2002
Levsky, L.K.Kononova, V.A., Levsky, L.K., Pervov, V.A., Ovchinnikova, G.V., BogatikovPb Sr Nd isotopic systematics of mantle sources of potassic ultramafic and mafic rocksPetrology, Vol. 10, 5, pp. 433-47.RussiaAlkaline rocks, Geochronology
DS2002-0877
2002
Levsky, L.K.Kononova, V.A., Levsky, L.K., Pervov, V.A., Ovchinnikova, G.V., BogatikovPb Sr Nd isotopic systematics of mantle sources of potassic ultramafic and mafic rocks in the north and east European platform.Petrology, Vol. 10, 5, pp. 433-47.Russia, UralsGeochronology, Alkaline rocks
DS2002-0878
2002
Levsky, L.K.Kononova, V.A., Levsky, L.K., Pervov, V.A., Ovchinnikova, G.V., Bogatikov, A.Pb Sr Nd isotopic systematics of mantle sources of potassic ultramafic and mafic rocksPetrology, Vol. 10, 5, pp. 433-47.Russia, Europe, Kola PeninsulaGeochronology
DS200412-2192
2004
Levsky, L.K.Yutkina, E.V., Kononova, V.A., Bogatikov, O.A., Knyazkov, A.P., Kozar, N.A., Ovchinnikova, G.V., Levsky, L.K.Kimberlites of eastern Priazove ( Ukraine) and geochemical characteristics of their sources.Petrology, Vol. 12, 2, pp. 134-148.Europe, UkraineDevonian age, Arkangelsk, Terskii Bereg, Novolaspinakay
DS201112-0540
2011
Levsky, L.K.Koreshkova, M.Yu., Downes, H., Levsky, L.K., Vladykin, N.V.Petrology and geochemistry of granulite xenoliths from Udachnaya and Komosomolskaya kimberlite pipes, Siberia.Journal of Petrology, Vol. 52, 10, pp. 1857-1885.Russia, SiberiaDeposit - Udachnaya, Komosmolskaya
DS201112-0541
2011
Levsky, L.K.Koreshkova, M.Yu., Downes, H., Levsky, L.K., Vladykin, N.V.Petrology and geochemistry of granulite xenoliths from Udachnaya and Komosomskaya kimberlite pipes, Siberia.Journal of Petrology, Vol. 52, no. 10, pp. 1857-1885.Russia, SiberiaDeposit - Udachnaya, Komosmskaya
DS201112-0542
2011
Levsky, L.K.Koreshkova, M.Yu., Downes, H., Levsky, L.K., Vladykin, N.V.Petrology and geochemistry of granulite xenoliths from Udachnaya and Komosomolskaya kimberlite pipes, Siberia.Journal of Petrology, Vol. 52, 10, pp. 1857-1885.Russia, SiberiaDeposit - Udachnaya, Komosomolskaya
DS200812-0652
2008
Levson, V.Levson, V.Geology of the northeast British Columbia and northwest Alberta: diamonds, shallow gas, gravel and glaciers.Canadian Journal of Earth Sciences, Vol. 45, 5, pp. 509-512.Canada, British Columbia, AlbertaDiamonds
DS1996-0838
1996
Levson, V.M.Levson, V.M., Morison, S.R.Geology of placer deposits in glaciated environmentsPast Glacial Environments, Menzies, pp. 441-478.GlobalGlacial - placer, alluvials, Not specific to diamonds
DS1996-0839
1996
Levson, V.M.Levson, V.M., Rutter, N.W.Evidence of Cordilleran Late Wisconsian glaciers in the ice free corridorQuaternary International, Vol. 32, pp. 33-51.AlbertaGeomorphology
DS1999-0410
1999
Levson, V.M.Levson, V.M.Till geochemistry and sampling techniques in the Canadian CordilleraAssocation of Exploration Geologists (AEG) 19th. Drift Exploration Glaciated, S.C., pp. 95-116.Cordillera, British ColumbiaGeomorphology, glacial, geochemistry, Drift prospecting - not specific to diamonds
DS200512-0989
2005
Levson, V.M.Simandl, G.J., Ferbey, T., Levson, V.M., Demchuk, T.E., Hewett, T., Smith, I.R.,KjarsgaardHeavy mineral survey and its significance for diamond exploration, Fort Nelson area, BC.British Columbia Mines, 2005-13, Canada, British ColumbiaGeochemistry - KIM
DS200512-0990
2005
Levson, V.M.Simandl, G.J., Ferbey, T., Levson, V.M., Demchuk, T.E., Mallory, S., Smith, L.R., Kjarsgaard, I.Kimberlite indicator minerals in the Fort Nelson area, northeastern British Columbia.British Columbia Geological Survey, Summary of Fieldwork, Paper 2005-1, pp. 325-343.Canada, British ColumbiaGeochemistry, geomorphology, glacial, KIMS
DS200612-1306
2005
Levson, V.M.Simandl, G.J., Ferbey, T., Levson, V.M., Robinson, N.D., Lane, R., Smith, R., Demchuk, Raudsepp, HickinKimberlite and diamond indicator minerals in northeast British Columbia, Canada - a reconnaissance survey.British Columbia Geological Survey, Geofile 2005-25, 25p.Canada, British ColumbiaGeochemistry, geochronology, Buffalo Head Terrane
DS201012-0437
2010
Levy, F.Levy, F., Jaupart, C., Mareschal, J-C., Bienfait, G., Limare, A.Low heat flux and large variations of lithospheric thickness in the Canadian Shield.Journal of Geophysical Research, Vol. 115, B6, B06404.CanadaGeophysics - seismics
DS201112-0588
2011
Levy, F.Levy, F., Jaupart, C.Temperature and rheological properties of the mantle beneath the North American craton from an analysis of heat flux and seismic data.Journal of Geophysical Research, Vol. 116, B01408, 25p.Canada, United StatesCraton, geothermometry
DS201212-0403
2012
Levy, F.Levy, F., Jaupart, C.The initiation of subduction by crustal extension at a continental margin.Geophysical Journal International, Vol. 188, 3, pp. 779-797.MantleSubduction
DS201212-0404
2012
Levy, F.Levy, F., Jaupart, C.The initiation of subduction by crustal extension at a continental margin.Geophysical Journal International, in press availableMantleSubduction
DS2000-0339
2000
Levy, I.W.Gilfillan, J.F., Levy, I.W.Monitoring the reserveMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 537-44.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS2000-0570
2000
Levy, I.W.Levy, I.W., West, R.F.Reporting of exploration resultsMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 631-34.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS1991-0984
1991
Levy, M.Levy, M., Christie-Blick, N.Tectonic subsidence of the early Paleozoic passive continental margin In eastern California and southern NevadaGeological Society of America (GSA) Bulletin, Vol. 103, No. 12, December pp. 1590-1606California, NevadaTectonics, Depositional aspects
DS1975-0418
1976
Levy, S.Smith, D., Levy, S.Petrology of the Green Knobs Diatreme and Implications for The Upper Mantle Below the Colorado Plateau.Earth Plan. Sci. Letters, Vol. 29, PP. 107-125.Colorado PlateauKimberlite, Rocky Mountains
DS1986-0174
1986
Lew, J.H.Deakin, A.S., Boxer, G.L., Meakins, A.E., Haebig, E., Lew, J.H.Geology of the Argyle alluvial diamond deposits #1Proceedings of the Fourth International Kimberlite Conference, Held, No. 16, pp. 451-453AustraliaDiamond exploration
DS1989-0345
1989
Lew, J.H.Deakin, A.S., Boxer, G.L., Meakins, A.E., Haebig, A.E., Lew, J.H.Geology of the Argyle alluvial diamond deposits #2Geological Society of Australia Inc. Blackwell Scientific Publishing, No. 14, Vol. 2, pp. 1108-1116AustraliaAlluvial-placers, Deposit -Argyle
DS1990-0924
1990
Lewchuck, M.T.Lewchuck, M.T., Symons, D.T.A.Paleomagnetism of the Clay-Howells carbonatite complex-constraints on Proterozoic motion in the Kapuskasing structural zone, Superior Province, CanadaTectonophysics, Vol. 172, No. 1-2, January 10, pp. 67-76OntarioCarbonatite -Clay Howells, Tectonics -Kapuskasing zo
DS1989-0880
1989
Lewchuk, M.T.Lewchuk, M.T., David, T.A.Age and petrogenesis of the middle Proterozoic Coldwell Complex of Ontario from paleomagntisM.Geological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A109. (abstract.)OntarioMid continent, Kapuskasing Lithoprobe
DS1989-1474
1989
Lewchuk, M.T.Symons, D.T.A., Lewchuk, M.T.Paleomagnetism of the Mississippian HP pipe and The western margin of The north American cratonIn: Deep structure and past kinetics of accreted terranes, Ed. J.W., Mon. 50 IUGG Vol. 5, pp. 113-125British ColumbiaPaleomagnetics, HP pipe
DS1990-0925
1990
Lewchuk, M.T.Lewchuk, M.T., Symons, D.T.A.Paleomagnetism of the late Precambrian Coldwell Complex, Ontario CanadaTectonophysics, Vol. 184, pp. 73-86OntarioCarbonatite, Coldwell Complex
DS1993-1388
1993
Lewin, E.Schiano, P., Algre, C.J., Dupre, B., Lewin, E., Joron, J-L.Variability of trace elements in basaltic suitesEarth and Planetary Science Letters, Vol. 119, No. 1-2, August pp. 37-52GlobalGeochemistry, Basalt
DS1998-0868
1998
Lewin, E.Lewin, E.Mantle convection from the geochemist point of viewMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 886.MantleGeophysics - seismics, Geochemistry
DS2001-0019
2001
Lewin, E.Allegre, C., Manhes, G., Lewin, E.Chemical composition of the Earth and the volatility control on planetary genesis.Earth and Planetary Science Letters, Vol. 185, No. 1-2, Feb.15, pp.49-69.GlobalGeochemistry
DS2002-0064
2002
Lewin, E.Arndt, N.T., Lewin, E., Albaredem, F.Strange partners: formation and survival of continental crust and lithospheric mantleGeological Society of London Special Publication, No. 199, pp. 91-104.MantleTectonics
DS200612-1488
2006
Lewin, E.Vlastelic, I., Lewin, E., Staudacher, T.Th/U and other geochemical evidence for the Reunion plume sampling a less differentiated mantle domain.Earth and Planetary Science Letters, Vol. 248, 1-2, Aug. 15, pp. 364-378.MantleGeochemistry
DS200712-0170
2007
Lewin, E.Chavel, C., Lewin, E., Carpentier, M., Marini, J-C.Recycled oceanic crust and sediments control the Hf-Nd mantle array.Plates, Plumes, and Paradigms, 1p. abstract p. A163.MantleKimberlite
DS200812-0206
2008
Lewin, E.Chauvel, C., Lewin, E., Carpenier, M., Arndt, N.T., Marini, J.C.Role of recycled oceanic basalt and sediment in generating the Hf Nd mantle array.Nature Geoscience, Vol. 1, 1, pp. 64-67.MantleGeochemistry
DS201212-0038
2012
Lewin, J.Ashworth, P.J., Lewin, J.How do big rivers come to be different.Earth Science Reviews, Vol. 114, 1-2, pp. 84-107.GlobalGeomorphology
DS201312-0535
2014
Lewin, J.Lewin, J., Ashworth, P.J.Defining large river channel patterns: alluvial exchange and plurality.Geomorphology, Vol. 215, pp. 83-98.GlobalRivers - not specific to diamonds
DS1997-0676
1997
Lewin, R.Lewin, R.Critical mass.... complexity theory... big extinctionsNew Scientist, Aug. 23, pp. 7GlobalComplexity theory, Random mathematics
DS1930-0279
1938
Lewinsohn, R.Lewinsohn, R.Barney Barnato, from Whitechapel Clown to Diamond KingNew York: E.p. Dutton, London: Routledge., 275P.South AfricaBiography, Kimberley
DS1999-0681
1999
Lewis, C.Smith, A.D., Lewis, C.Differential rotation of lithosphere amd mantle and the driving forces of plate tectonics.Journal of Geodynamics, Vol. 28, No. 2-3, Sept. 2, pp. 97-116.MantleGeophysics - thermodynamics, Lithosphere
DS1997-0677
1997
Lewis, C.J.Lewis, C.J.Diamond genesis in a subduction environment, Sierra Nevada USA *REF ONLYPh.d. Thesis, University of California, Berkeley REF ONLY, CaliforniaDiamond genesis
DS1997-0678
1997
Lewis, C.J.Lewis, C.J.Diamond genesis in a subduction environment, Sierra Nevada, USAUniversity of of California, Ph.d thesisCaliforniaDiamond genesis, Thesis
DS1995-0514
1995
Lewis, C.R.Eshuys, E., Lewis, C.R.Understanding the regolithic profileSouth African Mining, June pp. 21, 23, 27AustraliaLaterites, gold, Regolith
DS1998-0973
1998
Lewis, G.McClay, K.R., Dooley, T., Lewis, G.Analog modeling of progradational delta systemsGeology, Vol. 26, No. 9, Sept. pp. 772-4GlobalDelta systems, basins, model, Graben, Fold thrust, tectonics
DS1860-0598
1888
Lewis, H. CarvillLewis, H. CarvillThe Matrix of the DiamondGeology Magazine (London), Dec. 3, Vol. 5, PP. 129-131. ALSO: ZEITSCHR. KRYST. (LEIPZIGAfrica, South AfricaMineralogy, Geology, Kimberlite Mines And Deposits
DS1860-0517
1886
Lewis, H. Carvill.Lewis, H. Carvill.The Genesis of the Diamond - in Science by CarvillScience., Vol. 8, No. 193, PP. 345-347.Africa, South AfricaDiamond Genesis
DS1860-0518
1886
Lewis, H. Carvill.Lewis, H. Carvill.On a Diamondiferous Peridotite, and the Genesis of the Diamond.British Association Advanced Science (birmingham), Vol. 56, PP. 667-668. ALSO: Geology Magazine (London), Dec. 3, VOLSouth Africa, Griqualand WestGenesis, Mineralogy
DS1860-0996
1897
Lewis, H. Carvill.Lewis, H. Carvill.Kimberlite from the United StatesIn: The Genesis And Nature of The Diamond. Bonney, T.g. Edit, SECTION 3, PP. 61-67.United States, KentuckyGeology
DS1860-0997
1897
Lewis, H. Carvill.Lewis, H. Carvill.Papers and Notes on the Genesis and Matrix of the DiamondLondon: Longmans Green And Co., 72P. ALSO: STH. AFR. PHIL. SOC. Transactions, Vol. 10, No.Africa, South Africa, Cape Province, United States, KentuckyMineralogy
DS1970-0123
1970
Lewis, J.D.Lewis, J.D.The Geology of Some Carbonate Intrusions of the Mount Fraser Area Goldfield.Western Australia Department of Mines Report For 1970, PP. 506-556.Australia, Western AustraliaCarbonatite
DS1982-0298
1982
Lewis, J.D.Jaques, A.L., Gregory, G.P., Lewis, J.D., Ferguson, J.The Ultrapotassic Rocks of the West Kimberley Region, Western Australia, and a New Class of Diamondiferous Kimberlite.Proceedings of Third International Kimberlite Conference, TERRA COGNITA, ABSTRACT VOLUME., Vol. 2, No. 3, PP. 251-252, (abstract.).AustraliaKimberlite, Leucite, Lamproite, Ellendale, Calwynyardah, Noonkanb
DS1983-0439
1983
Lewis, J.D.Mcculloch, M.T., Jaques, A.L., Nelson, D.R., Lewis, J.D.Neodymium and Strontium Isotopes in Kimberlites and Lamproites from western Australia and Enriched Mantle Origin.Nature., Vol. 302, No. 5907, PP. 400-403.AustraliaIsotope, Lamproite, Kimberlite, Petrology
DS1984-0380
1984
Lewis, J.D.Jaques, A.L., Lewis, J.D., Smith, C.B., Gregory, G.P., Ferguson.The Diamond Bearing Ultrapotassic Lamproitic Rocks of the West Kimberley Region Western Australia.Proceedings of Third International Kimberlite Conference, Vol. 1, PP. 225-254.AustraliaLamproite, Geochronology, Ellendale, Calwynyardah, Noonkanbah
DS1990-0926
1990
Lewis, J.D.Lewis, J.D.Diamonds, 1990 #2Geological Survey of Western Australia, Geology and Mineral Resources of, Memoir No. 3, pp. 639-645AustraliaArgyle, Nullagine, West Kimberley, Ellendale, Diamond production
DS1990-0927
1990
Lewis, J.D.Lewis, J.D.Diatremes. Lamproites and kimberlites- controls of distribution-Argyle, Bow Hill dykesGeological Survey of Western Australia, Geology and Mineral Resources of Western, Chapter 5, pp. 566-589AustraliaLamproites, mineral analyses, Kimberlites
DS1991-0985
1991
Lewis, J.D.Lewis, J.D.LAMPNORM A scheme for calculating the normative minerals of lamproitesGeological Survey of Western Australia, Professional Paper, Report No. 30, pp. 65-71AustraliaComputer program -mineralogy, Lamproites -LAMPNORM.
DS1991-0174
1991
Lewis, K.A.Brice, W.C., Lewis, K.A.Exploration and development of minerals in MinnesotaSkillings Mining Review, Vol. 80, No. 40, October 5, pp. 4-7MinnesotaGeneral overview of exploration
DS200512-0629
2005
Lewis, M.Lewis, M.Canadian diamonds: an overview of exploration activities.British Columbia & Yukon Mineral Exploration Roundup, Jan.24-27th., p. 77-78.CanadaNews item - brief overview, Dundee
DS1997-0679
1997
Lewis, M.W.Lewis, M.W., Wigen, K.E.The myth of continents. a critique of metageographyUniversity of of California Press, $ 20.00GlobalBook - ad, Continents - geography
DS1982-0370
1982
Lewis, P.Lewis, P.Diamonds Lose their LustreMacleans Magazine., JUNE 21ST.GlobalInvestment, Sales, Cso
DS2002-0473
2002
Lewis, R.Foster, D.A., Mueller, P.A., Heatherington, A., Vogl, J., Meert, J., Lewis, R.Configuration of the 2.0 - 1.6 GA accretionary margin NW of the Wyoming Province:Geological Society of America Annual Meeting Oct. 27-30, Abstract p. 559.WyomingTectonics, Gondwana
DS1975-0247
1976
Lewis, R.D.Bolivar, S.L., Brookins, D.G., Lewis, R.D., Meyer, H.O.A.Geophysical Studies of the Prairie Creek Kimberlite Murfreesboro, Arkansaw.Eos, Vol. 57, No. 10, P. 762, (abstract.).United States, Gulf Coast, Arkansas, PennsylvaniaKimberlite, Geophysics, Groundmag, Gravity
DS1975-0324
1976
Lewis, R.D.Lewis, R.D., Meyer, H.O.A., Bolivar, S.L., Brookins, D.G.Mineralogy of the Diamond Bearing 'kimberlite' Murfreesboro, Arkansaw.Eos, Vol. 57, No. 10, P. 761. (abstract.).United States, Gulf Coast, Arkansas, PennsylvaniaGeochronology, Alteration, Petrography, Perovskite
DS1975-0554
1977
Lewis, R.D.Lewis, R.D.Mineralogy, Petrology and Geophysical Aspects of the Prairie Creek Kimberlite, Near Murfreesboro, Arkansaw.Msc. Thesis, Purdue Univ, West Lafayette, Indiana., United States, Gulf Coast, ArkansasKimberlite, Geophysics
DS1975-0555
1977
Lewis, R.D.Lewis, R.D., Meyer, H.O.A.Diamond Bearing Kimberlite of Prairie Creek, Murfreesboro, Arkansas.International Kimberlite Conference SECOND EXTENDED ABSTRACT VOLUME., United States, Gulf Coast, Arkansas, PennsylvaniaPetrology
DS1975-0572
1977
Lewis, R.D.Meyer, H.O.A., Lewis, R.D., Bolivar, S.L., Brookins, D.G.Prairie Creek Kimberlite, Mufreesboro Pike County, ArkansawInternational Kimberlite Conference SECOND, FIELD GUIDE., 14P.United States, Gulf Coast, Arkansas, PennsylvaniaPetrography, Mineral Chemistry
DS1975-0945
1979
Lewis, R.D.Bickford, M.E., Lewis, R.D.U-pb Geochronology of Exposed Basement Rocks in OklahomaGeological Society of America (GSA) Bulletin., Vol. 90, PP. 540-544.OklahomaMid-continent
DS1983-0459
1983
Lewis, R.D.Mitchell, R.H., Lewis, R.D.Priderite Bearing Xenoliths from the Prairie Creek Mica, Arkansas.Canadian Mineralogist., Vol. 21, PP. 59-64.United States, Gulf Coast, Arkansas, PennsylvaniaPetrology
DS1987-0412
1987
Lewis, R.D.Lewis, R.D., Mitchell, R.H.Alnoite intrusions associated with Permian rifting in the New Madrid seismic rift complexGeological Society of America, Vol. 19, No. 7 annual meeting abstracts, p.745. abstracGlobalMelilite
DS1987-0413
1987
Lewis, R.S.Lewis, R.S., Ming, T., Wacker, J.F., Anders, E., Steel, E.Interstellar diamonds in meteoritesNature, Vol. 326, No. 6109, March 12, pp. 160-161GlobalMeteorites
DS1989-0881
1989
Lewis, R.S.Lewis, R.S.Properties, detectability and origin of interstellar diamonds inmeteoritesNature, Vol. 339, No. 6220, May 11, pp. 117-121GlobalMeteorites
DS1990-0928
1990
Lewis, R.S.Lewis, R.S., Amari, S., Anders, E.Meteoritic silicon carbide: pristine material from carbon starsNature, Vol. 348, No. 6299, November 22, pp. 293-297GlobalMeteorites, Petrology
DS2000-0571
2000
Lewis, R.W.Lewis, R.W.The resource database: now and in the futureMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 43-8.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS1992-0941
1992
Lewis, T.Lewis, T., Wang, K.Geothermal research related to past climateEos, Vol. 73, No. 25, June 23, pp. 265, 269Ontario, QuebecGeothermal, Climate, deep drilling
DS1987-0414
1987
Lewis, T.J.Lewis, T.J., Drury, M.J.Heat flow and heat generation in the Churchill Province of the CanadianShield, and their paleotectonic significance-discussionTectonophysics, Vol.132, No.4, Jan. 15, pp. 343-350CanadaShield, Heat Flow
DS1991-0796
1991
Lewis, T.J.Jessop, A.M., Lewis, T.J., Drury, M.J.Terrestrial heat flow in CanadaTerrestrial Heat Flow and the Lithosphere Structure, editors Cermak, V. and, Springer Verlag, pp. 457-474CanadaHeat flow, Geophysics
DS1993-0959
1993
Lewis, T.J.Majorowicz, J.A., Gough, D.I., Lewis, T.J.Electrical conductivity and temperature in the Canadian Cordilleran crustEarth and Planetary Science Letters, Vol. 115, No. 1-4, March pp. 57-64.British Columbia, AlbertaGeophysics, Heat flow
DS1995-1902
1995
Lewis, T.J.Thompson, P.H., Judge, A.S., Lewis, T.J.Thermal parameters in rock units of the Winter Lake Lac de Gras area, implications for diamond genesis.Geological Survey of Canada Report of Activities, No. 1995-E, pp. 125-135.Northwest TerritoriesThermal model, Diamond genesis
DS1996-1424
1996
Lewis, T.J.Thompson, P.H., Judge, A.S., Lewis, T.J.Thermal parameters in rock units of the Winter Lake -Lac de Gras-implications for diamond genesis.northwest Territories Exploration overview 1995, March, p. 3-34. abstractNorthwest TerritoriesLithosphere, Geothermometry
DS1996-1425
1996
Lewis, T.J.Thompson, P.H., Judge, A.S., Lewis, T.J.Thermal evolution of the lithosphere in the central Slave Province:implications for diamond genesis.Geological Survey of Canada, LeCheminant ed, OF 3228, pp. 151-160.Northwest TerritoriesReflectance data, Thermal history, Slave Province
DS1999-0320
1999
Lewis, T.J.Hyndman, R.D., Lewis, T.J.Geophysical consequences of the Cordillera Craton thermal transition in southwestern Canada.Tectonophysics, Vol. 306, No. 3-4, pp. 397-422.Alberta, Western CanadaGeophysics - geothermometry, Craton
DS1999-0321
1999
Lewis, T.J.Hyndman, R.D., Lewis, T.J.Geophysical consequences of the Cordillera Craton thermal transition in southwestern Canada.Tectonophysics, Vol. 306, No. 3-4, June 20, pp. 397-422.Saskatchewan, Alberta, CordilleraGeophysics - seismics, Geothermometry
DS2003-0804
2003
Lewis, T.J.Lewis, T.J., Hyndman, R.D., Fluck, P.Heat flow, heat generation and crustal temperatures in the northern CanadianJournal of Geophysical Research, Vol. 108, 6, 10.1029/2002JB002090Northwest TerritoriesGeothermometry
DS2003-0805
2003
Lewis, T.J.Lewis, T.J., Hyndman, R.D., Fluck, P.Heat flow, heat generation, and crustal temperatures in the northern CanadianJournal of Geophysical Research, Vol. 108, B 6, p. 2321. June 28, 10.1029/2002JB002090Northwest TerritoriesBlank
DS200412-1123
2003
Lewis, T.J.Lewis, T.J., Hyndman, R.D., Fluck, P.Heat flow, heat generation, and crustal temperatures in the northern Canadian Cordillera: thermal control of tectonics.Journal of Geophysical Research, Vol. 108, B 6, p. 2321. June 28, 10.1029/2002 JB002090Canada, Northwest TerritoriesGeothermometry
DS200612-0615
2006
Lewis, T.J.Hyndman, R.D., Fluck, P., Mazzotti, S., Lewis, T.J., Ristau, J., Leonard, L.Current tectonics of the northern Canadian Cordillera.Canadian Journal of Earth Sciences, Vol. 42, 6, pp. 1117-1136.Canada, British ColumbiaTectonics
DS1987-0761
1987
LewryVan Schmus, W.R., Bickford, M.E., Lewry, Macdonalduranium-lead (U-Pb) geochronology in the Trans Hudson Orogen, northern SaskatchewanProg. in Phys. Geography, Vol. 24, pp. 407=24.SaskatchewanGeochronology
DS1999-0026
1999
LewryAshton, K.E., Heaman, L.M., Lewry, HartlaubAge and origin of the Jan Lake Complex: a glimpse at the buried Archean craton of the Trans Hudson Orogen.Canadian Journal of Earth Sciences, Vol. 36, No. 2, Feb. pp. 185-208.Manitoba, SaskatchewanLithoprobe, Geophysics - seismics
DS1992-0654
1992
Lewry, J.Hajnal, Z., Lewry, J.Lithoprobe: Trans-Hudson orogen transect. Report of transect meeting held March 9-10, 1992Lithoprobe, Report No. 26, 160p. Geological Society of Canada (GSC) ser QE11LS26Manitoba, Saskatchewan, North DakotaTrans-Hudson Orogen, Geophysics -seismics
DS1992-0942
1992
Lewry, J.Lewry, J.Lithotectonic elements of the exposed Trans-Hudson Orogen and their subsurface extensionEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 321SaskatchewanCOCORP -seismic, Williston Basin
DS1996-0583
1996
Lewry, J.Hajnal, Z., Lucas, S., White, D., Lewry, J., et al.Seismic reflection images of high angle faults and linked detachments In the Trans Hudson Orogen.Tectonics, Vol. 15, No. 2, April pp. 427-439.Manitoba, OntarioCraton, Superior, Lithoprobe
DS1998-0247
1998
Lewry, J.Chiarenzelli, J., Aspler, L., Villeneuve, M., Lewry, J.Early Proterozoic evolution of the Saskatchewan Craton and its allochthonous cover, Trans-Hudson OrogenJournal of Geology, Vol. 106, No. 3, May pp. 247-267SaskatchewanCraton - Glennie Domain, Geochronology
DS200512-0389
2005
Lewry, J.Hajnal, Z., Lewry, J., White, D., Ashton, K., Clowes, R., Stauffer, M., Gyorfi, I., Takacs, E.The Saskatchewan Craton and Hearne Province margin: seismic reflection studies in the western Trans Hudson Orogen.Canadian Journal of Earth Sciences, Vol. 42, 4, April pp. 403-419.Canada, Saskatchewan, ManitobaGeophysics - Lithoprobe
DS1986-0492
1986
Lewry, J.F.Lewry, J.F., Collerson, Bickford, Van SchmusAn evolutionary model of the Western Churchill Province and western Margin of the Superior Province and north central United States.Tectonophysics, Vol. 131, pp. 183-97.Saskatchewan, Alberta, MontanaTectonics
DS1987-0760
1987
Lewry, J.F.Van Schmus, W.R., Bickford, M.E., Lewry, J.F.uranium-lead (U-Pb) geochronology in the Trans Hudson Orogen, northern Canada.Canadian Journal of Earth Sciences, Vol. 24, pp. 407-424.SaskatchewanTrans Hudson Orogeny, Geochronology
DS1990-0201
1990
Lewry, J.F.Bickford, M.E., Collerson, K.D., Lewry, J.F., Van Schmus, W.R.Proterozoic collisional tectonism in the Trans-Hudsonorogen, SaskatchewanGeology, Vol. 18, No. 1, January pp. 14-18SaskatchewanProterozoic, Tectonics
DS1990-0202
1990
Lewry, J.F.Bickford, M.E., Collerson, K.D., Lewry, J.F., Van Schmus, W.R.Proterozoic collisional tectonism in the Trans-Hudson orogen SaskatchewanGeology, Vol. 18, No. 1, January pp. 14-18SaskatchewanTectonics, Craton, orogeny
DS1990-0345
1990
Lewry, J.F.Collerson, K.D., Lewry, J.F., Bickford, M.E., Van Schmus, W.R.Crustal evolution of the buried Precambrian of southern Saskatchewan:implications for diamond explorationModern Exploration Techniques, editors L.S. Beck, C.T. Harper, Saskatchewan, pp. 150-165SaskatchewanGeochronology, Alkaline rocks -potassic suites
DS1992-0123
1992
Lewry, J.F.Bickford, M.E., Collerson, K.D., Lewry, J.F.Subduction of Superior craton during Trans-Hudson collisional orogenesis:isotopic evidenceEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 322SaskatchewanLithoprobe, Seismic studies
DS1992-1055
1992
Lewry, J.F.Meyer, M.T., Bickford, M.E., Lewry, J.F.The Wathaman batholith: an early Proterozoic continental arc in the Trans-Hudson orogenic belt, CanadaGeological Society of America (GSA) Bulletin, Vol. 104, No. 9, September pp. 1073-1085Saskatchewan, ManitobaGeochemistry, Continental magmatic arc
DS1993-0298
1993
Lewry, J.F.Crocker, C.H., Collerson, K.D., Lewry, J.F.samarium-neodymium (Sm-Nd)-uranium-lead (U-Pb) (U-Pb), rubidium-strontium (Rb-Sr) geochronology and lithostructural relationships in thePrecambrian Research, Vol. 61, No. 1-2, February pp. 27-50Northwest Territories, Saskatchewan, AlbertaGeochronology, Rae Province
DS1993-1524
1993
Lewry, J.F.Stauffer, M.R., Lewry, J.F.Regional setting and kinematic features of the Needle Falls Shear Zone, Trans-Hudson orogenCanadian Journal of Earth Sciences, Vol. 30, No. 7, July, pp. 1338-1354SaskatchewanStructure, Trans-Hudson orogen
DS1994-0156
1994
Lewry, J.F.Bickford, M.E., Collerson, K.D., Lewry, J.F.Crustal history of Rae, Hearne provinces, southwest Canadian Shield: constraints from geochronologic, isotopic dataPrecambrian Research, Vol. 68, No. 1/2, June pp. 1-22SaskatchewanGeochronology, Craton -Rae, Herne
DS1994-0157
1994
Lewry, J.F.Bickford, M.E., Collerson, K.D., Lewry, J.F.Crustal history of the Rae and Hearne provinces, constraints from geochronologic and isotopic data.Precambrian Research, Vol. 68, No. 1-2, June pp. 1-22.SaskatchewanTectonics, Geochronology Rae, Hearne
DS1994-1033
1994
Lewry, J.F.Lewry, J.F., Hajnal, Z., Green, A., et al.Structure of a Paleoproterozoic continent-continent collision zone: a Lithoprobe seismic reflection profileTectonophysics, Vol. 232, pp. 143-160SaskatchewanGeophysics -seismics, lithoprobe, Orogen -Trans Hudson
DS1999-0527
1999
Lewry, J.F.Orrell, S.E., Bickford, M.E., Lewry, J.F.Crustal evolution and age of thermotectonic reworking in the westernhinterland of Trans Hudson Orogen.Precambrian Research, Vol. 95, No. 3-4, May 15, pp. 187-224.SaskatchewanTectonics, geothermometry, Orogen - Trans Hudson
DS2002-1706
2002
Lewry, J.F.White, D.J., Lucas, S.B., Bleeker, W., Hajnal, Z., Lewry, J.F., Zwanzig, H.V.Suture zone geometry along an irregular Paleoproterozoic margin: the Superior boundary zone, Manitoba, Canada.Geology, Vol.30,8,Aug.pp.735-8.ManitobaTectonics
DS200512-0085
2005
Lewry, J.F.Bickford, M.E., Mock, T.D., Collerson, K.D., Lewry, J.F., Steinhart III, W.E.Origin of the Archean Sask Craton and its extent within the Trans-Hudson orogen: evidence Pb Nd isotopic compositions basement rocks, post-orogenic intrusions.Canadian Journal of Earth Sciences, Vol. 42, 4, April pp. 659-684.Canada, SaskatchewanGeochronology
DS1993-0909
1993
Lewtwyle, K.Lewtwyle, K.A girl's best friend... diamond continues to resist efforts at economicsynthesis.Scientific American, Vol. 269, No. 6, December, p. 40-.GlobalEconomics, Diamond synthesis
DS1999-0488
1999
Lexa, J.Molnar, F., Lexa, J., Hedenquist, J.W.Eoithermal mineralization of the Western CarpathiansSociety of Economic Geologists Guidebook, Vol. 31, 260p.Hungary, SlovakiaBook - table of contents, Gold, metallogeny
DS200812-1027
2008
Lexa, O.Schulmann, K., Lexa, O., Stipska, P., Racek, M., Tajcmanova, L., Konpasek, Edel, Peschler, LehmannVertical extension and horizontal channel flow of orogenic lower crust: key exhumation mechanisms in large hot orogens?Journal of Metamorphic Geology, In press availableEurope, MantleGeophysics - bouguer
DS201112-1154
2011
Lexa, O.Zavada, P., Dedecek, P., Mach, K., Lexa, O., Potuzak, M.Emplacement dynamics of phonolite magma into maar-diatreme structures - correlation of field, thermal modeling and AMS analogue modeling data.Journal of Volcanology and Geothermal Research, Vol. 201, 1-4, pp. 210-226.EuropeGeodynamics - not specific to diamonds
DS200412-1938
2004
Ley, L.Strobel, P., Reidel, M., Ristein, J., Ley, L.Surface transfer doping of diamond.Nature, No. 6998, July 22, pp. 439-441.TechnologyDiamond morphology
DS1995-0652
1995
Leybourne, M.I.Goodfellow, W.D., Cecile, M.P., Leybourne, M.I.Geochemistry, petrogenesis and tectonic setting of lower Paleozoic alkalic and ultrapotassic rocks...Canadian Journal of Earth Sciences, Vol. 32, No. 8, Aug. pp. 1226-1254.Yukon, British ColumbiaBasanites, mineral chemistry, Deposit -Porter Puddle, Macmillan, Niddery, Mountain
DS1999-0411
1999
Leybourne, M.I.Leybourne, M.I., Van Wagoner, N., Ayres, L.D.Partial melting of a refractory subducted slab in a Paleoproterozoic islandarc: implications global cyclesGeology, Vol. 27, No. 8, Aug. pp. 731-34.MantleMagma - melting, geochemical, global cycles, Subduction
DS2003-1203
2003
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, M.B., Hamilton, S.M.Geochemistry of groundwater from Jurassic kimberlites in the Kirkland Lake and LakeGeological Survey of Canada Open File, No. 4515, 1 CD 26p. $ 26.00Ontario, Kirkland LakeGeochemistry
DS2003-1204
2003
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, M.B., Hamilton, S.M., RobertsonGroundwater interaction with kimberlites - a geochemical investigation in northeasternExplore ( AEG Newsletter), No. 118, January pp. 1-4.Ontario, Kirkland LakeGeochemistry, Analytical methods and results
DS2003-1205
2003
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, M.B., Hamilton, S.M., RobertsonField procedures and results of groundwater sampling in kimberlite from drillholes in theGeological Survey of Canada Current Research, 9p.Ontario, Kirkland LakeSampling - geomorphology
DS200412-1717
2003
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, M.B., Hamilton, S.M.Geochemistry of groundwater from Jurassic kimberlites in the Kirkland Lake and Lake Timiskaming kimberlite fields northeastern OGeological Survey of Canada Open File, No. 4515, 1 CD 26p. $ 26.00Canada, Ontario, Kirkland LakeGeochemistry
DS200412-1718
2003
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, M.B., Hamilton, S.M., Robertson, K.Field procedures and results of groundwater sampling in kimberlite from drillholes in the Kirkland Lake and Lake Temiskaming areGeological Survey of Canada Current Research, 9p.Canada, Ontario, Kirkland LakeSampling - geomorphology
DS200512-0924
2004
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, B., Sherwood Lollar, B., Hamilton, S.M.Low T serpentinization and the production of hydrogen and methane gas in kimberlites in northeastern Ontario, Canada.Geological Society of America South Central Meeting ABSTRACTS, Vol. 36, 1, p. 28.Canada, Ontario, Kirkland Lake, Lake TemiskamingA4, B30, C14, groundwater interaction
DS200712-0924
2007
Leybourne, M.I.Sader, J.A., Leybourne, M.I., McClenaghan, M.B., Hamilton, S.Low temperature serpentinization processes and kimberlite groundwater signature Kirkland Lake and Lake Timiskaming kimberlite fields: implications diamond exploration.Geochemistry: Exploration, Environment, Analysis, Vol. 7, 1, pp. 3-21.Canada, Ontario, Kirkland Lake, TimiskamingGeochemistry - diamond exploration
DS201610-1911
2016
Leybourne, M.I.Stern, R.J., Leybourne, M.I., Tsujimori, T.Kimberlites and the start of plate tectonics.Geology, Vol. 44, 10, pp. 799-802.MantleKimberlites - age distribution

Abstract: We want to know when plate tectonics began and will consider any important Earth feature that shows significant temporal evolution. Kimberlites, the primary source of diamonds, are rare igneous features. We analyze their distribution throughout Earth history; most are young (?95% are younger than 0.75 Ga), but rare examples are found as far back as the Archean (older than 2.5 Ga). Although there are differing explanations for this age asymmetry (lack of preservation, lack of exposure, fewer mantle plumes, or lack of old thick lithosphere in the Archean and Proterozoic), we suggest that kimberlite eruptions are a consequence of modern-style plate tectonics, in particular subduction of hydrated oceanic crust and sediments deep into the mantle. This recycling since the onset of modern-style plate tectonics ca. 1 Ga has massively increased mantle CO2 and H2O contents, leading to the rapid and explosive ascent of diamond-bearing kimberlite magmas. The age distribution of kimberlites, combined with other large-scale tectonic indicators that are prevalent only in the past ?1 Ga (blueschists, glaucophane-bearing eclogites; coesite- or diamond-bearing ultrahigh-pressure metamorphic rocks; lawsonite-bearing metamorphic rocks; and jadeitites), indicates that plate tectonics, as observed today, has only operated for <25% of Earth history.
DS202001-0027
2019
Leybourne, M.I.Lougheed, H.D., McClenaghan, M.B., Layton-Matthews, D., Leybourne, M.I.Evaluation of single use nylon screened sieves for use with fine grained sediment samples.Geological Survey of Canada, Open File 8613, 13p. PdfGlobalsieves
DS202111-1782
2021
Leybourne, M.I.Sader, J.A., Harrison, A.L., McClenaghan, M.B., Hamilton, S.M., Clark, I.D.Sherwood Lollar, B., Leybourne, M.I.Generation of high-pH groundwaters and H2 gas by groundwater-kimberlite interaction, northeastern Ontario.The Canadian Mineralogist, Vol. 59, pp. 1261-1276. doi:10.3749/canmin.2000048 pdfCanada, Ontariodeposit - Kirkland Lake

Abstract: We report new isotopic data for H2 and CH4 gases and Sr for groundwater collected from Jurassic Kirkland Lake kimberlites in northern Ontario, Canada. Groundwaters interacting with kimberlites have elevated pH (up to 12.4), are reducing (Eh as low as the H2-H2O couple), are dominated by OH? alkalinity, and have non-radiogenic (mantle) 87Sr/86Sr values (?0.706-0.707). Most significantly, the highest pH groundwaters have low Mg, high K/Mg, and are associated with abundant reduced gases (H2 ± CH4). Open system conditions favor higher dissolved inorganic carbon and CH4 production, whereas under closed system conditions low DIC, elevated OH? alkalinity, and H2 production are enhanced. Hydrogen gas is isotopically depleted (?2HH2 = ?771 to ?801‰), which, combined with ?2HH2O, yields geothermometry temperatures of serpentinization of 5-25 °C. Deviation of H2-rich groundwaters (by up to 10‰) from the meteoric water line is consistent with Rayleigh fractionation during reduction of water to H2. Methane is characterized by ?13CCH4 = ?35.8 to ?68‰ and ?2HCH4 = ?434‰. The origin of CH4 is inconclusive and there is evidence to support both biogenic and abiogenic origins. The modeled groundwater-kimberlite reactions and production of elevated concentrations of H2 gas suggest uses for diamond-production tailings, as a source of H2 for fuel cells and as a carbon sink.
DS2003-1206
2003
Leybourne, M.L.Sader, J.A., Leybourne, M.L., McClenaghan, M.B., Hamilton, S.M., RobertsonKimberlite exploration using aqueous geochemistry - a new exploration methodGeological Association of Canada Annual Meeting, Abstract onlyGlobalTechniues - geochemistry
DS200412-1719
2003
Leybourne, M.L.Sader, J.A., Leybourne, M.L., McClenaghan, M.B., Hamilton, S.M., Robertson, K.Kimberlite exploration using aqueous geochemistry - a new exploration method.Geological Association of Canada Annual Meeting, Abstract onlyTechnologyTechniues - geochemistry
DS200912-0005
2008
Leybov, M.B.Anastasenko, G.F., Leybov, M.B.Diamonds of Russia.Rocks and Minerals, Vol. 83, 6, pp. 508-517.RussiaBrief overview
DS201506-0269
2014
Leybov, M.B.Garanin, V.K., Leybov, M.B.Diamonds: a sketch portrait (History of discovery of Russian deposits and their genesis).Mineralogical Almanac, Vol. 19, 1, pp. 30-47.RussiaHistory
DS200712-1247
2007
Leyton, F.Zou, Z., Leyton, F., Koper, K.D.Partial melt in the lowermost mantle near the base of a plume.Journal of Geophysics International, Vol. 168, 2, pp. 809-817.MantleMelting
DS200712-1248
2007
Leyton, F.Zou, Z., Leyton, F., Koper, K.D.Partial melt in the lowermost mantle near the base of the plume.Geophysical Journal International, Vol. 168, 2, pp. 809-817.MantlePlume - melting
DS2003-0667
2003
Lezaeta, P.Jones, A.G., Lezaeta, P., Ferguson, I.J., Chave, A.D., Evans, R.L., Garcia, X.The electrical structure of the Slave CratonLithos, Vol. 71, 2-4, pp. 505-527.Northwest Territories, NunavutGeophysics - seismics
DS200412-0927
2003
Lezaeta, P.Jones, A.G., Lezaeta, P., Ferguson, I.J., Chave, A.D., Evans, R.L., Garcia, X., Spratt, J.The electrical structure of the Slave Craton.Lithos, Vol. 71, 2-4, pp. 505-527.Canada, NunavutGeophysics - seismics
DS200712-0621
2007
Lezaeta, P.Lezaeta, P., Chave, A., Jones, A.G., evans, R.Source field effects in the auroral zone: evidence from the Slave Craton NW Canada.Physics of the Earth and Planetary Interiors, Vol. 164, 1-2, pp. 21-35.Canada, Northwest TerritoriesGeophysics
DS1930-0255
1937
Lezard, A.Lezard, A.The Great Gold Reef. the Romantic History of the Rand Gold FieldsNew York: Bobbs-merrill, 313P.South AfricaKimberley, History, Biography
DS1930-0256
1937
Lezard, A.Lezard, A.The Great Gold ReefNew York: Bobbs Merrill, 313P.South AfricaKimberlite
DS2000-1027
2000
Lezuan, J.Worner, G., Lezuan, J., Wilke, H.G.Precambrian and Early Paleozoic evolution of the Andean basement at and Cerry Uyarani, Altiplano.Journal of South American Earth Sciences, Vol. 13, No. 8, Aug.pp. 717-38.Chile, BoliviaTectonics - not specific to diamonds
DS201112-0695
2011
Lezzi, G.Mollo, S., Vinciguerra, S., Lezzi, G., Iarocci, A., Scarlato, P., Heap, M.J., Dingwell, D.B.Volcanic edifice weakening via devolatization reactions.Geophysical Journal International, In press, availableMantleVolcanism - not specific to diamonds
DS200812-0392
2008
Lgel, A.Geldmacher, J., Hoernle, K., Lgel, A., Van den Bogaard, P., Bindeman, I.Geochemistry of a new enriched mantle type locality in the northern hemisphere: implications for the origin of the EM-I source.Earth and Planetary Science Letters, Vol. 265, 1-2, pp. 167-182.MantleGeophysics - EM
DS201012-0438
2009
L'Heureux, I.L'Heureux, I.Volatile bubble growth in a decompressing magmatic system: a many bubble model.Journal of Geophysical Research, Vol. 114, B12, B12202.MantleMagmatism
DS1991-0160
1991
l'Heureux, M.Bourne, J.H., l'Heureux, M.The petrography and geochemistry of the Clericy Pluton: an ultrapotassic pyroxenite-syenite suite of late Archean age from the Abitibi region, QuebecPrecambrian Research, Vol. 52, No. 1-2, pp. 37-51QuebecUltrapotassic, Geochemistry
DS2003-0800
2003
L'Heureux, M.Letendre, J.P.J., L'Heureux, M., Nowicki, T.E., Creaser, R.The Wemindji kimberlites: exploration and geology8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractQuebecKimberlite geology and economics, Deposit - Wemindji
DS200712-0482
2007
LHou, M-L.Jang, Y-H., Jiang, S-Y., LHou, M-L., Ling, H.F., Zhao, K., Ni, P.Geochemistry of Late Mesozoic lamprophyre dikes from the eastern North Chin a Craton: implications for subcontinental lithosphere evolution.Plates, Plumes, and Paradigms, 1p. abstract p. A445.ChinaLamprophyre
Author Index
A-An Ao+ B-Bd Be-Bk Bl-Bq Br+ C-Cg Ch-Ck Cl+ D-Dd De-Dn Do+ E F-Fn Fo+ G-Gh Gi-Gq Gr+ H-Hd He-Hn Ho+ I J K-Kg Kh-Kn Ko-Kq Kr+ L-Lh
Li+ M-Maq Mar-Mc Md-Mn Mo+ N O P-Pd Pe-Pn Po+ Q R-Rh Ri-Rn Ro+ S-Sd Se-Sh Si-Sm Sn-Ss St+ T-Th Ti+ U V W-Wg Wh+ X Y Z
 
 

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