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SDLRC - Scientific Articles all years by Author - W-Wg


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 - W-Wg
Posted/
Published
AuthorTitleSourceRegionKeywords
DS201812-2848
2018
WMao, W, Zhong, S.Slab stagnation in the transition zone is explained by a thin, weak layer and is transient on timescales of tens or millions of years, according to a global mantle convection model that includes phase changes and plate motion.Nature Geoscience, doi:10.038/s41561-018-0225-2 (pp. 876-881.)Mantleconvection

Abstract: The linear structures of seismically fast anomalies, often interpreted as subducted slabs, in the southern Asia and circum-Pacific lower mantle provided strong evidence for the whole mantle convection model. However, recent seismic studies have consistently shown that subducted slabs are deflected horizontally for large distances in mantle transition zone in the western Pacific and other subduction zones, suggesting that the slabs meet significant resistance to their descending motion and become stagnant in the transition zone. This poses challenges to the whole mantle convection model and also brings the origin of stagnant slabs into question. Here, using a global mantle convection model with realistic spine-post-spinel phase change (-2 MPa K?¹ Clapeyron slope) and plate motion history, we demonstrate that the observed stagnant slabs in the transition zone and other slab structures in the lower mantle can be explained by the presence of a thin, weak layer at the phase change boundary that was suggested by mineral physics and geoid modelling studies. Our study also shows that the stagnant slabs mostly result from subduction in the past 20-30 million years, confirming the transient nature of slab stagnation and phase change dynamics on timescales of tens of millions of years from previous studies.
DS202007-1159
2020
WLi, W, Yang, Z., Chiaradia, M., Yong, L., Caho, Yu., Zhang, J.Redox state of southern Tibetan mantle and ultrapotassic magmas. Lhasa TerraneGeology, Vol. 48, 7, pp. 733-736. pdfAsia, Tibetalkaline rocks

Abstract: The redox state of Earth’s upper mantle in several tectonic settings, such as cratonic mantle, oceanic mantle, and mantle wedges beneath magmatic arcs, has been well documented. In contrast, oxygen fugacity (graphic) data of upper mantle under orogens worldwide are rare, and the mechanism responsible for the mantle graphic condition under orogens is not well constrained. In this study, we investigated the graphic of mantle xenoliths derived from the southern Tibetan lithospheric mantle beneath the Himalayan orogen, and that of postcollisional ultrapotassic volcanic rocks hosting the xenoliths. The graphic of mantle xenoliths ranges from ?FMQ = +0.5 to +1.2 (where ?FMQ is the deviation of log graphic from the fayalite-magnetite-quartz buffer), indicating that the southern Tibetan lithospheric mantle is more oxidized than cratonic and oceanic mantle, and it falls within the typical range of mantle wedge graphic values. Mineralogical evidence suggests that water-rich fluids and sediment melts liberated from both the subducting Neo-Tethyan oceanic slab and perhaps the Indian continental plate could have oxidized the southern Tibetan lithospheric mantle. The graphic conditions of ultrapotassic magmas show a shift toward more oxidized conditions during ascent (from ?FMQ = +0.8 to +3.0). Crustal evolution processes (e.g., fractionation) could influence magmatic graphic, and thus the redox state of mantle-derived magma may not simply represent its mantle source.
DS201412-0957
2014
Waal, A.Waal, A., Orij, Rosman, R., Jantien, Zevenbergen, M.Applicabaility of the high performance organization framework in the diamond industry value chain.Journal of Strategy and Management , Vol. 7, 1, pp. 30-48.GlobalDiamond financial - economics
DS200612-1497
2006
Waanders, F.Waanders, F., Rabatho, J.Recovery of heavy minerals by means of ferrosilicon dense medium separation material.Hyperfine Interactions, Vol. 161, 1-4, Feb. pp. 55-60.TechnologyDMS diamond recovery
DS200612-1498
2006
Waanders, F.Waanders, F., Rabatho, J.Recovery of heavy minerals by means of ferrosilicon dense medium separation material.Hyperfine Interactions, Vol. 161, 1-4, Feb. pp. 55-60.TechnologyMining
DS1997-0130
1997
Waanders, F.B.Brink, M.C., Waanders, F.B., Bischoff, A.A.Vredefort: a model for the anatomy of an astroblemeTectonophysics, Vol. 270, No. 1, 2, Feb. 28, pp. 83-114.South AfricaAstrobleme, Model
DS1987-0413
1987
Wacker, J.F.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
DS1989-0842
1989
Wacker, J.F.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
DS1994-1914
1994
Wacker, J.F.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
DS2001-0494
2001
Wackerle, R.Hutchins, D.G., Wackerle, R.Government funded high resolution airborne geophysical surveys supporting exploration investment in Namibia.Prospectors and Developers Association of Canada (PDAC) 2001, 1p. abstractNamibiaNews item, Brief mention of diamonds
DS2002-0413
2002
Wackerle, R.Eberle, D.G., Andritzkym G., Hutchins, D.G., Wackerle, R.The regional magnetic data set of Namibia: compilation, contributions to crustal studies and support to natural resource management.South African Journal of Geology, Vol. 105, No. 4, pp. 361-80.NamibiaGeophysics - magnetics, Structure
DS200512-1102
2004
Wackerle, R.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
DS1995-2013
1995
Wackernagel, H.Wackernagel, H.Multivariate geostatisticsSpringer Verlag, 220pGlobalGeostatistics -multivariate, Table of contents
DS201702-0226
2016
Waczek, Z.Martin, R.F., Alarie, E., Minarik, W.G., Waczek, Z., McCammon, C.A.Titanium rich magneso-hastingite macrocrysts in a camptonite dike, Lafarge quarry, Montreal Island, Quebec: early crystallization in a pseudo-unary system.The Canadian Mineralogist, Vol. 54, pp. 65-78.Canada, QuebecCamptonite

Abstract: A prominent dike of camptonite cuts the Middle Ordovician Tétreauville Formation of the Trenton Group in the Montréal-Est quarry operated by Lafarge Canada Inc. The “Lafarge” dike is strikingly porphyritic, with largely anhedral macrocrysts of unzoned calcic amphibole up to 13 cm across. The macrocrysts are rimmed with ferri-kaersutite resembling the amphibole in the fine-grained matrix of the camptonite. The magnesio-hastingstite macrocrysts have virtually the same composition as the matrix; they thus grew without much of a boundary layer. The magma crystallized in a disequilibrium way as a pseudo-unary system. The macrocrysts are unusually enriched in Fe3+ (approximately 44% of the total iron), yet locally enclose globules of immiscible sulfide melt. The magma became oxygenated owing to preferential loss of hydrogen upon the dissociation of aqueous gas bubbles. The amygdaloidal macrocrysts have a relatively high dD value because of this loss of H2; the values of d18O are typical of an upper mantle source. Camptonite dikes are very common on Mont Royal. Like the Lafarge dike, they likely arose by the disequilibrium crystallization of batches of the parental melt of asthenospheric origin.
DS1970-0834
1973
Wada, H.Suma, K., Ona, S., Wada, H., Osaki, S.Isotope Geochemistry and Petrology of the African Carbonatites #11st International Kimberlite Conference, EXTENDED ABSTRACT VOLUME, PP. 297-300.South AfricaCarbonatite
DS1975-0198
1975
Wada, H.Suwa, K., Onan, S., Wada, H., Osaki, S.Isotope Geochemistry and Petrology of the African Carbonatites #2Physics and Chemistry of the Earth., Vol. 9, PP. 735-746.South AfricaRelated Rocks
DS200612-0289
2006
Wada, H.Crespo, E., Luque, F.J., Rodas, M., Wada, H., Gervilla, F.Graphite sulphide deposits in Ronda and Beni Bousera peridotites ( Spain and Morocco) and the origin of carbon in mantle derived rocks.Gondwana Research, Vol. 9, 3, pp. 279-290.Europe, Spain, Africa, MoroccoPeridotite
DS201412-0625
2014
Wada, H.Nguyen Thi, T., Wada, H., Ishikawa, T., Shimano, T.Geochemistry and petrogenesis of carbonatites from South Nam Xe, Lai Chau area, northwest Vietnam.Mineralogy and Petrology, Vol. 108, 3, pp. 371-390.Asia, VietnamCarbonatite
DS201412-0929
2014
Wada, H.Thi, T.N., Wada, H., Ishikawa, T., Shimano, T.Geochemistry and petrogenesis of carbonatites from south Nam Xe, Lai Chau area, northwest Vietnam.Mineralogy and Petrology, Vol. 108, pp. 371=390.Asia, VietnamCarbonatite
DS200812-1223
2008
Wada, I.Wada, I., Wang, K., He, J., Hyndman, R.D.Weakening of the subduction surface abd its effects on surface heat flow, slab dehydration, and mantle wedge serpentinization.Journal of Geophysical Research, Vol. 113, B4, B04402MantleSubduction
DS200812-1224
2008
Wada, I.Wada, I., Wang, K., He, J., Hyndman, R.D.Weakening of the subduction interface and its effects on surface heat flow, slab dehydration, and mantle wedge serpentinization.Journal of Geophysical Research, Vol. 113, B04402.MantleSubduction, geothermometry
DS201710-2220
2017
Wada, I.Cerpa, N.G., Wada, I., Wilson, C.R.Fluid migration in the mantle wedge: influence of mineral grain size and mantle compaction.Journal of Geophysical Research: Solid Earth, Vol. 122, 8, pp. 6247-6288.Mantlemineralogy

Abstract: Mineral grain size in the mantle affects fluid migration by controlling mantle permeability; the smaller the grain size, the less permeable the mantle is. Mantle shear viscosity also affects fluid migration by controlling compaction pressure; high mantle shear viscosity can act as a barrier to fluid flow. Here we investigate for the first time their combined effects on fluid migration in the mantle wedge of subduction zones over ranges of subduction parameters and patterns of fluid influx using a 2-D numerical fluid migration model. Our results show that fluids introduced into the mantle wedge beneath the forearc are first dragged downdip by the mantle flow due to small grain size (<1 mm) and high mantle shear viscosity that develop along the base of the mantle wedge. Increasing grain size with depth allows upward fluid migration out of the high shear viscosity layer at subarc depths. Fluids introduced into the mantle wedge at postarc depths migrate upward due to relatively large grain size in the deep mantle wedge, forming secondary fluid pathways behind the arc. Fluids that reach the shallow part of the mantle wedge spread trench-ward due to the combined effect of high mantle shear viscosity and advection by the inflowing mantle and eventually pond at 55-65 km depths. These results show that grain size and mantle shear viscosity together play an important role in focusing fluids beneath the arc.
DS201912-2832
2019
Wada, I.van Keken, P.E., Wada, I., Sime, N., Abers, G.A.Thermal structure of the forearc in subduction zones: a comparison of methodologies.Geochemistry, Geophysics, Geosystems, Vol. 20, pp. 3268-3288.Mantlesubduction

Abstract: Molnar and England (1990, https://doi.org/10.1029/JB095iB04p04833) introduced equations using a semianalytical approach that approximate the thermal structure of the forearc regions in subduction zones. A detailed new comparison with high-resolution finite element models shows that the original equations provide robust predictions and can be improved by a few modifications that follow from the theoretical derivation. The updated approximate equations are shown to be quite accurate for a straight-dipping slab that is warmed by heat flowing from its base and by shear heating at its top. The approximation of radiogenic heating in the crust of the overriding plate is less accurate but the overall effect of this heating mode is small. It is shown that the previous and updated approximate equations become increasingly inaccurate with decreasing thermal parameter and increasing variability of slab dip. It is also shown that the approximate equations cannot be extrapolated accurately past the brittle-ductile transition. Conclusions in a recent paper (Kohn et al., 2018, https://doi.org/10.1073/pnas.1809962115) that modest amount of shear heating can explain the thermal conditions of past subduction from the exhumed metamorphic rock record are invalid due to a number of compounding errors in the application of the Molnar and England (1990, https://doi.org/10.1029/JB095iB04p04833) equations past the brittle-ductile transition. The use of the improved approximate equations is highly recommended provided their limitations are taken into account. For subduction zones with variable dip and/or low thermal parameter finite element modeling is recommended.
DS201412-0445
2014
Wada, K.Kato, T., Kinoshita, Y., Nishiyama, N., Wada, K., Zhou, C., Irifune, T.Magnesium silicate perovskite coexisting with ring woodite in harzburgite stagnated at the lowermost mantle transition zone.Physics and Chemistry of the Earth Parts A,B,C, Vol. 232, pp. 26-29.MantlePerovskite
DS1995-2014
1995
Wada, N.Wada, N., et al.Noble gas isotopic compositions in cubic diamonds: modern mantle component trapped in fluid inclusions.Eos, Vol. 76, No. 46, Nov. 7. p.F643. Abstract.Democratic Republic of CongoDiamond morphology, Geochronology
DS1998-1557
1998
Wada, N.Wada, N., Matsuda, J.I.A noble gas study of cubic diamonds from Zaire: constraints on their mantlesource.Geochimica et Cosmochimica Acta, Vol. 62, No. 13, July pp. 2335-46.GlobalGeochemistry, Cubic diamonds
DS1993-1275
1993
Wadatsumi, K.Raghaven, V., Wadatsumi, K., Masumoto, S.Automatic extraction of lineament information from satellite images using digital eleveation dataNonrenewable Resources, Vol. 2, No. 2, Summer pp. 148-155JapanRemote sensing, Tectonics, structure
DS1993-1369
1993
Wadatsumi, K.Sakamoto, M., Shiono, K., Masumoto, S., Wadatsumi, K.A computerized geologic mapping system based on logical models of geologicstructuresNonrenewable Resources, Vol. 2, No. 2, Summer pp. 140-147GlobalComputer, Program -CIGMA.
DS1920-0198
1924
Wade, A.Wade, A.Petroleum Prospects of the Kimberley District of Western Australia and the Northern Territory.Commonwealth Australia Parl. Paper., Australia, Western AustraliaLeucite, Lamproite
DS1930-0265
1937
Wade, A.Wade, A.The Geological Succession in the West Kimberley District Of western Australia.Australasian Association Advanced Science, Vol. 23, P. 93.Australia, Western AustraliaLeucite, Lamproite
DS1930-0287
1938
Wade, A.Wade, A., Prider, R.T.The Geology and Petrology of the Kimberley District, Western Australia.British Association Advanced Science Report of The 108th. Meeting Held In, P. 419.Australia, Western AustraliaLeucite, Lamproite
DS1940-0019
1940
Wade, A.Wade, A., Prider, R.T.The Leucite Bearing Rocks of the West Kimberley Area, Western Australia.Quarterly Journal of Geological Society (London), Vol. 96, PT. 1, PP. 39-98.Australia, Western AustraliaLeucite, Lamproite, Fitzroyite, Wolgidite, Cedricite, Mamilite
DS1910-0444
1914
Wade, F.B.Wade, F.B.Diamonds, a Study of the Factors That Govern their ValueNew York: Putnams, XEROX.GlobalKimberlite, Kimberley, Janlib, Diamond
DS1910-0562
1918
Wade, F.B.Wade, F.B.A Textbook of Precious Stones for the Jewellers and the Gem loving Public.New York: Putnam's., 318P., ILLUS.GlobalKimberlite, Kimberley, Janlib, Gemology
DS1940-0223
1949
Wade, F.B.Wade, F.B.Another Rough Diamond Found in IndianaGems And Gemology, Vol. 6, No. 8, PP. 249-250.United States, Indiana, Great LakesDiamond Occurrences
DS200512-1158
2005
Wade, J.Wade, J., Wood, B.J.Core formation and the oxidation state of the Earth.Earth and Planetary Science Letters, Advanced in press,MantleAccretion, metal-silicate, perovskite
DS200612-1541
2006
Wade, J.Wood, B.J., Walter, M.J., Wade, J.Accretion of the Earth and segregation of its core.Nature, Vol. 441, June 15, pp. 825-833.MantleSilicate, magma ocean
DS200812-1262
2008
Wade, J.Wood, B.J., Wade, J., Kilburn, M.R.Core formation and the oxidation state of the Earth: additional constraints from Nb, V, Cr partitioning.Geochimica et Cosmochimca Acta, Vol. 72, 5, March 1, pp. 1415-1426.MantleAccretion
DS201212-0783
2012
Wade, J.Williams, H.M., Wood, B.J., Wade, J., Frost, D.J., Tuff, J.Isotopic evidence for internal oxidation of the Earth's mantle during accretion.Earth and Planetary Science Letters, Vol. 321-322, pp. 54-63.MantleAccretion
DS1982-0624
1982
Wade, W.Wade, W.Kimberlite Intrusions on Somerset Island, Northwest Territories: a petrographic Comparison with Local and Regional Structural Control.Bsc. Thesis, Brock University, 60P.Canada, Northwest TerritoriesTectonics
DS1992-1615
1992
Wadge, G.Wadge, G., Young, A.V., Mason, D.C.Simulation of geological processes using an expert systemJournal of Geology Society of London, Vol. 149, No. 3, May pp. 455-464GlobalComputers, Expert system
DS1940-0091
1944
Wadia, D.N.Wadia, D.N.Geology of IndiaMacmillan And Co. Ltd., PP. 90-99; PP. 355-357.IndiaDiamond Occurrences
DS202007-1144
2020
Wadsworth, F.B.Haddock, D., Manya, S., Brown, R.J., Jones, T.J., Wadsworth, F.B., Dobson, K.J., Gernon, T.M.Syn-eruptive agglutination of kimberlite volcanic ash. PyroclastsVolcanica, Vol. 3, 1, pp. 169-182. PdfAfrica, Tanzaniadeposit - Igwisi Hills

Abstract: Pyroclastic deposits of the Holocene Igwisi Hills kimberlite volcanoes, Tanzania, preserve unequivocal evidence for rapid, syn-eruptive agglutination. The unusual pyroclasts are composed of ash-sized particles agglutinated to each other by thin necks. The textures suggest the magma was disrupted into droplets during ascent. Collisions between particles occurred within a volcanic plume and on deposition within the conduit to form a weakly agglutinated, porous pyroclastic deposit. Theoretical considerations indicate that agglutination occurred over short timescales. Agglutinated clasts were entrained into weak volcanic plumes and deposited around the craters. Our results support the notion that agglutination can occur during kimberlite eruptions, and that some coherent, dense rocks in ancient kimberlite pipes interpreted as intrusive rocks could instead represent agglutinated pyroclastic rocks. Differentiating between agglutinated pyroclastic rocks and effusive or intrusive rocks in kimberlite pipes is important because of the potential effects that pyroclastic processes might have on diamond concentrations in deposits.
DS202011-2040
2020
Wadsworth, F.B.Haddock, D., Manya, S., Brown, R.J., Jones, T.J., Wadsworth, F.B., Dobson, K.J., Gernon, T.M.Syn-eruptive agglutination of kimberlite volcanic ash.Volcanica, 15p. PdfAfrica, Tanzaniadeposit - Igwisi Hills kimberlite

Abstract: Pyroclastic deposits of the Holocene Igwisi Hills kimberlite volcanoes, Tanzania, preserve unequivocal evidence for rapid, syn-eruptive agglutination. The unusual pyroclasts are composed of ash-sized particles agglutinated to each other by thin necks. The textures suggest the magma was disrupted into droplets during ascent. Collisions between particles occurred within a volcanic plume and on deposition within the conduit to form a weakly agglutinated, porous pyroclastic deposit. Theoretical considerations indicate that agglutination occurred over short timescales. Agglutinated clasts were entrained into weak volcanic plumes and deposited around the craters. Our results support the notion that agglutination can occur during kimberlite eruptions, and that some coherent, dense rocks in ancient kimberlite pipes interpreted as intrusive rocks could instead represent agglutinated pyroclastic rocks. Differentiating between agglutinated pyroclastic rocks and effusive or intrusive rocks in kimberlite pipes is important because of the potential effects that pyroclastic processes might have on diamond concentrations in deposits.
DS1983-0328
1983
Waenke, H.Jagoutz, E., Spettel, B., Waenke, H., Dawson, B.Identification of Early Differentiation Processes on the Earth.Meteoritics, Vol. 18, No. 4, PP. 319-320. (abstract.).GlobalGeochemistry, Kimberlite, Ultramafics
DS1984-0375
1984
Waenke, H.Jagoutz, E., Dawson, J.B., Hoernes, S., Spettel, B., Waenke, H.Anorthositic Oceanic Crust in the Archean EarthLunar and Planetary Science Conference 15th. Abstract Volume, Vol. 15, pp. 395-396GlobalAnorthosite
DS2001-0826
2001
Waerenborgh, J.C.Nasraqui, M., Waerenborgh, J.C.Iron speciation in weathered pyrochlores by iron Mossbauer spectroscopyJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 26. (abs)Brazil, Democratic Republic of CongoCarbonatite, Leushe, Araxa Complexes
DS2002-1677
2002
Waerenborgh, J.C.Waerenborgh, J.C., Figueoras, J., Mateus, Goncalves57Fe Mossbauer spectroscopy study of the correlation between Fe3+content and magnetic properties Cr spinelsEuropean Journal of Mineralogy, Vol.14,2,pp.437-46.GlobalSpectroscopy, Chrome spinels
DS2001-0825
2001
Waerenborogh, J.C.Nasraoui, M., Waerenborogh, J.C.iron speciation in weathered pyrochlore group minerals from Lueshe and Araxa Barreiro carbonatites-Canadian Mineralogist, Vol. 39, No. 4, Aug. pp.1073-80.Brazil, Democratic Republic of CongoSpectroscopy - weathering
DS201607-1299
2016
Wafik, A.Hajjar, Z., Wafik, A., Constantin, M., Bhilisse, M.Process of serpentinization in the ultramafic massif of Beni Bousera ( internal Rift, Morocco).Arabian Journal of Geosciences, Vol. 9, availableAfrica, MoroccoPeridotite
DS200512-0305
2005
Waggett, R.G.Fritsch, E., Moore, M., Rondeau, B., Waggett, R.G.X-ray topography of a natural twinned diamond of unusual pseudo-tetrahedral morphology.Journal of Crystal Growth, Vol. 280, 1-2, pp. 279-285.Diamond morphology
DS1990-1527
1990
Waggoner, J.Waggoner, J.GE produces a better diamondPhoton. Spec, Vol. 24, No. 8, August p. 34-GlobalDiamond, Synthetic diamond
DS2001-0331
2001
WagnerFranz, L., Romer, Klemd, Schmid, Oberhansli, WagnerEclogite facies quartz veins within metabasites of the Dabie Shan: P T time deformation path... fluid phase..Contributions to Mineralogy and Petrology, Vol. 141, No. 3, June, pp. 322-46.Chinaultra high pressure (UHP) - fluid flow, melting, exhumation
DS201712-2734
2017
Wagner, A.Wagner, A.Everything you ever wanted to know about perovskite, Earth's most abundant type of mineral - that we almost never see.Sciencemag.org, Nov. 17, videoTechnologyperovskite

Abstract: Perovskite is one of the most common crystal structures on the planet, but why is it so interesting to researchers from many scientific disciplines? Science looks into the properties of this odd cube of atoms, and what cutting-edge research is being performed on its many varieties.
DS201412-1024
2014
Wagner, A.J.Zhang, L., Meng, Y., Yang, W.,Wang, L., Mao, W.L., Zeng, Q-S., Jeong, J.S., Wagner, A.J., Mkhoyan, K.A., Liu, W., Xu, R., Mao, H-K.Disproportionation of (Mg,Fe) SiO3 perovskite in Earth's deep lower mantle.Science, Vol. 344, no. 6186, pp. 877-882.MantlePerovskite
DS1983-0625
1983
Wagner, C.Wagner, C.Phlogopite and richterite mineral asemblages in potassic hyperalkalinerocks.(in French)Ph.D. University of Paris 6, (in French), 145pMontanaUtah, Minette
DS1985-0706
1985
Wagner, C.Wagner, C., Velde, D.Mineralogy of two peralkaline, afrvedsonite bearing minettes; a new occurrence on zn rich chromiteBulletin. de Mineralogie, Vol. 108, No. 2, pp. 173-187GlobalMinette
DS1985-0707
1985
Wagner, C.Wagner, C., Velde, D.Mineralogy of 2 Peralkaline, Arfvedsonite-bearing Minettes-a New Occurrence of Zn Rich Chromite.Bulletin. MINERALOGIQUE., Vol. 108, No. 2, PP. 173-187.GlobalMinette
DS1986-0848
1986
Wagner, C.Wagner, C.Mineralogy of the type kyanite from Kalimantan similarities and differences with typical lamproitesBulletin. Mineralogie, Vol. 109, No. 5, pp. 589-598GlobalLamproites
DS1986-0849
1986
Wagner, C.Wagner, C.Mineralogy of the type Kajanite from Kalimantan simularities and differences with typical lamproitesBulletin. Mineralogie, Vol. 109, pp. 589-598GlobalLamproites, Mineralogy
DS1986-0850
1986
Wagner, C.Wagner, C., Velde, D.The mineralogy of K richterite bearing lamproites. A reviewAmerican Mineralogist, Vol. 71, No. 1-2, Jan-Feb. pp. 17-37GlobalAustralia, Lamproite
DS1986-0851
1986
Wagner, C.Wagner, C., Velde, D.Lamproites in north Vietnam- a re-examination of coecites(technicalnote)Journal of Geology, Vol. 94, No. 5, September pp. 770-776GlobalLamproite
DS1986-0852
1986
Wagner, C.Wagner, C., Velde, D.Davanite K2TiSi6O15 in the Smoky Butte lamproitesAmerican Mineralogist, Vol. 71, pp. 1473-1475MontanaLamproites, Mineralogy
DS1987-0773
1987
Wagner, C.Wagner, C., Velde, D.Aluminous spinels in lamproites: occurrence and probable significanceAmerican Mineralogist, Vol. 72, No. 7-8, pp. 689-696GlobalLamproite, Mica
DS1987-0774
1987
Wagner, C.Wagner, C., Velde, D., Mokhtari, A.Sector zones phlogopites in igneous rocksContributions to Mineralogy and Petrology, Vol. 96, pp. 186-191UtahShonkinite, Melilitite
DS1987-0775
1987
Wagner, C.Wagner, C., Velde, D., Mokhtari, A.Sector zoned phlogopites in igneous rocksContributions to Mineralogy and Petrology, Vol. 96, No.2, pp. 186-191UtahSmith Morehouse Canyon, Melilitite
DS1989-1548
1989
Wagner, C.Velde, D., Medenbach, O., Wagner, C., Schreyer, W.Chayesite, K(Mg,Fe2+)4 Fe3+[Si12)30American Mineralogist, Vol. 74, No. 11, 12 November-December, pp. 1368-1373UtahLamproite, chaysite, osumilite group, Chayesite -Moon Canyon, magnesium silicate
DS1993-1686
1993
Wagner, C.Wagner, C., Mokhtari, A., Velde, D.Xenocrystic richterite in an olivine nephelinite -destabilization and diffusion phenomena.Mineralogical Magazine, Vol. 57, No. 388, September pp. 515-525.GlobalMineralogy, Nephelinite
DS1993-1687
1993
Wagner, C.Wagner, C., Velde, D.Paleozoic olivine-bearing lamprophyre from the Couy (Cher, France)borehole. Mineral composition and alteration phenomena.European Journal of Mineralogy, Vol. 5, pp. 85-96.FranceLamprophyre, Olivine
DS1996-0986
1996
Wagner, C.Mokhtari, A., Wagner, C., Velde, D.Decouverte d'une enclave de carbonatite dans une camptonite de la region deTaourirt, northeast Maroc.C.r. Academy Of Science Paris, Vol. 323, 11a pp. 467-474.MoroccoCarbonatite, Camptonite
DS2003-1436
2003
Wagner, C.Wagner, C., Mokhtari, A., Deloule, E., Chabaux, F.Carbonatite and alkaline magmatism in Taourirt: petrological, geochemical and Sr NdJournal of Petrology, Vol. 44, 5, pp. 937-65.MoroccoCarbonatite
DS200412-2068
2003
Wagner, C.Wagner, C., Mokhtari, A., Deloule, E., Chabaux, F.Carbonatite and alkaline magmatism in Taourirt: petrological, geochemical and Sr Nd isotope characteristics.Journal of Petrology, Vol. 44, 5, pp. 937-65.Africa, MoroccoCarbonatite
DS200612-1154
2005
Wagner, C.Reisberg, L., Zhi, X., Lorand, J.P., Wagner, C., Peng, Z., Zimmermann, C.Re Os S systematics of spinel peridotite xenoliths from east central China: evidence for contrasting effects of melt percolation.Earth and Planetary Science Letters, Vol. 239, 3-4, pp. 286-308.ChinaGeochronology
DS200712-1126
2007
Wagner, C.Wagner, C., Deloule, E.Behaviour of Li and its isotopes during metasomatism of French Massif Central lherzolites.Geochimica et Cosmochimica Acta, Vol. 71, 17 Sept. 1, pp. 4279-4296.Europe, FranceMetasomatism
DS200812-1225
2008
Wagner, C.Wagner, C., Fialin, M.Xenolith glasses: a key to deciphering mantle processes.Goldschmidt Conference 2008, Abstract p.A990.Europe, FranceMassif Central
DS1989-1568
1989
Wagner, C.L.Wagner, C.L., Howarth, P.J., Singhroy, V.H.A spectral geobotanical study at Natal Lake, northern OntarioInternational Journal of Remote Sensing, Vol. 10, No. 11, November pp. 1721-1734OntarioGeobotany, Remote sensing
DS1997-1217
1997
Wagner, D.Wagner, D.Private sector political risk insurance. Presentation by Global Political Risks Lambert Fenchurch Group.Miga Conference Held Denver June 3-5, 23p.AfricaMining, not specific to diamonds, Security
DS1997-1218
1997
Wagner, D.Wagner, D.Private sector political risk indurance. Presentation by Global Political Risks Lambert Fenchurch GroupMiga Conference Held Denver June 3-5, 23pAfricaMining, Security, country risk
DS1991-1916
1991
Wagner, F.E.Yvon, J., Marion, P., Michot, L., Villieras, F., Wagner, F.E.Development of mineralogy applications in mineral processingEur. Journal of Mineral, Vol. 3, No. 4, pp. 667-676GlobalMineral processing, overview
DS2003-0834
2003
Wagner, G.A.Liu, S., Li, X., Fu, H., Wagner, G.A.The characteristics of ESR and 3-D TL spectra of diamondsNuclear Techniques, Vol. 26, 1, pp. 28-31.GlobalDiamond morphology
DS1975-0647
1977
Wagner, G.H.Wagner, G.H., Steele, K.F.The Chemical Composition of Carbonatite in Conway and Perry counties of Arkansaw.Arkansaw Academy of Science Proceedings, Vol. 31, PP. 121-123.United States, Gulf Coast, Arkansas, Conway County, PennsylvaniaPetrology
DS1975-0888
1978
Wagner, G.H.Wagner, G.H., Honig, R.H., Jones, M.D.Geochemistry of a Carbonatite in Montgomery County, ArkansawArkansaw Academy of Science Proceedings, Vol. 32, PP. 93-94.United States, Gulf Coast, Arkansas, PennsylvaniaGeochemistry
DS1975-1233
1979
Wagner, G.H.Steele, K.F., Wagner, G.H.Relationship of the Murfreesboro Kimberlite and Other Igneous Rocks of Arkansaw.International Kimberlite Conference SECOND Proceedings, Vol. 1, PP. 393-399.United States, Gulf Coast, Arkansas, Pennsylvania, OklahomaPetrology
DS1970-0291
1971
Wagner, H.C.Franks, P.C., Bickford, M.E., Wagner, H.C.Metamorphism of Precambrian Granitic Xenoliths in a Mica Peridotite at Rose Dome, Woodson County, Kansas. Pt. 2 Petrologic and Mineralogic Studies.Geological Society of America (GSA) Bulletin., Vol. 82, No. 10, PP. 2869-2889.United States, Kansas, Central StatesBlank
DS200912-0802
2008
Wagner, L.B.Wagner, L.B., Anderson, M.L., Jackson, J.M., Beck, S.L., Zandt,G.Seismic evidence for orthopyroxene enrichment in the continental lithosphere.Geology, Vol. 36, 12, Dec. pp. 936=938.MantleGeophysics - seismics
DS201601-0015
2015
Wagner, L.S.Eakin, C.M., Long, M.D., Scire, A., Beck, S.L., Wagner, L.S., Zandt, G., Tavera, H.Internal deformation of the subducted Nazca slab inferred from seismic anisotropy. ..new study suggests that the Earth's rigid tectonic plates stay strong when they slide under another plate, known as subduction, may not be universal.Nature Geoscience, 10.1038/ngeo2592MantleSubduction
DS201702-0215
2016
Wagner, L.S.Hopper, E., Fischer, K.M., Rondenay, S., Hawman, R.B., Wagner, L.S.Imaging crustal structure beneath the southern Appalachians with wavefield migration.Geophysical Research Letters, Vol. 43, 23, pp. 12,054-62.United StatesGeophysics - seismics

Abstract: To constrain crustal structures in the southern Appalachians and the suture zone with the Gondwanan-affinity Suwannee terrane, we applied the 2-D generalized Radon transform wavefield migration method to the scattered incident P wavefield recorded by the EarthScope Southeastern Suture of the Appalachian Margin Experiment and adjacent Transportable Array stations. We resolve the root of thickened crust beneath the high topography of the Blue Ridge Mountains and estimate its density contrast with the mantle to be only 104?±?20?kg/m3. A weak velocity contrast across the crustal root Moho is observed and may be related to an ongoing crustal delamination event, possibly contributing to local tectonic rejuvenation. Beneath the Suwannee terrane, we confirm prior observations of a gently south-southeastward dipping crustal suture, indicating the terminal collision of Laurentia and Gondwana involved several hundred kilometers of overthrusting.
DS1900-0807
1909
Wagner, P.A.Wagner, P.A.Studien an den Diamant fuehrenden Gesteinen SuedafrikasFreiburg: Ph. D. Thesis, Ing. Koning, Hochschule., 132P.Africa, South AfricaMining Geology, Kimberlite, Mineralogy, Petrology
DS1900-0808
1909
Wagner, P.A.Wagner, P.A.Die Diamant fuehrenden Gesteine Suedafrikas, Ihr Abbau und Ihre Aufbereitung.Berlin: Borntraeger., 207P.Africa, South AfricaMining Geology, Kimberlite, Mineralogy, Petrology
DS1900-0809
1909
Wagner, P.A.Wagner, P.A.Ueber Skelett formigen Apatit Aus Dem Kimberlit der de Beersgrube.Zentrall Bl. Min.(stuttgart), PP. 550-552.Africa, South AfricaMineralogy
DS1910-0110
1910
Wagner, P.A.Wagner, P.A.Reply to the Discussion of Wagner's Paper on "the Origin Of german Southwest Africa Diamonds".Geological Society of South Africa Proceedings, Vol. 13, PP. XLIII-XLVII.Southwest Africa, NamibiaDiamond Genesis, Marine Diamond Placers
DS1910-0111
1910
Wagner, P.A.Wagner, P.A.The Origin of the German Southwest Africa DiamondsGeological Society of South Africa Transactions, Vol. 13, PP. XLVI-XLVII. ALSO: Mining Engineering Journal of South Africa, VOSouthwest Africa, NamibiaDiamond Genesis, Marine Diamond Placers
DS1910-0222
1911
Wagner, P.A.Wagner, P.A.Petrography of the Premier Kimberlite. I. a Microscopic And chemical Study of the Rock- Varieties of Blue Ground in The mine and Some Interesting Analytical Results.Mining Engineering Journal of South Africa, Vol. 9, PT. 1, JULY 15TH. No. 436, PP. 819-820.BrazilPetrography, Kimberlite Genesis
DS1910-0223
1911
Wagner, P.A.Wagner, P.A.Petrography of the Premier Kimberlite. Pt. ISth, Afr. Min. Journal, Vol. 9, PT. 1, JULY 13TH. PP. 819-820.South AfricaPetrography, Kimberlite Genesis
DS1910-0224
1911
Wagner, P.A.Wagner, P.A.Petrography of the Premier Kimberlite. Ii. the Nodular Inclusions in the Blue Ground- an Interesting Graphite Bearing Specimen and the Problem of the Genetic Relationship.Mining Engineering Journal of South Africa, Vol. 9, PT. 1, JULY 22ND. No. 437, PP. 857-858.South AfricaPetrography, Kimberlite Genesis
DS1910-0225
1911
Wagner, P.A.Wagner, P.A.Petrography of the Premier Kimberlite. Iii. Later Intrusions in the Blue Ground- Dykes of Residual Magma and Some Fusion Experiments.South African Mining Journal, Vol. 9, PT. 1, JULY 29TH. No. 438, P. 902.South AfricaPetrography, Kimberlite Genesis
DS1910-0226
1911
Wagner, P.A.Wagner, P.A.Petrographical Notes on the Kimberlite Occurrences in Pretoria District. Part I #2Geological Society of South Africa Transactions, Vol. 14, PP. 43-46.South Africa, TransvaalPetrology, Kimberlite Mines And Deposits
DS1910-0227
1911
Wagner, P.A.Wagner, P.A.Petrographical Notes on the Kimberlite Occurrences in Pretoria District. Part I #1Mining Engineering Journal of South Africa, Vol. 9, PT. 1, JULY 15TH. PP. 819-820.South Africa, TransvaalPetrology, Kimberlite Mines And Deposits
DS1910-0445
1914
Wagner, P.A.Wagner, P.A.The Evidence of the Kimberlite Pipes on the Constitution Of the Outer Part of the Earth (1914)South African Journal of Science, Vol. 25, PP. 127-248.South AfricaGenesis
DS1910-0446
1914
Wagner, P.A.Wagner, P.A.The Diamond Fields of Southern AfricaJohannesburg: Transvaal Leader, Reprint 1971, 355P.South Africa, Southwest Africa, NamibiaKimberlite, Kimberley, Janlib, Diamond, Geology, Regional
DS1910-0447
1914
Wagner, P.A.Wagner, P.A.Note on Graphite Coated Diamonds from the Premier MineGeological Society of South Africa Transactions, Vol. 17, PP. 29-30. ALSO: Mining Engineering Journal of South Africa, Vol. 23South Africa, TransvaalCrystallography, Black Diamond
DS1910-0512
1916
Wagner, P.A.Wagner, P.A.Discussion on Diamonds Exhibited from the Simmer DeepGeological Society of South Africa Proceedings, Vol. 19, P. XXXVIII.South AfricaDiamonds From Precambrian Conglomerate
DS1910-0513
1916
Wagner, P.A.Wagner, P.A.Discussion on the Paper by Schwarz Entitled Diamonds from The Molteno Beds. #1Geological Society of South Africa Proceedings, Vol. 19, P. XLI.South Africa, Cape ProvinceAlluvial Diamond Placers
DS1910-0514
1916
Wagner, P.A.Wagner, P.A.Graphite Bearing Xenoliths from the Jagersfontein Diamond MineGeological Society of South Africa Transactions, Vol. 19, PP. 54-56.South Africa, Orange Free StateXenoliths, Eclogite
DS1910-0515
1916
Wagner, P.A.Wagner, P.A.The Geology and Mineral Industry of Southwest AfricaGeological Survey of South Africa, MEMOIR No. 7, 119P.South Africa, Southwest Africa, NamibiaDiamonds, Mineral Resources, Kimberley Littoral Diamond Placers
DS1910-0516
1916
Wagner, P.A.Wagner, P.A.The Kameelfontein Diamond DiggingSouth African Mining Journal, Vol. 25, PT. 2, JULY 15TH. No. 1294, PP. 359-360.South Africa, TransvaalAlluvial Diamond Placers
DS1910-0545
1917
Wagner, P.A.Wagner, P.A.Some Problems in South African GeologySth. Afr. Geological Society Proceedings, Vol. 20, PP. XIX-XXXIX. ALSO: South African Mining Journal Vol.South AfricaGenesis Of Diamond, Origin
DS1910-0546
1917
Wagner, P.A.Wagner, P.A.The Orange River Diamond FieldsSouth African Mining Journal, Vol. 26, PT. 1, No. 1325; Vol. 26, PT. 2, Feb. 17TH. PP. 564South Africa, Cape ProvinceAlluvial Diamond Placers, Geology
DS1920-0052
1920
Wagner, P.A.Wagner, P.A.Notes on the Volcanic Origin of the Saltpan on the Farm Zoutpan.Geological Society of South Africa Transactions, Vol. 23, PP. 52-58.; ALSO: Geological Society of South Africa Proceedings, Vol.South Africa, TransvaalAlkaline Related Rocks
DS1920-0092
1921
Wagner, P.A.Wagner, P.A.Note on the Kimberlite from the Belgian CongoSouth African Journal of Science, Vol. 10, PT. 1, PP. 179-191.Democratic Republic of Congo, Central AfricaPetrology, Kimberlite Mines And Deposits
DS1920-0120
1922
Wagner, P.A.Wagner, P.A.A Remarkable Rock from the Pretoria SaltpanGeological Society of South Africa Transactions, Vol. 25, PP. 101-106.South Africa, TransvaalAlkaline And Related Rocks
DS1920-0121
1922
Wagner, P.A.Wagner, P.A.The Pretoria Saltpan, a Soda CalderaGeological Survey of South Africa, MEMOIR No. 20, 136P.South Africa, TransvaalAlkaline And Related Rocks, Kimberley
DS1920-0199
1924
Wagner, P.A.Wagner, P.A.The Diamond Industry of Southern AfricaMining Engineering Journal of South Africa, YEARBOOK, PP. 6-9.South AfricaGeology, Mining
DS1920-0200
1924
Wagner, P.A.Wagner, P.A.The Pretoria Saltpan RevisitedSouth African Journal of IND., Vol. 7, PP. 19-21.South Africa, TransvaalAlkaline And Related Rocks
DS1920-0307
1926
Wagner, P.A.Wagner, P.A.Note on Kimberlite from Tanganyika TerritorySouth African Journal of Science, Vol. 23, PP. 204-205.Tanzania, East AfricaPetrology, Kimberlite Mines And Deposits
DS1920-0352
1927
Wagner, P.A.Wagner, P.A.Industrial Development in South AfricaJohannesburg:, South AfricaMineral Resources, Kimberley
DS1920-0353
1927
Wagner, P.A.Wagner, P.A.The Pipe Form of Ore DepositEconomic Geology, Vol. 22, PP. 740-741.South Africa, GlobalGeology
DS1920-0410
1928
Wagner, P.A.Wagner, P.A.The Evidence of the Kimberlite Pipes on the Constitution Of the Outer Part of the Earth (1928)South African Journal of Science, Vol. 25, PP. 127-148.South AfricaGeology, Upper Mantle, Kimberlite Mines And Deposits, Petrology
DS1920-0411
1928
Wagner, P.A.Wagner, P.A., Merensky, H.The Diamond Deposits on the Coast of Little NamaqualandGeological Society of South Africa Transactions, Vol. 31, PP. 1-41.South AfricaMarine Diamond Placers
DS1920-0412
1928
Wagner, P.A.Wagner, P.A., Merensky, H.Namaqualand Coastal DiamondsMining Engineering Journal of South Africa, Vol. 39, PT. 1, No. 1911, PP. 285-286; PT. 1, No. 1912, PP.South AfricaMarine Diamond Placers, Diamond Genesis
DS1920-0442
1929
Wagner, P.A.Dutoit, A.L., Rogers, A.W., Wagner, P.A.Kimberley (1929)International Geological Congress 15TH., GUIDEBOOK EXCURSION., No. AC., 34P.South Africa, Cape Province, Kimberley AreaGuidebook
DS1920-0465
1929
Wagner, P.A.Rogers, A.W., Hall, A.L., Wagner, P.A., Haughton, S.H.The Union of South AfricaHeidelberg: C. Winters Universitaetsbuchhandlung, 232P.South AfricaRegional Geology, Kimberley
DS1920-0472
1929
Wagner, P.A.Wagner, P.A.Volcanic Pipes Younger Than the Drakensberg Lavas and the Karroo Dolerites.In: Handbuch Der Regionaten Geologie Union Suedafrikas., Vol. 7, PT. 7A, PP. 148-158.South AfricaDiamonds
DS1920-0473
1929
Wagner, P.A.Wagner, P.A.Guidebook to ExcursionsInternational Geological Congress 15TH., SEE CONTENTSSouth AfricaKimberlite Mines And Deposits, Premier
DS1930-0044
1930
Wagner, P.A.Wagner, P.A., Reinecke, L.Mineral Deposits of the Union of South AfricaCommonwealth Min. Met. Congress 3rd., 310P.South AfricaKimberley, History, Geology
DS1970-0445
1971
Wagner, P.A.Wagner, P.A.The Diamond Fields of South Africa (1971)Cape Town: Struik, 355P.South AfricaGeology, Kimberley
DS1910-0112
1910
Wagner, R.E.Wagner, R.E.Diamond Reported in Northern OntarioLetter To Tiffany And Co., Canada, OntarioBlank
DS2001-1210
2001
Wagner, T.Wagner, T., Pletsch, T.No major thermal event on the mid-Cretaceous Cote d'Ivorie Ghana transform marginTerra Nova, Vol. 13, pp. 165-71.Ivory Coast, GhanaGeothermometry
DS200612-0355
2006
Wagner, T.Druppel, K., Wagner, T., Boyce, A.J.Evolution of sulfide mineralization in ferrocarbonatite, Swartbooisdiff, northwestern Namibia: constraints from mineral composition and sulfur isotopeCanadian Mineralogist, Vol. 44, 4, August pp. 877-894.Africa, NamibiaCarbonatite
DS201811-2602
2018
Wagner, T.Ranta, E., Stockmann, G., Wagner, T., Fusswinkel, T., Sturkell, E., Tollefsen, E., Skelton, A.Fluid-rock reactions in the 1.3 Ga siderite carbonatite of the Gronnedal-Ika alkaline complex, southwest Greenland.Contributions to Mineralogy and Petrology, Vol. 173, 26p. Doi.org/10.1007/s00410-018-1505-yEurope, Greenlandcarbonatite

Abstract: Petrogenetic studies of carbonatites are challenging, because carbonatite mineral assemblages and mineral chemistry typically reflect both variable pressure-temperature conditions during crystallization and fluid-rock interaction caused by magmatic-hydrothermal fluids. However, this complexity results in recognizable alteration textures and trace-element signatures in the mineral archive that can be used to reconstruct the magmatic evolution and fluid-rock interaction history of carbonatites. We present new LA-ICP-MS trace-element data for magnetite, calcite, siderite, and ankerite-dolomite-kutnohorite from the iron-rich carbonatites of the 1.3 Ga Grønnedal-Íka alkaline complex, Southwest Greenland. We use these data, in combination with detailed cathodoluminescence imaging, to identify magmatic and secondary geochemical fingerprints preserved in these minerals. The chemical and textural gradients show that a 55 m-thick basaltic dike that crosscuts the carbonatite intrusion has acted as the pathway for hydrothermal fluids enriched in F and CO2, which have caused mobilization of the LREEs, Nb, Ta, Ba, Sr, Mn, and P. These fluids reacted with and altered the composition of the surrounding carbonatites up to a distance of 40 m from the dike contact and caused formation of magnetite through oxidation of siderite. Our results can be used for discrimination between primary magmatic minerals and later alteration-related assemblages in carbonatites in general, which can lead to a better understanding of how these rare rocks are formed. Our data provide evidence that siderite-bearing ferrocarbonatites can form during late stages of calciocarbonatitic magma evolution.
DS1993-1262
1993
Wahab, A.Prijosoesilo, P., Sunarya, Y., Wahab, A.Recent progress of geological investigations in IndonesiaJournal of Southeast Asian Earth Sciences, Vol. 8, No. 104, pp. 5-23.IndonesiaMining, Mineral resources -0verview
DS1995-2015
1995
Wahl, J.L.Wahl, J.L.The geoscience networkProspectors and Developers Association of Canada (PDAC) Reprint, 7pCanadaMining, Communications
DS201708-1657
2017
Wahl, R.Campebll, D., Puumala, M., Eichenberg, D., Riemer, W., Wahl, R.Diamond field trip Marathon-White Ricer area. Guidebook, 15p. Pdf availableCanada, Ontarioguidebook
DS201906-1324
2019
Wahl, R.Mitchell, R., Wahl, R., Cohen, A.The Good Hope carbonatite, Ontario: a potential Nb deposit with pyrochlore-apatite cumulates.GAC/MAC annual Meeting, 1p. Abstract p. 145.Canada, Ontariodeposit - Good Hope

Abstract: The Good Hope carbonatite is located adjacent to the Prairie Lake ijolite-malignite-calcite carbonatite complex in northwestern Ontario. The carbonatite is a breccia consisting of diverse calcite and dolomite carbonatites, with lesser REE-rich ferrocarbonatites, containing xenoliths of amphibole syenite, potassium feldspar+phlogopite and pyrochlore-apatite cumulates. The occurrence outcrops over an area of 500 m x 500 m and has been proven by diamond drilling to extend to a minimum depth of 650 m. Pyrochlore-apatite cumulates occur as elongated and/or irregular clasts up to 5 cm in maximum dimension. In these, pyrochlore has crystallized before apatite and occurs as euhedral crystals (0.1-1 cm; up to 5 cm) and can comprise up to ca. 25 vol % of a clast. Prismatic apatite is commonly flow-aligned and in some instances forms isoclinal folds. The apatite does not exhibit optical- or BSE-compositional zonation. However, cathodoluminescence imagery shows blue-green cores with thin (< 500 µm) blue margins. The cores are enriched in light REE (833-941 ppm La; 1790-2200 ppm Ce; 8.2-13.6 Yb ppm; (La/Yb)CN 62-42. The pyrochlores are Na-Ca-F-pyrochlore of relatively-uniform composition with fully-occupied A-sites, and minor SrO (l-1.5 wt %) and low Ta2O5 (< 0.5 wt %). Some pyrochlores have irregular cores of resorbed Sr-bearing (6-11 wt % SrO) pyrochlore with overgrowths of Na-Ca-F-pyrochlore. Others contain inclusions of fersmite and/or columbite-(Fe). Pyrochlore also occurs as discrete crystals in calcite and dolomite hosts and represents disaggregated clasts. In accord with experimental data on the liquidus phase relationships of apatite and pyrochlore in haplocarbonatite melts the formation of apatite-pyrochlore cumulates in the initial stages of crystallization of such melts is to be expected. These cumulates were subsequently disrupted, disaggregated, and transported by pulses of later batches of carbonatite of diverse composition.
DS201911-2549
2019
Wahl, R.Mitchell, R.H., Wahl, R., Cohen, A.Mineralogy and geneis of pyrochlore-apatite from the Good Hope carbonatite, Ontario: a potential Nb deposit.Mineralogical Magazine, in press. 29p. Canada, Ontariodeposit - Good Hope
DS1970-0842
1973
Wahl, W.G.Wahl, W.G.Report on the Kimberlite Diamond RelationshipW.g. Wahl Ltd., UNPUBL. OCTOBER 9TH, 8P.CanadaGenesis
DS1983-0626
1983
Wahl, W.G.Wahl, W.G.Report on the Placer Diamond Deposits Sierra LeoneWahlex Limited, Report Submitted., 16P. UNPUBL.West Africa, Sierra Leone, YengemaGeology, Geomorphology, Genesis
DS1986-0853
1986
Wahl, W.G.Wahl, W.G.Brief mention: exploring for diamonds. a historical and practical review.No abstract or paper ever submittedProspectors and Developers Association Annual Meeting, March 10, Verbal presentation onlyGlobalBlank
DS1987-0776
1987
Wahl, W.G.Wahl, W.G.Geomorphology of the Yengema diamond placers Sierra LeonePreprint, 42p. 9 figs. 1 tableSierra LeoneGeomorphology, Placers
DS1989-1569
1989
Wahl, W.G.Wahl, W.G.Northeast extension of Proterozoic terranes of mid-continental NorthAmerica: discussion and replyGeological Society of America (GSA) Bulletin, Vol. 101, No. 5, May pp. 755-757MidcontinentTectonics
DS1989-1570
1989
Wahl, W.G.Wahl, W.G.Northeast extension of Proterozoic terranes of midcontinental NorthAmerica: discussion and replyGeological Society of America (GSA) Bulletin, Vol. 101, No. 5, May pp. 755-757Quebec, OntarioTectonics, Proterozoic
DS2000-0458
2000
Wahlgren, C.H.Juhlin, C., Wahlgren, C.H., Stephens, M.B.Seismic imaging in the frontal part of the Sveconorwegian Orogen, south western Sweden.Precambrian Research, Vol. 102, No. 1-2, July 1, pp. 135-SwedenGeophysics - seismics, Orogen - Sveconorowegian
DS1990-1528
1990
Wahr, J.Wahr, J.Getting to the core. Earth's boundaryNature, Vol. 345, June 7, pp. 476-477GlobalMantle, Core boundary
DS1994-1474
1994
Wahr, J.Rodgers, A., Wahr, J.The trade off between volumetric and topographic structure for seismictraveltimes: 660 km topography and mantle structure.Geophys. Journal of International, Vol. 117, No. 1, April pp. 19-32.MantleGeophysics -seismics, Tomography
DS200712-0101
2007
Waight, T.Brandon, A.D., Graham, D.W., Waight, T., Gautason, B.188 Os amd 187 Os enrichments and high 3He 4He sources in the Earth's mantle evidence from Iclandic picrites.Geochimica et Cosmochimica Acta, Vol. 71, 18, Sept. pp. 4570-91.Europe, IcelandPicrite
DS200712-0102
2007
Waight, T.Brandon, A.D., Graham, D.W., Waight, T., Gautason, B.Os He isotope systematics of Iceland picrites: evidence for a deep origin of the Iceland plume.Plates, Plumes, and Paradigms, 1p. abstract p. A119.Europe, IcelandPicrite
DS200712-1127
2007
Waight, T.Waight, T., Brandon, A.D., Graham, D.W., Gautason, B.Isotopic constraints on picritic magmatism, Iceland.Plates, Plumes, and Paradigms, 1p. abstract p. A1078.Europe, IcelandPicrite
DS201112-0798
2011
Waight, T.Pilbeam, L., Nielsen, T.F.D., Waight, T.Melt compositions and processes in the kimberlite province of southern West Greenland.Goldschmidt Conference 2011, abstract p.1643.Europe, GreenlandManitsoq
DS1998-1558
1998
Waight, T.E.Waight, T.E., Weaver, S.D., Maas, R., Eby, G.N.French Creek granite and Hohanu Dyke swarm: Late Cretaceous alkaline magmatism and opening of Tasman SeaAustralian Journal of Earth Sciences, Vol. 45, No. 6, Dec. pp. 823-36.GlobalAlkaline rocks
DS200412-1513
2004
Waight, T.E.Peate, D.W., Baker, J.A., Breddam, K., Waight, T.E., Skovgaard, A.C., Stecher, O., Prestvik, T., JonassonPb isotope heterogeneity of the mantle beneath Iceland.Geochimica et Cosmochimica Acta, 13th Goldschmidt Conference held Copenhagen Denmark, Vol. 68, 11 Supp. July, ABSTRACT p.A569.Europe, IcelandGeochronology
DS200912-0661
2009
Waight, T.E.Sand, K.K., Waight, T.E., Pearson, D.G., Nielsen, T.F.D., Makovicky, E., Hutchison, M.T.The lithospheric mantle below southern West Greenland: a geothermobarometric approach to diamond potential and mantle stratigraphy.Lithos, In press availableEurope, GreenlandDiamond prospectivity, geothermometry
DS201312-0706
2013
Waight, T.E.Pilbeam, L.H., Nielsen, T.F.D., Waight, T.E.Digestion fractional crystallization (DFC): an important process in the genesis of kimberlites. Evidence from olivine in the Majuagaa kimberlite, southern West Greenland.Journal of Petrology, Vol. 54, 7, July pp. 1399-1425.Europe, GreenlandDeposit - Majuagaa
DS201312-0933
2013
Waight, T.E.Van der Meer, Q.H.A., Klaver, M., Waight, T.E., Davies, G.R.The provenance of sub-cratonic mantle beneath the Limpopo mobile belt, (South Africa).Lithos, Vol. 170-171, pp. 90-104.Africa, South Africa, ZimbabweCraton, geothermobarometry, diamond potential
DS201412-0958
2014
Waight, T.E.Waight, T.E., Van der Meer, H.A., Palin, J.M., Cooper, A.F.,Munker, C.Metasomatized ancient lithospheric mantle beneath the young Zealandia microcontinent and its role in HIMU-like intraplate magmatism. Geophysics, Geochemistry, Geosystems, Vol. 15, pp. 3477-3501.New ZealandMagmatism
DS201604-0594
2016
Waight, T.E.Borst, A.M., Friis, H., Andersen, T., Nielsen, T.F.D., Waight, T.E., Smit, M.A.Zirconosilicates in the kakortokites of the Ilmmaussaq complex, South Greenland: implications for fluid evolution and high field strength and rare earth element mineralization in agpaitic systems.Mineralogical Magazine, Vol. 80, 1, pp. 5-30.Europe, GreenlandRare earths

Abstract: The layered agpaitic nepheline syenites (kakortokites) of the Ilímaussaq complex, South Greenland, host voluminous accumulations of eudialyte-group minerals (EGM). These complex Na-Ca-zirconosilicates contain economically attractive levels of Zr, Nb and rare-earth elements (REE), but have commonly undergone extensive autometasomatic/hydrothermal alteration to a variety of secondary mineral assemblages. Three EGM alteration assemblages are recognized, characterized by the secondary zirconosilicates catapleiite, zircon and gittinsite. Theoretical petrogenetic grid models are constructed to assess mineral stabilities in terms of component activities in the late-stage melts and fluids. Widespread alteration of EGM to catapleiite records an overall increase in water activity, and reflects interaction of EGM with late-magmatic Na-, Cl- and F-rich aqueous fluids at the final stages of kakortokite crystallization. Localized alteration of EGM and catapleiite to the rare Ca-Zr silicate gittinsite, previously unidentified at Ilímaussaq, requires an increase in CaO activity and suggests post-magmatic interaction with Ca-Sr bearing aqueous fluids. The pseudomorphic replacement of EGM in the kakortokites was not found to be associated with significant remobilization of the primary Zr, Nb and REE mineralization, regardless of the high concentrations of potential transporting ligands such as F and Cl. We infer that the immobile behaviour essentially reflects the neutral to basic character of the late-magmatic fluids, in which REE-F compounds are insoluble and remobilization of REE as Cl complexes is inhibited by precipitation of nacareniobsite-(Ce) and various Ca-REE silicates. A subsequent decrease in F- activity would furthermore restrict the mobility of Zr as hydroxyl-fluoride complexes, and promote precipitation of the secondary zirconosilicates within the confines of the replaced EGM domains.
DS201610-1904
2016
Waight, T.E.Scott, J.M., Liu, J., Pearson, D.G., Waight, T.E.Mantle depletion and metasomatism recorded in orthopyroxene in highly depleted peridotites.Chemical Geology, Vol. 441, pp. 280-291.MantleMetasomatism

Abstract: Although trace element concentrations in clinopyroxene serve as a useful tool for assessing the depletion and enrichment history of mantle peridotites, this is not applicable for peridotites in which the clinopyroxene component has been consumed (~ 25% partial melting). Orthopyroxene persists in mantle residues until ~ 40% melting and it is therefore this mineral that offers petrological insights into the evolution of refractory peridotites. Major and trace element concentrations in orthopyroxene ± clinopyroxene from two spinel facies harzburgitic xenolith suites from New Zealand are examined. Samples from Cape L'Evique (CLEV) on Chatham Island contain traces of clinopyroxene (< 2 modal %) but a suite from Lake Moana (MOA) in the South Island is devoid of this mineral. When compared with modelled orthopyroxene trace element budgets, which are constructed from a review of published source modes, melting modes and element/melt partition co-efficients, the measured orthopyroxene rare earth element data in both suites generally indicate minimums of 25-30% partial melting. These results are consistent with co-existing elevated Mg# in olivine (mostly 91.4 to 93.0) and orthopyroxene (mostly 91.3 to 93.6), high spinel Cr# (commonly > 45) and low orthopyroxene Al2O3 (generally < 3.1 wt%). However, comparison of modelled and measured orthopyroxene compositions shows that all samples, even the most refractory, have undergone metasomatism by small volume light rare earth element-bearing agents. Measured orthopyroxene Ti concentrations show that the metasomatic agent that affected the CLEV suite carried Ti, but that the MOA suite metasomatiser was Ti-poor. Orthopyroxene trace elements in the inspected rocks are therefore partly decoupled from the major element abundances, with the results demonstrating that even highly refractory peridotites can record evidence for mantle metasomatism.
DS201610-1907
2016
Waight, T.E.Smit. M.A., Waight, T.E., Nielsen, T.E.D.Millenia of magmatism recorded in crustal xenoliths from alkaline provinces in southwest Greenland.Earth and Planetary Science Letters, Vol. 451, pp. 241-250.Europe, GreenlandAillikite

Abstract: Mantle-derived CO2-rich magma ascends rapidly through the lithospheric column, supporting upward transport of large mantle-xenoliths and xenocryst (>30 vol%) loads to the (sub-)surface within days. The regional magmatism during which such pulses occur is typically well characterized in terms of general duration and regional compositional trends. In contrast, the time-resolved evolution of individual ultramafic dyke and pipe systems is largely unknown. To investigate this evolution, we performed a geochemical and speedometric analysis of xenoliths from ultramafic (aillikite) dykes in two Neoproterozoic alkaline provinces in West Greenland: 1) Sarfartôq, which overlies Archean ultra-depleted SCLM and yielded ultra-deep mineral indicators, and 2) Sisimiut, where the SCLM is refertilized and deep xenoliths (>120 km) are lacking. We focused on the rare and understudied crustal xenoliths, which preserve a rich record of melt injection. The xenoliths are derived from 25-36 km depth and were transported to the sub-surface within View the MathML source4±1h (Fe-in-rutile speedometry), during which they were exposed to the magmatic temperature of View the MathML source1,015±50°C (Zr-in-rutile thermometry). Garnet major-element speedometry shows that before the xenolith-ascent stage the lower crust had already been exposed to a variety of magmas for 700 (Sarfartôq) and 7,100 (Sisimiut) years. The Sisimiut samples contain exotic carbonate- and sulfide-rich assemblages, which occurred during the early stages of melt infiltration. Absence of such exotic assemblages and the faster magmatic development at Sarfartôq are tentatively linked to higher decarbonation kinetics in the more depleted SCLM at this location. The data reveal the so far unrecognized pre-eruptive development of ultramafic systems. This stage involves non-steady state melt-silicate interaction between ascending magmas and the immediate SCLM wall-rock, during which the composition of both is modified. The progress and duration of this interaction is strongly influenced by the composition of the SCLM. Kinetics factors describing this interaction could thus be used to model the chemistry of aillikite and similar ultramafic magmas.
DS1997-1219
1997
Wain, A.Wain, A.New evidence for coesite in eclogite and gneisses: defining an ultrahigh pressure province Western Gneiss.Geology, Vol. 25, No. 10, Oct., pp. 927-930.Norwaymetamorphism, Coesite
DS2000-0994
2000
Wain, A.Wain, A., Waters, D., Jephcoat, A., Olijnk, H.The high pressure to ultrahigh pressure eclogite transition in the Western Gneiss region, Norway.European Journal of Mineralogy, No. 3, pp. 667-88.NorwayEclogite, ultra high pressure (UHP)
DS2000-0995
2000
Wain, A.Wain, A., Waters, D., Olijynk, H.The high pressure to ultra high pressure eclogite transition in the Western Gneiss region, Norway.European Journal of Mineralogy, Vol. 12, No. 3, May 1, pp. 667-NorwayMineralogy, ultra high pressure (UHP)
DS2001-1211
2001
Wain, A.L.Wain, A.L., Waters, D.J., Austrheim, H.Metastability of granulites and processes of eclogitisation in the ultra high pressure (UHP) region of western Norway.Journal of Metamorphic Geology, Vol. 19, No. 5, Sept. pp. 607-24.Norwayultra high pressure (UHP), geochronology
DS201312-0944
2013
Wainwright, A.N.Wainwright, A.N., Luguet, A., Fonsec, R.O.C.Sulfide Re-Os dating in modally metasomatised peridotites, insights from Lethlhakane ( Botswana).Goldschmidt 2013, 1p. AbstractAfrica, BotswanaDeposit - Lethlhakane
DS201509-0435
2015
Wainwright, A.N.Wainwright, A.N., Luguet, A., Fonsec, R.O.C., Pearson, D.G.Investigating metasomatic effects on the 187Os isotopic signature: a case study on the micrometric base metal sulphides in metasomatised peridotite from the Letlhakane kimberlite, (Botswana). Lithos, Vol. 232, pp. 35-48.Africa, BotswanaDeposit - Letlhakane

Abstract: The peridotite xenoliths of the Letlhakane kimberlite (Botswana), which intrude the Proterozoic Magondi Belt on the western margin of the Zimbabwe craton, represent highly depleted melting residues. These residues suffered subsequent variable metasomatic overprinting, evidenced by cryptic trace element enrichments in the spinel peridotites to modal addition of phlogopite, clinopyroxene and spinel within the garnet peridotites. In order to assess the robustness of the Re–Os chronometer in such highly metasomatised peridotites, detailed investigations of base metal sulphide (BMS) petrography and single-BMS grain 187Os/188Os analyses have been undertaken in three representative peridotites.
DS201607-1319
2016
Wainwright, A.N.Wainwright, A.N., Luguet, A., Schreiber, A., Fonseca, R.O.C., Nowell, G.M.Nanoscale variations in 187Os isotopic composition and HSE systematics in a Bultfontein peridotite.Earth and Planetary Science Letters, Vol. 447, pp. 60-71.Africa, South AfricaDeposit - Bultfontein

Abstract: Understanding the mineralogical controls on radiogenic chronometers is a fundamental aspect of all geochronological tools. As with other common dating tools, it has become increasingly clear that the Re -Os system can be impacted by multiple mineral formation events. The accessory and micrometric nature of the Re -Os-bearing minerals has made assessing this influence complex. This is especially evident in cratonic peridotites, where long residence times and multiple metasomatic events have created a complex melting and re-enrichment history. Here we investigate a harzburgitic peridotite from the Bultfontein kimberlite (South Africa) which contains sub-micron Pt -Fe-alloy inclusions within base metal sulphides (BMS). Through the combination of the focused ion beam lift-out technique and low blank mass spectrometry we were able to remove and analyse the Pt -Fe-alloy inclusions for their Re -Os composition and highly siderophile element (HSE) systematics. Six repeats of the whole-rock yield 187Os/188Os compositions of 0.10893 -0.10965, which correspond to Re depletion model ages (TRD) of 2.69 -2.79 Ga. The Os, Ir and Pt concentrations are slightly variable across the different digestions, whilst Pd and Re remain constant. The resulting HSE pattern is typical of cratonic peridotites displaying depleted Pt and Pd. The Pt -Fe-alloys have PUM-like 187Os/188Os compositions of 0.1294±24 (2-s.d.) and 0.1342±38, and exhibit a saw-tooth HSE pattern with enriched Re and Pt. In contrast, their BMS hosts have unradiogenic 187Os/188Os of 0.1084±6 and 0.1066±3, with TRD ages of 2.86 and 3.09 Ga, similar to the whole-rock systematics. The metasomatic origin of the BMS is supported by (i) the highly depleted nature of the mantle peridotite and (ii) their Ni-rich sulphide assemblage. Occurrence of Pt -Fe-alloys as inclusions within BMS grains demonstrates the genetic link between the BMS and Pt -Fe-alloys and argues for formation during a single but continuous event of silicate melt percolation. While the high solubility of HSE within sulphide mattes rules out early formation of the alloys from a S-undersaturated silicate melt and subsequent scavenging in a sulphide matte, the alignment of the Pt -Fe-alloy inclusions attests that they are exsolutions formed during the sub-solidus re-equilibration of the high temperature sulphide phases. The significant difference in 187Os/188Os composition between the included Pt -Fe-alloys and their BMS host can only be accounted for by different Re/Os. This suggests that the formation of Pt -Fe-alloy inclusions within a BMS can result in the fractionation of Re from Os. A survey experiment examining the partitioning of Re and Os confirmed this observation, with the Re/Os of the Pt -Fe-alloy inclusion up to ten times higher than the co-existing BMS. This fractionation implies that, when Re is present in the sulphide melt, the TRD ages of BMS containing alloy inclusions do not date the loss of Re due to partial melting, but rather its fractionation into the Pt -Fe-alloys. As such, BMS ages should be used with caution when dating ancient partial melting events.
DS1998-1457
1998
Waissel, O.Teixeira, N., Gaspar, J., Waissel, O., Almeida, A.Geology of the Juin a Diamondiferous province7th International Kimberlite Conference Abstract, pp. 905-7.BrazilMaars, Rio Negro Jurena Mobile Belt
DS1989-0313
1989
Wait, J.R.Cruszka, T.P., Wait, J.R.Interaction of induced polarization and electromagnetic effects in boreholeprobingGeoexploration, Vol. 25, No. 4, June pp. 267-278GlobalGeophysics, IP and electromagnetic-borehole
DS1989-1571
1989
Waite Connor, C.Waite Connor, C.Poster session: a guide for preparationGsa News And Information, Vol. 11, No. 7, July pp. 164-167GlobalPoster preparation
DS1986-0360
1986
Waites, J.E.Herman, J.D., Waites, J.E.Surface expression of subsurface structures in the Michigan basinRemote Sensing for Exploration Geology, Fifth Thematic Conf, p. 64. (abstract.) Held Sept. 29, -Oct. 2Michigan, MidcontinentStructure, Tectonics
DS201312-0945
2013
Wakabayashi, D.Wakabayashi, D., Funamori, N.Equation of state of silicate melts with densified intermediate range order at the pressure condition of the Earth's deep upper mantle.Physics and Chemistry of Minerals, Vol. 40, 4, pp.MantleMelting
DS1992-1616
1992
Wakabayashi, J.Wakabayashi, J.Nappes, tectonics of oblique plate convergence, and metamorphic evolution related to 140 million years of continuous subduction, Franciscan Complex, CaliforniaJournal of Geology, Vol. 100, No. 1, January pp. 19-40CaliforniaTectonics, Subduction
DS1996-1492
1996
Wakabayashi, J.Wakabayashi, J.Tectono-metamorphic impact of a subduction transform transition-implications interpretation orogenic beltsInternational Geology Review, Vol. 38, No. 10, Oct. pp. 979-994GlobalOrogeny, Tectonics
DS2002-1085
2002
Wakabayashi, J.Moores, E.M., Wakabayashi, J., Unruh, J.R.Crustal scale cross section of the U.S. Cordillera, California and beyond, its tectonic significance and speculations on the Andean Orogeny.International Geology Review, Vol. 44, 6, pp. 479-500.United States, CaliforniaTectonics
DS1984-0753
1984
Wakatsuki, M.Wakatsuki, M.Synthesis Researches of DiamondIn: Material Science of the Earth's Interior Terra Science Publishing, pp. 351-374GlobalDiamond Morphology, Synthetic
DS2001-0560
2001
Wakatsuki, T.Kabeto, K., Sawada, Y., Lizumi, S., Wakatsuki, T.Mantle sources and magma crust interactions in volcanic rocks from northern Kenya Rift: geochemical evidenceLithos, Vol. 56, No. 2-3, Mar. pp. 111-39.KenyaGeochronology
DS2001-0561
2001
Wakatsuki, T.Kabeto, K., Sawada, Y., Wakatsuki, T.Different evolution trends in alkaline evolved lavas from the Northern Kenya riftJournal of African Earth Science, Vol. 32, No. 3, Apr. pp. 419-33.KenyaTectonics, Alkaline lavas
DS1993-0443
1993
Wake-Dyster, K.D.Finlayson, D.M., Owen, A., Johnstone, D., Wake-Dyster, K.D.Moho and petrologic crust-mantle bounday coincide under southeasternAustraliaGeology, Vol. 21, No. 8, August pp. 707-710AustraliaMantle, Petrology
DS1996-1054
1996
Wakefield, D.E.Oliver, E.M., Wakefield, D.E.Rehabilitation of mining lands: legislative amendments affecting Ontario's mining industryOsler, Hoskin and Harcourt, 10pOntarioEnvironmental, Rehabilitation
DS1996-1493
1996
Wakefield, D.E.Wakefield, D.E.Arctic mineral wealth: equitable participation with aboriginal landowners -a slow or fast process?The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Vol. 89, No. 1005, Nov. pp. 67-73.ArcticLand claims, aboriginals, Legal, environment
DS1990-0978
1990
Wakeling, T.R.M.Manby, C.N.D., Wakeling, T.R.M.Developments in soft-ground drilling, sampling and in-situ testingTransactions of the Institute of Mining and Metallurgy (IMM), Vol. 99, Sect. A., pp. A91-109GlobalDrilling techniques, Methodology
DS2000-0996
2000
Wake-Walker, R.Wake-Walker, R., Wyndham, C., Boyd, W.F.DICAN - the Canadian government diamond valuator and Canada's role in the World diamond industry.Geological Association of Canada (GAC)/Mineralogical Association of, 1p. abstract.Northwest TerritoriesEconomics - marketing - brief, DICAN.
DS200712-0223
2007
Wal, R.V.Davydov, V.A., Rakhmanina, A.V., Rols, S., Agafonov, V., Pulikkathara, M.X., Wal, R.V., Khabashesku, V.N.Size dependent phase transition of diamond to graphite at high pressures.Journal of Physical Chemistry , Vol. 111, no. 35, pp. 12918-12925. Ingenta 1074185621TechnologyUHP
DS201506-0267
2015
Walczak, K.Ferrero, S., Wunder, B., Walczak, K., O'Brien, P.J., Ziemann, M.A.Preserved near ultrahigh-pressure melt from continental crust subducted to mantle depths.Geology, Vol. 43, 5, pp. 447-450.MantleBohemian
DS201906-1360
2019
Walczak, K.Walczak, K., Cuthbert, S., Kooijman, E., Majka, J., Smit, M.A.U-PB zircon age dating of diamond bearing gneiss from Fjortoft reveals repeated burial of the Baltoscandian margin during the Caledonian Orogeny.Geological Magazine, doi.org:10.1017/S0016 756819000268 16p.Europe, Norwaygeochronology

Abstract: The first find of microdiamond in the Nordøyane ultra-high-pressure (UHP) domain of the Western Gneiss Region (WGR) of the Scandinavian Caledonides reshaped tectonic models for the region. Nevertheless, in spite of much progress regarding the meaning and significance of this find, the history of rock that the diamonds were found in is complex and still largely ambiguous. To investigate this, we report U-Pb zircon ages obtained from the exact crushed sample material in which metamorphic diamond was first found. The grains exhibit complicated internal zoning with distinct detrital cores overgrown by metamorphic rims. The cores yielded a range of ages from the Archaean to the late Neoproterozoic / early Cambrian. This detrital zircon age spectrum is broadly similar to detrital signatures recorded by metasedimentary rocks of the Lower and Middle allochthons elsewhere within the orogen. Thus, our dating results support the previously proposed affinity of the studied gneiss to the Seve-Blåhø Nappe of the Middle Allochthon. Metamorphic rims yielded a well-defined peak at 447 ± 2 Ma and a broad population that ranges between c. 437 and 423 Ma. The data reveal a prolonged metamorphic history of the Fjørtoft gneiss that is far more complex then would be expected for a UHP rock that has seen a single burial and exhumation cycle. The data are consistent with a model involving multiple such cycles, which would provide renewed support for the dunk tectonics model that has been postulated for the region.
DS201505-0248
2015
Wald, R.Toledo, V., Ward, J., de Wit, M., Spaggiari, R., Coopersmith, H., Wald, R.A transient fluvial placer in the mid reach of the Kishon Valley northern Israel: initial results of follow up exploration.Israel Geological Society, 1p.posterEurope, IsraelExploration results
DS201603-0429
2016
Wald, R.Wald, R., Toledo, V.Volcanic host rocks as sources of corundum recovered from Shefa Yamim's multi-commodity placer, northern Israel.Israel Geological Society, pp. 156-157. abstractEurope, IsraelKishon - corundum

Abstract: This talk focused on the proximal reach (closest to its source) of the Kishon River, covering the Yizre'el Valley and its margins. In this terrain Shefa Yamim's exploration area overlaps the PhD study area of Reli Wald, the company's geologist. The Yizre'el basin hosts a large volume of basalts, sourced mainly from fault planes, but also from volcanoes (vents). Combination of datasets gathered from intensive exploration of Shefa Yamim, including site specific geophysics (high resolution ground magnetometer) and three-dimensional (3D) geological and geophysical subsurface mapping of Reli Wald's PhD study, has enabled quantification of the basalt volume. Since the basalts are known as host rocks for corundum xenocrysts (both gem and industrial minerals), volume estimations become handy when analysing Shefa Yamim corundum species recoveries including the gem derivative sapphire. Corundum findings of the Mid Reach alluvial placer were explained by introducing the geological Miocene (geological period) volcanic setting of the hinterland (proximal reach), in terms of a supplier. Corundum crystals have crystallized in the uppermost mantle, been elevated by magmatic intrusions into the crust, and brought to surface by later, younger volcanism. Corundum findings thus emphasize rift-related setting and recurring magmatism in northern Israel whereas important questions regarding the connection between sapphire and corundum and the possibility for a deep subduction regime still await answers...
DS200612-0554
2006
Waldbauer, J.R.Hayes, J.M., Waldbauer, J.R.Exchange of C between mantle and crust and its effect on global redox budgets.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 19. abstract only.MantleGeochemistry - carbon
DS201412-0244
2014
Walde, D.Fernandes, A.F., Karfunkel, J., Hoover, D.B., Sgarbi, G.N.C., Walde, D., Gomes, J., Kambrock, K.O garimpo Canastrel, Coromandel-MG: ocorrencia de diamante no conglomerado cretaceo do grupo Mat a de Corda.6 Simposio Brasileiro de Geologia do Diamante, Aug. 3-7, 5p. AbstractSouth America, Brazil, Minas GeraisDeposit - Coromandel
DS201412-0442
2014
Walde, D.Karfunkel, J., Hoover, D.B., Fernandes, A.F., Sgarbi, G.N.C., Kambrock, K., Walde, D., Michelfelder, G.Origin of diamonds southeast of Coromandel ( Minas Gerais Brazil): a different hypothesis.6 Simposio Brasileiro de Geologia do Diamante, Aug. 3-7, 5p. AbstractSouth America, Brazil, Minas GeraisDeposit - Coromandel
DS201509-0408
2015
Walde, D.Karfunkel, J., Hoover, D., Fernandes, A.F., Sgarbi, G.M.C., Oliviera, G.D., Walde, D., Michelfelder, G.Surface source of Coromandel diamonds ( Minas Gerais State) Brazil and their possible origin from the Serra Negra/Salitre Supervolcano.Neues Jahrbuch fur Geologie und Palaontologie , Vol. 277, 2, pp. 237-250.South America, Brazil, Minas GeraisDeposit - Coromandel

Abstract: The origin of diamonds in the Coromandel area has been an enigma for many years, in spite of high investment in conventional and high tech prospecting methods by major mining companies for over half a century. The authors review the history, and then discuss the two principal hypotheses to explain the source of these alluvial diamonds. After mapping the headwater region of one of the richest alluvial diamond rivers, the Santo Antônio do Bonito River, they reject both principal hypotheses and conclude that the surficial source can be only the Upper Cretaceous Capacete Formation, composed of pyroclastics and epiclastics. Based on geophysical data from the literature, combined with field observations the authors suggest that the largest alkaline complex, situated within the diamond producing area, the Serra Negra/Salitre Complex has been the primary source for those pyroclastics of the Capacete Formation and the diamonds. The plugs of this complex are 15-30 times deeper than average kimberlites and other alkaline complexes in the region, and its excess of volume of the intrusive is three orders of magnitude larger than a typical kimberlite. With an intrusive volume of over 1000 km3 the complex is suggested to be a possible supervolcano. This explains the vast areal distribution of the pyroclastics and diamonds. This new hypothesis has advantages and disadvantages, some of them discussed in the paper and leading to the conclusion that further research is needed.
DS201510-1788
2015
Walde, D.Michelfelder, G.S., Karfunkel, J., Fernandes, A.F., Sgarbi, N.C., Hoover, D.B., Krambrock, K., Walde, D.Surface source of Coromandel diamonds ( Minas Gerais State), Brazil) and their possible origin from the Serra Negra/Salitre supervolcano.GSA Annual Meeting, Paper 300-1, 1p. Abstract only BoothSouth America, Brazil, Minas GeraisDeposit - Coromandel

Abstract: The origin of diamonds in the Coromandel area has been an enigma for many years, in spite of high investment in conventional and high tech prospecting methods by major mining companies for over half a century. The authors review the history, and then discuss the two principal hypotheses to explain the source of these alluvial diamonds. After mapping the headwater region of one of the richest alluvial diamond rivers, the Santo Antônio do Bonito River, they reject both principal hypotheses and conclude that the surficial source can be only the Upper Cretaceous Capacete Formation, composed of pyroclastics and epiclastics. Based on geophysical data from the literature, combined with field observations the authors suggest that the largest alkaline complex, situated within the diamond producing area, the Serra Negra/Salitre Complex has been the primary source for those pyroclastics of the Capacete Formation and the diamonds. The plugs of this complex are 15-30 times deeper than average kimberlites and other alkaline complexes in the region, and its excess of volume of the intrusive is three orders of magnitude larger than a typical kimberlite. With an intrusive volume of over 1000 km3 the complex is suggested to be a possible supervolcano. This explains the vast areal distribution of the pyroclastics and diamonds. This new hypothesis has advantages and disadvantages, some of them discussed in the paper and leading to the conclusion that further research is needed.
DS201710-2233
2017
Walde, D.Hoover, D.B., Karfunkel, J., Ribeiro, L.C.B., Michelfelder, G.., Moraes, R.A.V., Krambrock, K., Quintao, D., Walde, D.Diamonds of the Alto Paranaiba, Brazil: Nixon's prediction verified?The Australian Gemmologist, Vol. 26, 5&6, pp. 88-99.South America, Brazil, Minas Geraisdeposit - Alto Paranaiba

Abstract: The authors, in a paper in this journal in 2009, note a puzzle, that in spite of extensive exploration for diamonds by major producers in the Alto Paranaiba region of West Minas Gerais State, Brazil, no primary source, such as kimberlites, for the many diamonds produced since their discovery over 250 years has been found. To answer this puzzle we propose that the diamonds are present within a large extrusive volcanic unit probably derived from the Serra Negra alkaline-carbonatitic complex which comprises a super volcano. This origin fits with the 1995 prediction of Nixon on the future direction of diamona-exploration that extrusive units may contain very large volumes of ore, and that carbonatitic emplacement sources need to be considered. The authors argue, based on available evidence from geology and geophysics, that such an origin is compatible with the known data, but that much additional information is needed to substantiate these ideas. Diamonds of the Alto Paraniaba, Brazil: Nixon's prediction verified?
DS201809-2036
2018
Walde, D.Hoover, D.B., Karfunkel, J., Walde, D., Moraes, R.A.V., Michelfelder, G., Henger, F.E., Ribeira, L.C., Krambock, K.The Alto Paranaiba region, Brazil: a continuing source for pink diamonds?The Australian Gemmologist, Vol. 26, 9-10, pp. 196-204.South America, Brazildeposit - Alto Paranaiba
DS1992-1617
1992
Walde, T.Walde, T.Third world mining: no limits on pollution?Raw Materials Report, Vol. 8, No. 3, pp. 4-5GlobalLegal, Environmental, Mining
DS2003-1437
2003
Walde, T.Walde, T.Mining law reform in South AfricaMinerals & Energy, Vol. 17, pp. 10-17.South AfricaLegal
DS200512-0819
2005
Waldek Zerda, T.Pantea, C., Voronin, G.A., Waldek Zerda, T., Zhang, J., Wang, Y., Uchida, T., Zhao, Y.Kinetics of SIC formation during high P T reaction between diamond and silicon.Diamond and Related Materials, Vol. 14, 10, pp. 1611-1615.TechnologySIC
DS1992-1618
1992
Walden, J.Walden, J., Smith, J.P., Dackombe, R.V.The use of simultaneous R and Q mode factor analysis as a tool for assisting interpretation of mineral magnetic dataMath. Geol, Vol. 24, No. 3, pp. 227-247GlobalPaleomagnetism, Factor analysis
DS1994-0309
1994
Walder, J.S.Clark, P.U., Walder, J.S.Subglacial drainage, eskers and deforming beds beneath the Laurentide and Eurasian ice sheets.Geological Society of America Bulletin, Vol. 106, No. 2, February pp. 304-314.OntarioGeomorphology
DS1997-1220
1997
Walder, K.Walder, K.Additive models in mining and explorationNonrenewable Resources, Vol. 6, No. 1, March pp. 11-25GlobalModels - geostatistics, Kriging
DS201212-0759
2012
Waldie, C.Waldie, C., Whyte, J., Holland, R.NI 43-101 The new version and what you need to know.PDAC Short course, March 7, ppt manualCanadaLegal - reports
DS2003-1438
2003
Waldman, M.Waldman, M.Exploration updateRough Diamond Review, No. 2, September, pp. 5-10.Canada, Africa, Australia, India, Russia, South AmericaNews item - brief exploration overview
DS200412-2069
2003
Waldman, M.Waldman, M.Exploration update.Rough Diamond Review, No. 2, September, pp. 5-10.Canada, Africa, Australia, India, Russia, South AmericaNews item - brief exploration overview
DS1985-0708
1985
Waldman, M.A.Waldman, M.A., Mccandless, T.E., Dummett, H.T.Geology and Mineralogy of the Twin Knobs # 1 Lamproite Pikecounty, Arkansaw #2Geological Society of America (GSA), Vol. 17, No. 3, P. 196. (abstract.).United States, Gulf Coast, Arkansas, PennsylvaniaGeochronology, Evaluation
DS1985-0709
1985
Waldman, M.A.Waldman, M.A., Mccandless, T.E., Dummett, H.T.Geology and Mineralogy of the Twin Knobs # 1 Lamproite Pikecounty, Arkansaw #1Preprint of Paper Presented Geological Society of America (gsa), 17P. 12 FIGS. 1 TABLE.United States, Gulf Coast, Arkansas, PennsylvaniaLamproite, Prospecting, Geophysics, Geochemistry
DS1987-0777
1987
Waldman, M.A.Waldman, M.A., McCandless, T.E., Dummett, H.T.Geology and petrography of the Twin Knobs # 1 lamproite, Pike County, ArkansawMantle metasomatism and alkaline magmatism, edited E. Mullen Morris and, No. 215, pp. 205-216ArkansasAnalyses p. 212, 214
DS1990-1529
1990
Waldman, M.A.Waldman, M.A., Poling, G.W.North America's only large capacity diamond recovery plantDia Met Handout, Prospectors and Developers Association of Canada (PDAC) Meeting, Held March, 6pColoradoDiamond recovery plant, Overview
DS1991-0608
1991
Waldman, M.A.Griffin, W.L., O'Reilly, S.Y., Ryan, C.G., Waldman, M.A.Indicator minerals from Prairie Creek and Twin Knobs lamproites: relation to diamond gradeProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 139-141ArkansasMicroprobe, Analyses
DS1991-1091
1991
Waldman, M.A.McCandless, T.E., Waldman, M.A., Gurney, J.J.Macro and micro diamonds from Arkansaw lamproites: morphology, inclusion sand isotope geochemistryProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 264-266ArkansasDiamond morphology, Diamond inclusions, comparison to Ellendale
DS1991-1364
1991
Waldman, M.A.Poling, G.W., Waldman, M.A.Dia Met's diamond recovery pilot plant in ColoradoThe 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. 99. AbstractColoradoDiamond recovery, Mining applications-processing
DS1992-1216
1992
Waldman, M.A.Poling, G.W., Waldman, M.A.Dia Met Minerals' diamond recovery pilot plant in ColoradoThe Canadian Mining and Metallurgical Bulletin (CIM Bulletin), Vol. 85, No. 956, January pp. 72-83ColoradoDiamond processing, Diamond recovery - example
DS1993-1025
1993
Waldman, M.A.Meyer, H.O.A., Waldman, M.A., Garwood, B.L.Mantle xenoliths from kimberlite, Kirkland Lake area, OntarioGeological Society of America Annual Abstract Volume, Vol. 25, No. 6, p. A99 abstract onlyOntarioXenoliths, Garnet Lherzolites
DS1994-0663
1994
Waldman, M.A.Griffin, W.L., O'Reilly, S.Y., Ryan, C.G., Waldman, M.A.Indicator minerals from Prairie Creek and Twin Knobs lamproites: relations to diamond grade.Proceedings of Fifth International Kimberlite Conference, Vol. 2, pp. 302-311.ArkansasGeochemistry, Deposit -Prairie Creek, Crater of Diamonds, Twin Knobs
DS1994-1135
1994
Waldman, M.A.McCandless, T.E., Waldman, M.A., Gurney, J.J.Macrodiamonds, microdiamonds from Murfreesboro lamproites: morphology, inclusions, carbon isotope geochemistry.Proceedings of Fifth International Kimberlite Conference, Vol. 2, pp. 78-97.ArkansasDiamond morphology, Deposit -Crater of Diamonds
DS1994-1182
1994
Waldman, M.A.Meyer, H.O.A., Waldman, M.A., Garwood, B.L.Mantle xenoliths from kimberlite near Kirkland Lake, OntarioCanadian Mineralogist, Vol. 32, No. 2, June pp. 295-306.OntarioXenoliths, garnet lherzolite, Deposit -C-14 kimberlite
DS201512-1944
1994
Waldman, M.A.McCandless, T.E., Waldman, M.A., Gurney, J.J.Macro- and microdiamonds from Arkansas lamproites: morphology, inclusions and isotope geochemistry.Proceedings of the 5th. International Kimberlite Conference, Vol. 2, pp. 78-97.United States, ArkansasMicrodiamonds

Abstract: The first report of diamond in igneous rock in the United States originated at Prairie Creek, Arkansas. We have examined the morphological, carbon isotope, and inclusion characteristics of diamonds from Prairie Creek, and from the Twin Knobs # 1, #2, Black Lick, and American lamproites. White is the most common macrodiamond color at Prairie Creek (62% of total), with 20% brown and 16% yellow. This contrasts with Australian lamproites where brown predominates, and with other North American localities such as the Sloan, Colorado kimberlites where yellow is rare. Lamination lines indicate ductile deformation at mantle conditions. The macrodiamonds are very resorbed; 82% are equiform or distorted tetrahexahedroida and none are octahedra. Low relief surfaces indicate prolonged and/or intense resorption. Microdiamonds differ dramatically, with octahedra and fragn~ents common and tetrahexahedroida abscnL Serrate laminae, knob-like asperities, pointed plates, ribbing, and non-uniform resorption are the most common surface features. Diamonds from the Twin Knobs # 1 lamproite are similar to microdiamonds with respect to size and surface features. Magnetite and olivine (F093) are the only primary inclusions foqnd in the diamonds, although inclusions of peridotitic and eclogitic parageneses have been reported in previous studies. Carbon isotope B13c values for Prairie Creek macrodiamonds peak at-3.0 to -6.2 %o (ave. -4.7 %o for 19 stones) and -10.3 to -10.6 %o (ave. -10.5 %o for 2 stones). The diamonds with magnetite and olivine inclusions have B13c values of -5.1 %o and -4.0 %o respectively. Microdiamonds from Prairie Creek, Twin Knobs #2, American, and Black Lick are similar to Prairie Creek macrodiamonds ( -0.5 to -7 .8; ave. -4.1 %o for 8 stones). A Prairie Creek and a Black Lick microdiamond have B13c values of -26.1 and -25.2%orespectively, and the latter exhibits non-uniform resorption. Lamination lines on macrodiamonds and xenocrystic surface features on microdiamonds imply that both are xenocrysts in lamproite. Carbon isotopes are characteristic of a peridotitic or primordial carbon reservoir. Two 13cdepleted microdiamonds may be from a subducted carbon source. In comparison to macrodiamond populations from most kimberlites, Prairie Creek macrodiamonds are intensely resorbed, and lamproite may be more corrosive than kimberlite \\ ith respect to diamond resorption. Microdiamonds were probably encapsulated in xenolith material ani.! esca•,)ed resorption. The differences in size and color of Prairie Creek macrodiamonds relative to Sloan kimberlitic diamonds are genetic, and may be related to their formation in lithosphere of differing age and tectonic history.
DS1992-1619
1992
Waldron, K.A.Waldron, K.A., Oarsons, I.Feldspar microtextures and multistage thermal history of syenites from the Coldwell Complex, OntarioContributions to Mineralogy and Petrology, Vol. 111, No. 2, July pp. 222-234OntarioColdwell Complex, Alkaline rocks
DS1988-0745
1988
Waldrop, M.W.Waldrop, M.W.NeXT embraces a new way of programmingScience, Vol. 242, November 25, pp. 1126-1127. Database # 17562GlobalComputer, Program - NeXT.
DS1992-1620
1992
Walduck, G.P.Walduck, G.P.Decision making under risk in the mining industry: a risk appraisal casestudyGeological Society Special Publication, Case histories and methods in, No. 63, pp. 25-32GlobalComputer, Ore reserves, geostatistics
DS1992-1621
1992
Walduck, G.P.Walduck, G.P.Qualitative modelling: fractal geometry in mineral deposit evaluationGeological Society Special Publication, Case histories and methods in mineral, No. 63, pp. 299-305GlobalComputer, Ore reserves, geostatistics, Fractals
DS1960-0847
1967
Walford, M.E.R.Jones, D.L., Walford, M.E.R., Gifford, A.C.A Paleomagnetic Result from the Ventersdorp Lavas of South Africa.Earth and Planetary Science Letters, Vol. 2, No. 3, PP. 155-158.South AfricaDe Beers Mine, Paleomagnetics
DS201908-1784
2019
Wali Faryad, S.Kubinova, S., Wali Faryad, S.Mineral textures of olivine minette and their significance for crystallization history of parental magma: an example from the Moldanubian zone ( the Bohemian Massif).Mineralogy and Petrology, Vol. 113, 4, pp. 477-491.Europeminette

Abstract: One of the best-preserved dykes of olivine minette among the lamprophyre dyke swarm in the Moldanubian Zone of the Bohemian Massif (Czech Republic) was investigated. The minette, exposed at Horní Kožlí Village (near Prachatice town), has porphyric texture with phenocrysts of olivine, clinopyroxene, orthopyroxene and biotite in a fine-grained matrix consisting of K-feldspar, biotite, clinopyroxene and minor plagioclase and quartz. Accessory minerals are apatite, Cr-rich spinel and iron sulphides. Olivine is mostly replaced by talc and rimmed by two zones (coronas) - a talc-rich inner zone and a biotite-rich outer zone. Rarely, larger grains of quartz with a corona of clinopyroxene are present. The clinopyroxene grows mostly perpendicular to the quartz rim and radially penetrates the quartz crystal. Three stages of mineral crystallization were distinguished. The first stage with apatite, olivine, biotite, spinel, orthopyroxene and part of the clinopyroxene occurred in the mantle position. During the second stage, felsic phases (K-feldspar, plagioclase, quartz) in the matrix were crystallized. The enrichment of the residual melt by silica and Na occurred as the result of both fractionation and contamination during magma ascent through the granulite facies crust during post-collision orogeny in the Bohemian Massif. Minerals related to the third stage were formed during filling of the vesicles (quartz with reaction rims of clinopyroxene) and subsequent alteration (talc after olivine). The origin of quartz with clinopyroxene reaction rims (‘quartz ocelli’) is explained by filling of cavities formed by the escape of volatiles.
DS1998-0158
1998
WalkerBrandon, A.D., Walker, Morgan, Snow190 Pc 186 Os isotopic systematics of the upper mantle and some plumesMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 227-8.MantleConvection, Chromitites, peridotites
DS200712-1107
2007
WalkerVan Acken, D., Becker, H., Wombacher, Walker, McDonough, Ash, PiccoliFractionated HSE in suboceanic mantle: assessing the influence of refertilization processes on upper mantle peridotites.Plates, Plumes, and Paradigms, 1p. abstract p. A1051.Europe, SwitzerlandWebsterite
DS200812-0385
2008
WalkerGao, S., Rudnick, R.L., Xu, Yuan, Liu, Walker, Puchtel, Liu, Huang, Wang, WangRecycling deep cratonic lithosphere and generation of intraplate magmatism in the North Chin a Craton.Earth and Planetary Science Letters, Vol. 270, 1-2, June 15, pp. 41-53.ChinaTectonics - delamination, picrites
DS1859-0101
1849
Walker, A.M.Walker, A.M.Statistical Report on the Circar of WarangalMadras Journal of Literature And Science., Vol. 15, PP. 185-India, Andhra PradeshDiamond Occurrence
DS201212-0322
2012
Walker, A.M.Hunt, S.A., Davies, D.R., Walker, A.M., McCormack, R.J., Wills, A.S., Dobson, D.P., Li, Li.On the increase in thermal diffusivity caused by the perovskite to post-perovskite phase transition and its implications for mantle dynamics.Earth and Planetary Science Letters, Vol. 319-320, pp. 96-103.MantleGeodynamics
DS201312-0946
2013
Walker, A.M.Walker, A.M., Ammann, M.W., Stackhouse, S., Wookey, J., Bordholdt, J.P., Dobson, D.Anisotropy: a cause of heat flux variation at the CMB?Goldschmidt 2013, 1p. AbstractMantlePerovskite
DS201412-0641
2014
Walker, A.M.Nowacki, A., Walker, A.M., Wookey, J., Kendall, J-M.Evaluating post-perovskite as a cause of D" anisotropy in regions of paleosubduction.Geophysical Journal International, Vol. 192, 3, pp. 1085-1090.MantleGeophysics - seismics, rheology
DS1990-1530
1990
Walker, C.Walker, D., Walker, C.Herkimer diamonds #2Lapidary Journal, Vol. 44, No. 4, July, pp. 71-72GlobalNews item, Silicates
DS2003-1439
2003
Walker, C.Walker, C., Mooney, W.D., Detweiller, S.Seismicity and lithospheric structure in southern CaliforniaGeological Society of America, Annual Meeting Nov. 2-5, Abstracts p.15.CaliforniaGeophysics - seismics, lithosphere
DS200412-2070
2003
Walker, C.Walker, C., Mooney, W.D., Detweiller, S.Seismicity and lithospheric structure in southern California.Geological Society of America, Annual Meeting Nov. 2-5, Abstracts p.15.United States, CaliforniaGeophysics - seismics, lithosphere
DS1997-0712
1997
Walker, C.L.MacLeod, C.J., Tyler, P.A., Walker, C.L.Tectonic, magmatic, hydrothermal and biological segmentation of Mid-OceanRidgesGeological Society of London Special Paper, No. 118, 240p. approx. 200.00GlobalTectonics, Book - Table of contents
DS1982-0235
1982
Walker, C.S.H.Gurney, J.J., Walker, C.S.H., et al.Diamond Recoveries Near the Surf Zone of the Namaqualand Coast Near the olifants River.Sedimentology 82, Abstract Volume, Third Symposium of The, PP. 84-88.South AfricaMining, Alluvial, Methods, Recovery
DS1960-0199
1961
Walker, C.W.Walker, C.W.Diamond Mining in the Gold Coast and Sierra LeoneCornish Institute Eng. Transactions, Vol. 16, FOR 1960-1961, PP. 1-25.Sierra Leone, Gold Coast, West AfricaMining Methods, Recovery, Alluvial Placer
DS1982-0467
1982
Walker, D.Nisbet, E.G., Walker, D.Komatiites and the Structure of the Archean MantleEarth and Planetary Science Letters, Vol. 60, pp. 105-113.MantleTectonics - Convection
DS1985-0710
1985
Walker, D.Walker, D., Kiefer, W.S.Xenolith Digestion in Large Magma BodiesJournal of Geophysical Research, Vol. 90, B suppl. Feb. 15, pp. C 585-C590GlobalMantle
DS1989-0009
1989
Walker, D.Agee, C.B., Walker, D.Comments on constraints on element partition coefficients between MgSiO3perovskite and liquid determined by direct measurementsEarth and Planetary Science Letters, Vol. 94, pp. 160-163GlobalMantle, Petrogenesis
DS1989-1572
1989
Walker, D.Walker, D., Agee, C.Partioning "equilibrium",temperature gradients, and constraints on earthdifferentiationEarth and Planetary Science Letters, Vol. 96, pp. 49-60GlobalMantle petrogenesis -experimental petrology, Perovskites
DS1990-1530
1990
Walker, D.Walker, D., Walker, C.Herkimer diamonds #2Lapidary Journal, Vol. 44, No. 4, July, pp. 71-72GlobalNews item, Silicates
DS1992-0390
1992
Walker, D.Drahovzal, J.A., Harris, D.C., Wickstrom, L.H., Walker, D.The East continent rift basin: a new discoveryIndiana Publishing Cincinnati Arch Consortium Special Report, No. 52, 25pIndiana, Kentucky, OhioStructure, Rift Basin
DS1992-1622
1992
Walker, D.Walker, D., Misra, K.C.Tectonic significance of basalts of the Middle Run Formation in the East Continental Rift Basin, Indiana and KentuckyGeological Society of America (GSA) Abstracts with programs, 1992 Annual, Vol. 24, No. 7, abstract p. A330Indiana, KentuckyTectonics, Rifting
DS1993-0012
1993
Walker, D.Agee, C.B., Walker, D.Olivine flotation in mantle meltEarth and Planetary Science Letters, Vol. 114, No. 2/3, January pp. 315-324MantleGeochemistry, Olivine
DS1994-1484
1994
Walker, D.Rosenbaum, J.M., Walker, D., Kyser, T.K.Oxygen isotope fractionation in the mantleGeochimica et Cosmochimica Acta, Vol. 58, 21, pp. 4767-77.MantleGeochronology -oxygen isotope, Model
DS1994-1871
1994
Walker, D.Walker, D.Is core formation a hot topicEos, Vol. 75, No. 4, January 25, p. 42, 43.MantleCore
DS1997-0550
1997
Walker, D.Jana, D., Walker, D.The impact of carbon on element distribution during core formationGeochimica et Cosmochimica Acta, Vol. 61, No. 13, pp. 2759-2763.GlobalSilicate partition, Carbon
DS2000-0997
2000
Walker, D.Walker, D.Core precipitation in mantle geochemistry: Geochemical Society Ingersen Lecture.Geochimica et Cosmochimica Acta, Vol. 64, No. 17, pp. 2897-2911.MantleCore - geochemistry, fractionation, Bulk composition
DS2000-0998
2000
Walker, D.Walker, D.Core participation in mantle geochemistry. Geochemical Soc. Ingerson LectuGeochimica et Cosmochimica Acta, Vol. 64, No. 17, Sept. 1, pp. 2897-2912.MantleGeochemistry - overview
DS200612-0257
2006
Walker, D.Clar, S.M., Speciale, S., Jeanloz, R., Kunz, M., Caldwell, W.A., Walter, M., Walker, D.Using advanced accelerators to understand the lower mantle and beyond.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 104, abstract only.MantleGeochemistry
DS200612-0283
2006
Walker, D.Cottrell, E., Walker, D.Constraints on core formation from Pt partitioning in mafic silicate liquids at high temperatures.Geochimica et Cosmochimica Acta, in press,TechnologyMagmatism, platinum solubility, silicate
DS200612-1499
2005
Walker, D.Walker, D.Core mantle chemical issues.Canadian Mineralogist, Vol. 43, 5, Oct. pp. 1553-1564.MantleGeochemistry, redox, recycling, digestion
DS200712-0615
2007
Walker, D.Lehnert, K., Walker, D., Sarbas, B.EarthChem - geochemistry dat a network.Plates, Plumes, and Paradigms, 1p. abstract p. A559.TechnologyDatabase
DS200812-0264
2008
Walker, D.Dasgupta, R., Walker, D.Carbon solubility in core melts in a shallow magma ocean environment and distribution of carbon between the Earth's core and the mantle.Geochimica et Cosmochimica Acta, Vol. 72, 18, pp. 4627-4641.MantleMelting
DS1975-0889
1978
Walker, D.A.Walker, D.A.Textural and Compositional Studies of Eclogites from the Roberts Victor |kimberlite, South Africa.Msc. Thesis, Oxford University, 285P.South AfricaPetrography Xenoliths
DS1989-1560
1989
Walker, D.A.Villeneuve, M.E., Walker, D.A.Heavy minerals: detection and classification using automated image and x-ray microanalysisGeological Society of Canada (GSC) Forum 1989, P. 23 abstractGlobalSpectrometry, Heavy minerals
DS2001-0548
2001
Walker, D.A.Jones, H.G., Pomeroy, J.W., Walker, D.A., Hoham, R.W.Snow ecology: an inter disciplinary examination of snow-covered ecosystems. BOOK REVIEW Cambridge Univ. Press, 378p. @ 80.00 USGeoscience Canada, Vol.29,2, June pp. 89-90.CanadaBook - review, Snow ecosystem
DS1950-0245
1955
Walker, D.E.Walker, D.E.Adventure in DiamondsLondon: Evans Bros., 186P., ILLUS. CADET EDITION IN 1962, 190P.GlobalKimberley, Janlib, Fiction, Politics
DS2003-1440
2003
Walker, E.Walker, E.Archean diamond bearing volcanoclastic rocks, north of Wawa OntarioPdac Abstract 2003, March 12, 1p.Ontario, WawaMusquash metavolcanics
DS1989-1573
1989
Walker, E.C.Walker, E.C., Edgar, A.D.high pressure- high-temperature melting: experiments on a diamondiferous olivine lamproite from Prairie Creek ArkansawGeological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A23. (abstract.)ArkansasExperimental petrology, Lamproite
DS1991-1821
1991
Walker, E.C.Walker, E.C.Petrogenesis of the Prairie Creek, Arkansaw, Diamondiferous olivinelamproite.Ph.d. thesis University of Western Ontario, 287p.ArkansasLamproite, Petrology
DS1991-1822
1991
Walker, E.C.Walker, E.C., Edgar, A.D.Changing phase relations -mineral chemistry during ascent the Prairie Creek olivine lamproite, demons. by high pressure- high temp. suprasolidusexperiments.Geological Association of Canada (GAC)/Mineralogical Association of Canada/Society Economic, Vol. 16, Abstract program p. A130ArkansasMineral chemistry, Lamproite
DS1991-1823
1991
Walker, E.C.Walker, E.C., Sutcliffe, R.H., Shaw, C.S.J., Shore, G.T.Geology of the Coldwell alkaline complexOntario Geological Survey Summary of Field Work and Other Activities, No. 157, pp. 107-116OntarioAlkaline, Coldwell Complex
DS1993-1688
1993
Walker, E.C.Walker, E.C., Sutcliffe, R.H., Shaw, C.S.J., Shore, G.T.Preliminary report on the petrology and chemistry of the rare metal occurrences hosted by the Coldwell Alkaline ComplexOntario Geological Survey, Open File Report No. 5840, 20pOntarioAlkaline rocks, Rare earths
DS1994-1872
1994
Walker, E.C.Walker, E.C., Sutcliffe, R.H.Fractionation of syenite suites and formation of rare metal occurrences within the Coldwell alkaline complex, Marathon Ontario.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.OntarioAlkaline rocks, Coldwell Complex
DS1996-1494
1996
Walker, E.C.Walker, E.C.Petrological relationship between magma ascent and diamonds #2Geological Association of Canada (GAC) Annual Abstracts, Vol. 21, abstract only p.A99.GlobalPetrology, Diamond genesis
DS1996-1495
1996
Walker, E.C.Walker, E.C., Davidson, J.G.Petrological relationship between magma ascent and diamonds #1Society for Mining, Metallurgy and Exploration (SME)/American Institute, p. 49. AbstractGlobalPetrology, Lamproites
DS2001-1212
2001
Walker, E.C.Walker, E.C.Distribution of diamonds in Archean rocks north of Wawa, OntarioNw Mining Association Meet., Dec. 7, 1p. abstr.Ontario, WawaNews item
DS2001-1213
2001
Walker, E.C.Walker, E.C.Archean age diamond deposits of the Festival and GQ properties, north of WawaOntario Pros. Association Meeting, Held Dec. 10-12, p. 15. 1p.Ontario, WawaNews item, Band-Or, Pele Mountain
DS2002-1678
2002
Walker, E.C.Walker, E.C.Archean diamond bearing volcanics near Wawa OntarioUniversity of Western Ontario, SEG Student Chapter, March 8, pp. 16-18.OntarioKimberlite facies descriptions
DS2002-1679
2002
Walker, E.C.Walker, E.C.Archean diamond bearing volcanoclastic rocks north of Wawa. Musquash metavolcanic unit.Ontario Exploration Geological Survey Meeting, Dec.1-3, p. 18 Abstract.Ontario, WawaPetrology - description - brief
DS200512-0593
2005
Walker, E.C.Kurszlaukis, S., Walker, E.C., Stachel, T.Deep mantle derived diamond bearing Archean volcanogenic rocks from Wawa Ontario.GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Ontario, WawaDeeper mantle sources
DS200512-1038
2004
Walker, E.C.Stachel, T., Blackburn, L., Kurszlaukis, S., Barton, E., Walker, E.C.Diamonds from the Cristal and genesis volcanics, Wawa Ontario.32nd Yellowknife Geoscience Forum, Nov. 16-18, p.74-75. (talk)Canada, Ontario, WawaDiamond inclusions
DS200512-1040
2005
Walker, E.C.Stachel, T., Kurzlaukis, S., Walker, E.C.Archean diamonds from the Wawa area of Ontario (Canada).GAC Annual Meeting Halifax May 15-19, Abstract 1p.Canada, Ontario, WawaGenesi, Cristal, diamond morphology
DS200812-1226
2008
Walker, E.C.Walker, E.C.MW-93 diamond discovery Courageous Lake, NWT.Northwest Territories Geoscience Office, p. 61-62. abstractCanada, Northwest TerritoriesBrief overview - Consolidated Global Diamonds
DS2003-1441
2003
Walker, G.Walker, G.Snowball Earth.... ( Paul Hoffman's concepts discussed)Crown Publications, 249p.GlobalBook - climatology
DS200412-2071
2003
Walker, G.Walker, G.Snowball Earth.... ( Paul Hoffman's concepts discussed).Crown Publications, 249p.GlobalBook - climatology
DS200512-1159
2003
Walker, G.Walker, G.Snowball Earth: the story of the global catastrophe that spawned life as we know it.Crown Publications, ISBN 0-609-60973-4 $ 37,95Book review: Geoscience Canada 31,3, Sept 2004 p. 141
DS201610-1840
2016
Walker, G.Aravanis, T., Chen, J., Fuechsle, M., Grujic, M., Johnston, P., Kok, Y., Magaraggia, R., Mann, A., Mann, L., McIntoshm S., Rheinberger, G., Saxey, D., Smalley, M., van Kann, F., Walker, G., Winterflood, J.VK1 tm - a next generation airborne gravity gradiometer.ASEG-PESA-AIG 2016 25th Geophysical Conference, Abstract 5p.TechnologyGradiometer

Abstract: The minerals exploration industry’s demand for a highly precise airborne gravity gradiometer has driven development of the VK1TM Airborne Gravity Gradiometer, a collaborative effort by Rio Tinto and the University of Western Australia. VK1TM aims to provide gravity gradient data with lower uncertainty and higher spatial resolution than current commercial systems. In the recent years of VK1TM development, there have been significant improvements in hardware, signal processing and data processing which have combined to result in a complete AGG system that is approaching competitive survey-ready status. This paper focuses on recent improvements. Milestone-achieving data from recent lab-based and moving-platform trials will be presented and discussed, along with details of some advanced data processing techniques that are required to make the most use of the data.
DS200412-0268
2004
Walker, G.P.Canon Tapia, BE., Walker, G.P.Global aspects of volcanism: the perspectives of plate tectonics and volcanic systems.Earth Science Reviews, Vol. 66, no. 1-2, pp. 163-182.GlobalReview - volcanism
DS1989-1574
1989
Walker, G.P.L.Walker, G.P.L.Gravitational (density) controls on volcanism, magma chambers andintrusionsAustralian Journal of Earth Sciences, Vol. 36, pp. 149-165. Database #18068GlobalMagma, Geophysics-gravity
DS1992-1623
1992
Walker, G.P.L.Walker, G.P.L.Coherent intrusion complexes in large basaltic volcanoes- a new structuralmodelJournal of Volcanology and Geothermal Research, Vol. 50, No. 1/2, April 15, pp. 41-54GlobalVolcanoes, Structural model
DS1970-0843
1973
Walker, I.R.Walker, I.R.Stratigraphic Section through the Kalahari Beds at Jwaneng, ngwaketse District.Botswana Report., IRW/9/73, 1 FIGURE NO TEXT. (UNPUBL.).BotswanaProspecting
DS1970-1002
1974
Walker, I.R.Walker, I.R.Kimberlite and Post Karroo Dolerites. Diamonds: in Contribution to Kalatraverse Memoir.Botswana Geological Survey, BotswanaKimberlite, Orapa, Tectonics
DS1970-1003
1974
Walker, I.R.Walker, I.R.Kalatraverse I ContibutionBotswana Geological Survey, IRW/8/74, 28P. (UNPUBL.)BotswanaKimberlite, Prospecting, Tectonic
DS1996-1512
1996
Walker, J.A.Ward, R.L., Walker, J.A.Ocean Island Basalt (OIB) type mantle source for late Oligocene to early Miocene mafic rocks Trans Pecos Volcanic Province.Geological Society of America (GSA) Abstracts, Vol. 28, No. 1, Feb. p. 68.GlobalXenoliths, Lithosphere
DS2003-1442
2003
Walker, J.A.Walker, J.A., Roggensack, K., Patino, L.C., Cameron, B.I., Matias, O.The water and trace element contents of melt inclusions across an active subductionContributions to Mineralogy and Petrology, Vol. 146, 1, pp. 62-77.MantleSubduction - water
DS2003-1443
2003
Walker, J.A.Walker, J.A., Roggensack, K., Patino, L.C., Cameron, B.I., Matias, O.The water and trace element contents of melt inclusions across an active subductionContributions to Mineralogy and Petrology, Vol. 10.1007/s00410-003-0432-xMantleBlank
DS200412-2072
2003
Walker, J.A.Walker, J.A., Roggensack, K., Patino, L.C., Cameron, B.I., Matias, O.The water and trace element contents of melt inclusions across an active subduction zone.Contributions to Mineralogy and Petrology, Vol. 146, 1, pp. 62-77.MantleSubduction - water
DS1992-0482
1992
Walker, J.C.G.Francois, L.M., Walker, J.C.G.Modelling the Phanerozoic carbon cycle and climate: constraints from the87Sr/86Sr isotopic ratio of seawaterAmerican Journal of Science, Vol. 292, No. 2, February pp. 81-135GlobalCarbon cycle, Geochronology
DS1992-1624
1992
Walker, J.C.G.Walker, J.C.G., Sloan, L.C.Something is wrong with climate theoryGeotimes, Vol. 37, No. 6, June pp. 16-18GlobalGlobal change, Climate
DS1996-1496
1996
Walker, J.D.Walker, J.D., et al.Development of Geographic Information Systems -oriented databases for integrated geological and geophys. applicGsa Today, Vol. 6, No. 3, March pp. 1-7United StatesComputer, Databases -GIS
DS1999-0683
1999
Walker, J.D.Smith, E.I., Sanchez, A., Walker, J.D., Wang, K.Geochemistry of mafic magmas in the Hurricane volcanic field: Implications for small and large scale chemistyJournal of Geology, Vol. 107, No. 4, July pp. 433-48.UtahMagma, basanite, lithosphere xenoliths
DS2002-1684
2002
Walker, J.D.Wang, K., Plank, T., Walker, J.D., Smith, E.I.A mantle melting profile across the Basin and Range, southwest USAJournal of Geophysical Research, Vol.107, 1, ECV 5-1-21.Nevada, Colorado, WyomingMelt
DS200612-1500
2006
Walker, J.D.Walker, J.D., Bowers, T.D., Black, R.A., Glazner, A.F., Farmer, G.L., Carlson, R.W.A geochemical database for western North American volcanic and intrusive rocks. NAVDATIn: Sinha, A.K. Geoinformatics: data to knowledge, GSA Special Paper, 397, 397, pp.61-72United StatesGeochemistry - data
DS1993-1689
1993
Walker, J.S.Walker, J.S.State of the art techniques for backfilling abandoned mine voidsUnited States Bureau of Mines Information Circular, No. 9359, 17pUnited StatesEnvironmental, Mining -backfill
DS200512-1160
2005
Walker, K.T.Walker, K.T., Bokelmann, G.H.R., Klemperer, S.L., Nyblade, A.Shear wave splitting around hotspots: evidence for upwelling related mantle flow?Plates, Plumes, and Paradigms, pp. 171-192. ( total book 861p. $ 144.00)GlobalGeophysics - seismics
DS200612-1501
2005
Walker, K.T.Walker, K.T., Bokelmann, G.H., Klemperer, S.L., Bock, G.Shear wave splitting around the Eifel hotspot: evidence for a mantle upwelling.Geophysical Journal International, Vol. 163, 3,Dec. pp. 962-980.Europe, GermanyGeophysics - seismics
DS2003-1444
2003
Walker, M.Walker, M., Jourdan, P.Resource based sustainable development: an alternative approach to industrialization inMinerals and Energy, Raw Materials Report, Vol. 18, 3, Sept. pp. 25-34.South AfricaLegal, economics
DS200412-2073
2003
Walker, M.Walker, M., Jourdan, P.Resource based sustainable development: an alternative approach to industrialization in South Africa.Minerals & Energy - Raw Materials Report, Vol. 18, 3, Sept. pp. 25-34.Africa, South AfricaLegal, economics
DS200912-0082
2009
Walker, M.Buisman, I., Sparks, S., Walker, M.Towards a better understanding of the origin and evolution of kimberlite melts using melt phase relations in CMAS-CO2-H2O-K2O.Goldschmidt Conference 2009, p. A172 Abstract.MantleMelting
DS200712-1128
2007
Walker, M.J.Walker, M.J., Lowe, J.J.Quaternary science 2007: a 50 year retrospective.Journal of the Geological Society, Vol. 164, 6, pp. 1073-1092.TechnologyGeomorphology
DS1992-1625
1992
Walker, N.Walker, N.Middle Proterozoic geologic evolution of Llano uplift, Texas: evidence From the uranium-lead (U-Pb) (U-Pb) zircon geochronologyGeological Society of America (GSA) Bulletin, Vol 104, No. 4, April pp. 494-504GlobalProterozoic, Grenville, geochronology
DS200412-0790
2003
Walker, N.Hargrove, U.S., Hanson, R.E., Martin, M.W., Blenkinsop, T.G., Bowring, S.A., Walker, N., Munyanyiwa, H.Tectonic evolution of the Zambesi orogenic belt: geochronological, structural and petrological constraints from northern ZimbabwPrecambrian Research, Vol. 123, 2-4, pp. 159-186.Africa, ZimbabweTectonics
DS1991-0346
1991
Walker, N.W.Davis, L.L., McDowell, F.W., Smith, D., Walker, N.W.Potassic, mafic rocks at Twin Buttes, ColoradoEos, Spring Meeting Program And Abstracts, Vol. 72, No. 17, April 23, p. 295ColoradoMinette
DS1996-0338
1996
Walker, N.W.Davis, L.L., Smith, D., McDowell, F.W., Walker, N.W., BorgEocene potassic magmatism at Two Buttes, Colorado, with implications for Cenozoic tectonics and magma generationGeological Society of America (GSA) Bulletin., Vol. 108, No. 12, Dec. pp. 1567-1579.ColoradoAlkaline rocks, Tectonics
DS201811-2605
2018
Walker, O.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
Walker, O.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.
DS1992-1156
1992
Walker, P.Palacky, G.J., Holladay, J.S., Walker, P.Inversion of helicopter electromagnetic dat a along the Kapuskasingtransect, OntarioGeological Survey of Canada Paper, No. 92-1E, pp. 177-184OntarioGeophysics, Kapuskasing Rift
DS1990-1153
1990
Walker, P.W.Palacky, G.J., Holladay, .S., Walker, P.W.Use of inversion techniques in interpretation of helicopter electromagneticdat a for mapping quaternary sediments near Kapuskasing, Ontario CanadaSociety of Exploration Geophysicists, 60th. Annual Meeting held, San, Vol. 1, pp. 689-692. Extended abstractOntarioKapuskasing, Geophysics -electromagnetic
DS1991-1285
1991
Walker, P.W.Palacky, G.J., Holladay, J.S., Walker, P.W.Mapping of Quaternary sediments near Kapuskasing, Ontario with a helicopter electromagnetic systemGeological Survey of Canada Forum held January 21-23, 1990 in Ottawa, p. 13 AbstractOntarioGeophysics -electromagnetic, Sediments
DS1994-0438
1994
Walker, R.Doden, A.G., Gold, D.P., Walker, R.Geochemistry of diatremes and dikes with lamprophyric/carbonatitic affinities from discrete alkalic intrusive centres in Montana.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p. PosterMontanaCarbonatite, Geochemistry
DS1994-1085
1994
Walker, R.Madson, E., Madill, H., Walker, R.Exploration to development: DIAND's regulatory requirements. #2The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), pp. 25-38.Northwest TerritoriesLegal, environment, Regulations
DS1994-1086
1994
Walker, R.Madson, E., Madill, H., Walker, R.Exploration to development: DIAND's regulatory requirements. #1The Canadian Institute of Mining, Metallurgy and Petroleum (CIM), pp. 25-38.Northwest TerritoriesLegal, Environmental
DS201012-0453
2010
Walker, R.Liu, J., Rudnick, R., Walker, R., Gao, S., Wu, F., Xu, W., Xu, Y.OS isotope evidence for diachronous formation of lithospheric mantle beneath the Trans-North Chin a oorgen, north Chin a, craton.Goldschmidt 2010 abstracts, abstractChinaGeochronology
DS1989-1575
1989
Walker, R.J.Walker, R.J., Carlson, R.W., Shirey, S.B., Boyd, F.R.Osmimum, Strontium, neodymium and lead isotope systematics of Southern african peridotite xenoliths: implications for the chemical evolution of subcontinental mantleGeochimica et Cosmochimica Acta, Vol. 53, pp. 1583-1595South Africa, BotswanaXenoliths, Mineral chemistry
DS1997-1221
1997
Walker, R.J.Walker, R.J., Morgan, J.W., Hanski, E.J., Smolkin, V.F.Rhenium- Osmium (Re-Os) systematics of Early Proterozoic ferropicrites, Pechenga Russia: evidence for ancient plumes.Geochimica et Cosmochimica Acta, Vol. 61, No. 15, pp. 3145-60Russia, Kola PeninsulaGeochemistry, geochronology, layered intrusion, Pechenga Complex
DS2001-0768
2001
Walker, R.J.Meisel, T., Walker, R.J., Lorand, J-P.Osmium isotopic compositions of mantle xenoliths: a global perspectiveGeochimica et Cosmochimica Acta, Vol. 65, No. 8, Apr. 1311-24.MantleGeochronology, Xenoliths
DS2002-1680
2002
Walker, R.J.Walker, R.J., Nisbet, E.1870s isotopic constraints on Archean mantle dynamicsGeochimica et Cosmochimica Acta, Vol. 66,18, pp. 3317-25.MantleGeochronology
DS2002-1681
2002
Walker, R.J.Walker, R.J., Prichard. H.M., Ishiwatari, A., PimentelThe osmium isotopic composition of convecting upper mantle deduced from ophiolite chromites.Geochimica et Cosmochimica Acta, Vol. 66, No. 2, pp. 329-45.MantleGeochronology, Chromites
DS2003-1502
2003
Walker, R.J.Wu, F., Walker, R.J., Ren, X., Sun, D., Zhou, X.Osmium isotopic constraints on the age of lithospheric mantle beneath northeasternChemical Geology, Vol. 196, No. 1-4, pp. 107-129.ChinaGeochronology
DS200412-0696
2004
Walker, R.J.Gornostayev, S.S., Walker, R.J., Hanski, E.J., Popovchenko, S.E.Evidence for the emplacement of ca. 3.0 Ga mantle derived mafic ultramafic bodies in the Ukrainian Shield.Precambrian Research, Vol. 132, 4, July 15, pp.349-362.Europe, UkraineTectonics, chromitite
DS200412-2149
2003
Walker, R.J.Wu, F., Walker, R.J., Ren, X., Sun, D., Zhou, X.Osmium isotopic constraints on the age of lithospheric mantle beneath northeastern China.Chemical Geology, Vol. 196, no. 1-4, pp. 107-129.ChinaGeochronology
DS200512-0109
2005
Walker, R.J.Brandon, A.D., Walker, R.J.The debate over the core-mantle interaction.Earth and Planetary Science Letters, Vol. 232, 3-4, April 15, pp. 211-225.MantleIsotope systematics, boundary, geochronology
DS200512-0881
2005
Walker, R.J.Puchtel, I.S., Brandon, A.D., Humayun, M., Walker, R.J.Evidence for the early differentiation of the core from Pt-Re-Os isotope systematics of 2.8 Ga komatiites.Earth and Planetary Science Letters, Vol. 237, 1-2, Aug, 30, pp. 118-134.Europe, Baltic ShieldGeochronology, core-mantle interaction
DS200612-0106
2006
Walker, R.J.Becker, H., Horan, M.F., Walker, R.J., Gao, S., Lorand, J-P., Rudnick, R.L.Highly siderophile element composition of the Earth's primitive upper mantle: constraints from new dat a on peridotite massifs and xenoliths.Geochimica et Cosmochimica Acta, Vol. 70, 17, pp. 4528-4550.MantleMineral chemistry
DS200612-0165
2006
Walker, R.J.Brandon, A.D., Walker, R.J., Puchtel, I.S.Platinum osmium isotope evolution of the Earth's mantle: constraints from chondrites and Os rich alloys.Geochimica et Cosmochimica Acta, In pressMantleKomatiitie, chondrites, PGE, geochronology
DS200612-1502
2006
Walker, R.J.Walker, R.J., Ireland, T., Brandon, A.D.The search for evidence of chemical interactions between the core and mantle.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 2, abstract only.MantleGeochemistry
DS200612-1547
2006
Walker, R.J.Wu, F-Y., Walker, R.J., Yang, Y-H., Yuan, H-L., Yang, J-H.The chemical temporal evolution of lithospheric mantle underlying the North Chin a Craton.Geochimica et Cosmochimica Acta, Vol. 70, 19, pp. 5013-5034.ChinaDeposit - Tieling, Fuxian, Mengyin - geochemistry -SCLM
DS200612-1579
2006
Walker, R.J.Yuan, H.L., Gao, S., Rudnick, R.L., Jin, Z.M., Walker, R.J.Re Os evidence for age and origin of peridotites from the Dabie Sulu UHP belt.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 10. abstract only.ChinaUHP, geochronology
DS200812-1198
2008
Walker, R.J.Van Acken, D., Becker, H., Walker, R.J.Refertilization of Jurassic oceanic peridotites from the Tethys Ocean: implications for the Re Os systematics of the upper mantle.Earth and Planetary Science Letters, Vol. 268, 1-2, pp. 171-181.MantlePeridotite
DS200912-0001
2009
Walker, R.J.Ackerman, L., Walker, R.J., Puchtel, I.S., Pitcher, L., Jelinek, E., Strnad, L.Effects of melt percolation on highly siderophile elements and Os isotopes in subcontinental lithospheric mantle: a study of upper mantle profile central EuropeGeochimica et Cosmochimica Acta, Vol. 73, 8, pp. 2400-2414.Europe, Czech RepublicGeochonology
DS200912-0114
2009
Walker, R.J.Chu, Z-Y., Wu, F-Y., Walker, R.J., Rudnick, R.L., Pitcher, L., Puchtel, I.S., Yang, Y-H., Wilde, S.A.Temporal evolution of the lithospheric mantle beneath the North Chin a Craton.Journal of Petrology, Vol. 50, 10, pp. 1857-1898.ChinaGeodynamics
DS200912-0652
2009
Walker, R.J.Rudnick, R.L., Walker, R.J.Interpreting ages from Re-Os isotopes in peridotites.Lithos, In press availableTechnologyGeochronology
DS200912-0803
2009
Walker, R.J.Walker, R.J.Geochemical constraints on the core-mantle system?GAC/MAC/AGU Meeting held May 23-27 Toronto, Abstract onlyMantleBoundary
DS200912-0866
2009
Walker, R.J.Zhu-Yin Chu, Wu, F-Y., Walker, R.J., Rudnick, R.L., Pitcher, L., Puchtel, I.S., Yang, Y-H., Wilde, S.A.Temporal evolution of the lithospheric mantle beneath the eastern north Chin a craton.Journal of Petrology, Vol. 50, 10, October, pp. 1857-1898.ChinaTectonics
DS201112-0611
2011
Walker, R.J.Liu, J., Rudnick, R.L., Walker, R.J., Gao, S., Wu, F-y., Piccoli, P.M., Yuan, H., Xu, W-l., Xu, Yi-G.Mapping lithospheric boundaries using Os isotopes of mantle xenoliths: an example from the North Chin a Craton.Geochimica et Cosmochimica Acta, Vol. 75, 13, pp. 3881-3902.ChinaGeochronology
DS201212-0549
2012
Walker, R.J.Penniston-Dorland, S., Walker, R.J., Pitcher, L., Sorensen, S.S.Mantle crust interactions in a paleosubduction zone: evidence from highly siderophile element systematics of eclogite and related rocks.Earth and Planetary Science Letters, Vol. 319-320, pp. 295-306.MantleSubduction
DS201312-0746
2013
Walker, R.J.Rizo, H., Touboul, M., Carlson, R.W., Boyet, M., Puchtel, I.S., Walker, R.J.Early mantle composition and evolution inferred from 142 ND and 182 W variations in Isua samples.Goldschmidt 2013, AbstractMantleMineralogy
DS201606-1110
2016
Walker, R.J.Rizo, H., Walker, R.J., Carlson, R.W., Horan, M.F., Mukhopadhyay, S., Manthos, V., Francis, D., Jackson, M.G.Preservation of Earth forming events in the tungsten isotopic composition of modern flood basalts…… ancient rocksScience, Vol. 352, no. 6287, May 13, pp. 809-812.Canada, Nunavut, Baffin IslandGeochronology

Abstract: How much of Earth's compositional variation dates to processes that occurred during planet formation remains an unanswered question. High-precision tungsten isotopic data from rocks from two large igneous provinces, the North Atlantic Igneous Province and the Ontong Java Plateau, reveal preservation to the Phanerozoic of tungsten isotopic heterogeneities in the mantle. These heterogeneities, caused by the decay of hafnium-182 in mantle domains with high hafnium/tungsten ratios, were created during the first ~50 million years of solar system history, indicating that portions of the mantle that formed during Earth’s primary accretionary period have survived to the present
DS201702-0208
2017
Walker, R.J.Day, J.M.D., Walker, R.J., Warren, J.M.186Os-187Os and highly siderophile element abundance systematics of the mantle revealed by abyssal peridotites and Os rich alloys.Geochimica et Cosmochimica Acta, Vol. 200, pp. 232-254.MantlePeridotite

Abstract: Abyssal peridotites are oceanic mantle fragments that were recently processed through ridges and represent residues of both modern and ancient melting. To constrain the nature and timing of melt depletion processes, and the composition of the mantle, we report high-precision Os isotope data for abyssal peridotites from three ocean basins, as well as for Os-rich alloys, primarily from Mesozoic ophiolites. These data are complemented by whole-rock highly siderophile element (HSE: Os, Ir, Ru, Pt, Pd, Re), trace- and major-element abundances for the abyssal peridotites, which are from the Southwest Indian (SWIR), Central Indian (CIR), Mid-Atlantic (MAR) and Gakkel Ridges. The results reveal a limited role for melt refertilization or secondary alteration processes in modifying abyssal peridotite HSE compositions. The abyssal peridotites examined have experienced variable melt depletion (2% to >16%), which occurred >0.5 Ga ago for some samples. Abyssal peridotites typically exhibit low Pd/Ir and, combined with high-degrees of estimated total melt extraction, imply that they were relatively refractory residues prior to incorporation into their present ridge setting. Recent partial melting processes and mid-ocean ridge basalt (MORB) generation therefore played a limited role in the chemical evolution of their precursor mantle domains. The results confirm that many abyssal peridotites are not simple residues of recent MORB source melting, having a more complex and long-lived depletion history. Peridotites from the Gakkel Ridge, SWIR, CIR and MAR indicate that the depleted MORB mantle has 186Os/188Os of 0.1198356 ± 21 (2SD). The Phanerozoic Os-rich alloys yield an average 186Os/188Os within uncertainty of abyssal peridotites (0.1198361 ± 20). Melt depletion trends defined between Os isotopes and melt extraction indices (e.g., Al2O3) allow an estimate of the primitive mantle (PM) composition, using only abyssal peridotites. This yields 187Os/188Os (0.1292 ± 25), and 186Os/188Os of 0.1198388 ± 29, both of which are within uncertainty of previous primitive mantle estimates. The 186Os/188Os composition of the PM is less radiogenic than for some plume-related lavas, with the latter requiring sources with high long-term time-integrated Pt/Os. Estimates of primitive mantle HSE concentrations using abyssal peridotites define chondritic Pd/Ir, which differs from previous supra-chondritic estimates for Pd/Ir based on peridotites from a range of tectonic settings. By contrast, estimates of PM yield supra-chondritic Ru/Ir. The cause of enhanced Ru in the mantle remains enigmatic, but may reflect variable partitioning behavior of Ru at high pressure and temperature.
DS201907-1585
2019
Walker, R.J.Wu, F-Y., Yang, J-H., Xu, Y-G., Wilde, S.A., Walker, R.J.Destruction of the North China craton in the Mesozoic.Annual Reviews of Earth and Planetary Sciences, Vol. 47, pp. 173-195.Chinacraton

Abstract: The North China Craton (NCC) was originally formed by the amalgamation of the eastern and western blocks along an orogenic belt at ~1.9 Ga. After cratonization, the NCC was essentially stable until the Mesozoic, when intense felsic magmatism and related mineralization, deformation, pull-apart basins, and exhumation of the deep crust widely occurred, indicative of destruction or decratonization. Accompanying this destruction was significant removal of the cratonic keel and lithospheric transformation, whereby the thick (~200 km) and refractory Archean lithosphere mantle was replaced by a thin (<80 km) juvenile one. The decratonization of the NCC was driven by flat slab subduction, followed by a rollback of the paleo-Pacific plate during the late Mesozoic. A global synthesis indicates that cratons are mainly destroyed by oceanic subduction, although mantle plumes might also trigger lithospheric thinning through thermal erosion. Widespread crust-derived felsic magmatism and large-scale ductile deformation can be regarded as petrological and structural indicators of craton destruction.
DS1975-0890
1978
Walker, R.L.Walker, R.L.A Contribution to the Petrology of Kimberlite Fissures on Peiserton and Bellsbank.Msc Thesis, Rhodes University, 50P.South Africa, Barkly West, Hay DistrictPetrography, Microprobe Analyses, Olivine, Mica, Geochemistry
DS1920-0413
1928
Walker, R.T.Walker, R.T.Mineralized Volcanic Explosion PipesEngineering and Mining Journal, Vol. 126, Dec. 8TH. PP. 895-898.; Dec. 15TH. PP. 939-942.; DECGlobalDiamond Genesis
DS1994-1873
1994
Walker, R.T.Walker, R.T.Metallic and industrial mineral assessment report on the Pinhorn diamond/gold.Alberta Geological Survey, MIN 19940008AlbertaExploration - assessment, Marum Resources Inc.
DS1995-0063
1995
Walker, R.T.Ash, W.M., Pritchard, R.A., Walker, R.T.Metallic and industrial mineral assessment report on the Pinhorn and Black Butte diamond/gold prop. Milk R.Alberta Geological Survey, MIN 19950022AlbertaExploration - assessment, Marum Resources
DS201701-0037
2016
Walker, R.T.Walker, R.T., Telfer, M., Kahle, R.L., Dee, M.W., Kahle, J-L., Schwenninger, J-L., Sloan, R.A., Watts, A.B.Rapid mantle driven uplift along the Angolan margin in the Quaternary.Nature Geoscience, Vol. 9, pp. 909-914.Africa, AngolaTectonics

Abstract: Mantle flow can cause the Earth’s surface to uplift and subside, but the rates and durations of these motions are, in general, poorly resolved due to the difficulties in making measurements of relatively small vertical movements (hundreds of metres) over sufficiently large distances (about 1,000?km). Here we examine the effect of mantle upwelling through a study of Quaternary uplift along the coast of Angola. Using both optically stimulated luminescence on sediment grains, and radiocarbon dating of fossil shells, we date a 25?m coastal terrace at about 45 thousand years old, when sea level was about 75?m lower than today, indicating a rapid uplift rate of 1.8-2.6?mm?yr-1 that is an order of magnitude higher than previously obtained rates averaged over longer time periods. Automated extraction and correlation of coastal terrace remnants from digital topography uncovers a symmetrical uplift with diameter of more than 1,000?km. The wavelength and relatively short timescale of the uplift suggest that it is associated with a mantle process, possibly convective upwelling, and that the topography may be modulated by rapid short-lived pulses of mantle-derived uplift. Our study shows that stable continental regions far from the effects of glacial rebound may experience rapid vertical displacements of several millimetres per year.
DS1987-0736
1987
Walker, S.Thompson, G.R., Walker, S., McCarthy, D.Zoned K bentonites of western MontanaGeological Society of America, Vol. 19, No. 7 annual meeting abstracts, p.867. abstracMontanaSweetgrass Arch
DS2003-0890
2003
Walker, S.Masun, K.M., Doyle, B.J., Ball, S., Walker, S.The geology and mineralogy of the Anuri kimberlite, Nunavut, Canada31st Yellowknife Geoscience Forum, p. 63. (abst.)NunavutMineralogy
DS2003-0891
2003
Walker, S.Masun, K.M., Doyle, B.J., Ball, S.A., Walker, S.The geology and mineralogy of the Anuri kimberlite, Nunavut, Canada8ikc, Www.venuewest.com/8ikc/program.htm, Session 1 POSTER abstractNunavutKimberlite geology and economics, Deposit - Anuri
DS200412-1244
2003
Walker, S.Masun, K.M., Doyle, B.J., Ball, S., Walker, S.The geology and mineralogy of the Anuri kimberlite, Nunavut, Canada.31st Yellowknife Geoscience Forum, p. 63. (abst.Canada, NunavutMineralogy
DS200912-0076
2009
Walker, S.Brodholt, J., Amman, M., Hunt, S., Walker, S., Dobson, D.The rheological properties of post-perovskite and implications for D'.Goldschmidt Conference 2009, p. A162 Abstract.MantleBoundary
DS201112-1097
2011
Walker, S.Walker, S.Clarity matters: a look at world diamond mining industry, and some of the ethical issues that continue to dog it.Womp-int.com, Sept. 30, 8p.GlobalIndustry overview
DS201312-0947
2013
Walker, S.Walker, S.Eyes aloft - airborne drones extend remote sensing and interpretation capabilities. Buddy Doyle comments.Engineering and Mining Journaj, July pp. 44-45.TechnologyGeophysics
DS201710-2274
2017
Walker, S.Walker, S.Diamond miners respond… Suffering from lower jewelry demand over much of past 10 years, the world's diamond industry picked up last year.Engineering and Mining Journal, Sept. pp. 58-66.Globalindustry - overview

Abstract: Since the last occasion when E&MJ took an in-depth look at the world diamond industry (September 2011, pp.54-63), the world’s diamond producers have continued the process of restructuring that began in the early 2000s when De Beers began to relinquish its traditional role of industry custodian. In the intervening period, statistics compiled by the Kimberley Process Certification Scheme (KPCS) indicate that producers responded in no mean way to reduced consumer demand, particularly in the aftermath of the 2008 global economic downturn, with output fluctuating within a fairly narrow band between 2009 and 2015, and only showing signs of picking up again last year.
DS1900-0135
1902
Walker, T.L.Walker, T.L.The Geology of the Kalahandi State, Central ProvincesIndia Geological Survey Memoirs, Vol. 33, PT. 3, PP. 1-22.India, Madhya PradeshGeology
DS1999-0403
1999
WallLee, 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
WallLee, 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
DS2001-1084
2001
WallSitnikova, M.A., Zaitsev, Wall, Chakmouradian, SubbotinEvolution of chemical composition of rock forming carbonates in Sallanlatvi carbonatites, Kola PeninsulaJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 34.(abs)Russia, Kola PeninsulaCarbonatite, Sallanlatvi Complex
DS200712-0269
2007
Wall, A.G.Doroshkevich, A.G., Wall, A.G., Ripp, G.S.Magmatic graphite in dolomite carbonatite at Pogranichnoe, North Transbaikalia, Russia.Contributions to Mineralogy and Petrology, Vol. 153, 3, pp. 339-353.RussiaCarbonatite
DS201810-2360
2018
Wall, C.J.Nasdala, L., Corfu, F., Schoene, B., Tapster, S.R., Wall, C.J., Schmitz, M.D., Ovtcharova, M., Schaltegger, U., Kennedy, A.K., Kronz, A., Reiners, P.W., Yang, Y-H., Wu, F-Y., Gain, S.E.M., Griffin, W.L., Szymanowski, D., Chanmuang, C., Ende, N.M., ValleyGZ7 and GZ8 - two zircon reference materials for SIMS U-Pb geochronology.Geostandards and Geoanalytical Research, http://orchid.org/0000-0002-2701-4635 80p.Asia, Sri Lankageochronology

Abstract: Here we document a detailed characterization of two zircon gemstones, GZ7 and GZ8. Both stones had the same mass at 19.2 carats (3.84 g) each; both came from placer deposits in the Ratnapura district, Sri Lanka. The U-Pb data are in both cases concordant within the uncertainties of decay constants and yield weighted mean ²°6Pb/²³8U ages (95% confidence uncertainty) of 530.26 Ma ± 0.05 Ma (GZ7) and 543.92 Ma ± 0.06 Ma (GZ8). Neither GZ7 nor GZ8 have been subjected to any gem enhancement by heating. Structure-related parameters correspond well with the calculated alpha doses of 1.48 × 10¹8 g?¹ (GZ7) and 2.53 × 10¹8 g?¹ (GZ8), respectively, and the (U-Th)/He ages of 438 Ma ± 3 Ma (2s) for GZ7 and 426 Ma ± 9 Ma (2s) for GZ8 are typical of unheated zircon from Sri Lanka. The mean U concentrations are 680 µg g?¹ (GZ7) and 1305 µg g?¹ (GZ8). The two zircon samples are proposed as reference materials for SIMS (secondary ion mass spectrometry) U-Pb geochronology. In addition, GZ7 (Ti concentration 25.08 µg g?¹ ± 0.18 µg g?¹; 95% confidence uncertainty) may prove useful as reference material for Ti-in-zircon temperature estimates.
DS1990-0908
1990
Wall, F.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
DS1991-1824
1991
Wall, F.Wall, F.Comparison of element distribution in rare earth rich rocks from the Kanankunde and Knombwa carbonatite complexesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 446-448GlobalCarbonatite, Rare earths, rare earth elements (REE).
DS1991-1891
1991
Wall, F.Woolley, A.R., Barr, M.W.C., Din, V.K., Jones, G.C., Wall, F.Extrusive carbonatites from the Uyaynah area, United Arab EmiratesJournal of Petrology, Vol. 32, pt. 6, pp. 1143-1167GlobalCarbonatite, Rock, mineral chemistry
DS1992-0924
1992
Wall, F.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
DS1994-1874
1994
Wall, F.Wall, F., Barreiro, B.A., Spiro, B.Isotopic evidence for late stage processes in carbonatites: rare earth mineralization in carbonatitesMineralogical Magazine, Vol. 58A, pp. 951-952. AbstractMalawiCarbonatite
DS1995-2016
1995
Wall, F.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
DS1995-2017
1995
Wall, F.Wall, F., Williams, C.T., Woolley, A.R., Nasraoui, M.Pyrochlore from weathered carbonate at Lueshe, ZaireGeological Society Africa 10th. Conference Oct. Nairobi, p. 158-9. Abstract.Democratic Republic of CongoCarbonatite, Deposit -Lueshe
DS1995-2076
1995
Wall, F.Woolley, A.R., Williams, C.T., Wall, F., Garcia, D., MouteThe Bingo Carbonatite -ijolite - nepheline syenite complex Zaire: petrography, mineralogy ...Journal of African Earth Sciences, Vol. 21, No. 3, October pp. 329-348.Democratic Republic of CongoCarbonatite, Deposit -Bingo
DS1996-0697
1996
Wall, F.Jones, A.P., Wall, F., Williams, C.T.Rare earth minerals chemistry, origin and ore depositsChapman Hall, MSA., MSA No. 7, 360p. approx. $ 80.00 United StatesGlobalBook - table of contents, Rare earth minerals
DS1996-0698
1996
Wall, F.Jones, A.P., Wall, F., Williams, C.T.Rare earth minerals: chemistry, origin and ore deposits.Specific chapters cited separately.Mineralogical Soc. Series, No. 7, 372p. approx. $60.00USGlobalRare earth minerals, Carbonatite
DS1996-1497
1996
Wall, F.Wall, F., Mariano, A.N.Rare earth minerals in carbonatites: a discussion centred on the Kangankunde carbonatite, Malawi.Mineralogical Soc. Series, No. 7, pp. 193-226.MalawiRare earth minerals, Carbonatite, Deposit - Kangankunde
DS1996-1498
1996
Wall, F.Wall, F., Williams, C.T., Nasraoui, M.Pyrochlore from weathered carbonatite at Luesche, ZaireMineralogical Magazine, Vol. 60, No. 5, Oct 1, pp. 731-750.Democratic Republic of CongoCarbonatite
DS1996-1499
1996
Wall, F.Wall, F., Williams, C.T., Woolley, A.R., Nasraoui, M.Pyrochlore from weathered carbonatite at Luashe ZaireMineralogical Magazine, Vol. 60, No. 5, Oct. pp. 731-750.Democratic Republic of CongoCarbonatite, Mineralogy
DS1997-0141
1997
Wall, F.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
DS1997-1257
1997
Wall, F.Williams, C.T., Wall, F., Woolley, A.R., Phillipo, S.Compositional variation in pyrochlore from the Bingo carbonatite, ZaireJournal of African Earth Sciences, Vol. 25, No. 1, July pp. 137-146.Democratic Republic of CongoCarbonatite
DS1997-1287
1997
Wall, F.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
DS1997-1288
1997
Wall, F.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
Wall, F.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
DS2000-0830
2000
Wall, F.Rosatelli, G., Wall, F.Extrusive carbonatite from Rangwa caldera complex, KenyaIgc 30th. Brasil, Aug. abstract only 1p.KenyaCarbonatite
DS2000-0875
2000
Wall, F.Schurmann, L., Wall, F., Bowden, P.Processes in high level carbonatite magma chambers: evidence from Nooitgedacht, South Africa.Igc 30th. Brasil, Aug. abstract only 1p.South AfricaCarbonatite, Deposit - Nooitgedacht
DS2001-0130
2001
Wall, F.Bowden. P., Wall, F., Schurmann, L.Spinifex textured pegmatitic crystallization in carbonatitesJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 11 (abs)TanzaniaCarbonatite, Kerimasi Volcano
DS2001-0144
2001
Wall, F.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).
DS2001-1214
2001
Wall, F.Wall, F., Williams, C.T., Woolley, A.R.Production of niobium deposits in weathered carbonatite: an example at Sokli northern Finland.Institute of Mining and Metallurgy (IMM) Transactions. Durham Meeting absts., Vol. 110, p. B48. abstractFinlandCarbonatite
DS2001-1215
2001
Wall, F.Wall, F., Zaitsev, A.N., Mariano, A.N.Rare earth pegmatites in carbonatitesJournal of South African Earth Sciences, Vol. 32, No. 1, p. A 35-6.(abs)GlobalCarbonatite, Pegmatites - rare earth elements (REE).
DS2002-0372
2002
Wall, F.Demeny, A., Zaitsev, A.N., Wall, F., Sindem, S., Sitnikova, M.A., KarchevskyCarbon and isotope compositions of carbonatite complexes from the Kola Peninsula, Russia.18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.252.Russia, Kola PeninsulaCarbonatite - mineralogy
DS2002-1499
2002
Wall, F.Sitnikova, M.A., Wall, F., Jeffries, T., Zaitsev, A.N.Ancylite group minerals in the Sallaniatvi carbonatites, Kola Peninsula, Russia18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.251-2.Russia, Kola PeninsulaCarbonatite - mineralogy
DS2002-1769
2002
Wall, F.Zaitsev, A.N., Demeny, A., Sindern, S., Wall, F.Burbankite group minerals and their alteration in rare earth carbonatites - source of elements and fluids....Lithos, Vol.62,1-2,pp.15-33., Vol.62,1-2,pp.15-33.Russia, Kola PeninsulaGeochronology, Deposit - Khibina, Vuoriyarvi complex
DS2002-1770
2002
Wall, F.Zaitsev, A.N., Demeny, A., Sindern, S., Wall, F.Burbankite group minerals and their alteration in rare earth carbonatites - source of elements and fluids....Lithos, Vol.62,1-2,pp.15-33., Vol.62,1-2,pp.15-33.Russia, Kola PeninsulaGeochronology, Deposit - Khibina, Vuoriyarvi complex
DS2003-0483
2003
Wall, F.Goodenough, K.M., Coulson, I.M., Wall, F.Intraplate alkaline magmatism: mineralogy and petrogenesisMineralogical Magazine, Vol. 67, 5, pp. 829-30.GlobalAlkaline rocks
DS2003-1186
2003
Wall, F.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
DS200412-0693
2003
Wall, F.Goodenough, K.M., Coulson, I.M., Wall, F.Intraplate alkaline magmatism: mineralogy and petrogenesis.Mineralogical Magazine, Vol. 67, 5, pp. 829-30.TechnologyAlkalic
DS200412-1691
2003
Wall, F.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
DS200512-1055
2005
Wall, F.Stoppa, F., Rosatelli, G., Wall, F., Jeffries, T.Geochemistry of carbonatite silicate pairs in nature: a case history from central Italy.Lithos, Advanced in press,Europe, ItalyKamafugite, foidite
DS200512-1056
2005
Wall, F.Stoppa, F., Rosatelli, G., Wall, F., Jeffries, T.Geochemistry of carbonatite - silicate pairs in nature: a case history from central Italy.Lithos, Advanced in press,Europe, ItalySan Venanzo kamafugite, carbonatite
DS200512-1057
2003
Wall, F.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
DS200512-1161
2004
Wall, F.Wall, F.An illustration of the evolution and alteration of carbonatites using REE, Sr rich carbonatites at Nkomba Zambia.Deep seated magmatism, its sources and their relation to plume processes., pp. 48-67.Africa, ZambiaCarbonatite
DS200512-1162
2004
Wall, F.Wall, F., Zaitsev, A.N.Phoscorites and carbonatites from mantle to mine: the key example of the Kola Alkaline Province.Mineralogical Society of Great Britain, approx $ 160.Carbonatite
DS200612-0281
2006
Wall, F.Costanzo, A., Moore, K.R., Wall, F., Feely, M.Fluid inclusions in apatite from Jacupiranga calcite carbonatites: evidence for a fluid stratified carbonatite magma chamber.Lithos, In press available,South America, Brazil, Sao PauloCarbonatite, magmatism, chambers
DS200612-0785
2006
Wall, F.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
DS200612-1382
2005
Wall, F.Stoppa, F., Rosatelli, G., Wall, F., Jeffries, T.Geochemistry of carbonatite silicate pairs in nature: a case history from Central Italy.Lithos, Vol. 85, 1-4, Nov-Dec. pp. 26-47.Europe, ItalyCarbonatite, geochemistry
DS200612-1479
2005
Wall, F.Vichi, G., Stoppa, F., Wall, F.The carbonate fraction in carbonatitic Italian lamprophyres.Lithos, Vol. 85, 1-4, Nov-Dec. pp. 154-170.Europe, ItalyCarbonatite
DS200612-1503
2004
Wall, F.Wall, F., Zaitsev, A.N., editorsPhoscorites and carbonatites from mantle to mine: the key example of the Kola alkaline province.Mineralogical Society Series, Vol. 10, 498p. approx $160.USRussia, Kola PeninsulaBook - carbonatites, phoscorites
DS200712-0133
2007
Wall, F.Campbell, L.S., Wall, F., Henderson, P., Zhang, P., Tao, K., Yang, Z.The character and context of zircons from the Bayan Obo Fe Nb REE deposit, Inner Mongolia.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p. 97-98.Asia, MongoliaCarbonatite
DS200712-0134
2007
Wall, F.Campbell, L.S., Wall, F., Henderson, P., Zhang, P., Tao, K., Yang, Z.The character and context of zircons from the Bayan Obo Fe Nb REE deposit, Inner Mongolia.Frontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p. 97-98.Asia, MongoliaCarbonatite
DS200712-0253
2007
Wall, F.Dobosi, G., Wall, F., Jeffries, T.Trace element fractionation during exsolution of garnet from clinopyroxene in an eclogite xenolith from Obnazhennaya(Siberia).Plates, Plumes, and Paradigms, 1p. abstract p. A227.Russia, SiberiaObnazhennaya
DS200712-0268
2007
Wall, F.Doroshkevich, A., Wall, F., Ripp, G.Magmatic graphite in dolomite carbonatite at Pogranichnoe North Transbaikalia, Russia.Contributions to Mineralogy and Petrology, Vol. 153, 3, pp. 339-353.RussiaCarbonatite
DS200712-0270
2007
Wall, F.Doroshkevich, A.G., Wall, F., Ripp, G.S.Calcite bearing dolomite carbonatite dykes from Veseloe, north Transbaikala, Russia, and possible Cr rich mantle xenoliths.Mineralogy and Petrology, Vol. 90, 1-2, pp. 19-49.RussiaCarbonatite
DS200712-0271
2007
Wall, F.Doroshkevich, A.G., Wall, F., Ripp, G.S.Calcite bearing dolomite carbonatite dykes from Veseloe, North Transbaikalia, Russia and possible Cr rich mantle xenoliths.Mineralogy and Petrology, Vol. 90, 1-2, pp. 19-49.RussiaCarbonatite
DS200712-1129
2007
Wall, F.Wall, F., Niku-Paavola, V.N., Storey, C., Muller, A.,Jeffries, T.Xenotime from carbonatite dykes at Lofdal Namibia - an extension of carbonatite REE mineralization, first dating of xenotime overgrowths on zircon.LA-ICP-MS-U-PbFrontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p. 89-90.Africa, NamibiaCarbonatite
DS200712-1130
2007
Wall, F.Wall, F., Niku-Paavola, V.N., Storey, C., Muller, A.,Jeffries, T.Xenotime from carbonatite dykes at Lofdal Namibia - an extension of carbonatite REE mineralization, first dating of xenotime overgrowths on zircon.LA-ICP-MS-U-PbFrontiers in Mineral Sciences 2007, Joint Meeting of Mineralogical societies Held June 26-28, Cambridge, Abstract Volume p. 89-90.Africa, NamibiaCarbonatite
DS200812-0491
2008
Wall, F.Humphreys, E.R., Bailey, K., Wall, F., Hawkesworth, C.J., Kearms, S.Highly heterogeneous mantle sampled by rapidly erupted carbonate volcanism.9IKC.com, 3p. extended abstractEurope, ItalyCalatrava volcanic province
DS200812-1227
2008
Wall, F.Wall, F., Niku-Paavola, V.N., Storey, C., Muller, A., Jeffries, T.Xenotime - (Y) from carbonatite dykes at Lofdal, Namibia: unusually low LREE:HREE ratio in carbonatite, and the first dating of xenotime overgrowths on zircon.Canadian Mineralogist, Vol. 46, 4, August pp.Africa, NamibiaCarbonatite
DS200812-1228
2008
Wall, F.Wall, F., Rosatelli, G., Bailey, D.K., Jeffries, T.E., Kearne, S., Munoz, M.Comparison of calcite compositions from extrusive carbonatites at Kaisterstuhl, Germany and Calatrava, Spain: implications for mantle carbonate.9IKC.com, 3p. extended abstractEurope, Germany, SpainCarbonatite
DS200912-0320
2009
Wall, F.Humphreys, E.R., Bailey, K., Hawkesworth, C.J., Wall, F.Carbonate inclusions in mantle olivines: mantle carbonatite.Goldschmidt Conference 2009, p. A564 Abstract.Europe, SpainLeucitites
DS200912-0804
2009
Wall, F.Wall, F.A review of the main controls on ore forming carbonatitic magmas.Goldschmidt Conference 2009, p. A1402 Abstract.GlobalMagmatism
DS201012-0297
2010
Wall, F.Humprhreys, E.R., Bailey, K., Hawkesworth, C.J., Wall, F., Najorka, J., Rankin, A.H.Aragonite in olivine from Calatrava, Spain - evidence for mantle carbonatite melts from > 100km depth.Geology, Vol. 38, 10, pp. 911-914.Europe, SpainCarbonatite
DS201012-0416
2010
Wall, F.Kurzura, A.V., Wall, F., Jeffries, T., Litvin, Yu.A.Partitioning of trace elements between garnet, clinopyroxene and diamond forming carbonate silicate melt at 7 GPa.International Mineralogical Association meeting August Budapest, abstract p. 573.TechnologyGeochemistry
DS201012-0420
2010
Wall, F.Kuzyura, A.V., Wall, F., Jeffries, T., Litvin, Y.U.A.Partitioning of trace elements between garnet, clinopyroxene and diamond forming carbonate-silicate melt at 7 GPa.Mineralogical Magazine, Vol. 74, 2, pp. 227-239.TechnologyDiamond genesis
DS201012-0542
2010
Wall, F.Niku-Paavola, V.N., Wall, F., Ellmies, R., Sitnikova, M.A.Rare earth rich carbonatites at Lofdal, Namibia.International Mineralogical Association meeting August Budapest, abstract p. 574.Africa, NamibiaCarbonatite
DS201012-0826
2010
Wall, F.Wall, F., Rosatelli, G., Jeffries, T.Trace element partition coefficients for apatite, calcite and carbonatite melt at crustal pressures and temperatures.International Mineralogical Association meeting August Budapest, abstract p. 554.Europe, GermanyAlkalic
DS201112-0271
2011
Wall, F.Do Cabo, V., Sitnikova, M.A., Ellmies, R., Wall, F., Henjes-Kunst, F., Gerdes, A.Geological and geochemical characteristics of carbonatites of Lofdal, Namibia.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterAfrica, NamibiaCarbonatite
DS201112-0272
2011
Wall, F.Do Cabo, V., Sitnikova, M.A., Elmies, R., Wall, F., Henjes-Kunst, F., Gerdes, A.Geological and geochemical characteristics of carbonatites of Lofdal, NamibiaPeralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.140-143.Africa, NamibiaLofdal
DS201112-0273
2011
Wall, F.Do Cabo, V., Sitnikova, M.A., Elmies, R., Wall, F., Henjes-Kunst, F., Gerdes, A.Geological and geochemical characteristics of carbonatites of Lofdal, NamibiaPeralk-Carb 2011... workshop June 16-18, Tubingen, Germany, Abstract p.140-143.Africa, NamibiaLofdal
DS201112-0274
2011
Wall, F.Do Cabo, V.N., Wall, F., Sitnikova, M.A., Ellmies, R., Henjes-Kunst, F., Gerdes, A., Downes, H.Mid and heavy REE in carbonatites at Lofdal, Namibia.Goldschmidt Conference 2011, abstract p.770.Africa, NamibiaCarbonatite, dykes
DS201112-0755
2011
Wall, F.Okoemova, V.Yu., Vasiliev, P.G., Kuzyura, A.V., Litvin, Yu.A., Wall, F., Jeffries, T.Experimental study of partition of rare elements between minerals and melts of diamond forming eclogite carbonatite and peridotite carbonatites systems.Goldschmidt Conference 2011, abstract p.1566.TechnologyHP
DS201212-0116
2012
Wall, F.Chakhmouradian, A.R., Wall, F.Rare earth elements: minerals, mines, magnets and more.Elements, Vol. 8, 5, Oct. pp. 333-340.TechnologyMineralogy, REE, deposits, production
DS201212-0170
2012
Wall, F.Downes, H., Wall, F., Demeny, A., Szabo, C.S.Continuing the carbonatite controversy.Mineralogical Magazine, Vol. 76, 2, pp. 255-257.TechnologyCarbonatite, brief overview
DS201212-0760
2012
Wall, F.Wall, F.Carbonatite related rare earth deposits.Gordon Research Centre Conference July 15-20, AbstractTechnologyCarbonatite
DS201412-0494
2014
Wall, F.Kuzyura, A.V., Litvin, Yu.A., Vasilev, P.G., Jeffries, T., Wall, F.Partitioning of rare elements between diamond forming melts and minerals of the peridotite-carbonatite system.Doklady Earth Sciences, Vol. 455, 2, pp. 419-424.TechnologyPhysicochemical experiments
DS201412-1015
2014
Wall, F.Zaitsev, A.N., Williams, C.T., Jeffreis, T.E., Strekopytov, S., Moutte, J., Ivashchenkova, O.V., Spratt, J., Petrov, S.V., Wall, F., Seltmann, R., Borozdin, A.P.Rare earth elements in phoscorites and carbonatites of the Devonian Kola alkaline province, Russia: examples from Kovdor, Khibina, Vuoriyarvi and Turiy Mys complexes.Ore Geology Reviews, Vol. 64, pp. 204-225.Russia, Kola PeninsulaCarbonatite
DS201412-1017
2014
Wall, F.Zaitsev, A.N., Williams, C.T., Jeffries, T.E., Strekopytov, S., Moutte, J., Ivashchenkova, O.V., Spratt, J., Petrov, S.V., Wall, F., Seltmann, R., Borozdin, A.P.Rare earth elements in phoscorites and carbonatites of the Devonian Kola alkaline province, Russia: examples from Kovdor, Khibina, Vuoriyarvi and Turiy Mys complexes.Ore Geology Reviews, Vol. 61, pp. 204-225.Russia, Kola PeninsulaCarbonatite
DS201412-1019
2014
Wall, F.Zaitsev, A.N., Williams, C.T., Jeffries, T.E., Strekopytov, S., Moutte, J., Ivashchenkova, O.V., Spratt, J., Petrov, S.V., Wall, F., Seltmann, R., Borozdin, A.P.Rare earth elements in phoscorites and carbonatites of the Devonian Kola alkaline province, Russia: examples from Kovdor, Khibina, Vuoriyarvi and Turiy Mys complexes.Ore Geology Reviews, in press availableRussia, Kola PeninsulaCarbonatite
DS201604-0595
2016
Wall, F.Broom-Fendley, S., Styles, M.T., Appleton, J.D., Gunn, G., Wall, F.Evidence for dissolution reprecipitation of apatite and preferential LREE mobility in carbonatite derived late stage hydrothermal processes.American Mineralogist, Vol. 101, pp. 596-611.Africa, MalawiCarbonatite

Abstract: The Tundulu and Kangankunde carbonatite complexes in the Chilwa Alkaline Province, Malawi, contain late-stage, apatite-rich lithologies termed quartz-apatite rocks. Apatite in these rocks can reach up to 90 modal% and displays a distinctive texture of turbid cores and euhedral rims. Previous studies of the paragenesis and rare earth element (REE) content of the apatite suggest that heavy REE (HREE)-enrichment occurred during the late-stages of crystallization. This is a highly unusual occurrence in intrusions that are otherwise light REE (LREE) enriched. In this contribution, the paragenesis and formation of the quartz-apatite rocks from each intrusion is investigated and re-evaluated, supported by new electron microprobe (EPMA) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data to better understand the mechanism of HREE enrichment. In contrast to the previous work at Tundulu, we recognize three separate stages of apatite formation, comprising an “original” euhedral apatite, “turbid” apatite, and “overgrowths” of euhedral late apatite. The crystallization of synchysite-(Ce) is interpreted to have occurred subsequent to all phases of apatite crystallization. The REE concentrations and distributions in the different minerals vary, but generally higher REE contents are found in later-stage apatite generations. These generations are also more LREE-enriched, relative to apatite that formed earlier. A similar pattern of increasing LREE-enrichment and increased REE concentrations toward later stages of the paragenetic sequence is observed at Kangankunde, where two generations of apatite are observed, the second showing higher REE concentrations, and relatively higher LREE contents. The changing REE distribution in the apatite, from early to late in the paragenetic sequence, is interpreted to be caused by a combination of dissolution-reprecipitation of the original apatite and the preferential transport of the LREE complexes by F- and Cl-bearing hydrothermal fluids. Successive pulses of these fluids transport the LREE out of the original apatite, preferentially re-precipitating it on the rim. Some LREE remained in solution, precipitating later in the paragenetic sequence, as synchysite-(Ce). The presence of F is supported by the F content of the apatites, and presence of REE-fluorcarbonates. Cl is not detected in the apatite structure, but the role of Cl is suggested from comparison with apatite dissolution experiments, where CaCl2 or NaCl cause the reprecipitation of apatite without associated monazite. This study implies that, despite the typically LREE enriched nature of carbonatites, significant degrees of hydrothermal alteration can lead to certain phases becoming residually enriched in the HREE. Although at Tundulu the LREE-bearing products are re-precipitated relatively close to the REE source, it is possible that extensive hydrothermal activity in other carbonatite complexes could lead to significant, late-stage fractionation of the REE and the formation of HREE minerals.
DS201605-0880
2016
Wall, F.Neave, D.A., Black, M., Riley, T.R., Gibson, S.A., Ferrier, G., Wall, F., Broom-Fendley, S.On the feasibility of imaging carbonatite-hosted rare earth element deposits using remote sensing.Economic Geology, Vol. 111, pp. 641-665.China, United States, Europe, GreenlandDeposit - Bayan Obo, Mountain Pass, Motzfeldt, Ilimaussaq

Abstract: Rare earth elements (REEs) generate characteristic absorption features in visible to shortwave infrared (VNIR-SWIR) reflectance spectra. Neodymium (Nd) has among the most prominent absorption features of the REEs and thus represents a key pathfinder element for the REEs as a whole. Given that the world’s largest REE deposits are associated with carbonatites, we present spectral, petrographic, and geochemical data from a predominantly carbonatitic suite of rocks that we use to assess the feasibility of imaging REE deposits using remote sensing. Samples were selected to cover a wide range of extents and styles of REE mineralization, and encompass calcio-, ferro- and magnesio-carbonatites. REE ores from the Bayan Obo (China) and Mountain Pass (United States) mines, as well as REE-rich alkaline rocks from the Motzfeldt and Ilímaussaq intrusions in Greenland, were also included in the sample suite. The depth and area of Nd absorption features in spectra collected under laboratory conditions correlate positively with the Nd content of whole-rock samples. The wavelength of Nd absorption features is predominantly independent of sample lithology and mineralogy. Correlations are most reliable for the two absorption features centered at ~744 and ~802 nm that can be observed in samples containing as little as ~1,000 ppm Nd. By convolving laboratory spectra to the spectral response functions of a variety of remote sensing instruments we demonstrate that hyperspectral instruments with capabilities equivalent to the operational Airborne Visible-Infrared Imaging Spectrometer (AVIRIS) and planned Environmental Mapping and Analysis Program (EnMAP) systems have the spectral resolutions necessary to detect Nd absorption features, especially in high-grade samples with economically relevant REE accumulations (Nd > 30,000 ppm). Adding synthetic noise to convolved spectra indicates that correlations between Nd absorption area and whole-rock Nd content only remain robust when spectra have signal-to-noise ratios in excess of ~250:1. Although atmospheric interferences are modest across the wavelength intervals relevant for Nd detection, most REE-rich outcrops are too small to be detectable using satellite-based platforms with >30-m spatial resolutions. However, our results indicate that Nd absorption features should be identifiable in high-quality, airborne, hyperspectral datasets collected at meter-scale spatial resolutions. Future deployment of hyperspectral instruments on unmanned aerial vehicles could enable REE grade to be mapped at the centimeter scale across whole deposits.
DS201609-1707
2016
Wall, F.Broom-Fendley, S., Heaton, T., Wall, F., Gunn, G.Tracing the fluid source of heavy REE mineralization in carbonatites using a novel method of oxygen isotope analysis in apatite: the example of Songwe Hill, Malawi.Chemical Geology, Vol. 440, pp. 275-287.Africa, MalawiCarbonatite

Abstract: Stable (C and O) isotope data from carbonates are one of the most important methods used to infer genetic processes in carbonatites. However despite their ubiquitous use in geological studies, it is suspected that carbonates are susceptible to dissolution-reprecipitation and isotopic resetting, especially in shallow intrusions, and may not be the best records of either igneous or hydrothermal processes. Apatite, however, should be much less susceptible to these resetting problems but has not been used for O isotope analysis. In this contribution, a novel bulk-carbonatite method for the analysis of O isotopes in the apatite PO4 site demonstrates a more robust record of stable isotope values. Analyses of apatite from five carbonatites with magmatic textures establishes a preliminary Primary Igneous Apatite (PIA) field of d18O = + 2.5 to + 6.0‰ (VSMOW), comparable to Primary Igneous Carbonatite (PIC) compositions from carbonates. Carbonate and apatite stable isotope data are compared in 10 carbonatite samples from Songwe Hill, Malawi. Apatite is heavy rare earth element (HREE) enriched at Songwe and, therefore, oxygen isotope analyses of this mineral are ideal for understanding HREE-related mineralisation in carbonatites. Carbonate C and O isotope ratios show a general trend, from early to late in the evolution, towards higher d18O values (+ 7.8 to + 26.7‰, VSMOW), with a slight increase in d13C (- 4.6 to - 0.1‰, VPDB). Oxygen isotope ratios from apatite show a contrary trend, decreasing from a PIA field towards more negative values (+ 2.5 to - 0.7‰, VSMOW). The contrasting results are interpreted as the product of the different minerals recording fluid interaction at different temperatures and compositions. Modelling indicates the possibility of both a CO2 rich fluid and mixing between meteoric and deuteric waters. A model is proposed where brecciation leads to depressurisation and rapid apatite precipitation. Subsequently, a convection cell develops from a carbonatite, interacting with surrounding meteoric water. REE are likely to be transported in this convection cell and precipitate owing to decreasing salinity and/or temperature.
DS201610-1914
2004
Wall, F.Wall, F., Zaitsev, A.N. .Phoscorites and carbonatites from mantle to mine: the key example of the Kola alkaline province.Mineralogical Society Series, isbn 0-903056-22-4 on sale approx 20lbsRussia, Kola PeninsulaBook - volcanology

Abstract: The first response to the title of this book is often 'What is a phoscorite?'. The exact definition and characteristics of phoscorite are discussed in some detail in Chapter 2 and were the subject of varying opinions amongst the authors of this and other chapters. We nicknamed the book 'the dark side of carbonatites', which covers it nicely. Phoscorites are dark, often very handsome, sometimes economically valuable, magnetite-apatite-silicate rocks, almost always associated with carbonatite. They are key to understanding the longstanding question of how carbonate and carbonate-bearing magmas rise to the crust and the Earth's surface. Despite this, they have been given little attention; a search on geological literature databases will produce thousands of references to carbonatite (up to 4125 on Georef) but not more than thirty references to phoscorite. This book goes some way to redress this balance. Over the last ten years many European and North American scientists have studied Kola rocks in collaboration with Russian colleagues. The idea for this book came from one such project funded by the European organisation, INTAS (Grant No 97-0722). The Kola Peninsula, Russia, is one of the outstanding areas in the World for the concentration and economic importance of alkaline rocks. However, Russian work on the Kola complexes is still relatively Show Less
DS201701-0004
2016
Wall, F.Broom-Fendley, S., Brady, A.E., Wall, F., Gunn, G., Dawes, W.REE minerals at the Songwe Hill carbonatite, Malawi: HREE enrichment in late stage apatite.Ore Geology Reviews, Vol. 81, pp. 23-41.Africa, MalawiCarbonatite

Abstract: Compared to all published data from carbonatites and granitoids, the fluorapatite compositions in the Songwe Hill carbonatite, determined by EPMA and LA ICP-MS, have the highest heavy (H)REE concentration of any carbonatite apatite described so far. A combination of this fluorapatite and the REE fluorocarbonates, synchysite-(Ce) and parisite-(Ce), which are the other principal REE bearing minerals at Songwe, gives a REE deposit with a high proportion of Nd and a higher proportion of HREE (Eu-Lu including Y) than most other carbonatites. Since Nd and HREE are currently the most sought REE for commercial applications, the conditions that give rise to this REE profile are particularly important to understand. Multiple apatite crystallisation stages have been differentiated texturally and geochemically at Songwe and fluorapatite is divided into five different types (Ap-0-4). While Ap-0 and Ap-1 are typical of apatite found in fenite and calcite-carbonatite, Ap-2, -3 and -4 are texturally atypical of apatite from carbonatite and are progressively HREE-enriched in later paragenetic stages. Ap-3 and Ap-4 exhibit anhedral, stringer-like textures and their REE distributions display an Y anomaly. These features attest to formation in a hydrothermal environment and fluid inclusion homogenisation temperatures indicate crystallisation occurred between 200-350 °C. Ap-3 crystallisation is succeeded by a light (L)REE mineral assemblage of synchysite-(Ce), strontianite and baryte. Finally, late-stage Ap-4 is associated with minor xenotime-(Y) mineralisation and HREE-enriched fluorite. Fluid inclusions in the fluorite constrain the minimum HREE mineralisation temperature to approximately 160 °C. A model is suggested where sub-solidus, carbonatite-derived, (carbo)-hydrothermal fluids remobilise and fractionate the REE. Chloride or fluoride complexes retain LREE in solution while rapid precipitation of apatite, owing to its low solubility, leads to destabilisation of HREE complexes and substitution into the apatite structure. The LREE are retained in solution, subsequently forming synchysite-(Ce). This model will be applicable to help guide exploration in other carbonatite complexes.
DS201707-1310
2017
Wall, F.Broom-Fendley, S., Brady, A.E., Horstwood, M.S.A., Woolley, A.R., Mtegha, J., Wall, F., Dawes, W., Gunn, G.Geology, geochemistry and geochronology of the Songwe Hill carbonatite, Malawi.Journal of African Earth Sciences, Vol. 134, pp. 10-23.Africa, Malawicarbonatite - Songwe Hill

Abstract: Songwe Hill, Malawi, is one of the least studied carbonatites but has now become particularly important as it hosts a relatively large rare earth deposit. The results of new mapping, petrography, geochemistry and geochronology indicate that the 0.8 km diameter Songwe Hill is distinct from the other Chilwa Alkaline Province carbonatites in that it intruded the side of the much larger (4 x 6 km) and slightly older (134.6 ± 4.4 Ma) Mauze nepheline syenite and then evolved through three different carbonatite compositions (C1–C3). Early C1 carbonatite is scarce and is composed of medium–coarse-grained calcite carbonatite containing zircons with a U–Pb age of 132.9 ± 6.7 Ma. It is similar to magmatic carbonatite in other carbonatite complexes at Chilwa Island and Tundulu in the Chilwa Alkaline Province and others worldwide. The fine-grained calcite carbonatite (C2) is the most abundant stage at Songwe Hill, followed by a more REE- and Sr-rich ferroan calcite carbonatite (C3). Both stages C2 and C3 display evidence of extensive (carbo)-hydrothermal overprinting that has produced apatite enriched in HREE (<2000 ppm Y) and, in C3, synchysite-(Ce). The final stages comprise HREE-rich apatite fluorite veins and Mn-Fe-rich veins. Widespread brecciation and incorporation of fenite into carbonatite, brittle fracturing, rounded clasts and a fenite carapace at the top of the hill indicate a shallow level of emplacement into the crust. This shallow intrusion level acted as a reservoir for multiple stages of carbonatite-derived fluid and HREE-enriched apatite mineralisation as well as LREE-enriched synchysite-(Ce). The close proximity and similar age of the large Mauze nepheline syenite suggests it may have acted as a heat source driving a hydrothermal system that has differentiated Songwe Hill from other Chilwa carbonatites.
DS201709-1964
2017
Wall, F.Broom-Fendley, S., O'Neill, M., Wall, F.Are carbonate-fluorapatite rocks in carbonatite complexes the result of hydrothermal processes or weathering? Sokli, KovdorGoldschmidt Conference, abstract 1p.Europe, Finland, Russiacarbonatites, Sokli, Kovdor

Abstract: Carbonate-fluorapatite (also known as staffelite and/or francolite) can become a rock-forming mineral in the upper levels of some carbonatite complexes, such as at Sokli, Finland, and Kovdor, Russia. Carbonate-fluorapatite rocks are recognised as an important phosphate resource, but there is little consensus on their genesis. Two principal models are favoured: (1) a hydrothermal origin, from a late-stage, carbonatite-derived fluid or, (2) formation through supergene dissolution of carbonate and re-precipitation of apatite. In this contribution, we have investigated the texture and composition of different carbonate-fluorapatite generations (using cathodoluminescence microsopy and LA ICP MS) in order to evaluate the aforementioned formation mechanisms. Four carbonate-fluorapatite growth generations were identified: (1) primary apatite grains, with a rounded/euhedral habit and luminescing purple; (2) strongly luminescent epitactic rims on primary grains; (3) ‘aggregate’ apatite, forming a fine-grained groundmass, typically luminescing blue; (4) botryoidal growth zones, commonly luminescing blue, but in places green or non-luminescent. REE contents in secondary carbonate-fluorapatite generations (2–4) are markedly low, with some analyses below detection limit (typically <1 ppm). Furthermore, many of these analyses exhibit both positive and negative Ce anomalies, indicative of an oxidising environment. The low REE contents of the different carbonatefluorapatite generations indicates that negligible REE transfer occurred between different growth events, contrasting with hydrothermal apatite in other carbonatite complexes. Furthermore, the lack of any significant fractionation between subsequent carbonate-fluorapatite generations is interpreted as circumstantial evidence that these rocks did not form through hydrothermal alteration. This is compounded by the presence of a Ce anomaly, which is commonly interpreted as a weathering feature. While hydrothermal formation under different conditions, causing complete removal of the REE, cannot be ruled out, we conclude that the locations were, most-likely, formed in a supergene environment. Continued investigation of weathered carbonate-fluorapatite material from other localities is underway to assess this conclusion.
DS201709-1993
2017
Wall, F.Goodenough, K.M., Wall, F., Merriman, D.The Rare Earth Elements: demand, global resources and challenges for resourcing future generations.Natural Resources Research, in press available, 16p.Globalrare earths

Abstract: The rare earth elements (REE) have attracted much attention in recent years, being viewed as critical metals because of China’s domination of their supply chain. This is despite the fact that REE enrichments are known to exist in a wide range of settings, and have been the subject of much recent exploration. Although the REE are often referred to as a single group, in practice each individual element has a specific set of end-uses, and so demand varies between them. Future demand growth to 2026 is likely to be mainly linked to the use of NdFeB magnets, particularly in hybrid and electric vehicles and wind turbines, and in erbium-doped glass fiber for communications. Supply of lanthanum and cerium is forecast to exceed demand. There are several different types of natural (primary) REE resources, including those formed by high-temperature geological processes (carbonatites, alkaline rocks, vein and skarn deposits) and those formed by low-temperature processes (placers, laterites, bauxites and ion-adsorption clays). In this paper, we consider the balance of the individual REE in each deposit type and how that matches demand, and look at some of the issues associated with developing these deposits. This assessment and overview indicate that while each type of REE deposit has different advantages and disadvantages, light rare earth-enriched ion adsorption types appear to have the best match to future REE needs. Production of REE as by-products from, for example, bauxite or phosphate, is potentially the most rapid way to produce additional REE. There are still significant technical and economic challenges to be overcome to create substantial REE supply chains outside China.
DS201711-2535
2017
Wall, F.Wall, F., Rollat, A., Pell, R.S.Responsible sourcing for critical metals.Elements, Vol. 13, pp. 313-318.Globalresources, REE

Abstract: Most critical raw materials, such as the rare-earth elements (REEs), are starting products in long manufacturing supply chains. Unlike most consumers, geoscientists can become involved in responsible sourcing, including best environmental and social practices, because geology is related to environmental impact factors such as energy requirements, resource efficiency, radioactivity and the amount of rock mined. The energy and material inputs and the emissions and waste from mining and processing can be quantified, and studies for REEs show little difference between ‘hard rocks’, such as carbonatites, and easily leachable ion-adsorption clays. The reason is the similarity in the embodied energy in the chemicals used for leaching, dissolution and separation.
DS201712-2676
2017
Wall, F.Broom-Fendley, S., Wall, F., Spiro, B., Ullmann, C.V.Deducing the source and composition of rare earth mineralising fluids in carbonatites: insights from isotopic ( C,O,87Sr/86SR) dat a from Kangankunde, Malawi.Contributions to Mineralogy and Petrology, Vol. 172, 96Africa, Malawicarbonatite

Abstract: Carbonatites host some of the largest and highest grade rare earth element (REE) deposits but the composition and source of their REE-mineralising fluids remains enigmatic. Using C, O and 87Sr/86Sr isotope data together with major and trace element compositions for the REE-rich Kangankunde carbonatite (Malawi), we show that the commonly observed, dark brown, Fe-rich carbonatite that hosts REE minerals in many carbonatites is decoupled from the REE mineral assemblage. REE-rich ferroan dolomite carbonatites, containing 8-15 wt% REE2O3, comprise assemblages of monazite-(Ce), strontianite and baryte forming hexagonal pseudomorphs after probable burbankite. The 87Sr/86Sr values (0.70302-0.70307) affirm a carbonatitic origin for these pseudomorph-forming fluids. Carbon and oxygen isotope ratios of strontianite, representing the REE mineral assemblage, indicate equilibrium between these assemblages and a carbonatite-derived, deuteric fluid between 250 and 400 °C (d18O + 3 to + 5‰VSMOW and d13C - 3.5 to - 3.2‰VPDB). In contrast, dolomite in the same samples has similar d13C values but much higher d18O, corresponding to increasing degrees of exchange with low-temperature fluids (< 125 °C), causing exsolution of Fe oxides resulting in the dark colour of these rocks. REE-rich quartz rocks, which occur outside of the intrusion, have similar d18O and 87Sr/86Sr to those of the main complex, indicating both are carbonatite-derived and, locally, REE mineralisation can extend up to 1.5 km away from the intrusion. Early, REE-poor apatite-bearing dolomite carbonatite (beforsite: d18O + 7.7 to + 10.3‰ and d13C -5.2 to -6.0‰; 87Sr/86Sr 0.70296-0.70298) is not directly linked with the REE mineralisation.
DS201802-0231
2017
Wall, F.Dowman, E., Wall, F., Treloar, P.J., Rankin, A.H.Rare earth mobility as a result of multiple phases of fluid activity in fenite around the Chilwa Island carbonatite, Malawi.Mineralogical Magazine, Vol. 81, 6, pp. 1367-1395.Africa, Malawicarbonatite - Chilwa

Abstract: Carbonatites are enriched in critical raw materials such as the rare earth elements (REE), niobium, fluorspar and phosphate. A better understanding of their fluid regimes will improve our knowledge of how to target and exploit economic deposits. This study shows that multiple fluid phases penetrated the surrounding fenite aureole during carbonatite emplacement at Chilwa Island, Malawi. The first alkaline fluids formed the main fenite assemblage and later microscopic vein networks contain the minerals of potential economic interest such as pyrochlore in high-grade fenite and RE minerals throughout the aureole. Seventeen samples of fenite rock from the metasomatic aureole around the Chilwa Island carbonatite complex were chosen for study (Natural History Museum, London collection BM1968 P37). In addition to the main fenite assemblage of feldspar and aegirine ± arfvedsonite, riebeckite and richterite, the fenite contains micro-mineral assemblages including apatite, ilmenite, rutile, magnetite, zircon, RE minerals and pyrochlore in vein networks. Petrography using SEM-EDX showed that the RE minerals (monazite, bastnäsite and parisite) formed later than the fenite feldspar, aegirine and apatite and provide evidence of REE mobility into all grades of fenite. Fenite apatite has a distinct negative Eu anomaly (determined by LA-ICP-MS) that is rare in carbonatite-associated rocks and interpreted as related to pre-crystallisation of plagioclase and co-crystallisation with K-feldspar in the fenite. The fenite minerals have consistently higher mid REE/light REE ratios (La/Sm = ~1.3 monazite, ~1.9 bastnäsite, ~1.2 parisite) than their counterparts in the carbonatites (La/Sm = ~2.5 monazite, ~4.2 bastnäsite, ~3.4 parisite). Quartz in the low- and medium-grade fenite hosts fluid inclusions, typically a few µm in diameter, secondary and extremely heterogeneous. Single phase, 2- and 3-phase, single solid and multi solid-bearing examples are present, with 2-phase the most abundant. Calcite, nahcolite, burbankite and barite were found in the inclusions. Decrepitation of inclusions occurred at around 200°C before homogenisation but melting temperature data indicate that the inclusions contain relatively pure CO2. A minimum salinity of around 24 wt.% NaCl equivalent was determined. Among the trace elements in whole rock analyses, enrichment in Ba, Mo, Nb, Pb, Sr, Th and Y and depletion in Co, Hf and V are common to carbonatite and fenite but enrichment in carbonatitic type elements (Ba, Nb, Sr, Th, Y, and REE) generally increases towards the inner parts of the aureole. A schematic model contains multiple fluid events, related to first and second boiling of the magma, accompanying intrusion of the carbonatites at Chilwa Island, each contributing to the mineralogy and chemistry of the fenite. The presence of distinct RE mineral micro-assemblages in fenite at some distance from carbonatite could be developed as an exploration indicator of REE enrichment.
DS201802-0233
2018
Wall, F.Elliott, H.A.L., Wall, F., Chakmouradian, A.R., Siegfried, P.R., Dahlgren, S., Weatherley, S., Finch, A.A., Marks, M.A.W., Dowman, E., Deady, E.Fenites associated with carbonatite complexes: a review.Ore Geology Reviews, Vol. 92, pp. 38-59.Globalcarbonatites

Abstract: Carbonatites and alkaline-silicate rocks are the most important sources of rare earth elements (REE) and niobium (Nb), both of which are metals imperative to technological advancement and associated with high risks of supply interruption. Cooling and crystallizing carbonatitic and alkaline melts expel multiple pulses of alkali-rich aqueous fluids which metasomatize the surrounding country rocks, forming fenites during a process called fenitization. These alkalis and volatiles are original constituents of the magma that are not recorded in the carbonatite rock, and therefore fenites should not be dismissed during the description of a carbonatite system. This paper reviews the existing literature, focusing on 17 worldwide carbonatite complexes whose attributes are used to discuss the main features and processes of fenitization. Although many attempts have been made in the literature to categorize and name fenites, it is recommended that the IUGS metamorphic nomenclature be used to describe predominant mineralogy and textures. Complexing anions greatly enhance the solubility of REE and Nb in these fenitizing fluids, mobilizing them into the surrounding country rock, and precipitating REE- and Nb-enriched micro-mineral assemblages. As such, fenites have significant potential to be used as an exploration tool to find mineralized intrusions in a similar way alteration patterns are used in other ore systems, such as porphyry copper deposits. Strong trends have been identified between the presence of more complex veining textures, mineralogy and brecciation in fenites with intermediate stage Nb-enriched and later stage REE-enriched magmas. However, compiling this evidence has also highlighted large gaps in the literature relating to fenitization. These need to be addressed before fenite can be used as a comprehensive and effective exploration tool.
DS201803-0444
2017
Wall, F.Dowman, E., Wall, F., Treloar, P.J., Rankin, A.H.Rare earth mobility as a result of multiple phases of fluid activity in fenite around the Chilwa Island carbonatite, Malawi.Mineralogical Magazine, Vol. 81, 6, pp. 1367-1395.Africa, Malawicarbonatite

Abstract: Carbonatites are enriched in critical raw materials such as the rare earth elements (REE), niobium, fluorspar and phosphate. A better understanding of their fluid regimes will improve our knowledge of how to target and exploit economic deposits. This study shows that multiple fluid phases penetrated the surrounding fenite aureole during carbonatite emplacement at Chilwa Island, Malawi. The first alkaline fluids formed the main fenite assemblage and later microscopic vein networks contain the minerals of potential economic interest such as pyrochlore in high-grade fenite and RE minerals throughout the aureole. Seventeen samples of fenite rock from the metasomatic aureole around the Chilwa Island carbonatite complex were chosen for study (Natural History Museum, London collection BM1968 P37). In addition to the main fenite assemblage of feldspar and aegirine ± arfvedsonite, riebeckite and richterite, the fenite contains micro-mineral assemblages including apatite, ilmenite, rutile, magnetite, zircon, RE minerals and pyrochlore in vein networks. Petrography using SEM-EDX showed that the RE minerals (monazite, bastnäsite and parisite) formed later than the fenite feldspar, aegirine and apatite and provide evidence of REE mobility into all grades of fenite. Fenite apatite has a distinct negative Eu anomaly (determined by LA-ICP-MS) that is rare in carbonatite-associated rocks and interpreted as related to pre-crystallisation of plagioclase and co-crystallisation with K-feldspar in the fenite. The fenite minerals have consistently higher mid REE/light REE ratios (La/Sm = ~1.3 monazite, ~1.9 bastnäsite, ~1.2 parisite) than their counterparts in the carbonatites (La/Sm = ~2.5 monazite, ~4.2 bastnäsite, ~3.4 parisite). Quartz in the low- and medium-grade fenite hosts fluid inclusions, typically a few µm in diameter, secondary and extremely heterogeneous. Single phase, 2- and 3-phase, single solid and multi solid-bearing examples are present, with 2-phase the most abundant. Calcite, nahcolite, burbankite and barite were found in the inclusions. Decrepitation of inclusions occurred at around 200°C before homogenisation but melting temperature data indicate that the inclusions contain relatively pure CO2. A minimum salinity of around 24 wt.% NaCl equivalent was determined. Among the trace elements in whole rock analyses, enrichment in Ba, Mo, Nb, Pb, Sr, Th and Y and depletion in Co, Hf and V are common to carbonatite and fenite but enrichment in carbonatitic type elements (Ba, Nb, Sr, Th, Y, and REE) generally increases towards the inner parts of the aureole. A schematic model contains multiple fluid events, related to first and second boiling of the magma, accompanying intrusion of the carbonatites at Chilwa Island, each contributing to the mineralogy and chemistry of the fenite. The presence of distinct RE mineral micro-assemblages in fenite at some distance from carbonatite could be developed as an exploration indicator of REE enrichment.
DS201906-1278
2019
Wall, F.Broom-Fendley, S., Smith, M., Andrade, M.B., Ray, S., Banks, D.A., Loye, E., Atencio, D., Pickles, J.R., Wall, F.Sulphate bearing monazite (Ce) from silicified dolomite carbonatite, Eureka, Namibia: substitution mechanisms, redox state and HREE enrichment.3rd International Critical Metals Meeting held Edinburgh, 1p. Abstract p. 51.Africa, Namibiadeposit - Eureka
DS201906-1291
2019
Wall, F.Elliott, H.A.L., Broom-Fendley, S., Wall, F.Fenite exploration criteria surrounding carbonatite hosted critical metal deposits.3rd International Critical Metals Meeting held Edinburgh, 1p. Abstract p. 38.Europe, Finlanddeposit - Sokli
DS202003-0332
2020
Wall, F.Broom-Fendley, S., Smith, M.P., Andrade, M.B., Ray, S., Banks, D.A., Loye, E., Antencio, D., Pickles, J.P., Wall, F.Sulfur bearing monzazite (Ce) from the Eureka carbonatite, Namibia: oxidation state, substitution mechanism, and formation conditions.Mineralogical Magazine, pp. 1-14, pdfAfrica, Namibiacarbonatite, REE

Abstract: Sulfur-bearing monazite-(Ce) occurs in silicified carbonatite at Eureka, Namibia, forming rims up to ~0.5 mm thick on earlier-formed monazite-(Ce) megacrysts. We present X-ray photoelectron spectroscopy data demonstrating that sulfur is accommodated predominantly in monazite-(Ce) as sulfate, via a clino-anhydrite-type coupled substitution mechanism. Minor sulfide and sulfite peaks in the X-ray photoelectron spectra, however, also indicate that more complex substitution mechanisms incorporating S2 and S4+ are possible. Incorporation of S6+ through clino-anhydrite-type substitution results in an excess of M2+ cations, which previous workers have suggested is accommodated by auxiliary substitution of OH for O2. However, Raman data show no indication of OH, and instead we suggest charge imbalance is accommodated through F substituting for O2. The accommodation of S in the monazite-(Ce) results in considerable structural distortion that may account for relatively high contents of ions with radii beyond those normally found in monazite-(Ce), such as the heavy rare earth elements, Mo, Zr and V. In contrast to S-bearing monazite-(Ce) in other carbonatites, S-bearing monazite-(Ce) at Eureka formed via a dissolutionprecipitation mechanism during prolonged weathering, with S derived from an aeolian source. While large S-bearing monazite-(Ce) grains are likely to be rare in the geological record, formation of secondary S-bearing monazite-(Ce) in these conditions may be a feasible mineral for dating palaeo-weathering horizons.
DS202011-2027
2020
Wall, F.Anenburg, M., Mavrogenes, J.A., Frigo, C., Wall, F.Rare earth element mobility in and around carbonatites controlled by sodium, potassium, and silica.Science Advances, Vol. 6, 11p. 10.1126/sciadv.abb6570 pdfGlobalcarbonatites, REE

Abstract: Carbonatites and associated rocks are the main source of rare earth elements (REEs), metals essential to modern technologies. REE mineralization occurs in hydrothermal assemblages within or near carbonatites, suggesting aqueous transport of REE. We conducted experiments from 1200°C and 1.5 GPa to 200°C and 0.2 GPa using light (La) and heavy (Dy) REE, crystallizing fluorapatite intergrown with calcite through dolomite to ankerite. All experiments contained solutions with anions previously thought to mobilize REE (chloride, fluoride, and carbonate), but REEs were extensively soluble only when alkalis were present. Dysprosium was more soluble than lanthanum when alkali complexed. Addition of silica either traps REE in early crystallizing apatite or negates solubility increases by immobilizing alkalis in silicates. Anionic species such as halogens and carbonates are not sufficient for REE mobility. Additional complexing with alkalis is required for substantial REE transport in and around carbonatites as a precursor for economic grade-mineralization.
DS201709-2070
2017
Wall., F.Wall., F., Al Ali, S., Rollinson, G., Fitzpatrick, R., Dawes, W., Broom-Fendley, S.Geochemistry and mineralogy of rare earth processing.Goldschmidt Conference, abstract 1p.Africa, Malawicarbonatite - Songwe Hill

Abstract: The geochemistry and mineralogy of REE deposits is diverse, from carbonatite-related deposits, alkaline rocks, mineral sands and ion adsorption clays to potential by-products of phosphate and bauxite, and reuse of waste materials. Despite the large number of prospects that have been explored recently, very little additional REE production has started. A major challenge is to design effective, cost-efficient and environmentally-friendly processing and extraction. Processing flow sheets have to be constructed carefully for each deposit. Translating geochemistry and mineralogy studies, including quantitative mineralogy results, into processing characteristics can be illustrated using results from the Songwe Hill carbonatite, Malawi. Combining results with other published data then allows us to make some general conclusions about the common REE ore minerals and their geological environment, including the REE fluorcarbonate series, monazite and xenotime. The use of chemicals for REE extraction is often the largest environmental burden to mitigate. A new issue is that certain REE, such as Ce, are in oversupply, and are not being recovered in some proposed processing flowsheets. It will be important to understand the environmental and commercial implications of this development.
DS1998-0984
1998
WallaceMcNulty, B.A., Farber, Wallace, Lopez, PalaciosRole of plate kinematics and plate slip vector partitioning in continental magmatic arcs: evidenceGeology, Vol. 26, No. 9, Sept. pp. 827-30PeruCordillera Blanca, Tectonics
DS201212-0339
2012
Wallace, C.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
Wallace, C.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
DS1991-1674
1991
Wallace, D.A.Sun, S.S., Wallace, D.A., Hoatson, D.M., Glikson, A.V.Use of geochemistry as a guide to platinum group element potential of mafic ultramafic rocks- examples the West Pilbara block and Halls Creek Mobile Zone:Precambrian Research, Vol. 50, No. 102, April pp. 1-35AustraliaPlatinuM., Geochemistry - review
DS201906-1275
2019
Wallace, 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.
DS201112-0300
2011
Wallace, L.M.Ellis, S.M., Little,T.A., Wallace, L.M.,Hacker, B.R., Buiter, S.J.H.Feedback between rifting and diapirism can exhume ultrahigh pressure rocks.Earth and Planetary Science Letters, Vol. 311, 3-4, pp. 427-438.AustraliaUHP
DS201506-0272
2015
Wallace, L.M.Hamling, I.J., Wallace, L.M.Silent triggering: aseismic crustal faulting induced by a subduction slow slip event.Earth and Planetary Science Letters, Vol. 421, pp. 13-19.MantleSubduction
DS1988-0266
1988
Wallace, M.E.Green, D.H., Wallace, M.E.Mantle metasomatism by ephemeral carbonatite meltsNature, Vol. 336, np. 6198, Dec. 1, pp. 459-462GlobalMantle, Carbonatite
DS1988-0746
1988
Wallace, M.E.Wallace, M.E., Green, D.H.An experimental determination of primary carbonatite magma compositionNature, Vol. 335, No. 6188, Sept. 22, pp. 343-346GlobalCarbonatite, Magma
DS1990-1531
1990
Wallace, M.E.Wallace, M.E.Carbonate bearing mantle xenoliths from the Tumut-eucumbene tunnel, N.S.W.,AustraliaGeological Society of America (GSA) Annual Meeting, Abstracts, Vol. 22, No. 7, p. A254AustraliaMantle, Xenoliths
DS1991-1825
1991
Wallace, M.E.Wallace, M.E., Green, D.H.The effect of bulk rock composition on the stability of amphibole in The upper mantle- implications for solidus positions and mantle MetasomatismMineral. Petrol, Vol. 44, No. 1-2, pp. 1-19GlobalMantle, Geochemistry
DS1989-1576
1989
Wallace, P.Wallace, P., Carmichael, I.S.E.Minette lavas and associated leucitites from the western front of the Mexican volcanic belt: petrology, chemistry, and originContributions to Mineralogy and Petrology, Vol. 103, No. 4, pp. 470-492MexicoMinette, Leucitite
DS1991-0327
1991
Wallace, P.Culshaw, N., Corrigan, D., Jamieson, R.A., Ketchum, J., Wallace, P.Traverse of the Central Gneiss Belt, Grenville Province, Georgian Bay, OntarioGeological Association of Canada (GAC) Annual Meeting held Toronto May 1991, Guidebook, No. B3, 35pOntarioCentral Gneiss Belt, Structure
DS1987-0778
1987
Wallace, P.J.Wallace, P.J., Carmichael, I.S.E.Explosive minettes and olivine leucitite lavas in the volcanic front of acontinental arc, western MexicoEos, Vol. 68, No.44, November 3, p. 1520. abstract onlyMexicoMinette
DS201112-1105
2011
Wallace, P.J.Weaver, S.L., Wallace, P.J., Johnston, A.D.A comparative study of continental vs. intraoceanic arc mantle melting: experimentally determined phase relations of hydrous primitive melts.Earth and Planetary Science Letters, Vol. 308, 1-2, pp. 97-106.MantleMelting
DS201704-0623
2017
Wallace, P.J.Edmonds, M., Wallace, P.J.Volatiles and exsolved vapor in volcanic systems.Elements, Vol. 13, 1, pp. 29-34.MantleMagmatism

Abstract: The role of volatiles in magma dynamics and eruption style is fundamental. Magmatic volatiles partition between melt, crystal, and vapor phases and, in so doing, change magma properties. This has consequences for magma buoyancy and phase equilibria. An exsolved vapor phase, which may be distributed unevenly through reservoirs, contains sulfur and metals that are either transported into the atmosphere or into ore deposits. This article reviews the controls on volatile solubility and the methods to reconstruct the volatile budget of magmas, focusing particularly on the exsolved vapor phase to explore the role of volatiles on magma dynamics and on eruption style.
DS1975-0204
1975
Wallace, R.C.Wallace, R.C.Mineralogy and Petrology of Xenoliths in a Diatreme from South Westland, New Zealand.Contributions to Mineralogy and Petrology, Vol. 49, PP. 191-199.New Zealand, OceaniaDiatreme
DS1993-0429
1993
Wallace, T.Fan, G.W., Wallace, T., Beck, S.Flexure of the Brazilian shield and possible implications for the deepstructure.American Geophysical Union, EOS, supplement Abstract Volume, October, Vol. 74, No. 43, October 26, abstract p. 548.BrazilTectonics, Structure
DS1998-1000
1998
Wallace, T.Meyers, S.C., Beck, S., Wallace, T.Lithospheric scale structure across the Bolivian Andes from tomographic images of velocity and attentuation..Journal of Geophysical Research, Vol. 103, No. 9, Sept. 10, pp. 21, 233-52.Bolivia, AndesTomography, Tectonics
DS1996-0441
1996
Wallace, T.C.Fan, G., Wallace, T.C., Chase, C.G.Gravity anomaly and flexural model: constraints on the structure beneath the Peruvian AndesTectonophysics, Vol. 255, No. 1-2, April 20, pp. 99-110Andes, PeruTectonics, Geophysics -gravity
DS1996-1432
1996
Wallace, T.C.Tinker, M.A., Wallace, T.C., et al.Geometry and state of stress of the Nazca plate beneath Bolivia and its implication for evolution of OroclineGeology, Vol. 24, No. 5, May, pp. 387-390BoliviaTectonics, Nazca plate
DS201705-0887
2017
Wallace, T.C. Jr.Wallace, T.C. Jr.Colorado Diamonds. (Sloan and Kelsey Lake)lithographie.org, No. 19, pp. 110-113.United States, Colorado PlateauBook - history, deposits
DS2002-1288
2002
WallbrecherPuti, M., Korikovsky, Wallbrecher, Unzog, Olesen, FritzEvolution of an eclogitized continental fragment in the Eastern Alps ( Sieggraben Austria).Journal of Structural Geology, Vol. 24, No. 1, pp. 339-57.AustriaEclogites
DS200612-0416
2005
Wallbrecher, E.Fritz, H., Tenczer, V., Hauzenberger, C.A., Wallbrecher, E., Hoinkes, G., Muhongo, S.Central Tanzanian tectonic map: a step forward to decipher Proterozoic structural events.Tectonics, Vol. 24, 6, TC6013. 10.1029/2005 TC001796Africa, TanzaniaTectonics
DS201503-0146
2015
Walle, M.Guzmics, T., Zajacz, Z., Mitchell, R.H., Szabo, C., Walle, M.The role of liquid-liquid immiscibility and crystal fractionation in the genesis of carbonatite magmas: insights from Kerimasi melt inclusions.Contributions to Mineralogy and Petrology, Vol. 169, 18p.Africa, TanzaniaCarbonatite

Abstract: We have reconstructed the compositional evolution of the silicate and carbonate melt, and various crystalline phases in the subvolcanic reservoir of Kerimasi Volcano in the East African Rift. Trace element concentrations of silicate and carbonate melt inclusions trapped in nepheline, apatite and magnetite from plutonic afrikandite (clinopyroxene-nepheline-perovskite-magnetite-melilite rock) and calciocarbonatite (calcite-apatite-magnetite-perovskite-monticellite-phlogopite rock) show that liquid immiscibility occurred during the generation of carbonatite magmas from a CO2-rich melilite-nephelinite magma formed at relatively high temperatures (1,100 °C). This carbonatite magma is notably more calcic and less alkaline than that occurring at Oldoinyo Lengai. The CaO-rich (32-41 wt%) nature and alkali-"poor" (at least 7-10 wt% Na2O + K2O) nature of these high-temperature (>1,000 °C) carbonate melts result from strong partitioning of Ca (relative to Mg, Fe and Mn) in the immiscible carbonate and the CaO-rich nature (12-17 wt%) of its silicate parent (e.g., melilite-nephelinite). Evolution of the Kerimasi carbonate magma can result in the formation of natrocarbonatite melts with similar composition to those of Oldoinyo Lengai, but with pronounced depletion in REE and HFSE elements. We suggest that this compositional difference results from the different initial parental magmas, e.g., melilite-nephelinite at Kerimasi and a nephelinite at Oldoinyo Lengai. The difference in parental magma composition led to a significant difference in the fractionating mineral phase assemblage and the element partitioning systematics upon silicate-carbonate melt immiscibility. LA-ICP-MS analysis of coeval silicate and carbonate melt inclusions provides an opportunity to infer carbonate melt/silicate melt partition coefficients for a wide range of elements. These data show that Li, Na, Pb, Ca, Sr, Ba, B, all REE (except Sc), U, V, Nb, Ta, P, Mo, W and S are partitioned into the carbonate melt, whereas Mg, Mn, Fe, Co, Cu, Zn, Al, Sc, Ti, Hf and Zr are partitioned into the silicate melt. Potassium and Rb show no preferential partitioning. Kerimasi melt inclusions show that the immiscible calcic carbonate melt is strongly enriched in Sr, Ba, Pb, LREE, P, W, Mo and S relative to other trace elements. Comparison of our data with experimental results indicates that preferential partitioning of oxidized sulfur (as SO4 2-), Ca and P (as PO4 3-) into the carbonate melt may promote the partitioning of Nb, Ta, Pb and all REE, excluding Sc, into this phase. Therefore, it is suggested that P and S enrichment in calcic carbonate magmas promotes the genesis of REE-rich carbonatites by liquid immiscibility. Our study shows that changes in the partition coefficients of elements between minerals and the coexisting melts along the liquid line of descent are rather significant at Kerimasi. This is why, in addition to the REE, Nb, Ta and Zr are also enriched in Kerimasi calciocarbonatites. We consider significant amounts of apatite and perovskite precipitated from melilite-nephelinite-derived carbonate melt as igneous minerals can have high LREE, Nb and Zr contents relative to other carbonatite minerals.
DS201608-1418
2016
Walle, M.Kueter, N., Soesilo, J., Fedortchouk, Y., Nestola, F., Belluco, L., Troch, J., Walle, M., Giuillong, M., Von Quadt, A., Driesner, T.Tracing the depositional history of Kalimantan diamonds by zircon provenance and diamond morphology studies. ( kimberlite or lamproite)Lithos, in press availableIndonesia, BorneoDeposit - Kalimantan

Abstract: Diamonds in alluvial deposits in Southeast Asia are not accompanied by indicator minerals suggesting primary kimberlite or lamproite sources. The Meratus Mountains in Southeast Borneo (Province Kalimantan Selatan, Indonesia) provide the largest known deposit of these so-called “headless” diamond deposits. Proposals for the origin of Kalimantan diamonds include the adjacent Meratus ophiolite complex, ultra-high pressure (UHP) metamorphic terranes, obducted subcontinental lithospheric mantle and undiscovered kimberlite-type sources. Here we report results from detailed sediment provenance analysis of diamond-bearing Quaternary river channel material and from representative outcrops of the oldest known formations within the Alino Group, including the diamond-bearing Campanian-Maastrichtian Manunggul Formation. Optical examination of surfaces of diamonds collected from artisanal miners in the Meratus area (247 stones) and in West Borneo (Sanggau Area, Province Kalimantan Barat;
DS201703-0402
2016
Walle, M.Ferrero, S., Wunder, B., Ziemann, M.A., Walle, M., O'Brien, P.J.Carbonatitic and granitic melts produced under conditions of primary immiscibility during anatexis in the lower crust. Oberpfalz areaEarth and Planetary Science Letters, Vol. 454, pp. 121-131.Europe, Czech RepublicBohemian Massif

Abstract: Carbonatites are peculiar magmatic rocks with mantle-related genesis, commonly interpreted as the products of melting of CO2-bearing peridotites, or resulting from the chemical evolution of mantle-derived magmas, either through extreme differentiation or secondary immiscibility. Here we report the first finding of anatectic carbonatites of crustal origin, preserved as calcite-rich polycrystalline inclusions in garnet from low-to-medium pressure migmatites of the Oberpfalz area, SW Bohemian Massif (Central Europe). These inclusions originally trapped a melt of calciocarbonatitic composition with a characteristic enrichment in Ba, Sr and LREE. This interpretation is supported by the results of a detailed microstructural and microchemical investigation, as well as re-melting experiments using a piston cylinder apparatus. Carbonatitic inclusions coexist in the same cluster with crystallized silicate melt inclusions (nanogranites) and COH fluid inclusions, suggesting conditions of primary immiscibility between two melts and a fluid during anatexis. The production of both carbonatitic and granitic melts during the same anatectic event requires a suitable heterogeneous protolith. This may be represented by a sedimentary sequence containing marble lenses of limited extension, similar to the one still visible in the adjacent central Moldanubian Zone. The presence of CO2-rich fluid inclusions suggests furthermore that high CO2 activity during anatexis may be required to stabilize a carbonate-rich melt in a silica-dominated system. This natural occurrence displays a remarkable similarity with experiments on carbonate-silicate melt immiscibility, where CO2 saturation is a condition commonly imposed.
DS201707-1342
2017
Walle, M.Kueter, N., Soesilo, J., Fedortchouk, Y., Nestola, F., Belluco, L., Troch, J., Walle, M., Guillong, M., Von Quadt, A., Driesner, T.Tracing the depositional history of Kalimantan diamonds by zircon proveneance and diamond morphology studies. Appendix 1 and 2Academia.edu, Supplementary material app. 1 and 2, both 10p.Asia, Kalimantandeposit - Kalimantan

Abstract: Diamonds in alluvial deposits in Southeast Asia are not accompanied by indicator minerals suggesting primary kimberlite or lamproite sources. The Meratus Mountains in Southeast Borneo (Province Kalimantan Selatan, Indonesia) provide the largest known deposit of these so-called “headless” diamond deposits. Proposals for the origin of Kalimantan diamonds include the adjacent Meratus ophiolite complex, ultra-high pressure (UHP) metamorphic terranes, obducted subcontinental lithospheric mantle and undiscovered kimberlite-type sources. Here we report results from detailed sediment provenance analysis of diamond-bearing Quaternary river channel material and from representative outcrops of the oldest known formations within the Alino Group, including the diamond-bearing Campanian–Maastrichtian Manunggul Formation. Optical examination of surfaces of diamonds collected from artisanal miners in the Meratus area (247 stones) and in West Borneo (Sanggau Area, Province Kalimantan Barat; 85 stones) points toward a classical kimberlite-type source for the majority of these diamonds. Some of the diamonds host mineral inclusions suitable for deep single-crystal X-ray diffraction investigation. We determined the depth of formation of two olivines, one coesite and one peridotitic garnet inclusion. Pressure of formation estimates for the peridotitic garnet at independently derived temperatures of 930–1250 °C are between 4.8 and 6.0 GPa. Sediment provenance analysis includes petrography coupled to analyses of detrital garnet and glaucophane. The compositions of these key minerals do not indicate kimberlite-derived material. By analyzing almost 1400 zircons for trace element concentrations with laser ablation ICP-MS (LA-ICP-MS) we tested the mineral's potential as an alternative kimberlite indicator. The screening ultimately resulted in a small subset of ten zircons with a kimberlitic affinity. Subsequent U–Pb dating resulting in Cretaceous ages plus a detailed chemical reflection make a kimberlitic origin unfavorable with respect to the regional geological history. Rather, trace elemental analyses (U, Th and Eu) suggest an eclogitic source for these zircons. The age distribution of detrital zircons allows in general a better understanding of collisional events that formed the Meratus orogen and identifies various North Australian Orogens as potential Pre-Mesozoic sediment sources. Our data support a model whereby the majority of Kalimantan diamonds were emplaced within the North Australian Craton by volcanic processes. Partly re-deposited into paleo-collectors or residing in their primary host, these diamond-deposits spread passively throughout Southeast Asia by terrane migration during the Gondwana breakup. Terrane amalgamation events largely metamorphosed these diamond-bearing lithologies while destroying the indicative mineral content. Orogenic uplift finally liberated their diamond-content into new, autochthonous placer deposits.
DS201711-2511
2017
Walle, M.Ferrerro, S.., Wunder, B., Ziemann, M.A., Walle, M., O'Brien, P.J.Carbonatitic and granitic melts produced under conditions of primary immiscibility during anatexis in the lower crust.Earth and Planetary Science Letters, Vol. 454, pp. 121-131.Mantlecarbonatites

Abstract: Carbonatites are peculiar magmatic rocks with mantle-related genesis, commonly interpreted as the products of melting of CO2-bearing peridotites, or resulting from the chemical evolution of mantle-derived magmas, either through extreme differentiation or secondary immiscibility. Here we report the first finding of anatectic carbonatites of crustal origin, preserved as calcite-rich polycrystalline inclusions in garnet from low-to-medium pressure migmatites of the Oberpfalz area, SW Bohemian Massif (Central Europe). These inclusions originally trapped a melt of calciocarbonatitic composition with a characteristic enrichment in Ba, Sr and LREE. This interpretation is supported by the results of a detailed microstructural and microchemical investigation, as well as re-melting experiments using a piston cylinder apparatus. Carbonatitic inclusions coexist in the same cluster with crystallized silicate melt inclusions (nanogranites) and COH fluid inclusions, suggesting conditions of primary immiscibility between two melts and a fluid during anatexis. The production of both carbonatitic and granitic melts during the same anatectic event requires a suitable heterogeneous protolith. This may be represented by a sedimentary sequence containing marble lenses of limited extension, similar to the one still visible in the adjacent central Moldanubian Zone. The presence of CO2-rich fluid inclusions suggests furthermore that high CO2 activity during anatexis may be required to stabilize a carbonate-rich melt in a silica-dominated system. This natural occurrence displays a remarkable similarity with experiments on carbonate-silicate melt immiscibility, where CO2 saturation is a condition commonly imposed. In conclusion, this study shows how the investigation of partial melting through melt inclusion studies may unveil unexpected processes whose evidence, while preserved in stiff minerals such as garnet, is completely obliterated in the rest of the rock due to metamorphic re-equilibration. Our results thus provide invaluable new insights into the processes which shape the geochemical evolution of our planet, such as the redistribution of carbon and strategic metals during orogenesis.
DS1992-1626
1992
Waller, M.Waller, M., Ali Sha, M.Advances in drilling technologyTransactions of the Institute of Mining and Metallurgy (IMM), Vol. 101, Sept-Dec, pp. A 166-172GlobalDrilling, Overview of advances
DS1994-1875
1994
Waller-Hunter, J.H.Waller-Hunter, J.H.The commission on sustainable developmentNatural Resources forum, Vol. 18, No. 4, pp. 247-249GlobalEconomics, Sustainable development
DS1995-2018
1995
Wallich, P.Wallich, P.A widgets best friend - diamonds may bring new a new facet to motors andsensors.Scientific American, Vol. 272, No. 4, April p. 35.GlobalDiamond synthesis
DS1988-0405
1988
Wallin, E.T.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
DS1988-0747
1988
Wallin, E.T.Wallin, E.T., Van Schmus, W.R.Geochronological studies of the Archean Proterozoic transition North central United StatesGeological Society of America Abstracts with Program, Vol. 20, No. 2, January p. 131. Sth. Central, LawrenceIowa, South DakotaMid continent
DS1992-1681
1992
Wallin, E.T.Windom, K.E., Seifert, K.E., Van Schmus, W.R., Wallin, E.T.Archean and Proterozoic rocks from northwestern IowaGeological Society of America (GSA) Abstract Volume, Vol. 24, No. 4, April p. 71. abstract onlyIowaGeneral geology, Precambrian
DS1993-1745
1993
Wallin, E.T.Windom, K.E., Van Schmus, W.R., Seifert, K.E., Wallin, E.T., Anderson, R.R.Archean and Proterozoic tectono-magmatic activity along the southern Margin of the Superior Province in northwestern Iowa, United States.Canadian Journal of Earth Sciences, Vol. 30, No. 6, June pp. 1275-1285.IowaTectonics
DS200512-1163
2005
Wallis, S.Wallis, S., Tsuboi, M., Suzuki, K., Fanning, M., Jiang, L., Tanaka, T.Role of partial melting in the evolution of the Sulu (eastern China) ultrahigh pressure terrane.Geology, Vol. 33, 2, pp. 129-132.ChinaUHP
DS200812-0757
2008
Wallis, S.Mizukami, T., Wallis, S., Enami, M., Kagi, H.Forearc diamond from Japan.Geology, Vol. 36, 3 March pp. 219-222.JapanLamprophyre, dykes
DS2002-0053
2002
Wallis, S.R.Aoya, M., Uehara, S-I., Wallis, S.R.Thermal consequences of a subduction boundary jump: a numerical model for generating subduction related....Tectonics, Vol.21,1, Feb.pp. 17p.MantlePressure temperature paths - clockwise, Subduction - geothermometry
DS200612-0518
2006
Wallis, S.R.Hacker, B.R., Wallis, S.R., Ratschbacher, L., Grove, M., Gehrels, G.High temperature geochronology constraints on the tectonic history and architecture of the ultrahigh pressure Dabie-Sulu Orogen.Tectonics, Vol. 25, 5, TC5006ChinaUHP, tectonics
DS200912-0275
2009
Wallis, S.R.Hacker, B.R., Wallis, S.R., McWilliams, M.O., Gans, P.B.40 Ar 39AR constraints on the tectonic history and architecture of the ultrahigh pressure Sulu orogen.Journal of Metamorphic Geology, Vol. 27, 9, pp. 827-844.ChinaUHP
DS1992-1267
1992
Wallmach, T.Reimold, W.U., Colliston, W.P., Wallmach, T.Comment on the nature, distribution and genesis of the coesite and stishovite associated with the pseudotachylite of the Vredefort Dome, SouthAfricaEarth and Planetary Science Letters, Vol. 112, pp. 213-217South AfricaMineralogy, Coesite
DS1997-0765
1997
Wallmach, T.Merkle, R.K.W., Wallmach, T.Ultramafic rock in the centre of the Vredfort structure, South Africa:geochemical affinity..Chemical Geol, Vol. 143, No. 1-2, Nov. 17, pp. 43-64South AfricaBushveld, layered intrusions, Geochemistry
DS1998-0181
1998
Wallmach, T.Buick, I.S., Uken, R., Gibson, R.L., Wallmach, T.High delta 13 C Paleoproterozoic carbonates from the Transvaal South AfricaGeology, Vol. 26, No. 10, Oct. pp. 875-8South AfricaKaapvaal Craton, Geochronology, Carbon
DS200812-1116
2008
Wallner, A.Steier, P., Liechtenstein, V.K., Djokic, D., Golser, R., Wallner, A., Alexeev, A.G., Khrunov, V.S., KutscheraCharacterization and improvement of thin natural diamond detectors for spectrometry of heavy ions below 1 MeV/amu.Nuclear Instruments and Methods in Physics Research Section A., Vol. 590, 1-3, pp. 221-226.TechnologySpectrometry
DS1986-0334
1986
Walls, C.C.Hall, J.M., Walls, C.C.The relationship bewteen dike density in horizontal and vertical profiles through dike swarmsGeological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 76. (abstract.)GlobalDyke
DS1996-1500
1996
Walls, M.R.Walls, M.R.Developing an exploration decision support system (EDSS):strategy for combining information and analyticsNonrenewable Resources, Vol. 5, No. 3, pp. 181-192GlobalEconomics, Biased to petroleuM.
DS1996-1501
1996
Walls, M.R.Walls, M.R., Eggert, R.G.Managerial risk taking: a study of mining CEOsMining Engineering, Vol. 48, No. 3, March pp. 61-67Australia, GlobalEconomics, Risk taking, strategic investments
DS1920-0474
1929
Walls, R.R.Walls, R.R.The Geography of the DiamondGeogr. Magazine (scotland), Vol. 45, PP. 195-205.South Africa, GlobalGeography, Occurrences
DS1983-0385
1983
Walmsley, J.C.Lang, A.R., Walmsley, J.C.Apatite Inclusions in Natural Diamond CoatPhysics And Chemistry of Metals, Vol. 9, No. 1, PP. 6-9.GlobalBlank
DS1990-0334
1990
Walmsley, J.C.Clackson, S.G., Moore, M., Walmsley, J.C., Woods, G.S.The relationship between platelet size and the frequency of the B infrared adsorption peak in type 1a diamondPhil. Magazine, B., Vol. 62, No. 2, August pp. 115-128GlobalDiamond morphology
DS1992-1627
1992
Walmsley, J.C.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
Walmsley, J.C.Walmsley, J.C., Lang, A.R.Oriented biotite inclusions in diamond coatMineralogical Magazine, Vol. 56, March pp. 108-111GlobalDiamond morphology, Natural diamonds, biotite
DS1983-0627
1983
Walmsley, M.Walmsley, M.Dame Fortune Smiles on Mnr GeologistsMnr Publishing Aski, SPRING, P. 7.Canada, Ontario, Kirkland LakeProspecting
DS1970-0210
1970
Walper, J.L.Walper, J.L.Wrench Faulting in the Mid-continentShale Shaker., Vol. 21, No. 2, PP. 32-40.GlobalMid-continent
DS1975-0648
1977
Walper, J.L.Walper, J.L.Paleozoic Tectonics of the Southern Margin of North AmericaGulf Coast Association Geological Society Transactions, Vol. 27, PP. 230-241.Oklahoma, Texas, Virginia, North Carolina, South CarolinaMid Continent, Mississippi Embayment, Delaware Aulocogen, Wic
DS1984-0754
1984
Walper, J.L.Walper, J.L., Henk, F.H.JR.Double Indentation Tectonic Model for Suturing of North And south America and Formation of the Ouachita Orogenic Belt.Geological Society of America (GSA), Vol. 16, No. 2, FEBRUARY P. 116. (abstract.).GlobalMid-continent
DS201704-0652
2017
Walpole, J.Walpole, J., Wookey, J., Kendall, J-M., Masters, T-G.Seismic anisotropy and mantle flow below subducting slabs.Earth and Planetary Science Letters, Vol. 465, pp. 155-167.MantleSubduction

Abstract: Subduction is integral to mantle convection and plate tectonics, yet the role of the subslab mantle in this process is poorly understood. Some propose that decoupling from the slab permits widespread trench parallel flow in the subslab mantle, although the geodynamical feasibility of this has been questioned. Here, we use the source-side shear wave splitting technique to probe anisotropy beneath subducting slabs, enabling us to test petrofabric models and constrain the geometry of mantle fow. Our global dataset contains 6369 high quality measurements - spanning ~40,000?km~40,000?km of subduction zone trenches - over the complete range of available source depths (4 to 687?km) - and a large range of angles in the slab reference frame. We find that anisotropy in the subslab mantle is well characterised by tilted transverse isotropy with a slow-symmetry-axis pointing normal to the plane of the slab. This appears incompatible with purely trench-parallel flow models. On the other hand it is compatible with the idea that the asthenosphere is tilted and entrained during subduction. Trench parallel measurements are most commonly associated with shallow events (source depth <50?km<50?km) - suggesting a separate region of anisotropy in the lithospheric slab. This may correspond to the shape preferred orientation of cracks, fractures, and faults opened by slab bending. Meanwhile the deepest events probe the upper lower mantle where splitting is found to be consistent with deformed bridgmanite.
DS1990-0432
1990
Walraven, F.DuPlessis, C.P., Walraven, F.The tectonic setting of the Bushveld Complex in Southern Africa Part 1.Structural deformation and distributionTectonophysics, Vol. 179, pp. 305-319Southern AfricaTectonics -structure, Bushveld Complex
DS1993-1690
1993
Walraven, F.Walraven, F., Rumvegeri, B.T.Implications of whole rock lead-lead and zircon evaporation dates for the early metamorphic history of the Kasai craton, southern ZaireJournal of African Earth Sciences, Vol. 16, No. 4, pp. 395-404Democratic Republic of CongoGeochronology, Kasai craton
DS1993-1691
1993
Walraven, F.Walraven, F., Rumvegeri, B.T.Implications of whole rock lead-lead and zircon evaporation dates for the early metamorphic history of the Kasai craton, southern ZaireJournal of African Earth Studies, Vol. 16, No. 4, pp. 395-404Democratic Republic of CongoGeochronology, Kasai Craton
DS1994-1062
1994
Walraven, F.Lubala, R.T., Frick, C., Rogers, J.H., Walraven, F.Petrogenesis of syenites and granites of the Schiel alkaline complex, Northern Transvaal, South Africa.Journal of Geology, Vol. 102, No. 3, May pp. 307-317.South AfricaAlkaline rocks -Schiel, Petrogenesis
DS1995-2019
1995
Walraven, F.Walraven, F., Retief, E.A., Moen, H.F.G.Single zircon lead evaporation evidence for 2.77 Ga magmatism in northwesternTransvaal, South AfricaSouth Afri. Journal of Geology, Vol. 97, No. 2, pp. 107-113South AfricaGeochronology, Makoppa Dome
DS1997-1222
1997
Walraven, F.Walraven, F.Geochronology of the Rooiberg Group, Transvaal Supergroup, South AfricaEconomic Geology Research Unit, No. 316, Nov. 21pSouth AfricaGeochronology, volcanism.
DS1997-0034
1997
Walraven F.Anhaeusser, C.R., Walraven F.Polyphase crustal evolution of the Archean Kraaipan granite greenstoneterrane, Kaapvaal CratonEconomic Geology Research Unit, No. 313, 27pSouth AfricaGephysics - Bouguer gravity, Granite greenstone belts
DS200812-1229
2008
Walsby, J.Walsby, J.Geosure: a bridge between geology and decision makers.Geological Society of London Special Publication, No. 305, pp. 81-87.Media
DS201312-0948
2013
Walsh, A.Walsh, A., Hand, M., Collins, A., Brick, R.World's oldest eclogites? Phase equilibration temperatures constraints on 2 Ga metaleitic hosted eclogites frm the Usagaran orogen, Tanzania.Goldschmidt 2013, 1p. AbstractAfrica, TanzaniaEclogite
DS1997-0901
1997
Walsh, D.G.Pereira, C.P.G., Walsh, D.G.Current researchNewfoundland Department of Mines, Report 97-1, 300pNewfoundland, LabradorBook - table of contents, Metallogeny, deposits
DS1997-0902
1997
Walsh, D.G.Pereira, C.P.G., Walsh, D.G.Current research - Mokami Hill, Hunt River, Nain, magmatic deposits, greenstone belts...Newfoundland, Department of Mines and Energy, Report 97-1, 300pNewfoundland, LabradorBook - table of contents, Review of activities, nickel
DS2000-0999
2000
Walsh, E.H.Walsh, E.H., Hacker, B.R.Exhumation of Norwegian ultra high pressure (UHP) eclogites 1: foreland to hinterland regional variation in pressure - temperatureGeological Society of America (GSA) Abstracts, Vol. 32, No. 7, p.A-32.NorwayEclogites, Subduction - slab
DS200412-2074
2004
Walsh, E.O.Walsh, E.O., Hacker, B.R.The fate of subducted continental margins; two stage exhumation of the high pressure ultrahigh pressure Western Gneiss region, NJournal of Metamorphic Geology, Vol. 22, 7, pp. 671-687.Europe, NorwayUHP - metamorphism, eclogites
DS1991-1826
1991
Walsh, J.Walsh, J., Watterson, J., Yielding, G.The importance of small scale faulting in regional extensionNature, Vol. 351, No. 6325, May 30, p. 391-394GlobalStructure, Faulting - small scale
DS1996-0272
1996
Walsh, J.J.Childs, C., Watterson, J., Walsh, J.J.A model for the structure and development of fault zonesJournal of the Geological Society of London, Vol. 153, No. 3, May 1, pp. 337-340GlobalStructure, Fault zone model
DS2002-0923
2002
Walsh, J.N.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
DS2003-1207
2003
Walsh, J.N.Sahu, R., Kumar, A., Subbarao, K.V., Walsh, J.N., Biswal, T.K.Rb Sr age and Sr isotopic composition of alkaline dykes near Mumbai ( Bombay)Journal of Geological Society of India, Vol. 62, 5, pp. 641-646.IndiaAlkaline rocks
DS200412-1721
2003
Walsh, J.N.Sahu, R., Kumar, A., Subbarao, K.V., Walsh, J.N., Biswal, T.K.Rb Sr age and Sr isotopic composition of alkaline dykes near Mumbai ( Bombay) further evidence for the Deccan trap Reunion plumeJournal of Geological Society of India, Vol. 62, 5, pp. 641-646.IndiaAlkalic
DS201910-2285
2019
Walsh, J.P.S.Meyer, N.A., Wenz, M.D., Walsh, J.P.S., Jacobsen, S.D., Locock, A.J., Harris, J.W.Goldschmidtite, ( K,REE,Sr) (Nb,Cr)03: a new perovskite supergroup mineral found in diamond from Koffiefontein, South Africa.American Mineralogist, Vol. 104, pp. 1345-1350.Africa, South Africadeposit - Koffiefontein

Abstract: Goldschmidtite is a new perovskite-group mineral (IMA No. 2018-034) with the ideal formula (K,REE,Sr)(Nb,Cr)O3. A single grain of goldschmidtite with a maximum dimension of ~100 µm was found as an inclusion in a diamond from the Koffiefontein pipe in South Africa. In addition to the dark green and opaque goldschmidtite, the diamond contained a Cr-rich augite (websteritic paragenesis) and an intergrowth of chromite, Mg-silicate, and unidentified K-Sr-REE-Nb-oxide. Geothermobarometry of the augite indicates that the depth of formation was ~170 km. The chemical composition of gold-schmidtite determined by electron microprobe analysis (n = 11, WDS, wt%) is: Nb2O5 44.82, TiO2 0.44, ThO2 0.10, Al2O3 0.35, Cr2O3 7.07, La2O3 11.85, Ce2O3 6.18, Fe2O3 1.96, MgO 0.70, CaO 0.04, SrO 6.67, BaO 6.82, K2O 11.53, total 98.53. The empirical formula (expressed to two decimal places) is (K0.50La0.15Sr0.13Ba0.09Ce0.08)S0.95(Nb0.70Cr0.19Fe0.05Al0.01Mg0.04Ti0.01)S1.00O3. Goldschmidtite is cubic, space group Pm3m, with unit-cell parameters: a = 3.9876(1) Å, V = 63.404(6) Å3, Z = 1, resulting in a calculated density of 5.32(3) g/cm3. Goldschmidtite is the K-analog of isolueshite, (Na,La)NbO3. Raman spectra of goldschmidtite exhibit many second-order broad bands at 100 to 700 cm-1 as well as a pronounced peak at 815 cm-1, which is possibly a result of local ordering of Nb and Cr at the B site. The name goldschmidtite is in honor of the eminent geochemist Victor Moritz Goldschmidt (1888-1947), who formalized perovskite crystal chemistry and identified KNbO3 as a perovskite-structured compound.
DS201212-0488
2012
Walsh, K.J.Morbidelli, A., Lunine, J.I., O'Brien, D.P., Raymond, S.N., Walsh, K.J.Building terrestrial planets.Annual Review of Earth and Planetary Sciences, Vol. 40, pp. 251-275.MantleTectonics
DS2001-1216
2001
Walsh, K.L.Walsh, K.L., Siegfried, P., Hall, HughesTectonic implications of four recently discovered carbonatites along the Zambesi Escarpment Fault.Journal of South African Earth Sciences, Vol. 32, No. 1, p. A 36-7.(abs)ZimbabweCarbonatite, Marindagomo Complex, Dande-Doma
DS1996-0203
1996
Walsh, M.M.Byerly, G.R., Kroner, A., Walsh, M.M.Prolonged magmatism and time constraints for sediment deposition in the Early Archean Barberton greenstonePrecambrian Research, Vol. 78, No. 1-3, May 1, pp. 125-150South AfricaGreenstone belts, Barberton area
DS1992-1629
1992
Walsh, M.W.Walsh, M.W.The great Canadian diamond rush is on. Mining firms flock north following'91 discoveryLos Angeles Times, October 4, 2pNorthwest TerritoriesNews item, Dia Met, BHP, Kennecott
DS1991-1827
1991
Walsh, P.Walsh, P.A green depression. Current recession may be a depression. Edited version of a talk in Australia which emphasizes the problems and activities ofGreenpeaceAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 3, July pp. 58-59AustraliaEconomics, Environmental
DS1999-0778
1999
Walsham, B.Walsham, B., Treneham, B.Diamond opportunities in Angola: a Diamond works perspectiveProspectors and Developers Association of Canada (PDAC) abstract volume, p. 8.AngolaOverview
DS2002-0768
2002
Walshe, J.L.Jaques, A.L., Jareth, S., Walshe, J.L.Mineral systems of Australia: an overview of resources, settings and processesAustralian Journal of Earth Sciences, Vol. 49,4,August pp. 623-60.AustraliaResources, tectonics, mentions diamonds
DS1992-1630
1992
Walstrom, J.S.Walstrom, J.S., MacLeod, M.D., Rutherford, T.L.Environmental liability management for mineral processorsAmerican Institute of Mining, Metallurgical, and Petroleum Engineers (AIME) Preprint, Annual Meeting held Phoenix Arizona Feb. 24-27th. 1992, Preprint No. 92-16. 5pGlobalEnvironment, Legal, mineral processing
DS201709-1990
2017
Walsworth, R.L.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.
DS201412-0872
2014
Walte, N.P.Soustelle, V., Walte, N.P., Manthilake, M.A.G.M., Frost, D.J.Melt migration and melt rock reactions in the deforming Earth's upper mantle: experiments at high pressure and temperature.Geology, Vol. 42, pp. 83-86.MantleMelting
DS201504-0188
2015
Walte, N.P.Cerantola, V., Walte, N.P., Rubie, D.C.Deformation of a crystalline olivine aggregate containing two immiscible liquids: implications for early core-mantle differentiation.Earth and Planetary Science Letters, Vol. 417, pp. 67-77.MantleCore, mantle

Abstract: Deformation-assisted segregation of metallic and sulphidic liquid from a solid peridotitic matrix is a process that may contribute to the early differentiation of small planetesimals into a metallic core and a silicate mantle. Here we present results of an experimental study using a simplified system consisting of a polycrystalline Fo90-olivine matrix containing a small percentage of iron sulphide and a synthetic primitive MORB melt, in order to investigate whether the silicate melt enhances the interconnection and segregation of FeS liquid under deformation conditions at varying strain rates. The experiments have been performed at 2 GPa, 1450?°C and strain rates between 1×10-3 s-11×10-3 s-1 to 1×10-5 s-11×10-5 s-1. Our results show that the presence of silicate melt actually hinders the migration and segregation of sulphide liquid by reducing its interconnectivity. At low to moderate strain rates the sulphide liquid pockets preserved a roundish shape, showing the liquid behavior is governed mainly by surface tension rather than by differential stress. Even at the highest strain rates, insignificant FeS segregation and interconnection were observed. On the other hand the basaltic melt was very mobile during deformation, accommodating part of the strain, which led to its segregation from the matrix at high bulk strains leaving the sulphide liquid stranded in the olivine matrix. Hence, we conclude that deformation-induced percolation of sulphide liquid does not contribute to the formation of planetary cores after the silicate solidus is overstepped. A possible early deformation enhanced core-mantle differentiation after overstepping the Fe-S solidus is not possible between the initial formation of silicate melt and the formation of a widespread magma ocean.
DS200612-1342
2006
WalterSparks, R.S.J., Baker, Brooker, Brown, Field, Fontana, Gernon, Kavanagh, Shumacher, Stripp, Walter, Walters, White, WindsorDynamical constraints on kimberlite volcanism,Emplacement Workshop held September, 5p. abstractGlobalMagmatism, water, stages
DS1990-1532
1990
Walter, A.V.Walter, A.V., Flicoteaux, R., Girard, J.P., Loubet, M., Nahon, D.rare earth elements (REE) pattern in apatites from the Juquia carbonatite, BrasilChemical Geology ( Geochem. of the Earth's surface and of min. formation, 2nd., Vol. 84, No. 1-4, July 5, pp. 378-379. AbstractBrazilCarbonatite, Juquia
DS1995-2020
1995
Walter, A.V.Walter, A.V., Filocteaux, R., Parron, C., Loubet, M., NahonRare earth elements and isotopes (Strontium, neodymium, Oxygen, Carbon) in minerals from Juquia carbonatite Brasil: tracers evol.Chemical Geology, Vol. 120, No. 1-2, Feb. 1, pp. 27-44.BrazilCarbonatite, Deposit -Juquia
DS1995-2021
1995
Walter, A.V.Walter, A.V., Nahon, D., Flicoteaux, R., et al.Behaviour of major and trace elements and fractionation of rare earth elements (REE) undertropical weathering of apatite rich carb.Earth and Planetary Science Letters, Vol. 136, No. 3-4, pp. 591-602.BrazilCarbonatite, Laterites
DS1981-0181
1981
Walter, A.W.Ginzburg, A., Mooney, W.D., Lutter, W.J., Walter, A.W.Crustal Structure in the Mississippi Embayment: CrossprofileEos, Vol. 62, No. 45, P. 1046. (abstract.).GlobalMid-continent
DS1983-0256
1983
Walter, A.W.Ginzburg, A., Mooney, W.D., Walter, A.W., Lutter, W.J., Healy, J.Deep Structure of Northern Mississippi EmbaymentAmerican Association of Petroleum Geologists Bulletin., Vol. 67, No. 11, NOVEMBER PP. 2031-3046.GlobalMid Continent
DS201811-2617
2018
Walter, B.F.Walter, B.F., Parsapoor, A., Braunger, S., Marks, M.A.W., Wenzel, T., Martin, M., Markl, G.Pyrochlore as a monitor for magmatic and hydrothermal processes in carbonatites from the Kaiserstuhl volcanic complex ( SW Germany).Chemical Geology, Vol. 498, pp. 1-16.Europe, Germanycarbonatite

Abstract: Pyrochlore from the Kaiserstuhl volcanic complex (SW Germany) shows textural and compositional differences between various coarse-grained calcite-carbonatite bodies (Badberg, Degenmatt, Haselschacher Buck, Orberg) and extrusive carbonatites (Henkenberg, Kirchberg). Oscillatory-zoned F-rich pyrochlore with up to 69?wt% Nb2O5 is common in all coarse-grained calcite-carbonatite bodies and probably formed during magmatic conditions. However, only in some of the samples from the Badberg, partly resorbed U- and Ta-enriched pyrochlore cores with up to 22?wt% UO2 and 9?wt% Ta2O5 have been identified, which are interpreted as being inherited from underlying nosean syenites. Pyrochlore data from a drill core penetrating the Badberg indicate increasing contents of REE, U, and Ta with depth, while Nb, F and Na contents decrease. This may reflect the combined effects of fractional crystallization and assimilation (AFC) or indicates a multi-stage emplacement of the carbonatitic magma. Patchy-zoned ceriopyrochlore and REE- and Th-enriched pyrochlore with up to 19?wt% total REE2O3 and 6.5?wt% ThO2 is largely restricted to samples from the Orberg and probably formed during hydrothermal conditions. This can be related to the relatively evolved character of the Orberg carbonatites, based on their relatively high whole-rock Nb/Ta and Zr/Hf mass ratios. This study demonstrates that the textural and compositional variation of pyrochlore in carbonatites is a powerful tool to distinguish magmatic, hydrothermal and weathering processes in carbonatitic systems.
DS201903-0498
2019
Walter, B.F.Banks, G.J., Walter, B.F., Marks, M.A.W., Siegfried, P.R.A workflow to define, map and name a carbonatite-alkaline igneous-associated REE-HFSE mineral system: a case study from SW Germany.MDPI, Vol. 9, 97, 28p. PdfGlobalREE

Abstract: Security of supply of “hi-tech” raw materials (including the rare earth elements (REE) and some high-field-strength elements (HFSEs)) is a concern for the European Union. Exploration and research projects mostly focus on deposit- to outcrop-scale description of carbonatite- and alkaline igneous-associated REE-HFSE mineralization. The REE-HFSE mineral system concept and approach are at a nascent stage, so developed further here. However, before applying the mineral system approach to a chosen REE-HFSE metallogenic province its mineral system extent first needs defining and mapping. This shifts a mineral system project’s foundation from the mineral system concept to a province’s mineral system extent. The mapped extent is required to investigate systematically the pathways and potential trap locations along which the REE-HFSE mass may be distributed. A workflow is presented to standardize the 4-D definition of a REE-HFSE mineral system at province-scale: (a) Identify and hierarchically organize a mineral system’s genetically related sub-divisions and deposits, (b) map its known and possible maximum extents, (c) name it, (d) discern its size (known mineral endowment), and (e) assess the favorability of the critical components to prioritize further investigations. The workflow is designed to generate process-based perspective and improve predictive targeting effectiveness along under-evaluated plays of any mineral system, for the future risking, comparing and ranking of REE-HFSE provinces and plays.
DS201909-2042
2019
Walter, B.F.Giebel, R.J., Parsapoor, A., Walter, B.F., Braunger, S., Marks, M.A.W.Evidence for magma-wall rock interaction in carbonatites from the Kaiserstuhl volcanic complex ( southwest Germany).Journal of Petrology , Vol. 60, 6, pp. 1163-1194.Europe, Germanycarbonatite

Abstract: The mineralogy and mineral chemistry of the four major sövite bodies (Badberg, Degenmatt, Haselschacher Buck and Orberg), calcite foidolite/nosean syenite xenoliths (enclosed in the Badberg sövite only) and rare extrusive carbonatites of the Kaiserstuhl Volcanic Complex in Southern Germany provide evidence for contamination processes in the carbonatitic magma system of the Kaiserstuhl. Based on textures and composition, garnet and clinopyroxene in extrusive carbonatites represent xenocrysts entrained from the associated silicate rocks. In contrast, forsterite, monticellite and mica in sövites from Degenmatt, Haselschacher Buck and Orberg probably crystallized from the carbonatitic magma. Clinopyroxene and abundant mica crystallization in the Badberg sövite, however, was induced by the interaction between calcite foidolite xenoliths and the carbonatite melt. Apatite and micas in the various sövite bodies reveal clear compositional differences: apatite from Badberg is higher in REE, Si and Sr than apatite from the other sövite bodies. Mica from Badberg is biotite- and comparatively Fe2+-rich (Mg# = 72-88). Mica from the other sövites, however, is phlogopite (Mg# up to 97), as is typical of carbonatites in general. The typical enrichment of Ba due to the kinoshitalite substitution is observed in all sövites, although it is subordinate in the Badberg samples. Instead, Badberg biotites are strongly enriched in IVAl (eastonite substitution) which is less important in the other sövites. The compositional variations of apatite and mica within and between the different sövite bodies reflect the combined effects of fractional crystallization and carbonatite-wall rock interaction during emplacement. The latter process is especially important for the Badberg sövites, where metasomatic interaction released significant amounts of K, Fe, Ti, Al and Si from earlier crystallized nosean syenites. This resulted in a number of mineral reactions that transformed these rocks into calcite foidolites. Moreover, this triggered the crystallization of compositionally distinct mica and clinopyroxene crystals around the xenoliths and within the Badberg sövite itself. Thus, the presence and composition of clinopyroxene and mica in carbonatites may be useful indicators for contamination processes during their emplacement. Moreover, the local increase of silica activity during contamination enabled strong REE enrichment in apatite via a coupled substitution involving Si, which demonstrates the influence of contamination on REE mineralization in carbonatites.
DS201909-2061
2019
Walter, B.F.Marks, M.A.W., Giebel, R.J., Walter, B.F., Braunger, S., Wenzel, T., Markl, G.Evidence for wall-rock assimilation in carbonatites from the Kaiserstuhl (German).Goldschmidt2019, 1p. AbstractEurope, Germanydeposit - Kaiserstuhl

Abstract: Contamination of carbonatites with crustal or cogenetic intrusive rocks is generally not considered to play an important role during carbonatite magmatism, because carbonatitic melts have low densities and viscosities, enabling them to rapidly ascend. Potential contamination by silicate rocks in carbonatites cannot easily be detected by means of radiogenic isotope data (such as Sr, Nd and Pb isotope data) as carbonatites often show high concentrations of these elements and their isotope systems are thereby “buffered” against contamination with silicate rocks. Textural, mineralogical and geochemical observations in carbonatites from the Kaiserstuhl (Germany) provide evidence for the interaction of carbonatitic magma with previously emplaced nosean syenites. This caused replacement of alkali feldspar by haüyne and recrystallization of garnet and clinopyroxene in the xenoliths, which released larger amounts of K, Al, Si and Fe. As a result, blackwall-like mica seams around the xenoliths formed and and compositionally distinct mica and clinopyroxene crystallized in the surrounding carbonatite. Moreover, the local increase of silica activity during contamination enabled strong REE enrichment in apatite via a coupled substitution involving Si, which demonstrates the potential influence of Si contamination on REE mineralization in carbonatites. We further suggest that the presence and composition of clinopyroxene and mica in carbonatites may be useful indicators for contamination processes during their emplacement. Mass-balance calculations based on experimental constraints for the solubility of Al and Si in carbonatitic magmas suggest that only minor amounts of mica can form from carbonatitic melt. Therefore, larger amounts of mica and mica-dominated lithologies (glimmerites) as observed in many carbonatite complexes suggest that some Si and Al in carbonatites may be sourced from surrounding host rocks. We hypothesize that assimilation and contamination processes in carbonatites may be the rule rather than an exception.
DS201909-2104
2019
Walter, B.F.Walter, B.F., Steele-MacInnis, M., Giebel, R.J., Marks, M.A.W., Markl, G.Fluids exsolved from the Kaiserstuhl carbonatite, SW Germany: brine generation by boiling.Goldschmidt2019, 1p. AbstractEurope, Germanydeposit - Kaiserstuhl

Abstract: Studies on fluid inclusions in carbonatitic rocks are essential to understand the physicochemical processes involved in carbonatite-related hydrothermal ore mineralization. Although little is known about the composition of carbonatite-derived fluids. We investigated fluid inclusions in the Kaiserstuhl carbonatites, SW Germany [1,2] and identified four different types typically known from carbonatitic systems worldwide [3]: (I): Vapor-poor H2O-NaCl fluids with <50 wt.% salinity. (II): Vapor-rich H2O-NaCl-CO2 fluids with <5 wt.% salinity. (III): Multi-component fluids with high salinity and CO2. (IV): Multi-component fluids with high salinity, no CO2. Homogenization temperatures (156 to 530°C) of all fluid types generally show a wide range [this study, 2]. Primary type I fluid inclusions occur in early magmatic olivine/monticellite, as well as paragenetically later apatites and calcites [2]. This indicates a ubiquitous existence of a saline brine, which does not reach saturation with respect to halite, during early to late crystallization stages. Liquidus surface modelling based quantifications for fluid type III suggest that carbonatite melts predomonantly exsolve Na-K-sulfate-carbonate/bicarbonate-chloride brines (type III or IV, respectively). Such fluid inclusions, with type III (CO2-free) on one side and type IV (and II, both CO2-rich) on the other side, may represent immiscible fluids that were trapped after segregation by boiling from a parental highly saline brine (type I). Fluid boiling, in turn, is probably triggered by a rapid pressure release during “pneumatic hammer-like,” discontinuous melt ascent.
DS202006-0955
2020
Walter, B.F.Walter, B.F., Steele-MacInnis, M., Giebel, R.J., Marks, M.A.W., Markl, G.Complex carbonatite-sulfate brines in fluid inclusions from carbonatites: estimating compositions in the system H2O-Na-K-CO3-SO4-Cl. KaiserstuhlGeochimica et Cosmochimica Acta, Vol. 277, pp. 224-242. pdfEurope, Germanycarbonatite

Abstract: Studies of fluid inclusions in carbonatitic rocks are essential for understanding physicochemical processes involved in carbonatite-related hydrothermal ore mineralization and fenitization. However, the composition of many carbonatite-derived fluids is challenging to quantify, which hampers their detailed interpretation. Here, we present a systematic study of microthermometry of fluid inclusions found in carbonatites from the Kaiserstuhl (SW Germany), and a simple numerical model to estimate the compositions of such fluids, which are typical of numerous carbonatites worldwide. Four types of fluid inclusions have been identified in the Kaiserstuhl carbonatites: (I) vapor-poor H2O-NaCl fluids with <50?wt.% salinity; (II) vapor-rich H2O-NaCl-CO2 fluids with <5?wt.% salinity; (III) multi-component fluids with high salinity and high CO2 contents; and (IV) multi-component fluids with high salinity but little to no CO2. At present, it is only possible to quantify fluid compositions for types I and II. For the complex types III and IV, we conducted predictive modeling of the liquidus surface based on the Margules equations. The results suggest that carbonatite melts predominantly exsolve Na-K-sulfate-carbonate/bicarbonate-chloride brines (types III or IV). Such fluid inclusions may represent immiscible fluids that were trapped after segregation by boiling from a parental highly saline brine (type I). Fluid boiling, in turn, was probably triggered by a rapid pressure release during melt ascent. The present model enables quantification of fluid compositions associated with carbonatitic magmatism.
DS202007-1184
2020
Walter, B.F.Walter, B.F., Steele-MacInnis, M., Gielbel, R.J., Marks, M.A.W., Markl, G.Complex carbonatite-sulfate brines in fluid inclusions from carbonatites: estimating compositions in the system H2O-Na-K-CO3-SO4-ClGeochimica et Cosmochimica Acta, Vol. 277, pp. 224-242. pdfEurope, Germanydeposit - Kaiserstuhl

Abstract: Studies of fluid inclusions in carbonatitic rocks are essential for understanding physicochemical processes involved in carbonatite-related hydrothermal ore mineralization and fenitization. However, the composition of many carbonatite-derived fluids is challenging to quantify, which hampers their detailed interpretation. Here, we present a systematic study of microthermometry of fluid inclusions found in carbonatites from the Kaiserstuhl (SW Germany), and a simple numerical model to estimate the compositions of such fluids, which are typical of numerous carbonatites worldwide. Four types of fluid inclusions have been identified in the Kaiserstuhl carbonatites: (I) vapor-poor H2O-NaCl fluids with <50?wt.% salinity; (II) vapor-rich H2O-NaCl-CO2 fluids with <5?wt.% salinity; (III) multi-component fluids with high salinity and high CO2 contents; and (IV) multi-component fluids with high salinity but little to no CO2. At present, it is only possible to quantify fluid compositions for types I and II. For the complex types III and IV, we conducted predictive modeling of the liquidus surface based on the Margules equations. The results suggest that carbonatite melts predominantly exsolve Na-K-sulfate-carbonate/bicarbonate-chloride brines (types III or IV). Such fluid inclusions may represent immiscible fluids that were trapped after segregation by boiling from a parental highly saline brine (type I). Fluid boiling, in turn, was probably triggered by a rapid pressure release during melt ascent. The present model enables quantification of fluid compositions associated with carbonatitic magmatism.
DS1995-0781
1995
Walter, H.J.Hegner, E., Walter, H.J., Satir, M.lead, Strontium, neodymium isotope compositions and trace element geochemistry of megacrysts and melilitites from UrachContributions to Mineralogy and Petrology, Vol. 122, pp. 322-335.GermanyTertiary Urach field, isotopes, European Volcanic Province
DS1995-2042
1995
Walter, H.J.Wegner, E., Walter, H.J., Satir, M.lead, Strontium, neodymium isotopic compositions and trace element geochemistry of megacrysts and melilitites Tertiary...Contributions to Mineralogy and Petrology, Vol. 122, No. 3, pp. 322-GermanyMelts, isotopes, Urach volcanic field
DS1990-0109
1990
Walter, M.Aleinikoff, J.N., Winegarden, D.L., Walter, M.uranium-lead (U-Pb) (U-Pb) ages of zircon rims: a new analytical method using the air-abrasiontechniqueChemical Geology, Vol. 80, pp. 351-363GlobalGeochronology, Age determinations -uranium-lead (U-Pb) (U-Pb)
DS1994-1876
1994
Walter, M.Walter, M.A revolution in exploration of Proterozoic basinsAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 6, Dec. pp. 68-69AustraliaBasin interpretation -brief, Proterozoic
DS2003-0799
2003
Walter, M.Lesher, 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
Walter, M.Lesher, 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
DS200612-0257
2006
Walter, M.Clar, S.M., Speciale, S., Jeanloz, R., Kunz, M., Caldwell, W.A., Walter, M., Walker, D.Using advanced accelerators to understand the lower mantle and beyond.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 104, abstract only.MantleGeochemistry
DS200612-1504
2006
Walter, M.Walter, M., Elliott, T.Core mantle reactivity.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 4 abstract only.MantleGeochemistry
DS200912-0083
2008
Walter, M.Buisman, I., Sparks, S., Walter, M.The origin and evolution of kimberlite melts: stabilizing phlogopite in the CMAS-CO2-H2O-K2O system.American Geological Union, Fall meeting Dec. 15-19, Eos Trans. Vol. 89, no. 53, meeting supplement, 1p. abstractMantleMelting
DS201112-0026
2010
Walter, M.Araujo, D., Ribeiro, D., Bulanonva, G., Smith, C., Walter, M., Kohn, S.Diamond inclusions from the Juina-5 kimberlite, Brazil.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 43.South America, Brazil, Mato GrossoDiamond inclusions
DS201412-0816
2014
Walter, M.Shiry, S., Hauri, E., Thomson, A., Bulanova, G., Smith, C., Kohn, S., Walter, M.Water content of stishovite, majorite and perovskite inclusions in Juin a superdeep diamonds.Goldschmidt Conference 2014, 1p. AbstractSouth America, BrazilDeposit - Juina
DS1995-2022
1995
Walter, M.J.Walter, M.J.Melting reactions of fertile garnet peridotiteEos, Abstracts, Vol. 76, No. 17, Apr 25, p. S 297.MantleGarnet peridotite
DS1998-0820
1998
Walter, M.J.Kushiro, I., Walter, M.J.magnesium-iron partioning between olivine and mafic ultramafic meltsGeophysical Research. Letters, Vol. 25, No. 13, July pp. 2337-40MantleMelting
DS1998-1185
1998
Walter, M.J.Presnall, D.C., Walter, M.J.high pressure phase equilibrium constraints on the origin of eclogites7th. Kimberlite Conference abstract, pp. 705-7.MantleEclogites, Geochronology, petrology, mineral chemistry
DS1998-1559
1998
Walter, M.J.Walter, M.J.Melting of garnet peridotite and origin of komatiite and depletedlithosphereJournal of Petrology, Vol. 39, No. 1, Jan. ppMantleKomatiites
DS1998-1560
1998
Walter, M.J.Walter, M.J.Melting of garnet peridotite and the origin of komatiite and depletedlithosphere.Journal of Petrology, Vol. 39, No. 1, Jan. pp. 29-61.MantlePeridotite
DS2003-0734
2003
Walter, M.J.Koga, K.T., Van Orman, J.A., Walter, M.J.Diffusive relaxation of carbon and nitrogen isotope heterogeneity in diamond: a newPhysics of the Earth and Planetary Interiors, Vol. 139, 1-2, Sept. 30, pp. 35-43.GlobalPetrology, experimental, geothermometry, zoning
DS200412-1026
2003
Walter, M.J.Koga, K.T., Van Orman, J.A., Walter, M.J.Diffusive relaxation of carbon and nitrogen isotope heterogeneity in diamond: a new thermochronometer.Physics of the Earth and Planetary Interiors, Vol. 139, 1-2, Sept. 30, pp. 35-43.TechnologyPetrology, experimental, geothermometry, zoning
DS200412-2075
2004
Walter, M.J.Walter, M.J., Kubo, A., Yoshino, T., Brodholt, J., Koga, K.T., Ohishi, Y.Phase relations and equation of state aluminous Mg silicate perovskite and implications for Earth's lower mantle.Earth and Planetary Science Letters, Vol. 222, 2, pp. 501-516.MantlePerovskite
DS200412-2076
2004
Walter, M.J.Walter, M.J., TRonnes, R.G.Early Earth differentiation.Earth and Planetary Science Letters, Vol. 225, 3-4, Sept. 15, pp. 253-269.MantleCore, proto-crust, geochronology, Ni Co, partitioning
DS200612-0378
2006
Walter, M.J.Ertel, W., Walter, M.J., Drake, M.J., Sylvester, P.J.Experimental study of platinum solubility in silicate melt to 14 GPa and 2273 K: implications for accretion and core formation in Earth.Geochimica et Cosmochimica Acta, Vol. 70, 10, May 15, pp. 2591-2602.MantleMetasomatism - platinum, accretion, boundary
DS200612-1541
2006
Walter, M.J.Wood, B.J., Walter, M.J., Wade, J.Accretion of the Earth and segregation of its core.Nature, Vol. 441, June 15, pp. 825-833.MantleSilicate, magma ocean
DS200912-0719
2009
Walter, M.J.Sparks, R.S.J., Brooker, R.A., Field, M., Kavanagh, J., Schumacher, J.C., Walter, M.J., White, J.The nature of erupting kimberlite melts.Lithos, In press available, 30p.MantleMelting
DS200912-0805
2009
Walter, M.J.Walter, 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
DS201012-0079
2010
Walter, M.J.Bulanova, G.P., Walter, M.J., Smith, C.B.,Kohn, C.C.,Armstrong, L.S., Blundy, J.,Gobbo, L.Mineral inclusions in sublithospheric diamonds from Collier 4 kimberlite pipe, Juina, Brazil: subducted protoliths, carbonated melts and primary kimberlite ..Contributions to Mineralogy and Petrology, Vol. 160, 4, pp. 489-50.South America, BrazilMagmatism
DS201012-0546
2009
Walter, M.J.Ogilvie-Harris, R.C., Field, M., Sparks, R.S.J., Walter, M.J.Perovskite from the Dutoitspan kimberlite, Kimberley, South Africa: implications for magmatic processes.Mineralogical Magazine, Vol. 73, no. 6, pp. 915-928.Africa, South AfricaDeposit - Dutoitspan
DS201112-0029
2011
Walter, M.J.Armstrong, L.S., Walter, M.J.TAPP: retrograde Mg perovskite from subducted lithosphere.Goldschmidt Conference 2011, abstract p.453.MantleTAPP inclusions - diamond
DS201112-0533
2011
Walter, M.J.Kohn, S.C., Walter, M.J., Araujo, D., Bulanova, G.P., Smith, C.B.Subducted oceanic crust exhumed from the lower mantle.Goldschmidt Conference 2011, abstract p.1213.South America, BrazilJuina diamonds
DS201112-1098
2011
Walter, M.J.Walter, M.J., Kohn, Arajuo, Bulanova, Smith, Gaillou, Wang, Steele, ShireyDeep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions.Science, Vol. 334, 6052, pp. 51-52.MantleDiamond inclusions
DS201212-0017
2012
Walter, M.J.Arajo, D.P., Bulanova, G.P., Walter, M.J., Kohn, S.C., Smith, C.B., Gaspar, J.C., WangJuina-5 kimberlite ( Brazil): a source of unique lower mantle diamonds.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractSouth America, BrazilDeposit - Juina-5
DS201212-0024
2012
Walter, M.J.Armstrong, L.S., Walter, M.J.Tetragonal almandine pyrope phase ( TAPP): retrograde Mg-perovskite from subducted oceanic crust?European Journal of Mineralogy, Vol. 24, 4, pp. 587-597.TechnologyPerovskite
DS201212-0025
2012
Walter, M.J.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
DS201212-0095
2012
Walter, M.J.Buisman, I., Sparks, R.S.J., Walter, M.J., Brown, R.J., Manya, S., Kavanagh, J.Olivine chemistry of exceptionally young ( Holocene) kimberlite of the Igwisi Hills volcano, Tanzania.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, TanzaniaDeposit - Igwisi
DS201212-0096
2012
Walter, M.J.Bulanova, G.P., Marks, A., Smith, C.B., Kohn, S.C., Walter, M.J., Gaillou, E., Shiry, S.B., Trautman, R., Griffin, B.J.Diamonds from Sese and Murowa kimberlites ( Zimbabwe) - evidence of extreme peridotitic lithosphere depletion and Ti-REE metasomatism.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, ZimbabweDeposit - Sese, Murowa
DS201212-0367
2012
Walter, M.J.Kohn, S.C., McKay, A.P., Smith, C.B., Bulanova, G.P., Walter, M.J., Marks, A.The thermal history of Archean lithosphere. Constraints from FTIR studies of zoning in diamonds.emc2012 @ uni-frankfurt.de, 1p. AbstractAfrica, ZimbabweDeposit - Murowa
DS201212-0529
2012
Walter, M.J.Ogilvie-Harris, R.C., Field, M., Brooker, R.A., Walter, M.J., Sparks, R.S.J.The petrology of AK6, Botswana: implications of volcanic and igneous processes.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractAfrica, BotswanaDeposit - AK6
DS201212-0530
2012
Walter, M.J.Ogily-Harris, R.C., Brooker, R.A., Sparks, R.S.J., Walter, M.J.An experimental investigation of the carbonatite-kimberlite melt.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractAfrica, South AfricaDeposit - Dutoitspan
DS201212-0649
2012
Walter, M.J.Shirey, S.B., Cartigny, P., Frost, D.J., Nestola, F., Nimis, P., Pearson, D.G., Sobolev, N.V., Walter, M.J.Diamonds and the geology of Earth mantle carbon.GSA Annual Meeting, Paper no. 211-5, abstractMantleSubduction
DS201212-0728
2012
Walter, M.J.Thomson, A.R., Walter, M.J., Kohn, S.C., Russell, B.C., Bulanova, G.P., Araujo, D., Smith, C.B.Evidence for the role of carbonate melts in the origin of superdeep diamond inclusions from the Juina-5 kimberlite, Brazil.Goldschmidt Conference 2012, abstract 1p.South America, BrazilDeposit - Juina-5
DS201312-0111
2013
Walter, M.J.Burnham, A.D., Kohn, S.C., Potoszil, C., Walter, M.J., Bulanova, G.P., Thomson, A.R., Smith, C.B.The redox state of diamond forming fluids: constraints from Fe3/Fe2+ of garnets.Goldschmidt 2013, AbstractMantleGeothermometry
DS201312-0495
2013
Walter, M.J.Kohn, S.C., Wibberley, E., Smith, C.B., Bulanova, G.P., Walter, M.J.Platelet degradation in diamonds. Insights from infrared microscopy and implications for the thermal evolution of cratonic mantle.Goldschmidt 2013, AbstractMantleDiamond crystallography
DS201312-0815
2012
Walter, M.J.Shirey, S.B., Cartigny, P.,Frost, D.J., Nestola, F., Pearson, D.G., Sobolev, N.V., Walter, M.J.Diamonds and the geology of Earth mantle carbonGeological Society of America Annual Meeting abstract, Paper 211-5, 1/2p. AbstractMantleCarbon
DS201312-0816
2013
Walter, M.J.Shirey, S.B., Cartigny, P., Frost, D.J., Keshav, S., Nestola, F., Nimis, P., Pearson, D.G., Sobolev, N.V., Walter, M.J.Diamonds and the geology of mantle carbon.Reviews in Mineralogy and Geochemistry, Vol. 75, pp. 355-421.MantleDiamond genesis
DS201312-0817
2013
Walter, M.J.Shirey, S.B., Hauri, E.H., Thomason, A.R., Bulanova, G.P., Smith, C.B., Kohn, S.C., Walter, M.J.Water content of inclusions in superdeep diamonds.Goldschmidt 2013, 1p. AbstractSouth America, BrazilDeposit - Collier4
DS201312-0912
2013
Walter, M.J.Thomson, A.R., Walter, M.J., Kohn, S.C., Bulanova, G.P., Smith, C.B.An experimental investigation of the formation mechanisms of superdeep diamonds.Goldschmidt 2013, 1p. AbstractSouth America, BrazilDeposit - Collier 4, Juina5
DS201312-0949
2013
Walter, M.J.Walter, M.J., Smith, C.B., Bulanova, G.P., Mikhail, S., Khon, S.C.Diamonds and their inclusions from Dachine, French Guiana: a record of Paleoproterozoic subduction.Goldschmidt 2013, 1p. AbstractSouth America, French GuianaDeposit - Dachine
DS201412-0930
2014
Walter, M.J.Thomson, A.R., Kohn, S.C., Bulanova, G.P., Smith, C.B., Araujo, D., Walter, M.J.Origin of sub-lithopheric diamonds from the Juina-5 kimberlite ( Brazil): constraints from carbon isotopes and inclusion compositions.Contributions to Mineralogy and Petrology, Vol. 168, pp. 1081-1091.South America, BrazilDeposit - Juina-5
DS201502-0113
2014
Walter, M.J.Thomson, A.R., Kohn, S.C., Bulanova, G.P., Smith, C.B., Araujo, D., EMIF, Walter, M.J.Origin of sub-lithospheric diamonds from the Juina-5 kimberlite ( Brazil): constraints from carbon isotopes and inclusion compositions.Contributions to Mineralogy and Petrology, Vol. 168, pp. 1081-1110.South America, BrazilDeposit - Juina-5
DS201510-1813
2015
Walter, M.J.Walter, M.J., Thomson, A.R., Wang, W., Lord, O.T., Ross, J., McMahon, S.C., Baron, M.A., Melekhova, E., Kleppe, A K., Kohn, S.C.The stability of hydrous silicates in Earth's lower mantle: experimental constraints from the systems MgO-SiO2-H2O and MgO-Al2O3-SiO2-H2).Chemical Geology, Vol. 418, pp. 16-29.MantleExperimental petrology

Abstract: We performed laser-heated diamond anvil cell experiments on bulk compositions in the systems MgO-SiO2-H2O (MSH) and MgO-Al2O3-SiO2-H2O (MASH) that constrain the stability of hydrous phases in Earth’s lower mantle. Phase identification by synchrotron powder diffraction reveals a consistent set of stability relations for the high-pressure, dense hydrous silicate phases D and H. In the MSH system phase D is stable to ~ 50 GPa, independent of temperature from ~ 1300 to 1700 K. Phase H becomes stable between 35 and 40 GPa, and the phase H out reaction occurs at ~ 55 GPa at 1600 K with a negative dT/dP slope of ~ -75 K/GPa. Between ~ 30 and 50 GPa dehydration melting occurs at ~ 1800K with a flat dT/dP slope. A cusp along the solidus at ~ 50 GPa corresponds with the intersection of the subsolidus phase H out reaction, and the dT/dP melting slope steepens to ~ 15 K/GPa up to ~ 85 GPa.
DS201512-1900
2015
Walter, M.J.Burnham, A.D., Thomson, A.R., Bulanova, G.P., Kohn, S.C., Smith, C.B., Walter, M.J.Stable isotope evidence for crustal recycling as recorded by superdeep diamonds.Earth and Planetary Science Letters, Vol. 432, pp. 374-380.South America, BrazilDeposit - Juina-5, Collier-4, Machado River

Abstract: Sub-lithospheric diamonds from the Juina-5 and Collier-4 kimberlites and the Machado River alluvial deposit in Brazil have carbon isotopic compositions that co-vary with the oxygen isotopic compositions of their inclusions, which implies that they formed by a mixing process. The proposed model for this mixing process, based on interaction of slab-derived carbonate melt with reduced (carbide- or metal-bearing) ambient mantle, explains these isotopic observations. It is also consistent with the observed trace element chemistries of diamond inclusions from these localities and with the experimental phase relations of carbonated subducted crust. The 18O-enriched nature of the inclusions demonstrates that they incorporate material from crustal protoliths that previously interacted with seawater, thus confirming the subduction-related origin of superdeep diamonds. These samples also provide direct evidence of an isotopically anomalous reservoir in the deep (=350 km) mantle.
DS201602-0247
2016
Walter, M.J.Thomson, A.R., Walter, M.J., Kohn, S.C., Brooker, R.A.Slab melting as a barrier to deep carbon subduction. ( super deep diamonds)Nature, Vol. 529, Jan. 7, pp. 76-94.MantleSubduction

Abstract: Interactions between crustal and mantle reservoirs dominate the surface inventory of volatile elements over geological time, moderating atmospheric composition and maintaining a life-supporting planet. While volcanoes expel volatile components into surface reservoirs, subduction of oceanic crust is responsible for replenishment of mantle reservoirs. Many natural, 'superdeep' diamonds originating in the deep upper mantle and transition zone host mineral inclusions, indicating an affinity to subducted oceanic crust. Here we show that the majority of slab geotherms will intersect a deep depression along the melting curve of carbonated oceanic crust at depths of approximately 300 to 700 kilometres, creating a barrier to direct carbonate recycling into the deep mantle. Low-degree partial melts are alkaline carbonatites that are highly reactive with reduced ambient mantle, producing diamond. Many inclusions in superdeep diamonds are best explained by carbonate melt-peridotite reaction. A deep carbon barrier may dominate the recycling of carbon in the mantle and contribute to chemical and isotopic heterogeneity of the mantle reservoir.
DS201603-0366
2016
Walter, M.J.Bindi, L., Tamarova, A., Bobrov, A.V., Sirotkina, E.A., Tschauner, O., Walter, M.J., Irifune, T.in corporation of high amounts of Na in ringwoodite: possible implications for transport of alkali into lower mantle.American Mineralogist, Vol. 101, pp. 483-486.MantleRingwoodite
DS201608-1396
2016
Walter, M.J.Burnham, A.D., Bulanova, G.P., Smith, C.B., Whitehead, S.C., Kohn, S.C., Gobbo, L., Walter, M.J.Diamonds from the Machado River alluvial deposit, Rondona, Brazil, derived from both lithospheric and sublithospheric mantle.Lithos, in press available, 15p.South America, BrazilMorphology, textures, chemistry

Abstract: Diamonds from the Machado River alluvial deposit have been characterised on the basis of external morphology, internal textures, carbon isotopic composition, nitrogen concentration and aggregation state and mineral inclusion chemistry. Variations in morphology and features of abrasion suggest some diamonds have been derived directly from local kimberlites, whereas others have been through extensive sedimentary recycling. On the basis of mineral inclusion compositions, both lithospheric and sublithospheric diamonds are present at the deposit. The lithospheric diamonds have clear layer-by-layer octahedral and/or cuboid internal growth zonation, contain measurable nitrogen and indicate a heterogeneous lithospheric mantle beneath the region. The sublithospheric diamonds show a lack of regular sharp zonation, do not contain detectable nitrogen, are isotopically heavy (d13CPDB predominantly - 0.7 to - 5.5) and contain inclusions of ferropericlase, former bridgmanite, majoritic garnet and former CaSiO3-perovskite. This suggests source lithologies that are Mg- and Ca-rich, probably including carbonates and serpentinites, subducted to lower mantle depths. The studied suite of sublithospheric diamonds has many similarities to the alluvial diamonds from Kankan, Guinea, but has more extreme variations in mineral inclusion chemistry. Of all superdeep diamond suites yet discovered, Machado River represents an end-member in terms of either the compositional range of materials being subducted to Transition Zone and lower mantle or the process by which materials are transferred from the subducted slab to the diamond-forming region.
DS201610-1913
2016
Walter, M.J.Thomson, A.R., Kohn, S.C., Bulanova, G.P., Smith, C.B., Araujo, D., Walter, M.J.Trace element composition of silicate inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite: evidence for diamond growth from slab melts.Lithos, in press available 17p.South America, BrazilDeposit - Juina-5

Abstract: The trace element compositions of inclusions in sub-lithospheric diamonds from the Juina-5 kimberlite, Brazil, are presented. Literature data for mineral/melt partition coefficients were collated, refitted and employed to interpret inclusion compositions. As part of this process an updated empirical model for predicting the partitioning behaviour of trivalent cations for garnet-melt equilibrium calibrated using data from 73 garnet-melt pairs is presented. High levels of trace element enrichment in inclusions interpreted as former calcium silicate perovskite and majoritic garnet preclude their origin as fragments of an ambient deep mantle assemblage. Inclusions believed to represent former bridgmanite minerals also display a modest degree of enrichment relative to mantle phases. The trace element compositions of ‘NAL’ and ‘CF phase’ minerals are also reported. Negative Eu, Ce, and Y/Ho anomalies alongside depletions of Sr, Hf and Zr in many inclusions are suggestive of formation from a low-degree carbonatitic melt of subducted oceanic crust. Observed enrichments in garnet and ‘calcium perovskite’ inclusions limit depths of melting to less than ~ 600 km, prior to calcium perovskite saturation in subducting assemblages. Less enriched inclusions in sub-lithospheric diamonds from other global localities may represent deeper diamond formation. Modelled source rock compositions that are capable of producing melts in equilibrium with Juina-5 ‘calcium perovskite’ and majorite inclusions are consistent with subducted MORB. Global majorite inclusion compositions suggest a common process is responsible for the formation of many superdeep diamonds, irrespective of geographic locality. Global transition zone inclusion compositions are reproduced by fractional crystallisation from a single parent melt, suggesting that they record the crystallisation sequence and melt evolution during this interaction of slab melts with ambient mantle. All observations are consistent with the previous hypothesis that many superdeep diamonds are created as slab-derived carbonatites interact with peridotitic mantle in the transition zone.
DS201611-2142
2016
Walter, M.J.Smith, C.B., Walter, M.J., Bulanova, G.P., Mikhail, S., Burnham, A.D., Gobbo, L., Kohn, S.C.Diamonds from Dachine, French Guiana: a unique record of Early Proterozoic subduction.Lithos, in press available 66p.South America, French GuianaDeposit - Dachine

Abstract: Diamonds from Dachine, French Guiana, are unique among worldwide diamond populations. The diamonds were transported to the surface in an unusual ultramafic extrusive magma with an affinity to boninite or komatiite, which was emplaced within an arc geological setting at ~ 2.2 Ga. Dachine diamonds have internal and external morphologies indicative of relatively rapid growth from carbon oversaturated fluids or melts, and exhibit internal features consistent with residence in a high-strain environment. On the basis of nitrogen (N) defects the diamonds are categorized as Type Ib-IaA. The unusually low aggregation state of N places severe constraints on the thermal history of the diamonds, effectively ruling out derivation in convecting mantle. The carbon and N isotopic compositions of Dachine diamonds are consistent with a sedimentary source of carbon, with the majority of diamonds having d13C values < - 25‰ and d15N values > + 4‰. The primary carbon was presumably deposited on an early Proterozoic seafloor. Sulphide inclusions have low Ni and Cr and are comparable to lithospheric eclogitic-type sulphide inclusions. Three garnet and one clinopyroxene inclusion are also eclogitic in composition, and one garnet inclusion has a majorite component indicating an origin around 250 km depth. The silicate inclusions are highly depleted in many incompatible trace elements (e.g. LREE, Nb, Hf, Zr), and modelling indicates an eclogitic source lithology that contained a LREE-enriched trace phase such as epidote or allanite, and an HFSE-rich phase such as rutile. Four of the five inclusions are unusually enriched in Mn, as well as Ni and Co, and modelling indicates a protolith with the bulk composition of subducted normal MORB plus about 10% ferromanganese crust component. We suggest a model wherein Dachine diamonds precipitated from remobilized sedimentary carbon at the slab-mantle interface from liquids derived ultimately by deserpentinization of slab peridotite at depths of ~ 200 to 250 km. These fluids may also trigger melting in wedge peridotite, resulting in a volatile-rich ultramafic melt that transports the diamonds rapidly to the surface. The process of diamond formation and exhumation from the slab mantle interface likely occurred in a Paleoproterozoic subduction zone and over a very limited timespan, likely less than a million years.
DS201712-2711
2016
Walter, M.J.Nestola, F., Burnham, A.D., Peruzzo, L., Tauro, L., Alvaro, M., Walter, M.J., Gunter, M., Anzolini, C., Kohn, S.C.Tetragonal almandine-pyrope phase, TAPP: finally a name for it, the new name jeffbenite.Mineralogical Magazine, Vol. 80, pp. 1219-1232.Technologypyrope

Abstract: Jeffbenite, ideally Mg3Al2Si3O8, previously known as tetragonal-almandine-pyrope-phase (‘TAPP’), has been characterized as a new mineral from an inclusion in an alluvial diamond from São Luiz river, Juina district of Mato Grosso, Brazil. Its density is 3.576 g/cm3 and its microhardness is ~7. Jeffbenite is uniaxial (-) with refractive indexes ??=?1.733(5) and e?=?1.721(5). The crystals are in general transparent emerald green. Its approximate chemical formula is (Mg2.62Fe2+0.27)(Al1.86Cr0.16)(Si2.82Al0.18)O12 with very minor amounts of Mn, Na and Ca. Laser ablation ICP-MS showed that jeffbenite has a very low concentration of trace elements. Jeffbenite is tetragonal with space group I4¯2d, cell edges being a?=?6.5231(1) and c?=?18.1756(3) Å. The main diffraction lines of the powder diagram are [d (in Å), intensity, hkl]: 2.647, 100, 2 0 4; 1.625, 44, 3 2 5; 2.881, 24, 2 1 1; 2.220, 19, 2 0 6; 1.390, 13, 4 2 4; 3.069, 11, 2 0 2; 2.056, 11, 2 2 4; 1.372, 11, 2 0 12. The structural formula of jeffbenite can be written as (M1)(M2)2(M3)2(T1)(T2)2O12 with M1 dominated by Mg, M2 dominated by Al, M3 dominated again by Mg and both T1 and T2 almost fully occupied by Si. The two tetrahedra do not share any oxygen with each other (i.e. jeffbenite is classified as an orthosilicate). Jeffbenite was approved as a new mineral by the IMA Commission on New Minerals and Mineral Names with the code IMA 2014-097. Its name is after Jeffrey W. Harris and Ben Harte, two world-leading scientists in diamond research. The petrological importance of jeffbenite is related to its very deep origin, which may allow its use as a pressure marker for detecting super-deep diamonds. Previous experimental work carried out on a Ti-rich jeffbenite establishes that it can be formed at 13 GPa and 1700 K as maximum P-T conditions.
DS201809-2109
2018
Walter, M.J.Walter, M.J., Drewitt, J.W.E., Thomson, A.R., Zhang, H., Lord, O.T., Heinen, B.The fate of carbonate in oceanic crust subducted into Earth's mantle.Goldschmidt Conference, 1p. AbstractMantlesubduction

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.
DS201903-0503
2019
Walter, M.J.Drewitt, J.W.E., Walter, M.J., Zhang, H., McMahon, S.C., Edwards, D., Heinen, B.J., Lord, O.T., Anzellini, S., Kleppe, A.K.The fate of carbonate in oceanic crust subducted into Earth's lower mantle.Earth and Planetary Science Letters, Vol. 511, pp. 213-222.MantleBridgemanite

Abstract: We report on laser-heated diamond anvil cell (LHDAC) experiments in the FeO-MgO-SiO2-CO2 (FMSC) and CaO-MgO-SiO2-CO2 (CMSC) systems at lower mantle pressures designed to test for decarbonation and diamond forming reactions. Sub-solidus phase relations based on synthesis experiments are reported in the pressure range of ~35 to 90 GPa at temperatures of ~1600 to 2200 K. Ternary bulk compositions comprised of mixtures of carbonate and silica are constructed such that decarbonation reactions produce non-ternary phases (e.g. bridgmanite, Ca-perovskite, diamond, CO2-V), and synchrotron X-ray diffraction and micro-Raman spectroscopy are used to identify the appearance of reaction products. We find that carbonate phases in these two systems react with silica to form bridgmanite ±Ca-perovskite + CO2 at pressures in the range of ~40 to 70 GPa and 1600 to 1900 K in decarbonation reactions with negative Clapeyron slopes. Our results show that decarbonation reactions form an impenetrable barrier to subduction of carbonate in oceanic crust to depths in the mantle greater than ~1500 km. We also identify carbonate and CO2-V dissociation reactions that form diamond plus oxygen. On the basis of the observed decarbonation reactions we predict that the ultimate fate of carbonate in oceanic crust subducted into the deep lower mantle is in the form of refractory diamond in the deepest lower mantle along a slab geotherm and throughout the lower mantle along a mantle geotherm. Diamond produced in oceanic crust by subsolidus decarbonation is refractory and immobile and can be stored at the base of the mantle over long timescales, potentially returning to the surface in OIB magmas associated with deep mantle plumes.
DS201906-1361
2019
Walter, M.J.Wang, W., Walter, M.J., Peng, Y., Redfern, S., Wu, Z.Constraining olivine abundance and water content of the mantle at the 410 km discontinuity from the elasticity of olivine and wadsleyite.Earth and Planetary Science Letters, Vol. 519, pp. 1-11.Mantleolivine

Abstract: Velocity and density jumps across the 410-km seismic discontinuity generally indicate olivine contents of ~30 to 50 vol.% on the basis of the elastic properties of anhydrous olivine and wadsleyite, which is considerably less than the ~60% olivine in the widely accepted pyrolite model for the upper mantle. A possible explanation for this discrepancy is that water dissolved in olivine and wadsleyite affects their elastic properties in ways that can reconcile the pyrolitic model with seismic observations. In order to more fully constrain the olivine content of the upper mantle near the 410-km discontinuity, and to place constraints on the mantle water content at this depth, we determined the full elasticity of hydrous wadsleyite at the P-T conditions of the discontinuity based on density functional theory calculations. Together with previous determinations for the effect of water on olivine elasticity, we simultaneously modeled the density and seismic velocity jumps (??, , ) across the olivine-wadsleyite transition. Our models allow for several scenarios that can well reproduce the density and seismic velocity jumps across the 410-km discontinuity when compared to globally averaged seismic models. When the water content of olivine and wadsleyite is assumed to be equal as in a simple binary system, our modeling indicates a best fit for low water contents (<0.1 wt.%) with an olivine proportion of ~50%, suggesting a relatively dry, non-pyrolitic mantle at depths of the 410-km discontinuity. However, our modeling can be reconciled with a pyrolitic mantle if the water content in wadsleyite is ~0.9 wt.% and that in olivine is at its storage capacity of ~500-1500 ppm. The result would be consistent with a hydrous melt phase produced at depths just above the phase transition.
DS201907-1583
2019
Walter, M.J.Wang, W., Walter, M.J., Peng, Y., Redfern, S., Wu, Z.Constraining olivine abundance and water content of the mantle at the 410 km discontinuity from the elasticity of olivine and wadsleyite.Earth and Planetary Science Letters, Vol. 519, pp. 1-11.Mantleboundary

Abstract: Velocity and density jumps across the 410-km seismic discontinuity generally indicate olivine contents of ~30 to 50 vol.% on the basis of the elastic properties of anhydrous olivine and wadsleyite, which is considerably less than the ~60% olivine in the widely accepted pyrolite model for the upper mantle. A possible explanation for this discrepancy is that water dissolved in olivine and wadsleyite affects their elastic properties in ways that can reconcile the pyrolitic model with seismic observations. In order to more fully constrain the olivine content of the upper mantle near the 410-km discontinuity, and to place constraints on the mantle water content at this depth, we determined the full elasticity of hydrous wadsleyite at the P-T conditions of the discontinuity based on density functional theory calculations. Together with previous determinations for the effect of water on olivine elasticity, we simultaneously modeled the density and seismic velocity jumps (??, , ) across the olivine-wadsleyite transition. Our models allow for several scenarios that can well reproduce the density and seismic velocity jumps across the 410-km discontinuity when compared to globally averaged seismic models. When the water content of olivine and wadsleyite is assumed to be equal as in a simple binary system, our modeling indicates a best fit for low water contents (<0.1 wt.%) with an olivine proportion of ~50%, suggesting a relatively dry, non-pyrolitic mantle at depths of the 410-km discontinuity. However, our modeling can be reconciled with a pyrolitic mantle if the water content in wadsleyite is ~0.9 wt.% and that in olivine is at its storage capacity of ~500-1500 ppm. The result would be consistent with a hydrous melt phase produced at depths just above the phase transition.
DS201911-2563
2019
Walter, M.J.Smit, K.V., Walter, M.J., Pearson, G., Aulbach, S.Diamonds and the mantle geodynamics of carbon.Researchgate, Chapter 5, pp. 89-128. pdfMantlemineralogy

Abstract: he science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS201912-2825
2020
Walter, M.J.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and the mantle geodynamics of carbon: deep mantle carbon and evolution from the diamond record.IN: Deep carbon: past to present, Orcutt, Daniel, Dasgupta eds., pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202001-0039
2020
Walter, M.J.Shirey, S.B., Smit, K.V., Pearson, D.G., Walter, M.J., Aulbach, S., Brenker, F.E., Bureau, H., Burnham, A.D., Cartigny, P., Chacko, T., Frost, D.J., Hauri, E.H., Jacob, D.E., Jacobsen, S.D., Kohn, S.C., Luth, R.W., Mikhail, S., Navon, O., Nestola, F., NimDiamonds and mantle geodynamics of carbon: IN: Deep Carbon: past to present. Editors Orcutt, Danielle, Dasgupta, pp. 89-128.Mantlegeodynamics

Abstract: The science of studying diamond inclusions for understanding Earth history has developed significantly over the past decades, with new instrumentation and techniques applied to diamond sample archives revealing the stories contained within diamond inclusions. This chapter reviews what diamonds can tell us about the deep carbon cycle over the course of Earth’s history. It reviews how the geochemistry of diamonds and their inclusions inform us about the deep carbon cycle, the origin of the diamonds in Earth’s mantle, and the evolution of diamonds through time.
DS202001-0050
2020
Walter, M.J.Yaxley, G.M., Ghosh, S., Kiseeva, E.S., Mallick, A., Spandler, C., Thomson, A.R., Walter, M.J.Co2 rich melts in the earth.IN: Deep Carbon: past to present. Editors Orcutt, Danielle, Dasgupta, pp. 129-162.Mantlemelting

Abstract: This chapter reviews the systematics of partial melting of mantle lithologies - like peridotite and eclogite - in the presence of carbon dioxide. It discusses the composition of mantle-derived magmas generated in the presence of carbon dioxide and whether magmas erupted on Earth’s surface resemble carbonated magmas from the mantle. It reviews how the production of carbon dioxide-rich magma in the mantle varies as a function of tectonic settings - beneath continents and oceans and in subduction zones - and time.
DS202004-0519
2020
Walter, M.J.Howell, D., Stachel, T., Stern, R.A., Pearson, D.G., Nestola, F., Hardman, M.F., Harris, J.W., Jaques, A.L., Shirery, S.B., Cartigny, P., Smit, K.V., Aulbach, S., Brenker, F.E., Jacob, D.E., Thomassot, E., Walter, M.J., Navon, O.Deep carbon through time: Earth's diamond record and its implications for carbon cycling and fluid speciation in the mantle.(peridotite and eclogite used)Geochimica et Cosmochimica Acta, Vol. 275, pp. 99-122.Mantlecarbon

Abstract: Diamonds are unrivalled in their ability to record the mantle carbon cycle and mantle fO2 over a vast portion of Earth’s history. Diamonds’ inertness and antiquity means their carbon isotopic characteristics directly reflect their growth environment within the mantle as far back as ~3.5 Ga. This paper reports the results of a thorough secondary ion mass spectrometry (SIMS) carbon isotope and nitrogen concentration study, carried out on fragments of 144 diamond samples from various locations, from ~3.5 to 1.4 Ga for P [peridotitic]-type diamonds and 3.0 to 1.0 Ga for E [eclogitic]-type diamonds. The majority of the studied samples were from diamonds used to establish formation ages and thus provide a direct connection between the carbon isotope values, nitrogen contents and the formation ages. In total, 908 carbon isotope and nitrogen concentration measurements were obtained. The total d¹³C data range from -17.1 to -1.9 ‰ (P = -8.4 to -1.9 ‰; E = -17.1 to -2.1‰) and N contents range from 0 to 3073 at. ppm (P = 0 to 3073 at. ppm; E = 1 to 2661 at. ppm). In general, there is no systematic variation with time in the mantle carbon isotope record since > 3 Ga. The mode in d¹³C of peridotitic diamonds has been at -5 (±2) ‰ since the earliest diamond growth ~3.5 Ga, and this mode is also observed in the eclogitic diamond record since ~3 Ga. The skewness of eclogitic diamonds’ d¹³C distributions to more negative values, which the data establishes began around 3 Ga, is also consistent through time, with no global trends apparent. No isotopic and concentration trends were recorded within individual samples, indicating that, firstly, closed system fractionation trends are rare. This implies that diamonds typically grow in systems with high excess of carbon in the fluid (i.e. relative to the mass of the growing diamond). Any minerals included into diamond during the growth process are more likely to be isotopically reset at the time of diamond formation, meaning inclusion ages would be representative of the diamond growth event irrespective of whether they are syngenetic or protogenetic. Secondly, the lack of significant variation seen in the peridotitic diamonds studied is in keeping with modeling of Rayleigh isotopic fractionation in multicomponent systems (RIFMS) during isochemical diamond precipitation in harzburgitic mantle. The RIFMS model not only showed that in water-maximum fluids at constant depths along a geotherm, fractionation can only account for variations of <1‰, but also that the principal d¹³C mode of -5 ± 1‰ in the global harzburgitic diamond record occurs if the variation in fO2 is only 0.4 log units. Due to the wide age distribution of P-type diamonds, this leads to the conclusion that the speciation and oxygen fugacity of diamond forming fluids has been relatively consistent. The deep mantle has therefore generated fluids with near constant carbon speciation for 3.5 Ga.
DS1992-0879
1992
Walter, M.R.Knoll, A.H., Walter, M.R.Latest Proterozoic stratigraphy and earth historyNature, Vol. 356, No. 6371, April 23, pp. 673-677GlobalProterozoic, Stratigraphy
DS1997-0756
1997
Walter, M.R.McIlroy, D., Jenkins, R.J.F., Walter, M.R.The nature of the Proterozoic Cambrian transition in the northern AmadeusBasin, central AustraliaPrecambrian Research, Vol. 86, No. 1/2, Dec. 15, pp. 93-AustraliaProterozoic, Boundary
DS1997-1203
1997
Walter, M.R.Veevers, J.J., Walter, M.R., Scheibner, E.Neoproterozoic tectonics of Australia- Antarctica and Laurentia and the 560Ma birth of Pacific Ocean ...Journal of Geology, Vol. 105, No. 2, March pp. 225-242.GlobalPangean supercycle, Tectonics
DS200412-1022
2004
Walter, M.R.Knoll, A.H., Walter, M.R., Narbonne, G.M., Christie Blick, N.A new period for the Geologic Time Scale.Science, No. 5684, July 30, p. 621.TechnologyTime scale
DS201212-0675
2012
Walter, M.U.Smith, C.B., Bulanova, G.P., Walter, M.U., Kohn, S.C., Mikhail, S., Gobbo, L.Origin of diamonds from the Dachine ultramafic, French Guyana.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractSouth America, French GuianaDeposit - Dachine
DS2002-1224
2002
Walter, W.R.Pasyanos, M.E., Walter, W.R.Crust and upper mantle structure of North Africa, Europe and the Middle East from inversion surface wavesGeophysical Journal International, Vol.149,2,pp.463-81., Vol.149,2,pp.463-81.North Africa, Europe, Middle EastGeophysics - seismics, Tectonics
DS2002-1225
2002
Walter, W.R.Pasyanos, M.E., Walter, W.R.Crust and upper mantle structure of North Africa, Europe and the Middle East from inversion surface wavesGeophysical Journal International, Vol.149,2,pp.463-81., Vol.149,2,pp.463-81.North Africa, Europe, Middle EastGeophysics - seismics, Tectonics
DS202003-0367
2020
Walter Anthony, K.. OlefeldtTuretsky, 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.
DS1996-0067
1996
WaltersBaird, D.J., Nelson, K.D., Knapp, J.H., Walters, BrownCrustal structure and evolution of the Trans-Hudson Orogen: results from seismic reflection profiling.Tectonics, Vol. 15, No. 2, April pp. 416-426.Montana, North Dakota, Saskatchewan, Manitoba, AlbertaCraton, Wyoming, Hearne, Lithoprobe
DS200612-1342
2006
WaltersSparks, R.S.J., Baker, Brooker, Brown, Field, Fontana, Gernon, Kavanagh, Shumacher, Stripp, Walter, Walters, White, WindsorDynamical constraints on kimberlite volcanism,Emplacement Workshop held September, 5p. abstractGlobalMagmatism, water, stages
DS200612-0447
2006
Walters, A.Gernon, T.M., Gilbertson, M.A., Sparks, R.S.J., Walters, A., Field, M.Gas solid fluidisation in an experimental tapered bed: insights into processes in diverging volcanic conduits.Emplacement Workshop held September, 5p. extended abstractTechnologyFluidisation, emplacement
DS200612-1341
2006
Walters, A.Sparks, R.J.S., Baker, L., Brown, R.J., Field, M., Schumacher, J., Stripp, G., Walters, A.Dynamical constraints on kimberlite volcanism.Journal of Volcanology and Geothermal Research, in press availableAfrica, South AfricaGeodynamics, eruptions, diamonds, models, fluidization
DS200912-0218
2009
Walters, A.Field, M., Gernon, T.M., Mock, A., Walters, A., Sparks, R.S.J., Jerram, D.A.Variations of olivine abundance and grain size in the Snap lake kimberlite intrusion, Northwest Territories, Canada: a possible proxy for diamonds.Lithos, In press available 13p.Canada, Northwest TerritoriesDeposit - Snap Lake
DS200612-1505
2006
Walters, A.L.Walters, A.L., Phillips, J.C., Brown, R.J., Field, M., Gernon, T., Stripp, G., Sparks, R.S.J.The role of fluidisation in the formation of volcaniclastic kimberlite: grain size observations and experimental investigation.Journal of Volcanology and Geothermal Research, in press availableAfrica, South AfricaDeposit - Venetia, explosive eruption, fluidization
DS1993-0932
1993
Walters, C.Ludwig, D., Hilborn, R., Walters, C.Uncertainty, resource exploitation, conservation: lessons from historyScience, Vol. 260, April 2, pp. 17, 36GlobalEconomics
DS1992-0069
1992
Walters, J.Baird, D.J., Nelson, K.D., Walters, J., Hauck, M., Brown, L.D.Deep structure of the Proterozoic Trans-Hudson Orogen beneath the WillistonBasin: results from recent COCORP seismic reflection profilingEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 321SaskatchewanCOCORP -seismic, Williston Basin
DS1992-0683
1992
Walters, J.Hauck, M.L., Baird, D., Brown, L., Nelson, K.D., Walters, J.COCORP deep seismic reflection profiling across the Williston Basin and underlying Trans-Hudson Orogen: acquisition and analysisEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p. 321SaskatchewanCOCORP -seismic, Williston Basin
DS1997-0991
1997
Walters, L.J.Sacks, P.E., Nambiar, C.G., Walters, L.J.Dextral Pan-African shear along the southwestern edge of the Achanovilshear belt, constraints on GondwanaJournal of Geology, Vol. 105, No. 2, March pp. 275-284India, GondwanaTectonics, Shear zone
DS200812-0309
2008
Walters, R.Eaton-Magana, S., Post, J.E., Heaney, P.J., Frietas, J., Klein, P., Walters, R., Butler, J.E.Using phosphorescence as a fingerprint for the Hope and other blue diamonds.Geology, Vol. 36, 1, pp.TechnologyDiamond morphology
DS200612-0363
2006
Walters, R.A.Eaton-Magana, S., Post, J.E., Freitas, J.A., Klein, P.B., Walters, R.A., Heaney, P.J, Butler, J.E.Luminescence of the Hope diamond and other blue diamonds.GIA Gemological Research Conference abstract volume, Held August 26-27, p. 32. 1/2p.TechnologySpectroscopy
DS200712-0283
2006
Walters, R.A.Eaton-Magana, S., Post, J.E., Walters, R.A., Heaney, P.J., Butler, J.E.Fluoresence of fancy color natural diamonds.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.131-2. abstract onlyTechnologyDiamond colour - UV radiation
DS200812-0310
2007
Walters, R.A.Eaton-Magana, S., Post, J.E., Heaney, P.J., Walters, R.A., Breeding, C.M., Butler, J.E.Fluorescence spectra of colored diamonds using a rapid, mobile spectrometer.Gems & Gemology, Vol. 43, 4, Winter pp. 332-351.TechnologyType 1 a diamonds
DS1993-1692
1993
Walters, R.D.Walters, R.D.Reconstruction of allochthonous salt emplacement 3-D seismic reflectiondata, northern Gulf of Mexico.American Association of Petroleum Geologists Bulletin, Vol. 77, No. 5, May pp. 813-841.GlobalGeophysics -seismics
DS2002-1682
2002
Walters, S.Walters, S., Skrzecynski, B., Whiting, Bunting, ArnoldDiscovery and geology of the Cannington Ag Pb Zn deposit Mount Isa Eastern Succession: development ...Society of Economic Geologists Special Publication, No.9,pp.95-118.AustraliaSilver, lead, zinc, exploration model Broken Hill type, Deposit - Cannington
DS201903-0549
2019
Waltham, D.Waltham, D.Is Earth special?Earth-Science Reviews, 10.1016/j.earscirev.2019.02.008 128p.Mantlereview
DS1991-1095
1991
Waltham, D.A.McClay, K.R., Waltham, D.A., Scott, A.D., Abousetta, A.Physical and seismic modelling of listric normal fault geometriesThe geometry of normal faults, editors Roberts, A.M., Yielding, G., No. 56, pp. 231-239GlobalStructure -faults, Fault geometry -listric
DS1994-1877
1994
Walther, J.V.Walther, J.V.Fluid rock reactions during metamorphism at mid-crustal conditionsJournal of Geology, Vol. 102, No. 5, Sept. pp. 559-570Globalmetamorphism, Petrology -experimental
DS1994-1878
1994
Walther, J.V.Walther, J.V.Fluid rock reactions during metamorphism at mid crustal conditionsJournal of Geology, Vol. 102, pp. 559-70.MantleMetamorphism - model
DS1998-1561
1998
Walther, J.V.Walther, J.V.Fluids in the deep crustGeological Society of America (GSA) Annual Meeting, abstract. only, p.A243.GlobalTectonics, Geophysics - seismics
DS1992-1631
1992
Walthier, J.V.Walthier, J.V.Ionic association in H2O-CO2 fluids at mid-crustal conditionsJournal of Metamorphic Geology, Vol. 10, No. 6, November pp. 789-798GlobalCrust, Fluids
DS1993-1577
1993
Walton, D.R.M.Taylor, R., Walton, D.R.M.The chemistry of fullerenesNature, Vol. 363, June 24, pp. 685-693.GlobalFullerenes, Chemistry -review
DS1950-0195
1954
Walton, J.Walton, J.Physical GemologyLondon., GlobalKimberlite, Kimberley, Janlib, Gemology
DS1989-1577
1989
Walton, K.R.Walton, K.R., Dismukes, J.P., Krueger, R.A., Field, F.R. III, ClarkTechnology assessment for CVD-diamond-coated cutting tool insertsMaterials and Society, Vol. 13, No. 3, pp. 319-350GlobalDiamond synthesis, CVD -overview/good refs
DS1980-0242
1980
Walton, M.Mooney, H.M., Walton, M.Seismicity and Tectonic Relationships for Upper Great Lakes precambrian Shield Province.National Technical Information Service NUREG CR 1569, 85P.GlobalMid-continent
DS1975-0431
1976
Walton, M.S.Weiblen, P.W., Morey, G.B., Southwick, D.L., Walton, M.S.The Effect of Ancestral Structures on the Evolution of the Midcontinent Rift and the Duluth Complex.International Geological Congress, 25TH. Vol. 3, P. 695. (abstract.).GlobalMid-continent
DS1998-0862
1998
Walton, N.R.G.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
DS200812-1230
2008
Waltzer, U.Waltzer, U., Hendel, R.Mantle convection and evolution with growing continents.Journal of Geophysical Research, Vol. 113, B09405.MantleConvection
DS1997-1223
1997
Walzer, U.Walzer, U., Hendel, R.Tectonic episodicity and convective feed back mechanismPhysics of the Earth and Planetary Interiors, Vol. 100, No. 1-3, pp.MantleTectonics, Plumes
DS200412-2077
2004
Walzer, U.Walzer, U., Hendel, R., Baumgardner, J.The effects of a variation of the radial viscosity profile on mantle evolution.Tectonophysics, Vol. 384, 1-4, pp. 55-90.MantleGeophysics - seismics
DS200612-0483
2006
Walzer, U.Gottschaldt, K.D., Walzer, U., Hendel, R.F., Stegman, D.R., Baumgartner, J.R., Muhlhaus, H.B.Stirring in 3 d spherical models of convection in the Earth's mantle.Philosophical Magazine, Vol. 86, no. 21-22, pp. 3175-3204.MantleConvection
DS200812-1231
2008
Walzer, U.Walzer, U., Hendel, R.Mantle convection and evolution with growing continents.Journal of Geophysical Research, Vol. 113, B9, B09405.MantleConvection
DS201610-1915
2016
Wambeke, T.Wambeke, T., Benndorf, J.An integrated approch to simulate and validate orebody realizations with complex trends: a case study in heavy minerals sands.Mathematical Geosciences, Vol. 48, 7, pp. 767-789.TechnologyTrend modelling - not specific to diamonds

Abstract: Characterization of spatial variability in earth science commonly requires random fields which are stationary within delineated domains. This contribution presents an alternative approach for simulating attributes in combination with a non-stationary first-order moment. A new procedure is presented to unambiguously decompose the observed behaviour into a deterministic trend and a stochastic residual, while explicitly controlling the modelled uncertainty. The practicality of the approach resides in a straightforward and objective inference of the variogram model and neighborhood parameters. This method does not require a prior removal of the trend. The inference principle is based on minimizing the deviation between empirical and theoretical errors calculated for increasingly distant neighborhood shells. Further, the inference is integrated into a systematic simulation framework and accompanying validation guidelines are formulated. The effort results in a characterization of the resource uncertainty of an existing heavy mineral sand deposit.
DS201702-0250
2017
Wambeke, T.Wambeke, T., Benndorf, J.A simulation based geostatistical approach to real-time reconciliation of the grade control model.Mathematical Geosciences, Vol. 49, 1, pp. 1-37.TechnologyGeostatistics - not specific to diamonds

Abstract: One of the main challenges of the mining industry is to ensure that produced tonnages and grades are aligned with targets derived from model-based expectations. Unexpected deviations, resulting from large uncertainties in the grade control model, often occur and strongly impact resource recovery and process efficiency. During operation, local predictions can be significantly improved when deviations are monitored and integrated back into the grade control model. This contribution introduces a novel realization-based approach to real-time updating of the grade control model by utilizing online data from a production monitoring network. An algorithm is presented that specifically deals with the problems of an operating mining environment. Due to the complexity of the material handling process, it is very challenging to formulate an analytical approximation linking each sensor observation to the grade control model. Instead, an application-specific forward simulator is built, translating grade control realizations into observation realizations. The algorithm utilizes a Kalman filter-based approach to link forward propagated realizations with real process observations to locally improve the grade control model. Differences in the scale of support are automatically dealt with. A literature review, following a detailed problem description, presents an overview of the most recent approaches to solving some of the practical problems identified. The most relevant techniques are integrated and the resulting mathematical framework is outlined. The principles behind the self-learning algorithm are explained. A synthetic experiment demonstrates that the algorithm is capable of improving the grade control model based on inaccurate observations on blended material streams originating from two extraction points.
DS200812-1321
2008
Wamg, Lu.Zheng, J.P., Griffin, W.L., O'Reilly, S.Y., Hu, Zhang, Tang, Su, Zhang, Pearson, Wamg, Lu.Continental collision and accretion recorded in the deep lithosphere of central China.Earth and Planetary Science Letters, Vol. 269, 3-4 May 30, pp. 496-506.ChinaBasaltic diatremes, geochronology, craton, tectonics
DS201804-0751
2018
Wampler, J.Wampler, J. , Thiemens, M., Schuller, I.Natural superconductivity observed in meteorites.Bulletin of the American Physical Society, Mar. 7, 2p.Technologymeteorites

Abstract: Previous studies have shown that meteorites can contain unusual natural phases, such as quasicrystals, that have otherwise been found only in synthetic samples [1]. Because of this, meteorites are good candidates to search for natural superconductivity, which has only been found in Covellite [2]. Because natural samples are inhomogeneous and superconducting phases can be very small, we used Magnetic Field Modulated Microwave Spectroscopy (MFMMS), which can detect 10-12 cc of superconducting material, three orders of magnitude better than Vibrating Sample Magnetometry (VSM). We measured a series of meteorites, surveying representative samples from most major categories of meteorites. In two of the meteorites, we discovered superconducting phases above 5 K using MFMMS, and verified this using VSM. We characterized these phases using Energy-dispersive X-ray spectroscopy and Inductively Coupled Plasma Mass Spectroscopy. To our knowledge, these samples are the first identification of extraterrestrial superconducting phases. They are particularly significant because these materials could be superconducting in extraterrestrial environments.
DS1996-0135
1996
Wampler, J.M.Bhattacharji, S., Chatterjee, N., Wampler, J.M., Nyak, P.Indian intraplate and continental margin rifting, lithospheric extension and mantle upwelling K/T .....Journal of Geology, Vol. 104, No. 4, July pp. 379-398.IndiaTectonics, Lithosphere -mantle geodynamics
DS201709-1984
2017
Wamunyu, W.Feneyrol, J., Giuliani, G., Demaiffe, D., Ohenstetter, D., Fallick, A.E., Dubessy, J., Martelet, J-E., Rakotondrazafy, A.F.M., Omito, E., Ichangi, D., Nyamai, C., Wamunyu, W.Age and origin of the tsavorite and tanzanite mineralozing fluids in the Neoproterozoic Mozambique metamorphic belt.The Canadian Mineralogist, Vol. 55, pp. 763-786.Africa, Kenya, Tanzania, Madagascartanzanite

Abstract: The genetic model previously proposed for tsavorite- (and tanzanite-) bearing mineralization hosted in the Neoproterozoic Metamorphic Mozambique Belt (stretching from Kenya through Tanzania to Madagascar) is refined on the basis of new Sm-Nd age determinations and detailed Sr-O-S isotope and fluid-inclusion studies. The deposits are hosted within meta-sedimentary series composed of quartzites, graphitic gneisses, calc-silicate rocks intercalated with meta-evaporites, and marbles. Tsavorite occurs either in nodules (also called “boudins”) oriented parallel to the metamorphic foliation in all of the deposits in the metamorphic belt or in quartz veins and lenses located at the hinges of anticlinal folds (Lelatema fold belt and Ruangwa deposits, Tanzania). Gem tanzanite occurs in pockets and lenses in the Lelatema fold belt of northern Tanzania. The Sm-Nd isotopic data for tsavorites and tanzanites hosted in quartz veins and lenses from Merelani demonstrate that they formed at 600 Ma, during the retrograde metamorphic episode associated with the East African Orogeny. The tsavorites hosted in nodules do not provide reliable ages: their sedimentary protoliths had heterogeneous compositions and their Sm-Nd system was not completely rehomogenized, even at the local scale, by the fluid-absent metamorphic recrystallization. The initial 87Sr/86Sr isotopic ratios of calcite from marble and tanzanites from Merelani fit with the strontium isotopic composition of Neoproterozoic marine carbonates. Seawater sediment deposition in the Mozambique Ocean took place around 720 Ma. The quartz-zoisite O-isotopic thermometer indicates a temperature of formation for zoisite between 385 and 448 °C. The sulfur isotopic composition of pyrite (between –7.8 and –1.3‰ V-CDT) associated with tsavorite in the Lelatema fold belt deposits suggests the contribution of reduced marine sulfate. The sulfur in pyrite in the marbles was likely derived from bacterial sulfate reduction which produced H2S. Fluid inclusion data from tsavorite and tanzanite samples from the Merelani mine indicate the presence of a dominant H2S-S8±(CH4)±(N2)±(H2O)-bearing fluid. In the deposits in Kenya and Madagascar, the replacement of sulfate by tsavorite in the nodules and the boron isotopic composition of tourmaline associated with tsavorite are strong arguments in favor of the participation of evaporites in garnet formation.
DS200412-2169
2003
WanYang, J., Xu, Z., Dobrzhinetskaya, L.F., Green, H.W., Pei, X., Shi, R., Wu, C., Wooden, J.L., Zhang, J., WanDiscovery of metamorphic diamonds in central China: an indication of a > 4000 km long zone of deep subduction resulting from mulTerra Nova, Vol. 15, pp. 370-379.ChinaSubduction, Central Orogenic Belt, UHP
DS1986-0376
1986
Wan, G.Hu, S., Zhang, P., Wan, G.A review of the geology of some kimberlites in Chin a #1Proceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, Geological, No. 16, pp. 121-123ChinaBlank
DS1986-0854
1986
Wan, G.Wan, G.The distribution pattern of kimberlites and their cognate rocks inShandong, ChinaProceedings of the Fourth International Kimberlite Conference, Held Perth, Australia, No. 16, pp. 148-150ChinaBlank
DS1989-1578
1989
Wan, G.Wan, G.The distribution pattern of kimberlites and associated rocks in Shandong, ChinaGeological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 1, pp. 401-406ChinaKimberlites
DS1989-1682
1989
Wan, G.Zhang, P., Hu, S., Wan, G.A review of the geology of some kimberlites in Chin a #2Geological Society of Australia Inc. Blackwell Scientific Publishing, Special, No. 14, Vol. 1, pp. 392-400ChinaPetrology, Mineralogy
DS1996-1601
1996
Wan, H.Zhang, Y., Wan, H., Xu, C.The characteristics of the extrusive carbonatite in Guantian area WudingCounty, Yunnan Province.International Geological Congress 30th Session Beijing, Abstracts, Vol. 2, p. 398.ChinaCarbonatite
DS1999-0827
1999
Wan, T.Zeng, H., Wan, T.Gross differences between two isostatic gravity anomaly maps of ChinaTectonophysics, Vol. 306, No. 2, June 15, pp. 253-ChinaGeophysics - Gravity
DS200412-2166
2004
Wan, T.Yan, Q., Hanson, A.D., Wang, Z., Druschke, P.A., Yan, Z., Wan, T.Neoproterozoic subduction and rifting on the northern margin of the Yangtze Platform: Redonia reconstruction.International Geology Review, Vol.46, 9, Sept. pp. 817-832.ChinaSubduction
DS200812-0674
2008
Wan, Y.Liu, D., Wilde, S.A, Wan, Y., Wu, J., Zhou, H., Dong, C., Yin, X.New U Pb and Hf isotopic dat a confirm Anshan as the oldest preserved segment of the North Chin a Craton.American Journal of Science, Vol. 308, 3, pp. 200-231.ChinaGeochronology
DS200812-0679
2008
Wan, Y.Liu, Y., Williams, I.S., Chen, J., Wan, Y., Sun, W.The significance of Paleoproterozoic zircon in carbonatite dikes associated with the Bayan Obo REE Nb Fe deposit.American Journal of Science, Vol. 308, 3, pp. 379-397.ChinaCarbonatite
DS200812-1232
2008
Wan, Y.Wan, Y., Liu, D., Wilde, S., Nutman, A., Dong, C., Wang, W.The oldest rocks and zircons in China.Goldschmidt Conference 2008, Abstract p.A994.ChinaAnshan City
DS200912-0665
2009
Wan, Y.Santosh, M., Wan, Y., Liu, D., Chunyan, D., Li, J.Anatomy of zircons from an ultrahot orogen: the amalgamation of the North Chin a craton within the supercontinent Columbia.Journal of Geology, Vol. 117, pp. 429-443.ChinaCraton, geochronology
DS201412-0870
2013
Wan, Y.Sommer, H., Wan,Y., Kroner, A., Xie, H., Jacob, D.E.Shrimp zircon ages and petrology of lower crustal granulite xenoliths from the Letseng-La-Terae kimberlite, Lesotho: further evidence for a Namaquanatal connection.South Africa Journal of Geology, Vol. 116, 2, pp. 183-198.Africa, LesothoDeposit - Letseng
DS201903-0517
2019
Wan, Y-S.Huang, D-L., Wanf, X-L., Xia, X-P., Wan, Y-S., Zhang, F-F., Li, J-Y., Du, D-H.Neoproterozoic low delta 180 zircons revisited: implications for Rodinia configuration.Geophysical Research Letters, Vol. 46, 2, pp. 678-688.Globalcraton

Abstract: Low-d18O magma has received great attention and it has profound implications on geological and climate evolution. Neoproterozoic era is a unique period to breed low-d18O magmas and snowball Earth. This manuscript first report Neoproterozoic moderately 18O-depleted zircons from the central part of the Cathaysia Block in South China, and it builds a four end-member Hf-O isotopic mixing model to explain the global low-d18O magmas at Neoproterozoic era. Our compilation of low-d18O zircon data and our new data confirms that globally Neoproterozoic 18O-depleted magmatic activities generally began after 800 Ma and reached a peak at 780-760 Ma. This provides new information on the rifting of Rodinia supercontinent and suggests close connections between northwest India, Madagascar, and South China in the Rodinia supercontinent. This manuscript deals with the hot-debated topics on oxygen isotopes and supercontinent cycle. We believe that this manuscript will attract international readers from a wide scope of geosciences.
DS200812-1233
2008
Wan, Z.Wan, Z., Coogan, L.A., Canil, D.Experimental calibration of aluminum partitioning between olivine and spinel as a geothermometer.American Mineralogist, Vol. 93, pp. 1142-1147.TechnologyThermometry
DS1986-0429
1986
Wan Guo DongKeller, P.C., Wan Guo DongThe Changma diamond district, Mengyin Shandong Province, ChinaGems and Gemology, Vol. 22, No. 1, Spring, pp. 14-23ChinaOverview
DS1980-0342
1980
Wand, U.Wand, U., Nitzsche, H.M., Muehle, K., Wetzel, K.Nitrogen Isotope Composition in Natural Diamonds First Results.Chemie Erde., Vol. 39, No. 1, PP. 85-87.Southwest Africa, NamibiaMineral Chemistry
DS201112-0259
2010
Wanderson Andrade, K.de Sa Carneiro Chaves, M.L., Wanderson Andrade, K., Borges, F.M.Preservando a pedra rica (Grao Mogol, MG): primeira jazida de diamante minerada em rocha no mundo.5th Brasilian Symposium on Diamond Geology, Nov. 6-12, abstract p. 25-26.South America, Brazil, Minas GeraisBrief - history
DS1985-0711
1985
Wandless, G.A.Wandless, G.A., Padovani, E.R.Trace Element Geochemistry of Lower Crustal Xenoliths from kilbourne Hole Maar, New Mexico.Eos, Vol. 66, No. 46, NOVEMBER 12, P. 1110. (abstract.).United States, Colorado Plateau, New MexicoGeochemistry
DS1986-0628
1986
Wandless, G.A.Padovani, E.R., Wandless, G.A., Reid, M., Hart, S.R.Characterization of the deep crust in an active intracontinental rift:evidence from xenoliths at Kilbourne Hole MaarGeological Society of America, Vol. 18, No. 2, p. 168. AbstractGlobalTectonics
DS1990-1533
1990
Wandrey, C.J.Wandrey, C.J., Obuch, R.C.FORMATIONTOPS (version 1): a system to retrieve formation tops dataUnited States Geological Survey (USGS) Open File, No. 90-0530, 1 disc. $ 6.00GlobalComputer, Program -FORMATIONTOPS
DS201903-0517
2019
Wanf, X-L.Huang, D-L., Wanf, X-L., Xia, X-P., Wan, Y-S., Zhang, F-F., Li, J-Y., Du, D-H.Neoproterozoic low delta 180 zircons revisited: implications for Rodinia configuration.Geophysical Research Letters, Vol. 46, 2, pp. 678-688.Globalcraton

Abstract: Low-d18O magma has received great attention and it has profound implications on geological and climate evolution. Neoproterozoic era is a unique period to breed low-d18O magmas and snowball Earth. This manuscript first report Neoproterozoic moderately 18O-depleted zircons from the central part of the Cathaysia Block in South China, and it builds a four end-member Hf-O isotopic mixing model to explain the global low-d18O magmas at Neoproterozoic era. Our compilation of low-d18O zircon data and our new data confirms that globally Neoproterozoic 18O-depleted magmatic activities generally began after 800 Ma and reached a peak at 780-760 Ma. This provides new information on the rifting of Rodinia supercontinent and suggests close connections between northwest India, Madagascar, and South China in the Rodinia supercontinent. This manuscript deals with the hot-debated topics on oxygen isotopes and supercontinent cycle. We believe that this manuscript will attract international readers from a wide scope of geosciences.
DS1990-1630
1990
WangZhao, Xixi, Coe, R.S., Zhou Yaoxiu, Wu Haoruo, Wang, JieNew paleomagnetic results from northern China: collision and suturing with Siberia and KazakhstanTectonophysics, Vol. 181, pp. 43-81China, RussiaGeophysics, Paleomagnetics
DS1993-0242
1993
WangChen, Feng, Wang, Ming-Zai, et al.The first discovery of high-copper and high chlorine inclusions indiamond.Chinese Science Bulletin, Vol. 38, No. 10, May pp. 847-850.ChinaDiamond inclusions, Chlorine
DS1995-2024
1995
WangWang, liAutomatic identification of rocks in thin sections using texture analysisMath. Geol, Vol. 27, No. 7, pp. 847-865GlobalGeostatistics, Classification -texture
DS2001-0651
2001
WangLan, 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
DS200412-0464
2003
WangDobrzhinetskaya, L.F., Green, H.W., Weschler, M., Darus, M., Young-Chung, Wang, Massone, H-J., Stockhert, B.Focused ion beam technique and transmission electron microscope studies of microdiamonds from the Saxonian Erzgerbirge, Germany.Earth and Planetary Science Letters, Vol. 210, 3-4, May 30, pp.399-410.Europe, GermanyDiamond inclusions
DS200412-0534
2004
WangFan, W-M., Guo, F., Wang, Y-J, Zhang, M.Late Mesozoic volcanism in the northern Huaiyang tectono-magmatic belt: partial melts from lithospheric mantle with subducted coChemical Geology, Vol. 209, 1-2, pp. 27-48.ChinaUHP, Dabie Orogen, subduction
DS200412-2085
2004
WangWang, Yi, Wen, L.Mapping the geometry and geographic distribution of a very low velocity province at the base of the Earth's mantle.Journal of Geophysical Research, Vol. 109, B10, B10305 dx.doi.org/10.1029/2004 JB002674MantleGeophysics - seismics, stratigraphy
DS200712-0204
2007
WangCourtier, 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
DS200712-0347
2007
WangGao, S., Rudnick, R.L., Xu, W-L., Yuan, Liu, Puchtel, Liu, Huang, WangRecycling deep cratonic lithosphere and generation of intraplate magmatism.Plates, Plumes, and Paradigms, 1p. abstract p. A307.ChinaAlkaline rocks, picrites
DS200712-0452
2006
WangHu, S., Raza, A., Min, K., Kohn, B.P., Reiners, Ketcham, Wang, GleadowLate Mesozoic and Cenozoic thermotectonic evolution along a transect from the north Chin a craton through the Qinling orogen into the Yangtze craton, central.Tectonics, Vol. 25, 6, TC6009ChinaGeothermometry
DS200812-0385
2008
WangGao, S., Rudnick, R.L., Xu, Yuan, Liu, Walker, Puchtel, Liu, Huang, Wang, WangRecycling deep cratonic lithosphere and generation of intraplate magmatism in the North Chin a Craton.Earth and Planetary Science Letters, Vol. 270, 1-2, June 15, pp. 41-53.ChinaTectonics - delamination, picrites
DS200812-0385
2008
WangGao, S., Rudnick, R.L., Xu, Yuan, Liu, Walker, Puchtel, Liu, Huang, Wang, WangRecycling deep cratonic lithosphere and generation of intraplate magmatism in the North Chin a Craton.Earth and Planetary Science Letters, Vol. 270, 1-2, June 15, pp. 41-53.ChinaTectonics - delamination, picrites
DS200812-1241
2008
WangWang, Yi, Wen, L., Weidner, D.Upper mantle SH and P velocity structures and compositional model beneath southern Africa.Earth and Planetary Science Letters, Vol. 267, 3-4, pp.596-608.Africa, South AfricaGeophysics - seismics
DS201112-1098
2011
WangWalter, M.J., Kohn, Arajuo, Bulanova, Smith, Gaillou, Wang, Steele, ShireyDeep mantle cycling of oceanic crust: evidence from diamonds and their mineral inclusions.Science, Vol. 334, 6052, pp. 51-52.MantleDiamond inclusions
DS201212-0017
2012
WangArajo, D.P., Bulanova, G.P., Walter, M.J., Kohn, S.C., Smith, C.B., Gaspar, J.C., WangJuina-5 kimberlite ( Brazil): a source of unique lower mantle diamonds.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractSouth America, BrazilDeposit - Juina-5
DS201412-0070
2014
WangBreeding, C.M., Wang, WuyiA spectroscopic look at green and blue gem diamonds colored by artificial irradiation treatment.Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractTechnologyIrradiated diamonds
DS201412-0847
2014
WangSmit, K.V., Wang, Wuyi, Shirey, S.B., Wang, J.Growth conditions of mixed-habit diamonds from Marange, Zimbabwe.Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractAfrica, ZimbabweDiamond morphology
DS201412-0965
2014
WangWang, Wuyi, D'Haenens-Johansson, U., Smit, K., Breeding, C.M., Stern, R.Carbon isotope analysis of CVD synthetic gem diamonds.Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractTechnologySynthetics
DS201809-2016
2018
WangDuan, Yunfei, Sun, Ningyu, Wang, Siheng, Li, Xinyang, Guo, Xuan, Ni.Phase stability and thermal equation of state of delta -AIOOH: implication for water transportation in the deep lower mantle.Earth and Planetary Science Letters, Vol. 494, 1, pp. 92-98.Mantlewater

Abstract: In this study, we present new experimental constraints on the phase stability and thermal equation of state of an important hydrous phase, d-AlOOH, using synchrotron X-ray diffraction up to 142 GPa and 2500 K. Our experimental results have shown that d-AlOOH remains stable at the whole mantle pressure-temperature conditions above the D? layer yet will decompose at the core-mantle boundary because of a dramatic increase in temperature from the silicate mantle to the metallic outer core. At the bottom transition zone and top lower mantle, the formation of d-AlOOH by the decomposition of phase Egg is associated with a ~2.1-2.5% increase in density (?) and a ~19.7-20.4% increase in bulk sound velocity (VF). The increase in ? across the phase Egg to d-AlOOH phase transition can facilitate the subduction of d-AlOOH to the lower mantle. Compared to major lower-mantle phases, d-AlOOH has the lowest ? but greatest VF, leading to an anomalous low ? /VF ratio which can help to identify the potential presence of d-AlOOH in the region. More importantly, water released from the breakdown of d-AlOOH at the core-mantle boundary could lower the solidus of the pyrolitic mantle to cause partial melting and/or react with Fe in the region to form the low-velocity FeO2Hx phase. The presence of partial melting and/or the accumulation of FeO2Hx phase at the CMB could be the cause for the ultra-low velocity zone. d-AlOOH is thus an important phase to transport water to the lowermost mantle and helps to understand the origin of the ultra-low velocity zone.
DS201902-0332
2018
WangWang, Z, Kusky, T.M., Capitanio, F.A.Water transportation ability of flat lying slabs in the mantle transition zone and implications for craton destruction.Tectonophysics, Vol. 723, pp. 95-106.Mantlecraton

Abstract: Water transported by deep subduction to the mantle transition zone (MTZ) that is eventually released and migrates upwards is invoked as a likely cause for hydroweakening and cratonic lithosphere destruction. The destruction of the North China Craton (NCC) during the Mesozoic has been proposed to be related to hydroweakening. However, the source of water related to large-scale craton destruction in the NCC is poorly constrained. Some suggest that the water was mainly released from a flat-lying (or stagnating) slab in the MTZ, whereas others posit that most water was released from a previously existing strongly hydrous MTZ then perturbed by the stagnating subduction in the MTZ layer. In this study, we use numerical modeling to evaluate the water carrying ability of flat-lying slabs in the MTZ with different slab ages and water contents to simulate its maximum value and discuss its potential role on large-scale hydroweakening and craton destruction. Our results reveal that a single flat-lying slab in the MTZ cannot provide enough water for large-scale cratonic lithosphere hydroweakening and thinning. Water estimates invoked for craton destruction as experienced by the NCC can only be the result of long-term piling of multiple slabs in the MTZ or penetrating deeper into the lower mantle.
DS202002-0220
2019
WangXu, R., Liu, Y., Wang, X-C, Foley, S.F., Zhang, Y., Yuan, H.Generation of continental intraplate alkali basalts and deep carbon cycle.Earth Science Reviews, in press available, 38p. Doi.org/1010.1016 /jearsciev.2019.103073Globalcarbon

Abstract: Although the deep recycling of carbon has been proposed to play a key role in producing intraplate magmatism, the question of how it controls or triggers mantle melting remains poorly understood. In addition, generation of incipient carbonated melts in the mantle and their subsequent reaction with the mantle are critical processes that can influence the geochemistry of intraplate basalts, but the details of such processes are also unclear. Here we present geochemical evidence for the existence of pervasive carbonate melt in the mantle source of Cenozoic continental intraplate highly alkali basalts (SiO2 < 45 wt%), which are volumetrically minor but widespread in eastern China. The primary magma compositions of these basalts cannot be explained by either partial melting of a single mantle source lithology or mixing of magmas derived from distinct mantle sources, but can be adequately explained by carbonate-fluxed melting of eclogite and subsequent reaction between silica-rich melts and peridotite that ultimately transformed the initial carbonated silica-rich melts into silica-undersaturated alkalic magmas. The source of the carbonate is in subducted eclogites associated with the Pacific plate, which stagnated in the mantle transition zone (MTZ). The spatial distribution of the alkali basalts is in accord with large-scale seismic low-velocity anomalies in the upper mantle above the MTZ. Similar scenarios in central-western Europe and eastern Australia lead us to propose that reaction between carbonated silica-rich melt and peridotite may be a pivotal mechanism for the generation of continental intraplate alkali basalts elsewhere in the world.
DS1993-1693
1993
Wang, A.Wang, A., Dhamelincourt, P., Silvi, B.A high pressure-T structural form of chromite found as inclusions in diamondGeological Society of America Annual Abstract Volume, Vol. 25, No. 6, p. A217 abstract onlyGlobalDiamond inclusion, Chromite
DS1994-1879
1994
Wang, A.Wang, A., Dhamelin, P., Meyer, H.O.A., Guo, Lh.A carbon rich multiphase inclusion in a Chinese diamond and its geochemicalimplication.Contributions to Mineralogy and Petrology, Vol. 117, No. 1, June pp. 15-24.ChinaDiamond inclusion, Carbon
DS1994-1880
1994
Wang, A.Wang, A., Meyer, H.O.A., Dele-Dubois, M.L.Magnesite: an inclusion in natural diamondGeological Society of America (GSA) Abstract Volume, Vol. 26, No. 7, ABSTRACT only p. A417.South AfricaDiamond inclusion -magnesite, Deposit - Finsch
DS1996-1502
1996
Wang, A.Wang, A., Pasteris, J.D., Dele-Duboi, M.L.Magnesite bearing inclusion assemblage in natural diamondEarth and Planetary Science Letters, Vol. 141, No. 1-4, June 1, pp. 293-GlobalDiamond morphology, Magnesite inclusions
DS200612-1590
2006
Wang, A.Zhang, C-L., Li, Z.X., Li, X-H., Ye, H., Wang, A., Guo, K-Y.Neoproterozoic bimodal intrusive complex in the southwestern Tarim Block, northwest China: age, geochemistry, and implications for rifting of Rodinia.International Geology Review, Vol. 48, 2, Feb. pp. 112-128.ChinaGeochronology
DS201903-0516
2018
Wang, A-J.Hu, L., Li, Y-K., Wu, Z-J., Bai, Y., Wang, A-J.Two metasomatic events recorded in apatite from the ore hosting dolomite marble and implications for genesis of the giant Bayan Obo REE deposit, Inner Mongolia, northern China.Journal of Asian Earth Sciences, Vol. 172, pp. 56-65.China, Mongoliadeposit - Bayan Obo

Abstract: In the Bayan Obo REE deposit in Inner Mongolia, Northern China, three major orebodies are hosted in dolomite marble of the Bayan Obo Group. There are carbonatite dikes in the ore district. Apatite is a common accessary mineral in the ore-hosting dolomite marble (DM apatite) and in carbonatite dikes (IC apatite). These two types of apatite are both fluorapatite, and have low SiO2, uniform P2O5, and variable CaO contents. Total REY (REEs?+?Y) contents are correlated with Na2O contents, indicating that REY of both types of apatite enter lattice via the substitution reaction: Na+ + (REY)3+ = 2Ca2+. These features, combined with high REY (6230-18,906?ppm) and Sr (9653-17,200?ppm) contents of DM apatite, indicate that DM apatite likely had a carbonatite origin. Some DM apatite grains are partially replaced by albite and quartz. Fluid inclusions crosscutting both apatite and albite or quartz indicate that they formed later than quartz and albite replacement. The back-scattered electron images show that DM apatite grains contain many micro-pores (fluid inclusions), and monazite inclusions formed from the fluid inclusions. However, no monazite inclusions are observed within quartz and albite, excluding the possibility that the monazite inclusions were precipitated directly from the fluids. The monazite inclusions were therefore formed during fluid-induced dissolution-reprecipitation processes, where DM apatite served as the source of LREEs. This also explains the depletion of some LREEs in DM apatite. The formation of monazite inclusions in apatite requires fluids with relatively low Na and Si concentrations, different from the fluids responsible for quartz and albite replacement. DM apatite was affected by two stages of fluid activities: the first stage of metasomatism by alkaline fluids that were likely derived from carbonatite magmas when the deposit first formed (represented by quartz and albite replacement), followed by a second stage of modification that caused LREEs depletion and the formation of new REE minerals. Thus, the Bayan Obo REE ore deposit was modified by a significant thermal event after the formation, which provided negligible or only small amounts of REEs.
DS2001-1316
2001
Wang, B.Zhou, D., Grhan, S.A., Chang, E.Z., Wang, B., Hacker, B.Paleozoic tectonic amalgamation of the Chinese Tian Shan: evidence from a transect along the Dushanzi-KugaGeological Society of America Memoir, No. 194, pp. 23-46.ChinaTectonics
DS200912-0213
2009
Wang, B.Faure, M., Shu, L., Wang, B., Charvet, J., Choulet, F., Monie, P.Intracontinental subduction: a possible mechanism for the early Paleozoic orogen of SE China.Terra Nova, Vol. 21, pp. 360368.ChinaSubduction
DS201012-0827
2010
Wang, B.Wang, B., Niu, F.A broad 660 km discontinuity beneath northeast Chin a revealed by dense regional seismic networks in Chin a.Journal of Geophysical Research, Vol. 115, B6, B06308.ChinaGeophysics - seismic
DS201212-0127
2013
Wang, B.Cheng, C., Chen, L., Yao, H., Jiang, M., Wang, B.Distinct variations of crustal shear wave velocity structure and radial anisotropy beneath the North Chin a Craton and tectonic implications.Gondwana Research, Vol. 23, 1, pp. 25-38.ChinaTomography
DS202008-1461
2020
Wang, B.Zeyen, N., Wang, B., Wilson, S.A., von Gunten, K., Alessi, D.S., Paulo, C., Stubbs, A.R., Power, I.M.Cation exchange: a new strategy for mineral carbonation of smectite-rich kimberlites.Goldschmidt 2020, 1p. AbstractAfrica, South Africadeposit - Venetia

Abstract: Mineral carbonation is a form of carbon capture, utilization and storage (CCUS) that aims to transform excess CO2 into environmentally benign carbonate minerals which are geologically stable. Here, we investigated the reactivity of processed kimberlite and kimberlite ore from the Venetia Diamond Mine (South Africa). Highly reactive phases, such as brucite [Mg(OH)2], are uncommon in the samples collected from Venetia necessitating the development of new strategies for mineral carbonation. Kimberlite ore and tailings from this mine consist of a clay-rich mineral assemblage that is dominated by lizardite (a serpentine mineral) and smectites. Smectites are swelling clays that can act as a source of Mg and Ca for carbonation reactions via cation exchange, dissolution and/or direct replacement of smectites to form carbonate phases. Although carbonation of serpentine and brucite has long been a focus of CCUS in mine wastes [1], smectite carbonation has not been explored in this setting. Quantitative X-ray diffraction using Rietveld refinements coupled with Fourier-transform infrared spectroscopy indicate that smectites of stevensite-saponite composition are abundant in the Venetia samples (1.3-15.4 wt.%). Synchrotron-based X-ray fluorescence mapping correlated with scanning and transmission electron microscopy show that smectites are distributed as altered, smooth regions measuring from 1 to 20 µm in breadth. These phases are rich in Mg and Ca and Al-poor. To better understand the behaviour/reactivity of smectites during the cation exchange process, we have used batch experiments with pure endmembers of Ca-, Mg- and Na-montmorillonite under different treatment conditions (NH4-citrate, NH4-O-acetate, NH4-Cl and Na3-citrate). After 24 hours of reaction, ICP-MS analyses reveal that the four treatments have the same efficiency for Ca and Mg exchange, while NH4-Cl and NH4- O-acetate treatments minimize calcite dissolution. Our end goals are to optimize settling time and to maximize extraction of Ca and Mg for carbonation reactions during ore processing.
DS201603-0419
2016
Wang, B-W.Shang, R., Chen, S., Wang, B-W., Wang, Z-M., Gao, S.Temperature induced irreversible phase transition from perovskite to diamond but pressure-driven back-transition in an ammonium copper formate.Angewandte Chemie, Vol. 18. 6. pp. 2137-2140.TechnologyPerovskite

Abstract: The compound [CH3 CH2 NH3 ][Cu(HCOO)3 ] undergoes a phase transition at 357 K, from a perovskite to a diamond structure, by heating. The backward transition can be driven by pressure at room temperature but not cooling under ambient or lower pressure. The rearrangement of one long copper-formate bond, the switch of bridging-chelating mode of the formate, the alternation of N-H···O H-bonds, and the flipping of ethylammonium are involved in the transition. The strong N-H···O H-bonding probably locks the metastable diamond phase. The two phases display magnetic and electric orderings of different characters.
DS200412-2222
2004
Wang, C.Zheng, J., Griffin, W.L., O'Reilly, S.Y., Lu, F., Wang, C., Zhang, M., Li, M.3.6 Ga lower crust in central Chin a: new evidence on the assembly of the North Chin a craton.Geology, Vol. 32, 3, Mar. pp. 229-232.ChinaGeochronology, early Archean
DS200712-1191
2007
Wang, C.Xio, L., Wang, C., Pirajno, F.Is the underthrust Indian lithosphere split beneath the Tibetan Plateau?International Geology Review, Vol. 49, 1, pp. 90-98.IndiaTectonics
DS201012-0287
2010
Wang, C.Hou, G., Kusky, T.M., Wang, C., Wang, X.Mechanics of the giant radiating dyke swarm: a paleostress field modeling.Journal of Geophysical Research, Vol. 115, B2, B02402.Canada, Northwest TerritoriesDyke morphology
DS201012-0828
2010
Wang, C.Wang, C., Jin, Z., Gao, S., Zhang, J., Zheng, S.Eclogite- melt/peridotite reaction: experimental constraints of the destruction mechanism of the North Chin a craton.Science China Earth Sciences, Vol. 53, 6, pp. 797-809.ChinaMelting
DS201212-0814
2012
Wang, C.Zhang, J., Wang, C., Wang, Y.Experimental constraints on the destruction mechanism of the North Chin a craton.Lithos, Vol. 149, pp. 91-99.ChinaEclogite melt
DS201607-1322
2016
Wang, C.Zhang, Y., Wu, Y., Wang, C., Zhu, L., Jin, Z.Experimental constraints on the fate of subducted upper continental crust beyond the depth of no return.Geochimica et Cosmochimica Acta, Vol. 186, pp. 207-225.MantleSubduction, melting

Abstract: The subducted continental crust material will be gravitationally trapped in the deep mantle after having been transported to depths of greater than ~250 -300 km (the “depth of no return”). However, little is known about the status of this trapped continental material as well as its contribution to the mantle heterogeneity after achieving thermal equilibrium with the surrounding mantle. Here, we conduct an experimental study over pressure and temperature ranges of 9 -16 GPa and 1300 -1800 °C to constrain the fate of these trapped upper continental crust (UCC). The experimental results show that partial melting will occur in the subducted UCC along normal mantle geotherm to produce K-rich melt. The residual phases composed of coesite/stishovite + clinopyroxene + kyanite in the upper mantle, and stishovite + clinopyroxene + K-hollandite + garnet + CAS-phase in the mantle transition zone (MTZ), respectively. The residual phases achieve densities greater than the surrounding mantle, which provides a driving force for descent across the 410-km seismic discontinuity into the MTZ. However, this density relationship is reversed at the base of the MTZ, leaving the descended residues to be accumulated above the 660-km seismic discontinuity and may contribute to the “second continent”. The melt is ~0.6 -0.7 g/cm3 less dense than the surrounding mantle, which provides a buoyancy force for ascent of melt to shallow depths. The ascending melt, which preserves a significant portion of the bulk-rock rare earth elements (REEs), large ion lithophile elements (LILEs), and high-filed strength elements (HFSEs), may react with the surrounding mantle. Re-melting of the metasomatized mantle may contribute to the origin of the “enriched mantle sources” (EM-sources). Therefore, the deep subducted continental crust may create geochemical/geophysical heterogeneity in Earth’s interior through subduction, stagnation, partial melting and melt segregation.
DS201908-1821
2019
Wang, C.Wang, C., Song, S., Wei, C., Su, L., Allen, M.B., Niu, Y., Li, X-H., Dong, J.Paleoarchean deep mantle heterogeneity recorded by enriched plume remnants.Nature Geoscience, doi.org/10.1038/s41561-019-0410-y 10p pdfMantlePlumes, hotspots

Abstract: The thermal and chemical state of the early Archaean deep mantle is poorly resolved due to the rare occurrences of early Archaean magnesium-rich volcanic rocks. In particular, it is not clear whether compositional heterogeneity existed in the early Archaean deep mantle and, if it did, how deep mantle heterogeneity formed. Here we present a geochronological and geochemical study on a Palaeoarchaean ultramafic-mafic suite (3.45-Gyr-old) with mantle plume signatures in Longwan, Eastern Hebei, the North China Craton. This suite consists of metamorphosed cumulates and basalts. The meta-basalts are iron rich and show the geochemical characteristics of present-day oceanic island basalt and unusually high mantle potential temperatures (1,675?°C), which suggests a deep mantle source enriched in iron and incompatible elements. The Longwan ultramafic-mafic suite is best interpreted as the remnants of a 3.45-Gyr-old enriched mantle plume. The first emergence of mantle-plume-related rocks on the Earth 3.5-3.45?billion years ago indicates that a global mantle plume event occurred with the onset of large-scale deep mantle convection in the Palaeoarchaean. Various deep mantle sources of these Palaeoarchaean mantle-plume-related rocks imply that significant compositional heterogeneity was present in the Palaeoarchaean deep mantle, most probably introduced by recycled crustal material.
DS201909-2110
2019
Wang, C.Zhang, Y., Wang, C., Zhu, L., Jin, Z., Li, W.Partial melting of mixed sediment-peridotite mantle source and its implications.Journal of Geophysical Research: Solid Earth, Vol. 124, 7, pp. 6490-6503.Mantleperidotite

Abstract: Subducted sediments play an important role in the transport of incompatible elements back into the Earth's mantle. In recent years, studies of volcanic rocks from Samoan (Jackson et al., 2007, https://doi.org/10.1038/nature06048), NE China (Wang, Chen, et al., 2017, https://doi.org/10.1016/j.epsl.2017.02.028), and Gaussberg, Antarctica (Murphy et al., 2002, https://doi.org/10.1093/petrology/43.6.981), have shown geochemical records of a sediment-influenced mantle source from the deep Earth. However, experimental studies on the partial melting behavior of mixed sediment-peridotite mantle beyond subarc depths are very rare. In this study, we conducted experiments to investigate the partial melting behavior of mixed sediment-peridotite mantle at 4-15 GPa and 1200-1800 °C. The experimental solidi of mixed sediment-peridotite and K-feldspar-peridotite systems (Mixes A and B) cross the hot mantle geotherm at depths of around the X discontinuity (seismic discontinuity, ~300-km depth). The trace element compositions of the corresponding partial melts in Mix A showed similar characteristics to those of the Samoan basaltic lavas, potassic basalts from NE China, and Gaussberg lamproites. Therefore, the experimental results provide a possible explanation for the origin of some unusual mantle-derived volcanic rocks that contain recycled sediment signatures and have very deep origins. At depths of ~300 km (X discontinuity), a mixed sediment-peridotite source was heated by a hot-upwelling mantle and produced enriched melt. The enriched melt may interact with the surrounding mantle before incorporated into the upwelling mantle plume and becoming involved in the origin of some volcanic rocks. The experiments also provide a possible link between the enriched-mantle source in the deep mantle and the X discontinuity.
DS202003-0362
2020
Wang, C.Sha, X., Yue, W., Zhang, H., Qin, W., She, D., Wang, C.Thermal stability of polycrystalline diamond compact sintered with boron coated diamond particles.Diamond & Related Materials, in press available, 34p. PdfGlobalboron

Abstract: The polycrystalline diamond compact (PDC), which consists of a polycrystalline diamond layer on a tungsten carbide (WC)/cobalt (Co) substrate, is extensively utilized as drilling bits. However, the poor thermal stability due to the graphitization and oxygen susceptibility of diamond severely limits the application of PDCs to high-temperature drilling work. In this study, a new PDC with improved thermal stability is successfully synthesized with boron (B)-coated diamond particles, which forms a uniform boron carbide (B4C) barrier. The as-received B4C phase acts as a protective barrier, which enhances the initial graphitization and oxidizing temperatures to 800 °C and 780 °C, respectively, which are ~100 °C and ~30 °C higher than those (700 °C and 750 °C) of the PDC sintered with uncoated diamond particles. The B4C barrier protects diamond grains from direct contact with the Co phase, prohibiting the cobalt-catalytic graphitization. In addition, the oxidation of the B4C barrier occurs prior to that of the diamond grains, which inhibits the PDC from oxidation.
DS202101-0040
2021
Wang, C.Wang, C., Mitchell, Ross.N., Murphy, J.B., Peng, P., Spencer, C.J.The role of megacontinents in the supercontinent cycle.Geology, in press availabe 5p. PdfMantlePangea

Abstract: Supercontinent Pangea was preceded by the formation of Gondwana, a “megacontinent” about half the size of Pangea. There is much debate, however, over what role the assembly of the precursor megacontinent played in the Pangean supercontinent cycle. Here we demonstrate that the past three cycles of supercontinent amalgamation were each preceded by ~200 m.y. by the assembly of a megacontinent akin to Gondwana, and that the building of a megacontinent is a geodynamically important precursor to supercontinent amalgamation. The recent assembly of Eurasia is considered as a fourth megacontinent associated with future supercontinent Amasia. We use constraints from seismology of the deep mantle for Eurasia and paleogeography for Gondwana to develop a geodynamic model for megacontinent assembly and subsequent supercontinent amalgamation. As a supercontinent breaks up, a megacontinent assembles along the subduction girdle that encircled it, at a specific location where the downwelling is most intense. The megacontinent then migrates along the girdle where it collides with other continents to form a supercontinent. The geometry of this model is consistent with the kinematic transitions from Rodinia to Gondwana to Pangea.
DS202101-0044
2021
Wang, C.Zhang, M., Wang, C., Zhang, Qi., Qin, Y., Shen, J., Hu, X., Zhou, G., Li, S.Temporal-spatial analysis of alkaline rocks based in GEOROC. Not specific to diamondsApplied Geochemistry, Vol. 124, 104853 8p. PdfAsia, TibetGEOROC
DS201312-0536
2014
Wang, -C.Li, J., Wang,-C., Ren, Z-Y., Xu, J-F., He, B., Xu, Y-G.Chemical heterogeneity of the Emeishan mantle plume: evidence from highly siderophile element abundances in picrites.Journal of Asian Earth Studies, Vol. 79, A, pp. 191-205.ChinaPicrite
DS1986-0365
1986
Wang, C.Y.Hirsch, L.M., Wang, C.Y.Electrical conductivity of olivine during high temperature creepJournal of Geophysical Research, Vol. 91, No. B10, September, pp. 10, 429-10, 441GlobalUpper mantle, diamond
DS201802-0250
2018
Wang, C.Y.Liu, Y-L., Ling, M-X., Williams, I.S., Yang, X-Y., Wang, C.Y.The formation of the giant Bayan Obo REE Nb Fe deposit, North China, Mesoproterozoic carbonatite and overprinted Paleozoic dolomitization.Ore Geology Reviews, Vol. 92, pp. 73-83.Chinadeposit - Bayan Obo

Abstract: The Bayan Obo ore deposit in Inner Mongolia, North China, the largest-known rare earth element (REE) deposit in the world, is closely associated with carbonatite dykes. Scarce zircon grains, with a wide range of ages and diverse origins, have been extracted from the Wu dyke, a REE-enriched calcitic carbonatite dyke 2?km from the East Ore Body of the Bayan Obo deposit. Three zircon populations were identified based on ages and trace element compositions: 1) Captured zircons with Paleoproterozoic and Archean ages. These zircons have REE patterns and moderate Th/U ratios similar to zircon with silicate inclusions from basement igneous rocks, which have been recognized as contaminants from wall rocks. 2) Carbonatite magmatic zircons with Mesoproterozoic ages. These zircons have high to extremely high Th/U ratios (13-1600), a characteristic signature of the Bayan Obo deposit. Two zircon grains yielded concordant 206Pb/238U ages (1.27?±?0.11?Ga?~?1.42?±?0.18?Ga) and 208Pb/232Th age (1.26?±?0.20?Ga) with calcite inclusions, indicating that the Wu dyke was emplaced at ca. 1.34?Ga, which coincides with a worldwide generation of Mesoproterozoic kimberlites, lamprophyres, carbonatites, and anorogenic magmatism. 3) Hydrothermal zircons with Caledonian and Triassic ages. The Caledonian zircon has 206Pb/238U age of 381?±?4?Ma and 208Pb/232Th age of 367?±?14?Ma with dolomite inclusion. These evidences are consistent with multiple stages of mineralization, Mesoproterozoic calcite carbonatite magmatism interacted by protracted fluxing of subduction-released Caledonian fluids during the closure of the Palaeo-Asian Ocean, coupled with interaction with the mantle wedge and metasomatism of overlying sedimentary carbonate.
DS2003-1445
2003
Wang, C-Y.Wang, C-Y., Chan, W.W., Mooney, W.D.Three dimensional velocity structure of crust and upper mantle in southwestern ChinaJournal of Geophysical Research, Vol. 108, B9, Sept. 25, 10.1029/2002JB001973ChinaTectonics
DS200412-2078
2003
Wang, C-Y.Wang, C-Y., Chan, W.W., Mooney, W.D.Three dimensional velocity structure of crust and upper mantle in southwestern Chin a and its tectonic implications.Journal of Geophysical Research, Vol. 108, B9, Sept. 25, 10.1029/2002 JB001973ChinaTectonics
DS201312-0151
2013
Wang, C-Y.Chen, W-P., Yu, C-Q., Tseng, T-L., Wang, C-Y.Moho, seismogenesis, and rheology of the lithosphere.Tectonophysics, Vol. 609, pp. 491-503.MantleModels
DS1986-0564
1986
Wang, D.Meureu, R.F., Wang, D., Lkuhn, O., et al.The 1982 COCRUST seismic experiment across the Ottawa Bonneschere graben and Grenville Front in Ontario and QuebecGeophys. Journal of Roy. Astron. Soc, Vol. 84, pp. 491-514Ontario, Quebec, MidcontinentTectonics
DS2003-1449
2003
Wang, D.Wang, Q., Li, R., Wang, D., Li, S.Eclogites preserved as pebbles in Jurassic conglomerate, Dabie Mountains, ChinaLithos, Vol. 70, 3-4, pp. 345-57.ChinaUHP, eclogites
DS200412-2082
2003
Wang, D.Wang, Q., Li, R., Wang, D., Li, S.Eclogites preserved as pebbles in Jurassic conglomerate, Dabie Mountains, China.Lithos, Vol. 70, 3-4, pp. 345-57.ChinaUHP, eclogites
DS200412-2160
2004
Wang, D.Xu, W., Liu, X., Wang, Q., Lin, J., Wang, D.Garnet exsolution in garnet clinopyroxenite and clinopyroxenite xenoliths in early Cretaceous intrusions from the Xuzhou region,Mineralogical Magazine, Vol. 68, 3, June 1, pp. 443-453.ChinaXenolith - geochemistry
DS200512-1208
2004
Wang, D.Xu, W., Wang, Q., Wang, D.Processes and mechanism of Mesozoic lithospheric thinning in eastern North Chin a Craton: evidence from Mesozoic igneous rocks and deep seated xenoliths.Earth Science Frontiers, Vol. 11, 4, pp. 309-318. Ingenta 1045384777ChinaXenoliths
DS200812-1234
2008
Wang, D.Wang, D., li, H., Li, S.Baoping.The electrical conductivity of upper mantle rocks: water content in the upper mantle.Physics and Chemistry of Minerals, Vol. 35, 3, pp. 157-162.MantleHydrous
DS201112-0592
2011
Wang, D.Li, H., Wang, D., Cheng, X.Metamorphic fluid activities and their effects on petrologgical and geochemical characteristics of UHP rocks, southern Sulu UHP terrane, China.Goldschmidt Conference 2011, abstract p.1310.ChinaUHP - eclogites
DS201212-0796
2012
Wang, D.Xu, S., Wu, W., Lu, Y., Wang, D.Tectonic setting of the low grade metamorphic rocks of the Dabie Orogen, central eastern China.Journal of Structural Geology, Vol. 37, pp. 134-149.ChinaUHP
DS201608-1441
2016
Wang, D.Song, Z., Lu, T., Tang, S., Ke, J., Su, J., Gao, B., Bi, L., Wang, D.Identification of colourless HPHT grown synthetic diamonds from Shandong China.The Journal of Gemmology, Vol. 35, 2, pp. 14-147.ChinaSynthetics
DS201803-0485
2018
Wang, D.Wang, D., Wang, X-L., Cai, Y., Goldstein, S.L., Yang, T.Do Hf isotopes in magmatic zircons represent those of their host rocks?Journal of Asian Earth Sciences, Vol. 154, pp. 202-212.Mantlezircons

Abstract: Lu-Hf isotopic system in zircon is a powerful and widely used geochemical tracer in studying petrogenesis of magmatic rocks and crustal evolution, assuming that zircon Hf isotopes can represent initial Hf isotopes of their parental whole rock. However, this assumption may not always be valid. Disequilibrium partial melting of continental crust would preferentially melt out non-zircon minerals with high time-integrated Lu/Hf ratios and generate partial melts with Hf isotope compositions that are more radiogenic than those of its magma source. Dissolution experiments (with hotplate, bomb and sintering procedures) of zircon-bearing samples demonstrate this disequilibrium effect where partial dissolution yielded variable and more radiogenic Hf isotope compositions than fully dissolved samples. A case study from the Neoproterozoic Jiuling batholith in southern China shows that about half of the investigated samples show decoupled Hf isotopes between zircons and the bulk rocks. This decoupling could reflect complex and prolonged magmatic processes, such as crustal assimilation, magma mixing, and disequilibrium melting, which are consistent with the wide temperature spectrum from ~630?°C to ~900?°C by Ti-in-zircon thermometer. We suggest that magmatic zircons may only record the Hf isotopic composition of their surrounding melt during crystallization and it is uncertain whether their Hf isotopic compositions can represent the primary Hf isotopic compositions of the bulk magmas. In this regard, using zircon Hf isotopic compositions to trace crustal evolution may be biased since most of these could be originally from disequilibrium partial melts.
DS201903-0550
2019
Wang, D.Wang, D., Vervoort, J.D., Fisher, C.M., Cao, H. Li, G.Integrated garnet and zircon - titanate geochronology constrains the evolution of ultra high pressure terranes: an example from the Sulu orogen.Journal of Metamorphic Geology, in press availableChinaUHP

Abstract: Dating ultrahigh-pressure (UHP) metamorphic rocks provides important timing constraints on deep subduction zone processes. Eclogites, deeply subducted rocks now exposed at the surface, undergo a wide range of metamorphic conditions (i.e., deep subduction and exhumation) and their mineralogy can preserve a detailed record of chronologic information of these dynamic processes. Here we present an approach that integrates multiple radiogenic isotope systems in the same sample to provide a more complete timeline for the subduction-collision-exhumation processes, based on eclogites from the Dabie-Sulu orogenic belt in eastern China, one of the largest ultrahigh-pressure (UHP) terranes on Earth. In this study, we integrate garnet Lu-Hf and Sm-Nd ages with zircon and titanite U-Pb ages for three eclogite samples from the Sulu UHP terrane. We combine this age information with Zr-in-rutile temperature estimates, and relate these multiple chronometers to different P-T conditions. Two types of rutile, one present as inclusions in garnet and the other in the matrix, record the temperatures of UHP conditions and a hotter stage, subsequent to the peak pressure (“hot exhumation”), respectively. Garnet Lu-Hf ages (c. 238 to 235 Ma) record the initial prograde growth of garnet, while coupled Sm-Nd ages (c. 219 to 213 Ma) reflect cooling following hot exhumation. The maximum duration of UHP conditions is constrained by the age difference of these two systems in garnet (c. 235 to 220 Ma). Complementary zircon and titanite U-Pb ages of c. 235 - 230 Ma and c. 216 - 206 Ma provide further constraints on the timing of prograde metamorphism and the "cold exhumation", respectively. We demonstrate that timing of various metamorphic stages can thus be determined by employing complementary chronometers from the same samples. These age results, combined with published data from adjacent areas, show lateral diachroneity in the Dabie-Sulu orogeny. Three sub-blocks are thus defined by progressively younger garnet ages: western Dabie (243 - 238 Ma), eastern Dabie-northern Sulu (238 - 235 Ma,) and southern Sulu terranes (225 - 220 Ma), which possibly correlate to different crustal slices in the recently proposed subduction channel model. These observed lateral chronologic variations in a large UHP terrane can possibly be extended to other suture zones.
DS201911-2572
2019
Wang, D.Wang, D., Romer, R.L., Guo, J-h., Glodny, J.Li and B isotopic fingerprint of Archean subduction.Geochimica et Cosmochimica Acta, in press available. 45p.Mantlesubduction

Abstract: Archean peridotite xenoliths in the ~2.52 Ga Zhulagou diorite (Yinshan Block, North China Craton) show chemical and Li isotopic evidence for metasomatism above an ancient subduction zone. The peridotite xenoliths are composed of olivine + orthopyroxene + amphibole + phlogopite + serpentine. The peridotite xenoliths have low whole-rock Mg# (80-81) and low Mg# (81-84) in olivine, indicating that they are cumulates that formed near the crust-mantle boundary. Petrological observations, mineral trace element data and isotopic ages show that the sequence of hydrous minerals is amphibole-serpentine-phlogopite. SIMS U-Pb dating of zircon from peridotites yielded an upper intercept age at ~2.53 Ga, and a U-Pb lower intercept age at ~1.8 Ga. The age of ~2.53 Ga is interpreted to date the crystallization of zircon from the metasomatized mantle melt that formed the Zhulagou cumulate peridotite. Rb-Sr mineral isochrons date phlogopite formation at ~1760 Ma, consistent with the lower intercept age of zircon. Pargasitic amphibole from the Zhulagou peridotites has fractionated REE, pronounced depletions of Nb, Ta, Zr and Ti, and heavy d7Li (~+14‰) and light d11B (~-11‰). Combined with slightly depleted mantle whole rock eNd (~+1.3) and high zircon d18O (+5.6 to +7.0‰), the amphibole composition reflects that the peridotite xenoliths formed from melts that carried the geochemical and isotopic fingerprint typical for a metasomatized mantle wedge above a subduction zone. The Zhulagou peridotite xenoliths have the highest d7Li values (~+12‰) recorded in Archean peridotites. Isotopically heavy Li and light B in olivine, orthopyroxene, and amphibole from the peridotite xenoliths show that Li and B may decouple during partial melting or fluid release from the subducted slab. The decoupling of Li and B may have a variety of reasons, including different host minerals for Li and B in the source and different protoliths in the subducted slab. The Li and B isotopic record on the recycling of ancient material demonstrates that modern-style subduction operated already in the late Archean.
DS202001-0046
2019
Wang, D.Wang, D., Romer, R.L., Guo, J-h., Glodny, J.Li and B isotopic fingerprint of Archean subduction.Geochimica et Cosmochimica Acta, in press available pdf 45p.Chinacraton

Abstract: Archean peridotite xenoliths in the ~2.52?Ga Zhulagou diorite (Yinshan Block, North China Craton) show chemical and Li isotopic evidence for metasomatism above an ancient subduction zone. The peridotite xenoliths are composed of olivine?+?orthopyroxene?+?amphibole?+?phlogopite?+?serpentine. The peridotite xenoliths have low whole-rock Mg# (80-81) and low Mg# (81-84) in olivine, indicating that they are cumulates that formed near the crust-mantle boundary. Petrological observations, mineral trace element data and isotopic ages show that the sequence of hydrous minerals is amphibole-serpentine-phlogopite. SIMS U-Pb dating of zircon from peridotites yielded an upper intercept age at ~2.53?Ga, and a U-Pb lower intercept age at ~1.8?Ga. The age of ~2.53?Ga is interpreted to date the crystallization of zircon from the metasomatized mantle melt that formed the Zhulagou cumulate peridotite. Rb-Sr mineral isochrons date phlogopite formation at ~1760?Ma, consistent with the lower intercept age of zircon. Pargasitic amphibole from the Zhulagou peridotites has fractionated REE, pronounced depletions of Nb, Ta, Zr and Ti, and heavy d7Li (~+14‰) and light d11B (~-11‰). Combined with slightly depleted mantle whole rock eNd (~+1.3) and high zircon d18O (+5.6 to +7.0‰), the amphibole composition reflects that the peridotite xenoliths formed from melts that carried the geochemical and isotopic fingerprint typical for a metasomatized mantle wedge above a subduction zone. The Zhulagou peridotite xenoliths have the highest d7Li values (~+12‰) recorded in Archean peridotites. Isotopically heavy Li and light B in olivine, orthopyroxene, and amphibole from the peridotite xenoliths show that Li and B may decouple during partial melting or fluid release from the subducted slab. The decoupling of Li and B may have a variety of reasons, including different host minerals for Li and B in the source and different protoliths in the subducted slab. The Li and B isotopic record on the recycling of ancient material demonstrates that modern-style subduction operated already in the late Archean.
DS202009-1676
2020
Wang, D.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
Wang, D.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.
DS2000-1033
2000
Wang, D.P.Xu, M., Midleton, M.F., Xue, L.F., Wang, D.P.Structure of the lithosphere and Mesozoic sedimentary basins in western Liaoning Northern Liaoning.International Geology Review, Vol. 42, No. 3, March pp. 269-78.China, northeastTectonics
DS201505-0240
2015
Wang, D.V.Kalnins, L.M., Simons, F.J., Kirby, J.F., Wang, D.V., Olhede, S.C.On the robustness of estimates of mechanical anisotropy in the continental lithosphere: a North American case study and global reanalysis.Earth and Planetary Science Letters, Vol. 419, pp. 43-51.United States, CanadaTectonics
DS201709-2078
2017
Wang, D-Z.Zhu, R-N, Ni, P., Ding, J-Y., Wang, D-Z., Ju, Y., Kang, N.Petrography, chemical composition, and Raman spectra of chrome spinel: constraints on the diamond potential of the no. 30 pipe kimberlite in Wafandian, North Chin a Craton.Ore Geology Reviews, in press available, 40p.Chinadeposit - No. 30 Wafangdian

Abstract: Conventional diamond exploration seldom searches directly for diamonds in rock and soil samples. Instead, it focuses on the search for indicator minerals like chrome spinel, which can be used to evaluate diamond potential. Chrome spinels are preserved as pristine minerals in the early Paleozoic (~465 Ma), hydrothermally altered, Group I No. 30 pipe kimberlite that intruded the Neoproterozoic Qingbaikou strata in Wafangdian, North China Craton (NCC). The characteristics of the chrome spinels were investigated by petrographic observation (BSE imaging), quantitative chemical analysis (EPMA), and Raman spectral analysis. The results show that the chrome spinels are mostly sub-rounded with extremely few grains being subhedral, and these spinels are macrocrystic, more than 500 µm in size. The chrome spinels also have compositional zones: the cores are classified as magnesiochromite as they have distinctly chromium-rich (Cr2O3 up to 66.56 wt%) and titanium-poor (TiO2 < 1 wt%) compositions; and the rims are classified as magnetite as they have chromium-poor and iron-rich composition. In the cores of chrome spinels, compositional variations are controlled by Al3+-Cr3+ isomorphism, which results in a strong Raman spectra peak (A1g mode) varying from 690 cm-1 to 702.9 cm-1. In the rims of chrome spinel, compositional variations result in the A1g peak varying from 660 cm-1 to 672 cm-1. The morphology and chemical compositions indicate that the chrome spinels are mantle xenocrysts. The cores of the spinel are remnants of primary mantle xenocrysts that have been resorbed, and the rims were formed during kimberlite magmatism. The compositions of the cores are used to evaluate the diamond potential of this kimberlite through comparison with the compositions of chrome spinels from the Changmazhuang and No. 50 pipe kimberlites in the NCC. In MgO, Al2O3 and TiO2 versus Cr2O3 plots, the chrome spinels from the Changmazhuang and No. 50 pipe kimberlites are mostly located in the diamond stability field. However, only a small proportion of chrome spinels from No. 30 pipe kimberlite have same behavior, which indicates that the diamond potential of the former two kimberlites is greater than that of the No. 30 pipe kimberlite. This is also supported by compositional zones in the spinel grains: there is with an increase in Fe3+ in the rims, which suggests that the chrome spinels experienced highly oxidizing conditions. Oxidizing conditions may have been imparted by fluids/melts that have a great influence on diamond destruction. Here, we suggest that chrome spinel compositions can be a useful tool for identifying the target for diamond potential in the North China Craton.
DS201703-0438
2017
Wang, E.Wang, E.Timing of the initial collision between the Indian and Asian continents.Science China Earth Sciences, Vol. 60, 10p.Asia, IndiaSubduction

Abstract: There exist three mainstream opinions regarding the timing of the initial collision between the Indian and Eurasian continents, namely, 65±5, 45±5, and 30±5 Ma. Five criteria are proposed for determining which tectonic event was related to the initial collision between India and Asia: the rapid decrease in the rate of plate motion, the cessation of magmatic activity originating from the subduction of oceanic crust, the end of sedimentation of oceanic facies, the occurrence of intracontinental deformation, and the exchange of sediments sourced from two continents. These criteria are used to constrain the nature of these tectonic events. It is proposed that the 65±5 Ma tectonic event is consistent with some of the criteria, but the upshot of this model is that the magmatic activity originating from the Tethyan subduction since the Mesozoic restarted along the southern margin of the Asian continent in this time after a brief calm, implying that the subduction of the Neotethys slab was still taking place. The magmatic activity that occurred along the southern margin of the Asian continent had a 7-Myr break during 72-65 Ma, which in this study is interpreted as having resulted from tectonic transformation from subduction to transform faulting, indicating that the convergence between the Indian and Asian continents was once dominated by strike-slip motion. The 30±5 Ma tectonic event resulted in the uplift of the Tibetan Plateau, which was related to the late stage of the convergence between these two continents, namely, a hard collision. The 45±5 Ma tectonic event is in accordance with most of the criteria, corresponding to the initial collision between these two continents.
DS201804-0752
2018
Wang, E.Wang, E., Unsworth, M., Chacko, T.Geoelectric structure of the Great Slave Lake shear zone in northwest Alberta: implications for structure and tectonic history.Canadian Journal of Earth Sciences, Vol. 55, pp. 295-307.Canada, Albertageophysics - electromagnetics, magnetotellurics

Abstract: The study of ancient plate boundaries can provide insights into the past and present-day tectonic processes. Here, we describe a magnetotellurics (MT) study of the Precambrian basement of the Hay River Fault (HRF) in northwest Alberta, which is the southwest segment of the Great Slave Lake shear zone. New broadband MT data were collected to give a clearer image of the crustal structure. The Western Canada Sedimentary Basin was imaged as a low-resistivity layer above the resistive crystalline basement. Four basement conductors were defined, and correlate with the terrane boundaries delineated with aeromagnetic data. These are (1) a major conductor in the Kiskatinaw domain, (2) a conductor on the boundary of the Ksituan and Chinchaga domains, (3) a conductor on the boundary of the Chinchaga and Buffalo Head domains, and (4) a conductor near the HRF. Both (1) and (2) correspond to areas of high seismic reflectivity. The low resistivity can be explained by interconnected grain boundary graphite or sulfide phases deposited by metamorphic fluid migration. The HRF was not definitively located in previous studies. The new data show that the HRF could be thin (1 km) or wide (10 km) and located at the boundary of the contrasting aeromagnetic anomalies or further to the north. Various tectonic processes are proposed to interpret the possible locations of the HRF. No electrical anisotropy structure is required to interpret the MT data in this study.
DS1995-1850
1995
Wang, F.Sun, P., Wang, F., et al.The rheological characteristics of the Cenozoic upper mantle and the tectonic significance Hebi area, Henan.Geological Society of America (GSA) Abstracts, Vol. 27, No. 6, abstract p. A 35.China, HenanTectonics, Hebi area
DS2003-0521
2003
Wang, F.Guo, F., Fan, W., Wang, F., Lin, G.Geochemistry of late Mesozoic mafic magmatism in west Shandong Province, easternGeochemical Journal, Vol. 37, pp. 63-77.ChinaBlank
DS200412-0746
2003
Wang, F.Guo, F., Fan, W., Wang, F., Lin, G.Geochemistry of late Mesozoic mafic magmatism in west Shandong Province, eastern China: characterizing the lost lithospheric manGeochemical Journal, Vol. 37, pp. 63-77.ChinaUHP, xenoliths
DS200612-1595
2006
Wang, F.Zhang, Z., Mahoney, J., Mao,J., Wang, F.Geochemistry of picritic and associated basalt flows of the western Emeishan flood basalt province, China.Journal of Petrology, Vol. 47, 10, pp. 1997-2019.ChinaPicrite
DS200812-1235
2007
Wang, F.Wang, F., Lu, X-X., Lo, C-H., Wu, F-Y., He, H-Y., Yang, L-K., Zhu, R-X.Post collisional, potassic monzonite-minette complex Shahewan in the Qinling Mountains: 40Ar 39Ar thermochronology, petrogenesis, implications - dynamicJournal of Asian Earth Sciences, Vol. 31, 2, October pp. 153-166.ChinaMinette
DS201907-1524
2019
Wang, F.Anzolini, C., Wang, F., Harris, G.A., Locock, A.J., Zhang, D., Nestola, F., Peruzzo, L., Jacobsen, S.D., Pearson, D.G.Nixonite, Na2Ti6O13, a new mineral from a metasomatized mantle garnet pyroxenite from the western Rae Craton, Darby kimberlite field, Canada.American Mineralogist, in press available 26p.Canada, Nunavutdeposit - Darby

Abstract: Nixonite (IMA 2018-133), ideally Na2Ti6O13, is a new mineral found within a heavily-metasomatized pyroxenite xenolith from the Darby kimberlite field, beneath the west central Rae Craton, Canada. It occurs as microcrystalline aggregates, 15 to 40 µm in length. Nixonite is isostructural with jeppeite, K2Ti6O13, with a structure consisting of edge- and corner-shared titanium-centered octahedra that enclose alkali-metal ions. The Mohs hardness is estimated to be between 5 and 6 by comparison to jeppeite and the calculated density is 3.51(1) g/cm3. Electron microprobe wavelength-dispersive spectroscopic analysis (average of 6 points) yielded: Na2O 6.87, K2O 5.67 CaO 0.57, TiO2 84.99, V2O3 0.31, Cr2O3 0.04, MnO 0.01, Fe2O3 0.26, SrO 0.07, total 98.79 wt%. The empirical formula, based on 13 O atoms, is: (Na1.24K0.67Ca0.06)S1.97(Ti5.96V0.023Fe0.018)S6.00O13 with minor amounts of Cr and Mn. Nixonite is monoclinic, space group C2/m, with unit-cell parameters a = 15.3632(26) Å, b = 3.7782(7) Å, c = 9.1266(15) Å, ß = 99.35(15)º and V = 522.72(1) Å3, Z = 2. Based on the average of seven integrated multi-grain diffraction images, the strongest diffraction lines are [dobs in Å (I in %) (h k l)]: 3.02 (100) (3 1 0) , 3.66 (75) (1 1 0), 7.57 (73) (2 0 0), 6.31 (68) (2 0 -1), 2.96 (63) (3 1 -1), 2.96 (63) (2 0 -3) and 2.71 (62) (4 0 2). The five main Raman peaks of nixonite, in order of decreasing intensity, are at: 863, 280, 664, 135 and 113 cm-1. Nixonite is named after Peter H. Nixon, a renowned scientist in the field of kimberlites and mantle xenoliths. Nixonite occurs within a pyroxenite xenolith in a kimberlite, in association with rutile, priderite, perovskite, freudenbergite and ilmenite. This complex Na-K-Ti rich metasomatic mineral assemblage may have been produced by a fractionated Na-rich kimberlitic melt that infiltrated a mantle-derived garnet pyroxenite and reacted with rutile during kimberlite crystallization.
DS201904-0804
2017
Wang, G.Zhou, Z., Wang, G., Di, Y-J,m Gu, Y-C., Zhang, D., Zhu, W-p., Liu, C., Wu, C., Li, H., Chen, L.-z.Discovery of Mesoproterozoic kimberlite from Dorbed Benner, Inner Mongolia and its tectonic significance.Geochemistry International, doi:10.1002/gi.2939 14p.China, Mongoliadeposit - Longtou Shan

Abstract: Porphyritic olivine kimberlitic breccia, discovered in the Dörbed Banner of Inner Mongolia, Western China, is referred to as Longtou Shan Kimberlite in our study. This kimberlite occurs as a pipe in the Halahuogete Formation of Bayan Obo Group. Zircon U-Pb ages of Longtou Shan Kimberlite reveals a Mesoproterozoic age of ~1,552 Ma, constraining the deposition age of Halahuogete Formation to the Mesoproterozoic. Compared with Mesoproterozoic kimberlite of the ancient landmass, it can be inferred that the North China Craton is a member of the Ur ancient continent of the Columbia supercontinent. Furthermore, according to the tectonic background of the Bayan Obo Group, we raise this possibility that “Bayan Obo Aulacogen” should be renamed the “Bayan Obo Continental Rift.”
DS200512-0659
2005
Wang, G.F.Lu, P.J., Yao, N., So, J.F., Harlow, G.E., Lu, J.F., Wang, G.F., Chaikin, P.M.The earliest use of corundum and diamond in prehistoric China.Archeometry, Vol. 47,1, Feb. pp. 1-12. Blackwell PublicationsChinaHistory
DS201909-2111
2019
Wang, G.G.Zhu, R.Z., Ni, P., Ding, J.Y., Wang, G.G., Fan, M.S., Li, S.N.Metasomatic processes in the lithospheric mantle beneath the No. 30 kimberlite ( Wafangdian region, North China craton).canminportal.org, Vol. 57, pp. 499-517.Chinadeposit - No. 30

Abstract: This paper presents the first major and trace element compositions of mantle-derived garnet xenocrysts from the diamondiferous No. 30 kimberlite pipe in the Wafangdian region, and these are used to constrain the nature and evolution of mantle metasomatism beneath the North China Craton (NCC). The major element data were acquired using an electron probe micro-analyzer and the trace element data were obtained using laser ablation inductively coupled plasma-mass spectrometry. Based on Ni-in-garnet thermometry, equilibrium temperatures of 1107-1365 °C were estimated for peridotitic garnets xenocrysts from the No. 30 kimberlite, with an average temperature of 1258 °C, and pressures calculated to be between 5.0 and 7.4 GPa. In a CaO versus Cr2O3 diagram, 52% of the garnets fall in the lherzolite field and 28% in the harzburgite field; a few of the garnets are eclogitic. Based on rare earth element patterns, the lherzolitic garnets are further divided into three groups. The compositional variations in garnet xenocrysts reflect two stages of metasomatism: early carbonatite melt/fluid metasomatism and late kimberlite metasomatism. The carbonatite melt/fluids are effective at introducing Sr and the light rare earth elements, but ineffective at transporting much Zr, Ti, Y, or heavy rare earth elements. The kimberlite metasomatic agent is highly effective at element transport, introducing, e.g., Ti, Zr, Y, and the rare earth elements. Combined with compositional data for garnet inclusions in diamonds and megacrysts from the Mengyin and Wafangdian kimberlites, we suggest that these signatures reflect a two-stage evolution of the sub-continental lithospheric mantle (SCLM) beneath the NCC: (1) early-stage carbonatite melt/fluid metasomatism resulting in metasomatic modification of the SCLM and likely associated with diamond crystallization; (2) late-stage kimberlite metasomatism related to the eruption of the 465 Ma kimberlite.
DS201708-1586
2017
Wang, G-S.Zhou, Z-G., Wang, G-S., Di, Y-J., Gu, Y-C., Zhang, D., Zhu, W-P., Liu, C-F., Wu, C., Li, H-Y., Chen, L-Z.Discovery of Mesoproterozoic kimberlite from Dorbed Banner Inner Mongolia and its tectonic significance.Geological Journal, pp. 1-13.Asia, Mongoliadeposit - Longtou Shan

Abstract: Porphyritic olivine kimberlitic breccia, discovered in the Dörbed Banner of Inner Mongolia, Western China, is referred to as Longtou Shan Kimberlite in our study. This kimberlite occurs as a pipe in the Halahuogete Formation of Bayan Obo Group. Zircon U–Pb ages of Longtou Shan Kimberlite reveals a Mesoproterozoic age of ~1,552 Ma, constraining the deposition age of Halahuogete Formation to the Mesoproterozoic. Compared with Mesoproterozoic kimberlite of the ancient landmass, it can be inferred that the North China Craton is a member of the Ur ancient continent of the Columbia supercontinent. Furthermore, according to the tectonic background of the Bayan Obo Group, we raise this possibility that “Bayan Obo Aulacogen” should be renamed the “Bayan Obo Continental Rift.”
DS200612-1591
2005
Wang, H.Zhang, J., Wang, H.Gravity and magnetic characteristics and tectonic divisions of the Uanshan area: evidence from olivines in picritic komatiitic rocks from Emeishan (LIP) Large Igneous Province, southwest China.Acta Geologica Sinica, Vol. 26, 4, pp. 349-354.ChinaPicrite
DS200812-1314
2008
Wang, H.Zhang, Y., Bi, H., Yu, L., Sun, S., Qui, J., Xu, C., Wang, H., Wang, R.Evidence for metasomatic mantle carbonatitic magma extrusion in Mesoproterozoic ore hosting dolomite rocks in the middle Kunyang rift, central Yunnan China.Progress in Natural Science, Vol. 18, 8, pp. 965-974.ChinaCarbonatite
DS200812-1315
2007
Wang, H.Zhang, Y., Xu, M., Zhu, M., Wang, H.Silicate melt properties and volcanic eruptions.Reviews of Geophysics, Vol. 45, RG 4004MantleMagmatism
DS201112-1099
2011
Wang, H.Wang, H., Wu, Y-B., Gao, S., Liu, X-C., Gong, H-J., Li, Q-L., Li, X-H., Yuan, H-L.Eclogite origin and timing in the North Qinling terrane, and their bearing on the amalgamation of the South and North Chin a blocks.Journal of Metamorphic Geology, in press available,ChinaCraton
DS201412-0959
2014
Wang, H.Wang, H., Van Hunen, J., Pearson, D.G., Allen, M.B.Craton stability and longevity: the roles of composition- dependent rheology and buoyancy.Earth and Planetary Science Letters, Vol. 391, 1, pp. 224-233.MantleCraton
DS201412-0960
2014
Wang, H.Wang, H., Wu, Y-B., Gao, S., Zheng, J-P., Liu, Q., Liu, X-C., Qin, Z-W., Yang, S-H., Gong, H-J.Deep subduction of continental crust in accretionary orogen: evidence from U-Pb dating on diamond-bearing zircons from the Qinling orogen, central China.Lithos, Vol. 190-191, pp. 420-429.ChinaUHP
DS201702-0251
2017
Wang, H.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, in press available, 10p.MantleCraton, tectonics

Abstract: Archean tectonics was capable of producing virtually indestructible cratonic mantle lithosphere, but the dominant mechanism of this process remains a topic of considerable discussion. Recent geophysical and petrological studies have refuelled the debate by suggesting that thickening and associated vertical movement of the cratonic mantle lithosphere after its formation are essential ingredients of the cratonization process. Here we present a geodynamical study that focuses on how the thick stable cratonic lithospheric roots can be made in a thermally evolving mantle. Our numerical experiments explore the viability of a cratonization process in which depleted mantle lithosphere grows via lateral compression into a > 200-km thick, stable cratonic root and on what timescales this may happen. Successful scenarios for craton formation, within the bounds of our models, are found to be composed of two stages: an initial phase of tectonic shortening and a later phase of gravitational self-thickening. The initial tectonic shortening of previously depleted mantle material is essential to initiate the cratonization process, while the subsequent gravitational self-thickening contributes to a second thickening phase that is comparable in magnitude to the initial tectonic phase. Our results show that a combination of intrinsic compositional buoyancy of the cratonic root, rapid cooling of the root after shortening, and the long-term secular cooling of the mantle prevents a Rayleigh-Taylor type collapse, and will stabilize the thick cratonic root for future preservation. This two-stage thickening model provides a geodynamically viable cratonization scenario that is consistent with petrological and geophysical constraints.
DS201703-0439
2016
Wang, H.Wang, H., Li, J., Zhang, H., Xu, L., Li, W.The absolute paleoposition of the North Chin a block during the middle Ordovician.Science China Earth Sciences, Vol. 59, 3, pp. 573-582.ChinaCraton, North China

Abstract: Present-day hot spots and Phanerozoic large igneous provinces (LIPs) and kimberlites mainly occur at the edges of the projections of Large Low Shear Wave Velocity Provinces (LLSVPs) on the earth’s surface. If a plate contains accurately dated LIPs or kimberlites, it is possible to obtain the absolute paleoposition of the plate from the LIP/kimberlite and paleomagnetic data. The presence of Middle Ordovician kimberlites in the North China Block provides an opportunity to determine the absolute paleoposition of the block during the Middle Ordovician. In addition to paleobiogeographical information and the results of previous work on global plate reconstruction for the Ordovician Period, we selected published paleomagnetic data for the North China Block during the Middle Ordovician and determined the most reasonable absolute paleoposition of the North China Block during the Middle Ordovician: paleolatitude of approximately 16.6°S to 19.1°S and paleolongitude of approximately 10°W. The block was located between the Siberian Plate and Gondwana, close to the Siberian Plate. During the Cambrian and Ordovician periods, the North China Block may have moved toward the Siberian Plate and away from the Australian Plate.
DS201706-1114
2017
Wang, H.Zhu, Y-S., Yang, J-H., Sun- J-F., Wang, H.Zircon Hf-0 isotope evidence for recycled oceanic and continental crust in the sources of alkaline rocks.Geology, Vol. 45, 5, pp. 407-410.Mantlealkaline rocks
DS201707-1380
2016
Wang, H.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, in press availableMantlecraton

Abstract: Archean tectonics was capable of producing virtually indestructible cratonic mantle lithosphere, but the dominant mechanism of this process remains a topic of considerable discussion. Recent geophysical and petrological studies have refuelled the debate by suggesting that thickening and associated vertical movement of the cratonic mantle lithosphere after its formation are essential ingredients of the cratonization process. Here we present a geodynamical study that focuses on how the thick stable cratonic lithospheric roots can be made in a thermally evolving mantle. Our numerical experiments explore the viability of a cratonization process in which depleted mantle lithosphere grows via lateral compression into a > 200-km thick, stable cratonic root and on what timescales this may happen. Successful scenarios for craton formation, within the bounds of our models, are found to be composed of two stages: an initial phase of tectonic shortening and a later phase of gravitational self-thickening. The initial tectonic shortening of previously depleted mantle material is essential to initiate the cratonization process, while the subsequent gravitational self-thickening contributes to a second thickening phase that is comparable in magnitude to the initial tectonic phase. Our results show that a combination of intrinsic compositional buoyancy of the cratonic root, rapid cooling of the root after shortening, and the long-term secular cooling of the mantle prevents a Rayleigh-Taylor type collapse, and will stabilize the thick cratonic root for future preservation. This two-stage thickening model provides a geodynamically viable cratonization scenario that is consistent with petrological and geophysical constraints.
DS201801-0078
2017
Wang, H.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, in press available, 10p.Mantlecraton

Abstract: Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.
DS201809-2119
2018
Wang, H.Zhu, Y-S., Yang, J-H., Wang, H., Wu, F-Y.A Paleoproterozoic basement beneath the Rangrim massif revealed by in situ U-Pb ages and Hf isotopes of xenocrystic zircons from Triassic kimberlites of the North Korea.Goldschmidt Conference, 1p. AbstractAsia, North Koreadeposit - Rangrim

Abstract: Zircon xenocrysts from the kimberlites offer a unique opportunity to identify the cryptic basement components hidden in the deep crust and thus to image lithospheric structure and crustal evolution. Zircon xenocrysts from the Triassic kimberlites, exposed in the Rangrim massif of North Korea, were selected for in situ U-Pb and Hf analyses. These zircon xenocrysts are all crust-derived. Their U-Pb age spectrum is characterized by one prominent age population at ca. 1.9-1.8 Ga without any Archean ages, indicating a Paleoproterozoic-dominated basement in the depth of the Rangrim massif. Archean basement should be very limited or absent at depth. This is different with the previous thought of the Rangrim massif being an Archean terrane. However, most of those Paleoproterozoic zircons display negative eHf(t) values (-9.7~+0.7) with the average Hf model age of 2.83 ± 0.09 Ga (2s), implying that protoliths of those zircons were not juvenile but derived from reworking of the pre-existed Archean basement. These observations argue for a strong crustal reworking event occurred in the Rangriam massif during Paleoproterozoic, which exhausted most of the preexisted Archean basement rocks and generated a large abundance of Paleoproterozoic rocks. The 1.9~1.8 Ga thermal event has been well documented in the adjacent Jiao- Liao-Ji orogenic belt of the North China Craton. Both of them are characterized by the widely distributed 1.9~1.8 Ga magmatism and share similar igneous rock assemblage. We suggest that the Rangrim massif may be the eastern extension of the Jiao-Liao-Ji belt in North Korea, constituting part of a huge Paleoproterozoic orogen in the eastern margin of the Sino-Korean craton.
DS201901-0085
2018
Wang, H.Wang, H., van Hunen, J., Pearson, D.G.Making Archean cratonic roots by lateral compression: a two stage thickening and stabilization model.Tectonophysics, Vol. 746, pp. 562-571.Mantlemelting

Abstract: Archean tectonics was capable of producing virtually indestructible cratonic mantle lithosphere, but the dominant mechanism of this process remains a topic of considerable discussion. Recent geophysical and petrological studies have refuelled the debate by suggesting that thickening and associated vertical movement of the cratonic mantle lithosphere after its formation are essential ingredients of the cratonization process. Here we present a geodynamical study that focuses on how the thick stable cratonic lithospheric roots can be made in a thermally evolving mantle. Our numerical experiments explore the viability of a cratonization process in which depleted mantle lithosphere grows via lateral compression into a > 200-km thick, stable cratonic root and on what timescales this may happen. Successful scenarios for craton formation, within the bounds of our models, are found to be composed of two stages: an initial phase of tectonic shortening and a later phase of gravitational self-thickening. The initial tectonic shortening of previously depleted mantle material is essential to initiate the cratonization process, while the subsequent gravitational self-thickening contributes to a second thickening phase that is comparable in magnitude to the initial tectonic phase. Our results show that a combination of intrinsic compositional buoyancy of the cratonic root, rapid cooling of the root after shortening, and the long-term secular cooling of the mantle prevents a Rayleigh-Taylor type collapse, and will stabilize the thick cratonic root for future preservation. This two-stage thickening model provides a geodynamically viable cratonization scenario that is consistent with petrological and geophysical constraints.
DS201902-0336
2019
Wang, H.Zhu, Y-S., Yang, J-H., Wang, H., Wu, F-Y.A Paleoproterozoic basement beneath the Rangnim Massif revealed by the in-situ U-Pb ages and Hf isotopes of xenocrystic zircons from the Triassic kimberlites of North Korea.Geological Magazine, on line available Asia, Koreakimberlites

Abstract: In situ U-Pb and Hf analyses were used for crustal zircon xenocrysts from Triassic kimberlites exposed in the Rangnim Massif of North Korea to identify components of the basement hidden in the deep crust of the Rangnim Massif and to clarify the crustal evolution of the massif. The U-Pb age spectrum of the zircons has a prominent population at 1.9-1.8 Ga and a lack of Archaean ages. The data indicate that the deep crust and basement beneath the Rangnim Massif are predominantly of Palaeoproterozoic age, consistent with the ages of widely exposed Palaeoproterozoic granitic rocks. In situ zircon Hf isotope data show that most of the Palaeoproterozoic zircon xenocrysts have negative ?Hf ( t ) values (-9.7 to +0.7) with an average Hf model age of 2.86 ± 0.02 Ga (2 s ), which suggests that the Palaeoproterozoic basement was not juvenile but derived from the reworking of Archaean rocks. Considering the existence of Archaean remanent material in the Rangnim Massif and their juvenile features, a strong crustal reworking event is indicated at 1.9-1.8 Ga, during which time the pre-existing Archaean basement was exhausted and replaced by a newly formed Palaeoproterozoic basement. These features suggest that the Rangnim Massif constitutes the eastern extension of the Palaeoproterozoic Liao-Ji Belt of the North China Craton instead of the Archaean Liaonan Block as previously thought. A huge Palaeoproterozoic orogen may exist in the eastern margin of the Sino-Korean Craton.
DS201911-2579
2019
Wang, H.Zhu, Y-S., Yang, J-H., Wang, H., Wu, F-Y.A paleoproterozoic basement beneath the Rangnim Massif revealed by the in situ U-Pb ages and Hf isotopes of xenocrystic zircons from Triassic kimberlites of North Korea.Geological Magazine, Vol. 156, 10, pp. 1657-1667.Asia, Koreakimberlites

Abstract: n situ U-Pb and Hf analyses were used for crustal zircon xenocrysts from Triassic kimberlites exposed in the Rangnim Massif of North Korea to identify components of the basement hidden in the deep crust of the Rangnim Massif and to clarify the crustal evolution of the massif. The U-Pb age spectrum of the zircons has a prominent population at 1.9-1.8 Ga and a lack of Archaean ages. The data indicate that the deep crust and basement beneath the Rangnim Massif are predominantly of Palaeoproterozoic age, consistent with the ages of widely exposed Palaeoproterozoic granitic rocks. In situ zircon Hf isotope data show that most of the Palaeoproterozoic zircon xenocrysts have negative ?Hf(t) values (-9.7 to +0.7) with an average Hf model age of 2.86 ± 0.02 Ga (2s), which suggests that the Palaeoproterozoic basement was not juvenile but derived from the reworking of Archaean rocks. Considering the existence of Archaean remanent material in the Rangnim Massif and their juvenile features, a strong crustal reworking event is indicated at 1.9-1.8 Ga, during which time the pre-existing Archaean basement was exhausted and replaced by a newly formed Palaeoproterozoic basement. These features suggest that the Rangnim Massif constitutes the eastern extension of the Palaeoproterozoic Liao-Ji Belt of the North China Craton instead of the Archaean Liaonan Block as previously thought. A huge Palaeoproterozoic orogen may exist in the eastern margin of the Sino-Korean Craton.
DS201805-0990
2018
Wang, H.A.O.Wang, H.A.O., Cartier, L.E., Baumgartner, L.P., Bouvier, A-S., Begue, F., Chalain, J-P., Krzemnicki, M.S.A preliminary SIMS study using carbon isotopes to separate natural from synthetic diamonds.Journal of Gemmology, Vol. 36, 1, pp. 38-43.Technologysynthetics
DS1986-0614
1986
Wang, H.F.Nyquist, J.E., Wang, H.F.Lithospheric flexure and the evolution of the Midcontinent RiftGeoscience Wisconsin, Vol. 11, September pp. 19-22GlobalBlank
DS1988-0513
1988
Wang, H.F.Nyquist, J.E., Wang, H.F.Flexural modeling of the midcontinent rift #2Journal of Geophysical Research, Vol. 93, No. B8, August 10, pp. 8852-8868MidcontinentTectonics, Rifting
DS1988-0514
1988
Wang, H.F.Nyquist, J.E., Wang, H.F.Flexural modeling of the midcontinent rift #1Journal of Geophysical Research, Vol. Part B Paper No.7B6047MidcontinentBlank
DS1992-1041
1992
Wang, H.F.Medaris, L.G.Jr., Wang, H.F.Tectonic implications of garnet peridotite cooling rates: potential andproblemsGeological Society of America (GSA) Abstracts with programs, 1992 Annual, Vol. 24, No. 7, abstract p. A218Norway, Czechoslovakia, Switzerland, SpainPetrology, Garnet peridotite
DS201710-2275
2017
Wang, H.S.Wang, H.S., et al.The elemental abundances ( with uncertainties) of the most Earth-like planet.Icarus, 10.1016/ j.icarus. 2017.08.024Mantlechemical composition

Abstract: To first order, the Earth as well as other rocky planets in the Solar System and rocky exoplanets orbiting other stars, are refractory pieces of the stellar nebula out of which they formed. To estimate the chemical composition of rocky exoplanets based on their stellar hosts' elemental abundances, we need a better understanding of the devolatilization that produced the Earth. To quantify the chemical relationships between the Earth, the Sun and other bodies in the Solar System, the elemental abundances of the bulk Earth are required. The key to comparing Earth's composition with those of other objects is to have a determination of the bulk composition with an appropriate estimate of uncertainties. Here we present concordance estimates (with uncertainties) of the elemental abundances of the bulk Earth, which can be used in such studies. First we compile, combine and renormalize a large set of heterogeneous literature values of the primitive mantle (PM) and of the core. We then integrate standard radial density profiles of the Earth and renormalize them to the current best estimate for the mass of the Earth. Using estimates of the uncertainties in i) the density profiles, ii) the core-mantle boundary and iii) the inner core boundary, we employ standard error propagation to obtain a core mass fraction of 32.5±0.3 wt%. Our bulk Earth abundances are the weighted sum of our concordance core abundances and concordance PM abundances. Our concordance estimates for the abundances of Mg, Sn, Br, B, Cd and Be are significantly lower than previous estimates of the bulk Earth. Our concordance estimates for the abundances of Na, K, Cl, Zn, Sr, F, Ga, Rb, Nb, Gd, Ta, He, Ar, and Kr are significantly higher. The uncertainties on our elemental abundances usefully calibrate the unresolved discrepancies between standard Earth models under various geochemical and geophysical assumptions.
DS1996-0478
1996
Wang, J.Gao, H., Wang, J., Zhao, P.The updated kriging variance and optimal sample designMathematical Geology, Vol. 28, No. 3, pp. 295-313GlobalComputer, Program -kriging variance, sample design
DS2000-0423
2000
Wang, J.Hu, S., He, L., Wang, J.Heat flow in the continental area of China: a new dat a setEarth and Planetary Science Letters, Vol. 179, No. 2, June 30, pp. 407-ChinaGeothermometry, Heat flow
DS2001-0239
2001
Wang, J.De, S., Heaney, P.J., Wang, J.Chemical heterogeneity in carbonado, an enigmatic polycrystalline diamondEarth and Plan. Sci. Letters, Vol. 185, No. 3-4, Feb. 28, pp. 315-30.Central African RepublicGeochemistry - carbonado, Cathodluminescence
DS2002-0681
2002
Wang, J.Hauri, E.H., Wang, J., Pearson, D.G., Bulanova, G.P.Microanalysis of 13C 15 N and N abundances in diamonds by secondary ion mass spectrometry.Chemical Geology, Vol.145, 1-2, Apr.15, pp. 149-63.Russia, SiberiaDiamond - inclusions, carbon, nitrogen isotopes
DS2003-0817
2003
Wang, J.Li, Z.X., Li, X.H., Kinny, P.D., Wang, J., Zhang, S., Zhou, H.Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, SouthPrecambrian Research, Vol. 122, 1-4, pp.85-109.China, RodiniaGeochronology, Magmatism
DS2003-1414
2003
Wang, J.Van Orman, J.A., Fei, Y., Hauri, E.H., Wang, J.Diffusion in MgO at high pressures: constraints on deformation mechanisms andGeophysical Research Letters, Vol. 30, 2, Jan. 15. p. 28.MantleGeochemistry
DS2003-1446
2003
Wang, J.Wang, J., Li, Z.X.History of neoproterozoic rift basins in South China: implications for Rodinia break upPrecambrian Research, Vol. 122, 1-4, pp.141-158.China, RodiniaTectonics
DS200412-1134
2003
Wang, J.Li, Z.X., Li, X.H., Kinny, P.D., Wang, J., Zhang, S., Zhou, H.Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South Chin a and correlations with other continents: evPrecambrian Research, Vol. 122, 1-4, pp.85-109.China, RodiniaGeochronology Magmatism
DS200412-2041
2003
Wang, J.Van Orman, J.A., Fei, Y., Hauri, E.H., Wang, J.Diffusion in MgO at high pressures: constraints on deformation mechanisms and chemical transport at the core mantle boundary.Geophysical Research Letters, Vol. 30, 2, Jan. 15. p. 28.MantleGeochemistry
DS200412-2079
2003
Wang, J.Wang, J., Li, Z.X.History of neoproterozoic rift basins in South China: implications for Rodinia break up.Precambrian Research, Vol. 122, 1-4, pp.141-158.China, RodiniaTectonics
DS200412-2096
2003
Wang, J.Wei, Q., Wang, J., Xie, G.The chemical composition characteristics of clinopyroxenes from spinel lherzolite xenoliths in Maguan area, Eastern Tibet and itEarth Science Frontiers, Vol. 10, 3, pp. 87-92. Ingenta 1035303170China, TibetXenoliths - not specific to diamonds
DS200512-0306
2005
Wang, J.Fu, R., Wang, J., Chang, X., Huang, J., Dai, Z., Zha, X.Upper mantle convection driving by density anomaly and a test model.Acta Seismologica Sinica, Vol. 18, 1, pp. 27-33.MantleGeophysics - seismics
DS200612-0097
2006
Wang, J.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
DS200712-1131
2007
Wang, J.Wang, J., Hattori, K., Killan, R., Stern, C.Metasomatism of sub arc mantle peridotites below southernmost South America: reduction of f02 by slab melt.Contributions to Mineralogy and Petrology, Vol. 153, 5, pp. 607-624.South AmericaMelting
DS200712-1132
2007
Wang, J.Wang, J., Nittler, L.R., Burnett, D.Solar wind Mg, Cr and Fe abundances in diamond like carbon collector from Gemesis mission.Plates, Plumes, and Paradigms, 1p. abstract p. A1085.TechnologyCarbon
DS201112-1123
2011
Wang, J.Wu, Y., Gao, S., Liu, X., Wang, J., Peng, M., Gong, H., Yuan, H.Two stage exhumation of the ultrahigh pressure metamorphic rocks from the Western Dabie Orogen, central China.Journal of Geology, Vol. 119, pp. 15-32.ChinaUHP
DS201112-1124
2011
Wang, J.Wu, Y., Gao, S., liu, X., Wang, J., peng, M., Gong, H., Yuan, H.Two stage exhumation of ultrahigh pressure metamorphic rocks from the western Dabie orogen, Central China.Journal of Geology, Vol. 119, 1, Jan. pp. 15-31.ChinaUHP
DS201112-1125
2011
Wang, J.Wu, Y., Gao, S., Liu, X., Wang, J., Peng, M., Gong, H., Yuan, H.Two stage exhumation of ultrahigh pressure metamorphic rocks from the western Dabie Orogen, central China.Journal of Petrology, Vol. 119, no. 1, pp. 15-31.ChinaUHP
DS201312-0950
2013
Wang, J.Wang, J., Hattori, K., Xie, Z.Oxidation state of lithospheric mantle along the northeastern margin of the North Chin a craton: implications for geodynamic processes.International Geology Review, Vol. 55, no. 11, pp. 1418-1444.ChinaGeodynamics
DS201312-0987
2013
Wang, J.Xie, Z., Hattori, K., Wang, J.Origins of ultramafic rocks in the Sulu ultrahigh pressure terrane, eastern China.Lithos, Vol. 178, pp. 158-170.ChinaUHP
DS201412-0847
2014
Wang, J.Smit, K.V., Wang, Wuyi, Shirey, S.B., Wang, J.Growth conditions of mixed-habit diamonds from Marange, Zimbabwe.Geological Society of America Conference Vancouver Oct. 19-22, 1p. AbstractAfrica, ZimbabweDiamond morphology
DS201701-0031
2016
Wang, J.Smith, E.M., Shirey, S.B., Nestola, F., Bullock, E.S., Wang, J., Richardson, S.H., Wang, W.Large gem diamonds from metallic liquid in Earth's deep mantle.