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SDLRC - Scientific Articles all years by Author - Gi-Gq


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 - Gi-Gq
Posted/
Published
AuthorTitleSourceRegionKeywords
DS2003-0844
2003
GIALoupe, GIASmithsonian Institution exhibit showcases seven of the world's rarest diamondsThe Loupe, GIA, Summer p. 7 ( 1p.)GlobalDiamonds - notable, Steinmetz Pink, Millenium Star colo
DS200712-0359
2007
GIAGIADo you know your diamond? GIA launches its first U.S. National public awareness campaign.GIA, Oct. 12, 1p.United StatesNews item - Diamond Grading Reports
DS201807-1492
2018
GIAGIADr. D. Twitchen ( CVD Element Six) discussion using magnetic resonance and optical techniques to study how defects in diamond affect colour and electrical conductivity. Keynote speakerGIA Symposium , Oct. 7-9, Carlsbad CA United States, Californiasynthetics
DS201212-0240
2012
GIA LabGIA LabCVD synthetic diamonds identified in Hong Kong laboratory.G & G Brief, Vol. 3, 10, July 10, 1/4p.TechnologySynthetic diamonds
DS201112-0368
2011
GIA LaboratoryGIA LaboratoryLab examines a very large HPHT- treated diamond. 38.59 ctGems & Gemology Lab Notes, March 1, 1/4p.TechnologyDiamond - treatment
DS201608-1408
2016
GIA LibraryGIA LibraryRecommended reading & bibliographiesgia.edu/library, Available as a resourceTechnologyGIA Library
DS2001-1025
2001
Giacomelli, L.Scandone, R., Giacomelli, L.The slow boiling of magma chambers and the dynamics of explosive eruptionsJour. Vol. Geotherm. Res., Vol. 110, No. 1-2, Sept. pp. 121-36.GlobalMagma, Phreatomagmatic
DS2000-0053
2000
Giacomo, S.M.Baker, C.K., Giacomo, S.M.Resources and reserves: their uses and abuses by the equity marketsMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 667-76.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS200412-1228
2004
Giadini, D.Marone, F., Van der Meijde, M., Van der Lee, S., Giadini, D.Joint inversion of local, regional and teleseismic dat a for crustal thickness in the Eurasia Africa plate boundary region.Geophysical Journal International, Vol. 154, 2, pp. 499-514.Europe, AsiaGeophysics - seismics, boundary
DS2002-0565
2002
Giambiagi, L.B.Giambiagi, L.B., Ramos, V.A.Structural evolution of the Andes in a transitional zone beneath flat and normal subduction 33-33 ....Journal of South American Earth Sciences, Vol.15,1,Apr.pp.101-116.Argentina, Chile, AndesTectonics
DS1997-0394
1997
Giampaolo, C.Giampaolo, C., Godano, R.F., Barrese, E.The alteration of leucite bearing rocks: a possible mechanismEuropean Journal of Mineralogy, Vol. 9, No. 6, Nov. 1, pp. 1277-1292.ItalyLeucite
DS1985-0521
1985
Giampiero, P.Peccerillo, A., Giampiero, P.Primary Potassic Magmas in the Roman Province: Condition Of genesis and Geodynamic Implications.Geological Association of Canada (GAC)., Vol. 10, P. A47, (abstract.).ItalyBlank
DS201911-2526
2019
Giampouras, M.Giampouras, M., Garrido, C.J., Zwicker, J., Vadillo, I., Smrzka, D., Bach, W., Peckmann, J., Jemenez, P., Benavente, J., Garcia-Ruiz, J.M.Geochemistry and mineralogy of serpentinization driven hyperalkaline springs in the Ronda peridotite.Lithos, doi 10.1016/j.lithos.2019.105215, 75p. PdfEurope, Spaindeposit - Ronda

Abstract: We present a detailed study of the water geochemistry, mineralogy and textures in serpentinization-related hyperalkaline springs in the Ronda peridotites. Ronda waters can be classified into hyperalkaline fluids and river waters that are broadly similar to Ca2+-OH- and Mg2+-HCO3- water types described in serpentinite-hosted alkaline springs elsewhere. At the discharge sites of the fluids (fractures or human made outlets) and ponds along the fluid flow paths, the fluids are hyperalkaline (10.9 < pH < 12) and characterized by low Mg and high Na, K, Ca, and Cl concentrations. River waters, occurring near the spring sites, are mildly alkaline (8.5 < pH < 8.9) and enriched in Mg and DIC compared to Na, K, Ca and Cl. The chemistry of Ronda Mg-HCO3 river waters is likely due to the hydrolysis of ferromagnesian peridotite minerals in equilibrium with the atmosphere by infiltrated meteoric water and shallow groundwater in the serpentinized peridotite. The Ronda Ca-OH hyperalkaline fluids are generated by the combination of low temperature serpentinization reactions from infiltrated surface Mg-HCO3 river waters —or Ca-HCO3 waters from near karst aquifers— and deep carbonate precipitation isolated from atmospheric CO2. Mass balance calculations indicate that the weathering of Ca-bearing peridotite silicates such as diopside is a feasible source of Ca in Ronda Ca-OH hyperalkaline fluids; however, it requires steady-state dissolution rates substantially greater than those determined experimentally. Travertine, crystalline crusts and sediment deposits are the main types of solid precipitates observed in Ronda hyperalkaline spring sites. Calcite and aragonite, minor dolomite and Mg-Al-rich clays are the main minerals in the spring sites. As illustrated in the Baños del Puerto spring site, (i) calcite-dominated precipitation is due to hyperalkaline fluid uptake of atmospheric CO2 during discharge, and (ii) aragonite-dominated precipitation is due to mixing of Ca-OH hyperalkaline fluids with Mg- HCO3 river waters. Aragonite and dolomite contents increase away from the springs and toward the river waters that uniquely reflects the effect of Mg ions on the precipitation of aragonite versus calcite. Other potential factors controlling the precipitation of these CaCO3 polymorphs are the Mg/Ca ratio, the CO2 content, and the temperature of the fluids. Dolomite forms during lithification of travertine due to periodic flooding of river water combined with subsequent evaporation.
DS201904-0714
2019
Gianese, A.Anzolini, C., Nestola, F., Mazzucchelli, M.L., Alvaro, M., Nimis, P., Gianese, A., Morganti, S., Marone, F., Campione, M., Hutchison, M.T., Harris, J.W.Depth of diamond formation obtained from single periclase inclusions. SDD ( Super Deep Diamonds)Geology , Vol. 47, 3, pp. 219-222.South America, Brazil, Guyanadiamond genesis

Abstract: Super-deep diamonds (SDDs) are those that form at depths between ~300 and ~1000 km in Earth’s mantle. They compose only 1% of the entire diamond population but play a pivotal role in geology, as they represent the deepest direct samples from the interior of our planet. Ferropericlase, (Mg,Fe)O, is the most abundant mineral found as inclusions in SDDs and, when associated with low-Ni enstatite, which is interpreted as retrogressed bridgmanite, is considered proof of a lower-mantle origin. As this mineral association in diamond is very rare, the depth of formation of most ferropericlase inclusions remains uncertain. Here we report geobarometric estimates based on both elasticity and elastoplasticity theories for two ferropericlase inclusions, not associated with enstatite, from a single Brazilian diamond. We obtained a minimum depth of entrapment of 15.7 (±2.5) GPa at 1830 (±45) K (~450 [±70] km depth), placing the origin of the diamond-inclusion pairs at least near the upper mantle-transition zone boundary and confirming their super-deep origin. Our analytical approach can be applied to any type of mineral inclusion in diamond and is expected to allow better insights into the depth distribution and origin of SDDs.
DS201610-1893
2016
Gianni, M.Pamato, M.G., Kurnosov, A., Boffa Ballaran, T., Frost, D.J., Ziberna, L., Gianni, M., Speziale, S., Tkachev, S.N., Zhuravlev, K.K., Prakapenka, V.B.Single crystal elasticity of majoritic garnets: stagnant slabs and thermal anomalies at the base of the transition zone.Earth and Planetary Science Letters, Vol. 451, pp. 114-124.MantleSubduction

Abstract: The elastic properties of two single crystals of majoritic garnet (Mg3.24Al1.53Si3.23O12 and Mg3.01Fe0.17Al1.68Si3.15O12), have been measured using simultaneously single-crystal X-ray diffraction and Brillouin spectroscopy in an externally heated diamond anvil cell with Ne as pressure transmitting medium at conditions up to ~30 GPa and ~600 K. This combination of techniques makes it possible to use the bulk modulus and unit-cell volume at each condition to calculate the absolute pressure, independently of secondary pressure calibrants. Substitution of the majorite component into pyrope garnet lowers both the bulk (KsKs) and shear modulus (G ). The substitution of Fe was found to cause a small but resolvable increase in KsKs that was accompanied by a decrease in ?Ks/?P?Ks/?P, the first pressure derivative of the bulk modulus. Fe substitution had no influence on either the shear modulus or its pressure derivative. The obtained elasticity data were used to derive a thermo-elastic model to describe VsVs and VpVp of complex garnet solid solutions. Using further elasticity data from the literature and thermodynamic models for mantle phase relations, velocities for mafic, harzburgitic and lherzolitic bulk compositions at the base of Earth's transition zone were calculated. The results show that VsVs predicted by seismic reference models are faster than those calculated for all three types of lithologies along a typical mantle adiabat within the bottom 150 km of the transition zone. The anomalously fast seismic shear velocities might be explained if laterally extensive sections of subducted harzburgite-rich slabs pile up at the base of the transition zone and lower average mantle temperatures within this depth range.
DS2001-0465
2001
Giannuzzi, L.Heaney, P.J., Vicenzi, E.P., Giannuzzi, L., Livi, K.J.T.Focused ion beam milling: a method of site specific sample extraction for microanalysis of Earth materials.American Mineralogist, Vol. 86, pp. 1094-99.GlobalMicroanalysis - TEM, FIB
DS201904-0738
2019
Gianola, O.Galli, A., Grassi, D., Sartori, G., Gianola, O., Burg, J-P., Schmidt, M.W.Jurassic carbonatite and alkaline magmatism in the Ivrea zone ( European Alps) related to the breakup of Pangea.Geology, Vol. 47, 3, pp. 199-202..Europecarbonatite

Abstract: We report on pipe-like bodies and dikes of carbonate rocks related to sodic alkaline intrusions and amphibole mantle peridotites in the Ivrea zone (European Southern Alps). The carbonate rocks have bulk trace-element concentrations typical of low-rare earth element carbonatites interpreted as cumulates of carbonatite melts. Faintly zoned zircons from these carbonate rocks contain calcite inclusions and have trace-element compositions akin to those of carbonatite zircons. Laser ablation-inductively coupled plasma-mass spectrometry U-Pb zircon dating yields concordant ages of 187 ± 2.4 and 192 ± 2.5 Ma, coeval with sodic alkaline magmatism in the Ivrea zone. Cross-cutting relations, ages, as well as bulk and zircon geochemistry indicate that the carbonate rocks are carbonatites, the first ones reported from the Alps. Carbonatites and alkaline intrusions are comagmatic and were emplaced in the nascent passive margin of Adria during the Early Jurassic breakup of Pangea. Extension caused partial melting of amphibole-rich mantle domains, yielding sodic alkaline magmas whose fractionation led to carbonatite-silicate melt immiscibility. Similar occurrences in other rifts suggest that small-scale, sodic and CO2-rich alkaline magmatism is a typical result of extension and decompression-driven reactivation of amphibole-bearing lithospheric mantle during passive continental breakup and the evolution of magma-poor rifts.
DS1950-0148
1953
Giardini, A.A.Mitchell, R.S., Giardini, A.A.Oriented Olivine Inclusions in DiamondAmerican Mineralogist., Vol. 38, No. 1-2, PP. 136-138.GlobalDiamond Morphology
DS1970-0915
1974
Giardini, A.A.Giardini, A.A., Hurst, V.J., Melton, C.E., Stormer, J.C.Jr.Biotite As a Primary Inclusion in Diamond: its Nature and Significance.American Mineralogist., Vol. 59, PP. 783-789.United States, Gulf Coast, Arkansas, Pennsylvania, South AfricaMineral Chemistry
DS1970-0959
1974
Giardini, A.A.Melton, C.E., Giardini, A.A.The Composition and Significance of Gas Released from Natural Diamonds from Africa and Brasil.American MINERALOGIST., Vol. 59, No. 7-8, PP. 775-782.South Africa, BrazilMineralogy, Diamond Genesis
DS1975-0081
1975
Giardini, A.A.Giardini, A.A., Melton, C.E.Chemical Dat a on a Colorless Arkansaw Diamond and its Black amorphous C Iron Nickel S Inclusion.American Mineralogist., Vol. 60, PP. 934-936.United States, Gulf Coast, Arkansas, PennsylvaniaMineral Chemistry, Age Of Diamonds
DS1975-0082
1975
Giardini, A.A.Giardini, A.A., Melton, C.E.The Nature of Cloud Like Inclusions in Two Arkansaw DiamondsAmerican Mineralogist., Vol. 60, PP. 932-933.United States, Gulf Coast, Arkansas, PennsylvaniaMineralogy
DS1975-0135
1975
Giardini, A.A.Melton, C.E., Giardini, A.A.Experimental Results and a Theoretical Interpretation of Gaseous Inclusions Found in Arkansaw Natural Diamonds.American Mineralogist., Vol. 60, PP. 413-417.United States, Gulf Coast, Arkansas, PennsylvaniaMineral Chemistry
DS1975-0577
1977
Giardini, A.A.Mitchell, R.S., Giardini, A.A.Some Mineral Inclusions from African and Brazilian Diamonds: Their Nature and Significance.American MINERALOGIST., Vol. 62, No. 7-8, PP. 756-762.South Africa, BrazilMineral Chemistry
DS1975-0588
1977
Giardini, A.A.Newton, M.G., Melton, C.E., Giardini, A.A.Mineral Inclusion in an Arkansaw DiamondAmerican Mineralogist., Vol. 62, No. 5-6, PP. 583-586.United States, Gulf Coast, Arkansas, PennsylvaniaMineralogy, Murfreesboro
DS1975-0750
1978
Giardini, A.A.Gogineni, S.V., Melton, C.E., Giardini, A.A.Some Petrological Aspects of the Prairie Creek Diamond Bearing Kimberlite Diatreme, Arkansaw.Contributions to Mineralogy and Petrology, Vol. 66, No. 3, PP. 251-262.United States, Gulf Coast, Arkansas, PennsylvaniaPetrology, Lamproite
DS1980-0233
1980
Giardini, A.A.Melton, C.E., Giardini, A.A.The Isotopic Composition of Argon Included in an Arkansaw Diamond and its Significance.Geophysical Research. LETTERS, Vol. 7, No. 6, PP. 461-464.United States, Gulf Coast, Arkansas, PennsylvaniaIsotope, Inclusion, Mineral Chemistry
DS1981-0298
1981
Giardini, A.A.Melton, C.E., Giardini, A.A.The Nature and Significance of Occluded Fluids in Three Indian Diamonds.American Mineralogist., Vol. 66, No. 7-8, JULY-AUGUST PP. 746-750.India, PannaMineral Chemistry
DS1982-0429
1982
Giardini, A.A.Melton, C.E., Giardini, A.A.The Evolution of the Earth's Atmosphere and OceansGeophysical Research Letters, Vol. 9, No. 5, May pp. 579-82.ArkansasDiamonds
DS1987-0464
1987
Giardini, A.A.Melton, C.E., Giardini, A.A.A model to explain the earth's magnetic field and othergeodynamicphenomenaJournal of Petroleum Geology, Vol. 10, No. 4, October pp. 441-452GlobalGeophysics
DS1999-0053
1999
Giardini, D.Becker, T.W., Faccena, C., Giardini, D.The development of slabs in the upper mantle: insights from numerical and laboratory experiments.Journal of Geophysical Research, Vol. 104, No. 7, July 10, pp. 15207-26.MantleExperimental, Subduction
DS2003-0198
2003
Giardini, D.Cammarano, F., Goes, S., Vacher, P., Giardini, D.Inferring upper mantle temperatures from seismic velocitiesPhysics of the Earth and Planetary Interiors, Vol. 138, 3-4, pp. 197-222.MantleGeophysics - seismics
DS2003-1412
2003
Giardini, D.Van der Meijde, M., Marone, F., Giardini, D., Van Der Lee, S.Seismic evidence for water deep in Earth's upper mantleScience, No. 5625, June 6, p. 1556-57.MantleWater
DS200412-0255
2003
Giardini, D.Cammarano, F., Goes, S., Vacher, P., Giardini, D.Inferring upper mantle temperatures from seismic velocities.Physics of the Earth and Planetary Interiors, Vol. 138, 3-4, pp. 197-222.MantleGeophysics - seismics
DS200412-0592
2004
Giardini, D.Funicello, F., Faccenna, C., Giardini, D.Role of lateral mantle flow in the evolution of subduction systems: insights from laboratory experiments.Geophysical Journal International, Vol. 157, 3, pp. 1393-1406.MantleSubduction
DS200412-1227
2004
Giardini, D.Marone, F., Van der Lee, S., Giardini, D.Three dimensional upper mantle S velocity model for the Eurasia Africa plate boundary region.Geophysical Journal International, Vol. 158, 1, pp.109-130.Africa, EuropeTectonics, geophysics - seismics
DS200412-2039
2003
Giardini, D.Van der Meijde, M., Marone, F., Giardini, D., Van Der Lee, S.Seismic evidence for water deep in Earth's upper mantle.Science, No. 5625, June 6, p. 1556-57.MantleWater
DS200512-0131
2005
Giardini, D.Cammarano, F., Deuss, A., Goes, S., Giardini, D.One dimensional physical reference models for the upper mantle and transition zone: combining seismic and mineral physics constraints.Journal of Geophysical Research, Vol. 110, B1, B01306MantleGeophysics - seismics
DS200512-0132
2005
Giardini, D.Cammarano, F., Goes, S., Deuss, A., Giardini, D.Is a pyrolitic adiabatic mantle compatible with seismic data?Earth and Planetary Science Letters, Vol. 232, 3-4, April 15, pp. 227-243.MantleGeophysics - seismics
DS200712-0143
2007
Giardini, D.Capitanio, F.A., Goes, S., Morra, G., Giardini, D.Signatures of downgoing plate buoyancy driven subduction in motions and seismic coupling at major subduction zones.Earth and Planetary Science Letters, Vol. 262, 1-2, pp. 286-306.MantleSubduction
DS202005-0751
2020
Giardini, D.Munch, F.D., Khan, A., Tauzin, B., vn Driel, M., Giardini, D.Seismological evidence for thermo-chemical heterogeneity in Earth's continental mantle.Earth and Planetary Science Letters, Vol. 539, 116240 9p. PdfMantlegeophysics - seismics

Abstract: Earth's thermo-chemical structure exerts a fundamental control on mantle convection, plate tectonics, and surface volcanism. There are indications that mantle convection occurs as an intermittent-stage process between layered and whole mantle convection in interaction with a compositional stratification at 660 km depth. However, the presence and possible role of any compositional layering in the mantle remains to be ascertained and understood. By interfacing inversion of a novel global seismic data set with petrologic phase equilibrium calculations, we show that a compositional boundary is not required to explain short- and long-period seismic data sensitive to the upper mantle and transition zone beneath stable continental regions; yet, radial enrichment in basaltic material reproduces part of the complexity present in the data recorded near subduction zones and volcanically active regions. Our findings further indicate that: 1) cratonic regions are characterized by low mantle potential temperatures and significant lateral variability in mantle composition; and 2) chemical equilibration seems more difficult to achieve beneath stable cratonic regions. These findings suggest that the lithologic integrity of the subducted basalt and harzburgite may be better preserved for geologically significant times underneath cratonic regions.
DS1991-0568
1991
Giarmita, M.J.Giarmita, M.J., Sorenson, S.S.Fluids attending moderate depths of subduction: evidence from fluid inclusions in Type-C eclogites from high grade rocksGeological Society of America Annual Meeting Abstract Volume, Vol. 23, No. 5, San Diego, p. A 447GlobalEclogites, Subduction
DS1992-0559
1992
Giavocazzo, C.Giavocazzo, C.Fundamentals of crystallographyBlackwell Scientific, 500pGlobalCrystallography, Book -ad
DS1998-0712
1998
Gibb, A.J.Kamber, B.S., Frei, R., Gibb, A.J.pit falls and new approaches in granulite chronometry. an example from the Limpopo Belt, ZimbabwePrecambrian Research, Vol. 91, No. 3-4, Aug. 31, pp. 269-286ZimbabweGeochronology, Limpopo Belt
DS1996-0520
1996
Gibb, F.G.Gibb, F.G.Magmatic processes: do the answers lie in the rocks?Mineralogical Magazine, Vol. 60, No. 398, Feb. pp. 1-3.MantleTectonics - plate, Magmatism
DS1980-0085
1980
Gibb, F.G.F.Carswell, D.A., Gibb, F.G.F.Geothermometry of the Garnet Lherzolite Nodules with Special Reference to Those Kimberlites of Northern Lesotho.Contributions to Mineralogy and Petrology, Vol. 74, No. 4, PP. 403-416.LesothoGeothermometry
DS1980-0086
1980
Gibb, F.G.F.Carswell, D.A., Gibb, F.G.F.The Equilibrium Conditions and Petrogenesis of European Crustal Garnet Lherzolites.Lithos, Vol. 13, No. 1, PP. 19-30.ScandinaviaPetrography
DS1980-0141
1980
Gibb, F.G.F.Gibb, F.G.F.Geothermometry of Garnet Lherzolite Nodules with Special Reference to Those from the Kimberlites of Northern Lesotho.Contributions to Mineralogy and Petrology, Vol. 74, PP. 403-416.LesothoGeothermometry
DS1981-0112
1981
Gibb, F.G.F.Carswell, D.A., Dawson, J.B., Gibb, F.G.F.Equilibrium Conditions of Upper Mantle Eclogites: Implications for Kyanite Bearing and Diamondiferous Varieties.Mineralogical Magazine., Vol. 44, PP. 79-89.South AfricaRoberts Victor, Bellsbank, Petrology
DS1987-0089
1987
Gibb, F.G.F.Carswell, D.A., Gibb, F.G.F.Evaluation of mineral thermometers and barometers applicable to garnetlherzolite assemblagesContributions to Mineralogy and Petrology, Vol. 95, No. 4, pp. 499-511GlobalGeochemistry, Geobarometry
DS1987-0090
1987
Gibb, F.G.F.Carswell, D.A., Gibb, F.G.F.Garnet lherzolite xenoliths in the kimberlites of northernLesotho:revised P-T equilibraium conditions and upper mantlePaleogeotherM.Contributions to Mineralogy and Petrology, Vol. 97, No. 4, pp. 473-487LesothoKimberlite, Geothermometry
DS1996-0521
1996
Gibb, F.G.F.Gibb, F.G.F., Henderson, C.M.B.Magmatic processes - introductionMineralogical Magazine, Vol. 60, No. 1, Feb pp. 1-4GlobalMagmatic processes
DS1970-0295
1971
Gibb, R.A.Gibb, R.A., et al.A Precambrian Suture in the Canadian ShieldEarth and Planetary Science Letters, Vol. 10, pp. 417-22.Labrador, QuebecTectonics - Lineaments
DS1983-0249
1983
Gibb, R.A.Gibb, R.A.Model for Suturing of Superior and Churchill Plates: an Example of Double Indentation Tectonics.Geology, Vol. 11, No. 7, PP. 413-417.CanadaGeotectonics
DS1983-0250
1983
Gibb, R.A.Gibb, R.A., et al.Geophysics of Proposed Proterozoic Sutures in CanadaPrecambrian Research, Vol. 19, pp. 349-384.Canada, Shield, Northwest Territories, OntarioTectonics - Lineaments
DS1983-0251
1983
Gibb, R.A.Gibb, R.A., et al.Model for suturing of Superior and Churchill plates: an example of double indentation tectonics.Geology, Vol. 11, No. 7, July pp. 413-17.Ontario, Labrador, QuebecTectonics - Lineaments
DS1989-1217
1989
Gibb, R.A.Pilkington, M., Grieve, R.A.F., Gibb, R.A., Halpenny, J.F.Derived potential field dat a sets for North AmericaGeological Society of Canada (GSC) Forum 1989, P. 20 abstractGlobalMidcontinent, Geophysics
DS1991-1711
1991
Gibb, R.A.Teskey, D.J., Thomas, M.D., Gibb, R.A., Dods, S.D., Kucks, R.P.High resolution aeromagnetic survey of Lake SuperiorEos, Vol. 72, No. 8, February 19, p. 81, 85, 86Ontario, MichiganBlank
DS1993-1584
1993
Gibb, R.A.Teskey, D.J., Dumont, R., Stone, P.E., Gibb, R.A.The aeromagnetic survey program of the Geological Society of Canada (GSC)- implications for kimberliteexploration.Mid-continent diamonds Geological Association of Canada (GAC)-Mineralogical Association of Canada (MAC) Symposium ABSTRACT volume, held Edmonton May, pp. 27-30.Northwest TerritoriesGeophysics
DS1994-0617
1994
Gibb, R.A.Gibb, R.A., Hinze, W.J., Thomas, M.D.Potential field studies of continental rifts -The Great Lakes region:introduction.Canadian Journal of Earth Sciences, Vol. 31, No. 4, April pp. 617-618.Ontario, MichiganGeophysics -seismics, Tectonics -Midcontinent rift
DS2000-0904
2000
Gibbard, P.L.Smith, G.R., Woodward, J.C., Gibbard, P.L.Interpreting Pleistocene glacial features from SPOT HRV dat a using fuzzy techniques.Computers and Geosciences, Vol. 26, No. 4, Apr. pp. 479-90.GlobalGeomorphology - not specific to diamonds, Remote sensing
DS1859-0098
1849
Gibbes, R.W.Gibbes, R.W.Report on the Geology of South Carolina South Quarterly Rev., Vol. 16, Oct. PP. 161-178.United States, North Carolina, South Carolina, Georgia, AppalachiaDiamond Occurrence
DS1860-0843
1894
Gibbins, H.J.Gibbins, H.J.Curiousities of DiamondThe Gentleman's Magazine., Vol. 52, PP. 243-250.Africa, South AfricaHistory
DS1992-0560
1992
Gibbins, W.A.Gibbins, W.A., Atkinson, D.Diamond exploration in the Northwest Territories #2northwest Territories Geology Division, Revised edition March 1992, 12 p. 7 figuresNorthwest TerritoriesDiamond exploration overview, Lac de Gras, Blackwater River, North Plateau, Somerset
DS1992-0561
1992
Gibbins, W.A.Gibbins, W.A., Atkinson, D.Diamond exploration in the Northwest Territories #1northwest Territories Geology Division, DIAND Yellowknife, 16pNorthwest TerritoriesOverview -history, Diamond exploration -current activities
DS1960-0346
1963
Gibbons, G.S.Gibbons, G.S., Pogson, D.J.Report on the Airly Mountain Diamond ProspectNew South Wales Geological Survey Report., GS 1963/001, (UNPUBL.).AustraliaKimberlite
DS1960-0347
1963
Gibbons, G.S.Gibbons, G.S., Pogson, D.J.Diamond Deposits at Mount Rose, Copeton, New South WalesNew South Wales Geological Survey Report., GS 1963/002, (UNPUBL.).AustraliaKimberlite
DS1960-0348
1963
Gibbons, G.S.Gibbons, G.S., Webster, S.S., Pogson, D.J.Investigations of Airly Mountains Diamond ProspectNew South Wales Geological Survey Report., GS 1963/064, (UNPUBL.).AustraliaKimberlite
DS1991-0165
1991
Gibbons, G.S.Branagan, D.F., Gibbons, G.S., Williams, K.L.The geological mapping of two southern continentsEdgeworth David Socity Department of Geology and Geophysics, University of, Australia, AntarcticaBook -ad, Geological mapping
DS201710-2218
2017
Gibbons, J.Burness, S., Smart, K.A., Stevens, G., Tappe, S., Sharp, Z.D., Gibbons, J.S-bearing metasomatism of mantle eclogites: constraints from the Kaapvaal craton and experiments.Goldschmidt Conference, 1p. AbstractAfrica, South Africadeposit - Roberts Victor, Jagersfontein
DS1989-0509
1989
Gibbs, A.Gibson, I.L., Roberts, R.G., Gibbs, A.An extensional fault model for the early development of greenstone belts- areplyEarth and Planetary Science Letters, Vol. 92, No. 1, February pp. 127-128OntarioGreenstone belt, Tectonics
DS1990-0215
1990
Gibbs, A.D.Blundell, D.J., Gibbs, A.D.Tectonic evolution of the North Sea riftsClarendon Press, Oxford, 272p. Cost?North SeaTectonics, Rifting
DS1983-0252
1983
Gibbs, A.K.Gibbs, A.K., Barron, C.N.The Guiana Shield ReviewedEpisodes, 1983, No. 2, PP. 7-14.South America, Guiana, Venezuela, Guyana, Suriname, French GuianaRegional Geology, Geotectonics, Stratigraphy, Roraima, Parguazan
DS1984-0303
1984
Gibbs, A.K.Gibbs, A.K., Payne, B., Setzer, T., Brown, L.D., Oliver, J.E.Seismic Reflection Study of the Precambrian Crust of Central Minnesota.Geological Society of America (GSA) Bulletin., Vol. 95, No. 3, PP. 280-294.GlobalMid-continent
DS1985-0231
1985
Gibbs, A.K.Gibbs, A.K.Contrasting Styles of Continental Mafic Intrusions in the Guiana Shield.International Symposium ON MAFIC DIKE SWARMS, HELD TORONTO, JUNE 4-7TH, 22P. 5 FIGS.South America, Guiana, Brazil, Venezuela, GuyanaLamprophyres, Carbonatite, Geotectonics
DS1985-0232
1985
Gibbs, A.K.Gibbs, A.K., Wirth, K.R.Origin and Evolution of the Amazonian CratonLunar Planetary Science Institute, Nasa Workshop On Early Cr, JUNE-JULY , 4P.South America, Guiana, French Guiana, BrazilGeotectonics, Granite, Greenstone Belts
DS1987-0250
1987
Gibbs, A.K.Gibbs, A.K.Contrasting styles of continental mafic intrusions in the Guiana Shieldin: Mafic dyke swarms, editors, Halls, H.C., Fahrig, W.F. Geological, Special Paper 34, pp. 457-465VenezuelaRoraima Group p. 461
DS1992-0562
1992
Gibbs, A.K.Gibbs, A.K., Barron, C.N.Geology of the Guyana shieldOxford University of Press, 304p. 1 color map approx.$ 85.00 United StatesGuyanaGeology, Regional
DS1992-0563
1992
Gibbs, A.K.Gibbs, A.K., Barron, C.N.Geology of the Kapuskasing-Groundhog-Missinaibi River area, Folyet andKapuskasingOxford University Press, 304pGuyana ShieldGeology Guyana shield, Book -ad
DS1993-0536
1993
Gibbs, A.K.Gibbs, A.K., Barron, C.N.Archean-Proterozoic supracrustals, Trans-Amazonian.The Geology of the Guiana Shield, Oxford University Press, approx. cost, 246pGlobalShield, Regional geology
DS1993-0537
1993
Gibbs, A.K.Gibbs, A.K., Barron, C.N.Mention of diamonds in index - SurimamThe Geology of the Guiana Shield, Oxford University Press, approx. cost, 246p. pp. 187, 192-195Guyana, Brazil, Roraima, Venezuela, French GuianaGeology, Guiana Shield
DS1993-0538
1993
Gibbs, A.K.Gibbs, A.K., Barron, C.N.The geology of the Guiana ShieldOxford University Press, 250pSouth AmericaGuiana shield, Book -table of contents
DS1993-0539
1993
Gibbs, A.K.Gibbs, A.K., Barron, C.N.Mention of diamonds in index - SurimamThe Geology of the Guiana Shield, Oxford University Press, approx. cost, 246p. pp. 189, 192SurinameGeology
DS1991-0569
1991
Gibbs, B.Gibbs, B., Krajewski, S.Directory of mining programs and public domain software for earthGibbs Associates, Directory $ 75.00 United States Software handbook $ 25.00 United StatesGlobalComputer, Program -directory
DS1991-0570
1991
Gibbs, B.Gibbs, B., Krajewski, S.Public domain software for earth scientists: handbook of public domain and inexpensive softwareGibbs and Associates, 189p. $ 40.00United StatesComputer programs, Lists
DS1991-0571
1991
Gibbs, B.Gibbs, B., Krajewski, S.A.Workshop attendees compare ore modeling and mine planning softwaresystemsMining Engineering, Vol. 43, No. 7, July pp. 732-737GlobalGeostatistics, Computer -programs for ore modeling comparisons
DS1992-0564
1992
Gibbs, B.L.Gibbs, B.L., Krajewski, S.A.Surface and underground mine modelling with computersMining Engineering, Vol. 44, No. 7, July pp. 689-693GlobalComputers, Program -Mine modelling
DS1994-0944
1994
Gibbs, B.L.Krajewski, S.A., Gibbs, B.L.Computers contouring generates artifactsGeotimes, Vol. 39, No. 4, April pp. 15-19GlobalComputer programs, Applications - artifacts
DS1996-0025
1996
Gibbs, B.L.Anderson, D.A., Gibbs, B.L.Mining the internet.Mining Engineering, Vol. 48, No. 2, Feb. pp. 48-52United StatesMining, Computers -internet
DS1997-0395
1997
Gibbs, B.L.Gibbs, B.L.Exploring with modern technology.... WEB for minerals informationEngineering and Mining Journal, Vol. 198, No. 12, Dec. pp. 32J-L.GlobalComputer - programs, WEB news
DS2003-0462
2003
Gibbs, B.L.Gibbs, B.L.Modeling makes the difference. Virtual designs result in more efficient productionEngineering and Mining Journal, April pp. 22-26.GlobalComputer - software - not specific to diamonds
DS200412-0659
2003
Gibbs, B.L.Gibbs, B.L.Modeling makes the difference. Virtual designs result in more efficient production.Engineering and Mining Journal, April pp. 22-26.TechnologyComputer - software - not specific to diamonds
DS2002-1370
2002
Gibbs, G.V.Ross, N.L., Gibbs, G.V., Rosso, K.M.Potential proton sites in high pressure silicates18th. International Mineralogical Association Sept. 1-6, Edinburgh, abstract p.80.MantleUHP mineralogy - perovskites
DS2003-0463
2003
Gibbs, G.V.Gibbs, G.V.The silica polymorph coesite: an exploration of the electron density distributionGeological Society of America, Annual Meeting Nov. 2-5, Abstracts p. 535.GlobalMineralogy - experimental
DS200412-0660
2003
Gibbs, G.V.Gibbs, G.V.The silica polymorph coesite: an exploration of the electron density distribution.Geological Society of America, Annual Meeting Nov. 2-5, Abstracts p. 535.TechnologyMineralogy - experimental
DS1997-0396
1997
Gibbs, W.W.Gibbs, W.W.Taking computers to taskScientific American, July pp. 82-89GlobalComputers - productivity
DS201912-2783
2019
Gibbs, W.W.Gibbs, W.W.A new form of pure carbon dazzles and attracts.Science, Vol. 366, 6467, pp. 782-783.Mantlecarbon

Abstract: A "happy accident" has yielded a new, stable form of pure carbon made from cheap feedstocks, researchers say. Like diamond and graphene, two other guises of carbon, the material seems to have extraordinary physical properties. It is harder than stainless steel, about as conductive, and as reflective as a polished aluminum mirror. Perhaps most surprising, the substance appears to be ferromagnetic, behaving like a permanent magnet at temperatures up to 125°C. The discovery, announced in a talk here at the International Symposium on Clusters and Nanomaterials, could lead to lightweight coatings, medical products, and novel electronic devices. The news has elicited both excitement and caution among the dozens of researchers attending the meeting. Experts note that carbon is much lighter than other ferromagnetic elements such as manganese, nickel, and iron. Moreover, carbon is nontoxic in the body—which could mean the substance could be used for making biosensors or drug-delivery carriers.
DS2003-0464
2003
Gibert, B.Gibert, B., Sepold, U., Tommasi, A., Mainprice, D.Thermal diffusivity of upper mantle rocks: influence of temperature, pressure and theJournal of Geophysical Research, Vol. 108, 8, ECV 1 , DOI 10.1029/2002JB002108MantleGeothermometry
DS200412-0661
2003
Gibert, B.Gibert, B., Sepold, U., Tommasi, A., Mainprice, D.Thermal diffusivity of upper mantle rocks: influence of temperature, pressure and the deformation fabric.Journal of Geophysical Research, Vol. 108, 8, ECV 1 , DOI 10.1029/2002 JB002108MantleGeothermometry
DS201212-0241
2012
Gibert, G.Gibert, G., Gerbault, M., Hassani, R., Tric, E.Dependency of slab geometry on absolute velocities and conditions for cyclicity: insights from numerical modelling.Geophysical Journal International, in press availableMantleSubduction
DS2000-0013
2000
Gibling, M.R.Alsop, G.I., Brown, J.P., Gibling, M.R.The geometry of drag zones adjacent to salt diapirsJournal of Geological Society of London, Vol. 157, No. 5, Sept.pp.1019-30.GlobalStructure - diapirs ( salt) not specific to diamond
DS201412-0289
2014
Gibney, E.Gibney, E.First buckball molecules created from boron.Nature, Vol. 511, July 17, pp. 330-333.TechnologyBrunswick anomaly
DS201112-0640
2011
GibsherMalkovets, V.G., Zedgenizov, Sobolev, Kuzmin, Gibsher, Shchukina, Golovin, Verichev, PokhilenkoContents of trace elements in olivines from diamonds and peridotite xenoliths of the V.Grib kimberlite pipe ( Arkhangel'sk Diamondiferous province, Russia).Doklady Earth Sciences, Vol. 436, 2, pp. 301-307.RussiaDeposit - Grib
DS201012-0234
2010
Gibsher, A.Gibsher, A., Malkovets, V., Travin, A.New Ar Ar dat a of the lamprophyric dykes of west Sangilen ( southeast Tuva south Russia): the oldest mantle xenoliths bearing basaltic hosts.International Dyke Conference Held Feb. 6, India, 1p. AbstractRussia, TuvaGeochronology
DS201903-0512
2018
Gibsher, A.Gibsher, A.Mineral inclusions in Siberian diamonds: mineralogy, geochemistry and application to diamond exploration.7th Symposio Brasleiro de geologia do diamante, 22 ppts. Pdf availableRussia, Siberiadiamond inclusions
DS201212-0242
2012
Gibsher, A.A.Gibsher, A.A., Malkovets, V.G., Griffin, W.L., O'Reilly, S.Y.Petrogenesis of composite xenoliths from alkaline basalts ( West Sangilen) Russia10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussiaAlkalic
DS201212-0583
2012
Gibsher, A.A.Rezvukhin, D.I., Malkovets, V.G., Gibsher, A.A., Kuzmin, D.V., Griffin, W.L., Pokhilenko, N.P., O'Reilly, S.Y.Mineral inclusions in pyropes from some kimberlite pipes of Yakutia.10th. International Kimberlite Conference Held Bangalore India Feb. 6-11, Poster abstractRussia, YakutiaDeposit - Internationskaya
DS201605-0887
2016
Gibsher, A.A.Rezvukhin, D.I., Malkovets, V.G., Sharygin, I.S., Kuzmin, D.V., Litasov, K.D., Gibsher, A.A., Pokhilenko, N.P., Sobolev, N.V.Inclusions of Cr- and Cr-Nb-Rutile in pyropes from the Internationalnaya kimberlite pipe, Yakutia.Doklady Earth Sciences, Vol. 466, 2, Feb. pp. 173-176.Russia, YakutiaDeposit - International

Abstract: The results of study of rutile inclusions in pyrope from the Internatsionalnaya kimberlite pipe are presented. Rutile is characterized by unusually high contents of impurities (up to 25 wt %). The presence of Cr2O3 (up to 9.75 wt %) and Nb2O5 (up to 15.57 wt %) are most typical. Rutile inclusions often occur in assemblage with Ti-rich oxides: picroilmenite and crichtonite group minerals. The Cr-pyropes with inclusions of rutile, picroilmenite, and crichtonite group minerals were formed in the lithospheric mantle beneath the Mirnyi field during their joint crystallization from melts enriched in Fe, Ti, and other incompatible elements as a result of metasomatic enrichment of the depleted lithospheric mantle.
DS201605-0888
2016
Gibsher, A.A.Rezvukhin, D.I., Malkovets, V.G., Sharygin, I.S., Kuzmin, D.V., Litasov, K.D., Gibsher, A.A., Pokhilenko, N.P., Sobolev, N.V.Inclusions of crichonite group minerals in pyropes from the Internatsionalnaya kimberlite pipe, Yakutia.Doklady Earth Sciences, Vol. 466, 2, Feb. pp. 206-209.Russia, YakutiaDeposit - International
DS201612-2320
2016
Gibsher, A.A.Malkovets, V.G., Rezvukhin, D.I., Belousova, E.A., Griffin, W.L., Sharygin, I.S., Tretiakov, I.G., Gibsher, A.A., O'Reilly, S.Y., Kuzmin, D.V., Litasov, K.D., Logvinova, A.M., Pokhilenko, N.P., Sobolev, N.V.Cr-rich rutile: a powerful tool for diamond exploration.Lithos, Vol. 265, pp. 304-311.Russia, SiberiaDeposit - Internationalskaya

Abstract: Mineralogical studies and U-Pb dating have been carried out on rutile included in peridotitic and eclogitic garnets from the Internatsionalnaya pipe, Mirny field, Siberian craton. We also describe a unique peridotitic paragenesis (rutile + forsterite + enstatite + Cr-diopside + Cr-pyrope) preserved in diamond from the Mir pipe, Mirny field. Compositions of rutile from the heavy mineral concentrates of the Internatsionalnaya pipe and rutile inclusions in crustal almandine-rich garnets from the Mayskaya pipe (Nakyn field), as well as from a range of different lithologies, are presented for comparison. Rutile from cratonic mantle peridotites shows characteristic enrichment in Cr, in contrast to lower-Cr rutile from crustal rocks and off-craton mantle. Rutile with Cr2O3 > 1.7 wt% is commonly derived from cratonic mantle, while rutiles with lower Cr2O3 may be both of cratonic and off-cratonic origin. New analytical developments and availability of standards have made rutile accessible to in situ U-Pb dating by laser ablation ICP-MS. A U-Pb age of 369 ± 10 Ma for 9 rutile grains in 6 garnets from the Internatsionalnaya pipe is consistent with the accepted eruption age of the pipe (360 Ma). The equilibrium temperatures of pyropes with rutile inclusions calculated using Ni-in-Gar thermometer range between ~ 725 and 1030 °C, corresponding to a depth range of ca ~ 100-165 km. At the time of entrainment in the kimberlite, garnets with Cr-rich rutile inclusions resided at temperatures well above the closure temperature for Pb in rutile, and thus U-Pb ages on mantle-derived rutile most likely record the emplacement age of the kimberlites. The synthesis of distinctive rutile compositions and U-Pb dating opens new perspectives for using rutile in diamond exploration in cratonic areas.
DS201801-0060
2018
Gibsher, A.A.Shatsky, V.S., Malkovets, V.G., Belousova, E.A., Tretiakova, I.G., Griffin, W.L., Ragozin, A.L., Wang, Q., Gibsher, A.A., O'Reilly, S.Y.Multi-stage modification of Paleoarchean crust beneath the Anabar tectonic province ( Siberian craton).Precambrian Research, Vol. 305, pp. 125-144.Russiacraton - Siberian

Abstract: According to present views, the crustal terranes of the Anabar province of the Siberian craton were initially independent blocks, separated from the convecting mantle at 3.1 (Daldyn terrane), 2.9 (Magan terrane) and 2.5?Ga (Markha terrane) (Rosen, 2003, 2004; Rosen et al., 1994, 2005, 2009). Previous studies of zircons in a suite of crustal xenoliths from kimberlite pipes of the Markha terrane concluded that the evolution of the crust of the Markha terrane is very similar to that of the Daldyn terrane. To test this conclusion we present results of U-Pb and Hf-isotope studies on zircons in crustal xenoliths from the Zapolyarnaya kimberlite pipe (Upper Muna kimberlite field), located within the Daldyn terrane, and the Botuobinskaya pipe (Nakyn kimberlite field) in the center of the Markha terrane. The data on xenoliths from the Botuobinskaya kimberlite pipe record tectonothermal events at 2.94, 2.8, 2.7 and 2?Ga. The event at 2?Ga caused Pb loss in zircons from a mafic granulite. U-Pb dating of zircons from the Zapolyarnaya pipe gives an age of 2.7?Ga. All zircons from the studied crustal xenoliths have Archean Hf model ages ranging from 3.65 to 3.11?Ga. This relatively narrow range suggests that reworking of the ancient crust beneath the Nakyn and Upper Muna kimberlite fields was minor, compared with the Daldyn and Alakit-Markha fields (Shatsky et al., 2016). This study, when combined with dating of detrital zircons, implies that tectonic-thermal events at 2.9-2.85, 2.75-2.7 and 2.0-1.95?Ga occurred everywhere on the Anabar tectonic province, and could reflect the upwelling of superplumes at 2.9, 2.7 and 2?Ga. The presence of the same tectonic-thermal events in the Daldyn and Markha terranes (Rosen et al., 2006a,b) supports the conclusion that the identification of the Markha terrane as a separate unit is not valid.
DS201808-1788
2018
Gibsher, A.A.Shatsky, V.S., Malkovets, V.G., Belousova, E.A., Tretiakova, I.G., Griffin, W.L., Ragozin, A.L., Wang, Q., Gibsher, A.A., O'Reilly, S.Y.Multi stage modification of Paleoarchean crust beneath the Anabar tectonic provnce ( Siberian craton).Precambrian Research, Vol. 305, pp. 125-144.Russiatectonics

Abstract: According to present views, the crustal terranes of the Anabar province of the Siberian craton were initially independent blocks, separated from the convecting mantle at 3.1 (Daldyn terrane), 2.9 (Magan terrane) and 2.5?Ga (Markha terrane) (Rosen, 2003, 2004; Rosen et al., 1994, 2005, 2009). Previous studies of zircons in a suite of crustal xenoliths from kimberlite pipes of the Markha terrane concluded that the evolution of the crust of the Markha terrane is very similar to that of the Daldyn terrane. To test this conclusion we present results of U-Pb and Hf-isotope studies on zircons in crustal xenoliths from the Zapolyarnaya kimberlite pipe (Upper Muna kimberlite field), located within the Daldyn terrane, and the Botuobinskaya pipe (Nakyn kimberlite field) in the center of the Markha terrane. The data on xenoliths from the Botuobinskaya kimberlite pipe record tectonothermal events at 2.94, 2.8, 2.7 and 2?Ga. The event at 2?Ga caused Pb loss in zircons from a mafic granulite. U-Pb dating of zircons from the Zapolyarnaya pipe gives an age of 2.7?Ga. All zircons from the studied crustal xenoliths have Archean Hf model ages ranging from 3.65 to 3.11?Ga. This relatively narrow range suggests that reworking of the ancient crust beneath the Nakyn and Upper Muna kimberlite fields was minor, compared with the Daldyn and Alakit-Markha fields (Shatsky et al., 2016). This study, when combined with dating of detrital zircons, implies that tectonic-thermal events at 2.9 -2.85, 2.75 -2.7 and 2.0 -1.95?Ga occurred everywhere on the Anabar tectonic province, and could reflect the upwelling of superplumes at 2.9, 2.7 and 2?Ga. The presence of the same tectonic-thermal events in the Daldyn and Markha terranes (Rosen et al., 2006a,b) supports the conclusion that the identification of the Markha terrane as a separate unit is not valid.
DS201911-2544
2019
Gibsher, A.A.Malkovets, V.G., Rezvukhin, D.I., Griffin, W.L., Tretiakova, I.G., Pearson, N.J., Gibsher, A.A., Belousova, E.A., Zedgenizov, D.A., O'Reilly, S.Y.Re-Os dating of sulfide inclusions in Cr-pyropes from the Upper Muna kimberlites.Goldschmidt2019, 1p. AbstractRussiadeposit - Upper Muna

Abstract: Archean cratons are underlain by highly depleted subcontinental lithospheric mantle (SCLM). However, there are extensive evidences that Archean SCLM has been extensively refertilized by metasomatic processes, with the addition of Fe, Ca, and Al to depleted protoliths. The distribution of sub-calcic Cr-rich garnets in the SCLM beneath the Siberian craton suggests (1) sub-calcic garnets and diamonds are metasomatic phases in the cratonic SCLM; (2) the distribution of both phases is laterally heterogeneous on relatively small scales and related to ancient structural controls [1]. Re-Os isotopic compositions of twenty six sulfide inclusions in lherzolitic Cr-pyropes from Upper Muna kimberlites have been determined by laser ablation MCICPMS. Most analysed sulfides (~92%) have very low Re/Os ratios (<0.07), and their Re-depletion ages (TRD) form three major peaks: 3.4-2.8, 2.2-1.8 and 1.4-1.2 Ga (±0.03 Ga, mean 2s analytical uncertainty). One sulfide give the oldest TRD age at 4 Ga. Our data suggest that refertilization of the highly depleted SCLM and the introduction of Cr-pyrope garnet occurred in several episodes. The oldest age of ca 4 Ga indicate on the beginning of the formation of the depleted SCLM of the Siberian Craton in Hadean time [2].
DS202010-1840
2020
Gibsher, A.A.Dymshits, A., Sharygin, I., Malkovets, V., Yakovlev, I.V., Gibsher, A.A., Alifirova, T.A., Vorobei, S.S., Potapov, S.V., Garanin, V.K.Thermal state, thickness and composition of the lithospheric mantle beneath the Upper Muna kimberlite field, Siberian Craton, constrained by clinopyroxene xenocrysts and comparison with Daldyn and Mirny fields.Minerals, 10.1039/DOJA00308E 20p. PdfRussiadeposit - Muna

Abstract: To gain better insight into the thermal state and composition of the lithospheric mantle beneath the Upper Muna kimberlite field (Siberian craton), a suite of 323 clinopyroxene xenocrysts and 10 mantle xenoliths from the Komsomolskaya-Magnitnaya (KM) pipe have been studied. We selected 188 clinopyroxene grains suitable for precise pressure (P)-temperature (T) estimation using single-clinopyroxene thermobarometry. The majority of P-T points lie along a narrow, elongated field in P-T space with a cluster of high-T and high-P points above 1300 °C, which deviates from the main P-T trend. The latter points may record a thermal event associated with kimberlite magmatism (a “stepped” or “kinked” geotherm). In order to eliminate these factors, the steady-state mantle paleogeotherm for the KM pipe at the time of initiation of kimberlite magmatism (Late Devonian-Early Carboniferous) was constrained by numerical fitting of P-T points below T = 1200 °C. The obtained mantle paleogeotherm is similar to the one from the nearby Novinka pipe, corresponding to a ~34-35 mW/m2 surface heat flux, 225-230 km lithospheric thickness, and 110-120 thick "diamond window" for the Upper Muna field. Coarse peridotite xenoliths are consistent in their P-T estimates with the steady-state mantle paleogeotherm derived from clinopyroxene xenocrysts, whereas porphyroclastic ones plot within the cluster of high-T and high-P clinopyroxene xenocrysts. Discrimination using Cr2O3 demonstrates that peridotitic clinopyroxene xenocrysts are prevalent (89%) among all studied 323 xenocrysts, suggesting that the Upper Muna mantle is predominantly composed of peridotites. Clinopyroxene-poor or -free peridotitic rocks such as harzburgites and dunites may be evident at depths of 140-180 km in the Upper Muna mantle. Judging solely from the thermal considerations and the thickness of the lithosphere, the KM and Novinka pipes should have excellent diamond potential. However, all pipes in the Upper Muna field have low diamond grades (<0.9, in carats/ton), although the lithosphere thickness is almost similar to the values obtained for the high-grade Udachnaya and Mir pipes from the Daldyn and Mirny fields, respectively. Therefore, other factors have affected the diamond grade of the Upper Muna kimberlite field.
DS202104-0591
2021
Gibsher, A.A.Malkovets, V.G., Shatsky, V.S., Dak, A.I., Gibsher, A.A., Yakovlev, I.V., Belousova, E.A., Tsujimori, T., Sobolev, N.V.Evidence for multistage and polychronous alkaline-ultrabasic Mesozoic magmatism in the area of diamondiferous placers of the Ebelyakh River basin, ( eastern slope of the Anabar shield).Doklady Earth Sciences, Vol. 496, 1, pp. 48-52.Russiadeposit - Anabar

Abstract: New mineralogical and isotope-geochemical data for zircon megacrysts (n = 48) from alluvium of Kholomolokh Creek (a tributary of the Ebelakh River) are reported. Using the geochemical classification schemes, the presence of zircons of kimberlitic and carbonatitic genesis was shown. The U-Pb dating of zircons revealed two major age populations: the Triassic (258-221 Ma, n = 18) and Jurassic (192-154 Ma, n = 30). Weighted mean 206Pb/238U ages allowed us to distinguish the following age stages: 155 ± 3, 161 ± 2, 177 ± 1.5, 183 ± 1.5, 190 ± 2, 233 ± 2.5, and 252 ± 4 Ma. It is suggested that the Ebelyakh diamonds could have been transported from the mantle depths by kimberlite, as well as by other related rocks, such as carbonatite, lamprophyre, lamproite, olivine melilitite, etc. Diamonds from the Ebelyakh placers most likely have polygenic native sources and may be associated with polychronous and multistage Middle Paleozoic and Mesozoic kimberlite and alkaline-ultrabasic magmatism in the eastern slope of the Anabar Shield (the Ebelyakh, Mayat, and Billyakh river basins).
DS2000-0133
2000
GibsonByron, M.J., Gibson, Watkinson, Whitehead, McDonaldExtraordinary accessory minerals of the Mat a Da Corda Formation: implications for rock type classificationGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Calgary May 2000, 5p.BrazilPetrology, mineralogy, exploration, diamond, igneous, Mata Da Corda Formation
DS2001-0134
2001
GibsonBrod, J., Gaspar, De Araujo, Gibson, Thompson, JunqueiraPhlogopite and tetra ferriphlogopite from Brazilian carbonatite complexes and implications for systematicsJournal of African Earth Sciences, Vol. 19, No. 3, Apr. pp.265-296.BrazilCarbonatite, Mineral chemistry systematics
DS2002-1591
2002
GibsonThompson, R.N., Smith, P.M., Gibson, Mattey, DickinAnkerite carbonatite from Swartbooisdrif Namibia: the first evidence for magmatic ferrocarbonatite.Contribution to Mineralogy and Petrology, Vol.143,3,June,pp. 377-96., Vol.143,3,June,pp. 377-96.NamibiaCarbonatite
DS2002-1592
2002
GibsonThompson, R.N., Smith, P.M., Gibson, Mattey, DickinAnkerite carbonatite from Swartbooisdrif Namibia: the first evidence for magmatic ferrocarbonatite.Contribution to Mineralogy and Petrology, Vol.143,3,June,pp. 377-96., Vol.143,3,June,pp. 377-96.NamibiaCarbonatite
DS201112-0409
2011
Gibson, B.Hannam, S., Bailey, B.L., Lindsay, M.B.J., Gibson, B., Blowes, D.W., Paktunc, A.D., Smith, L., Sego, D.C.Diavik waste rock project: geochemical and mineralogical characterization of waste rock weathering at the Diavik diamond mine.Yellowknife Geoscience Forum Abstracts for 2011, abstract p. 43-44.Canada, Northwest TerritoriesMining - waste rock
DS202003-0367
2020
Gibson, C.Turetsky, M.R., Abbott, B.W., Jones, M.C., Walter Anthony, K.. Olefeldt, D., Schuur, E.A.G., Grosse, G., Kuhry, P., Higelius, G., Koven, C., Lawrence, D.M., Gibson, C., Sannel, A.B.K., McGuire, A.D.Carbon release through abrupt permafrost thaw. ( not specific to diamonds but interest)Nature Geoscience, Vol. 13, pp. 138-143.Mantlecarbon

Abstract: The permafrost zone is expected to be a substantial carbon source to the atmosphere, yet large-scale models currently only simulate gradual changes in seasonally thawed soil. Abrupt thaw will probably occur in <20% of the permafrost zone but could affect half of permafrost carbon through collapsing ground, rapid erosion and landslides. Here, we synthesize the best available information and develop inventory models to simulate abrupt thaw impacts on permafrost carbon balance. Emissions across 2.5?million?km2 of abrupt thaw could provide a similar climate feedback as gradual thaw emissions from the entire 18?million?km2 permafrost region under the warming projection of Representative Concentration Pathway 8.5. While models forecast that gradual thaw may lead to net ecosystem carbon uptake under projections of Representative Concentration Pathway 4.5, abrupt thaw emissions are likely to offset this potential carbon sink. Active hillslope erosional features will occupy 3% of abrupt thaw terrain by 2300 but emit one-third of abrupt thaw carbon losses. Thaw lakes and wetlands are methane hot spots but their carbon release is partially offset by slowly regrowing vegetation. After considering abrupt thaw stabilization, lake drainage and soil carbon uptake by vegetation regrowth, we conclude that models considering only gradual permafrost thaw are substantially underestimating carbon emissions from thawing permafrost.
DS1990-0566
1990
Gibson, D.W.Gibson, D.W., Edwards, D.E.An overview of Triassic stratigraphy and depositional environments in the Rocky Mountain foothills and western interior plains, Peace River Arch regionGeology of the Peace River Arch, ed. Sc.C. O'Connell, J.S. Bell, Bulletin. Can., Vol. 38A, Special Volume, December pp. 146-158AlbertaPeace River area, Tectonics, structure
DS1984-0018
1984
Gibson, E.K.Andrawes, F., Holzer, G., Roedder, E., Gibson, E.K., Oro, J.Gas Chromatographic Analysis of Volatiles in Fluid and Gas Inclusions.Journal of Chromatography, Vol. 302, PP. 181-193.GlobalFluid Inclusions, Diamonds, Geochemistry
DS201312-0968
2013
Gibson, G.M.White, L.T., Gibson, G.M., Lister, G.S.A reassessment of paleogeographic reconstructions of eastern Gondwana: bringing geology back into the equation.Gondwana Research, Vol. 24, 3-4, pp. 984-998.IndiaTectonic models
DS202103-0396
2021
Gibson, H.D.Neil, B.J.C., Gibson, H.D., Pehrsson, S.J., Martel, E., Thiessen, E.J., Crowley, J.L.Provenance, stratigraphic and precise depositional age constraints for an outlier of the 1.9 to 1.8 Ga Nonacho Group, Rae craton, Northwest Territories, Canada.Precambrian Research, Vol. 352, 105999, 15p. PdfCanada, Northwest Territoriesgeochronology

Abstract: The Nonacho Group comprises six formations of continental clastic rocks that were deposited between 1.91 and 1.83?Ga. The Nonacho Group is part of a broader assemblage of conglomerate and sandstone that was deposited atop the Rae craton in response to the amalgamation of Laurentia and supercontinent Nuna, but the details of its tectonic setting are contentious. This paper documents an outlier of Nonacho Group rocks ~50?km east of the main Nonacho basin. Field observations and LA-ICPMS (laser ablation inductively coupled plasma mass spectrometry) U-Pb detrital zircon geochronology are integrated with previous studies of the main basin to better understand the group’s depositional history, provenance and tectonic setting. The lithology and detrital zircon age spectra of the outlier allow for its correlation to the upper two formations of the Nonacho Group. CA-ID-TIMS (chemical abrasion isotope dilution thermal ionization mass spectrometry) analyses of two fragments of the youngest detrital zircon provide a maximum depositional age of 1901.0?±?0.9?Ma. A felsic volcanic cobble dated at ca. 2.38?Ga provides evidence of volcanism during the Arrowsmith orogeny. Detrital zircon dates recovered from the outlier (ca. 3.4-3.0, 2.7, 2.5-2.3 and 2.0-1.9?Ga) are consistent with derivation from topography of the Taltson and/or Thelon orogens on the western margin of the Rae craton. Taltson-Thelon (2.0 to 1.9?Ga) aged detritus is only abundant in the upper two formations of the Nonacho Group, marking a change in provenance from the lower formations. This change in provenance may have coincided with a period of renewed uplift and the unroofing of Taltson-Thelon plutons. The detrital zircon provenance and depositional age of the Nonacho Group is consistent with models that link its deposition to the Taltson and/or Thelon orogens. However, tectonism associated with the 1.9 to 1.8?Ga Snowbird and Trans-Hudson orogens to the east could also have affected basin formation or the change in provenance from the lower to upper Nonacho Group. This study highlights the importance of CA-ID-TIMS in establishing accurate and precise maximum depositional ages for sedimentary successions.
DS2000-0132
2000
Gibson, H.L.Byron, M.J., Gibson, H.L., Whitehead, Watkinson, WinterThe Quintinos pipe: a polyphase kamafugite intrusion of the Mat a da Corda Formation, Minas Gerais, Brasil.Geological Association of Canada (GAC)/Mineralogical Association of, 4p. abstractBrazil, Minas GeraisLamproite, Deposit - Quintinois
DS1975-0157
1975
Gibson, I.L.Paul, D.K., Potts, P.J., Gibson, I.L., Harris, P.G.Rare Earth Abundances in Indian KimberlitesEarth and Planetary Science Letters, Vol. 25, PP. 151-158.IndiaRare Earth Elements (ree), Geochemistry
DS1981-0317
1981
Gibson, I.L.Nixon, P.H., Rogers, N.W., Gibson, I.L., Grey, A.Depleted and Fertile Mantle Xenoliths from Southern Africankimberlites.Annual Review of Earth and Planetary Science, Vol. 9, PP. 285-309.South AfricaKimberlite Genesis
DS1989-0509
1989
Gibson, I.L.Gibson, I.L., Roberts, R.G., Gibbs, A.An extensional fault model for the early development of greenstone belts- areplyEarth and Planetary Science Letters, Vol. 92, No. 1, February pp. 127-128OntarioGreenstone belt, Tectonics
DS1995-0537
1995
Gibson, J.G.Field, M., Gibson, J.G., Wilkes, T.A., Gababotse, KhujweThe geology of the Orapa A/K1 kimberlite, Botswana: further insight into the emplacement of kimb. pipes.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 155-57.BotswanaKimberlite genesis, Deposit -Orapa A/K1
DS1988-0278
1988
Gibson, R.Guptill, S.C., Cotter, D., Gibson, R., Liston, R., Tom, H., Trainor, T.A process for evaluating geographic information systemsUnited States Geological Survey (USGS) Open File, No. 88-0105, 55p. $ 21.25GlobalGIS, Technology Group
DS1995-0629
1995
Gibson, R.L.Gibson, R.L., Reimold, W.U.Magnetic anomaly near center of Vredefort structure: implications for impact related magnetic signatures:Geology, Vol. 23, No. 12, Dec. pp. 1149-52South AfricaGeophysics -magnetics, Vredefort Structure
DS1996-1372
1996
Gibson, R.L.Stevens, G., Gibson, R.L., Droop, G.T.R.Polyphase granulite metamorphism in the Vredefort Dome: a window into the deep Kaapvaal craton at 2.06 GaEconomic Geology Research Unit, No. 297, 27pSouth AfricaCraton -Kaapvaal, Greenstone remnants
DS1997-0397
1997
Gibson, R.L.Gibson, R.L., Stevens, G.Regional metamorphism due to anorogenic intracratonic magmatismEconomic Geology Research Unit, No. 311, 23pSouth AfricaVerdefort Dome, impact structure, Kaapvaal Craton, Mantle derived magmas
DS1997-0398
1997
Gibson, R.L.Gibson, R.L., Stevens, G.Regional metamorphism due to anorogenic intracratonic magmatismEconomic Geology Research Unit, No. 311, 23p.South AfricaKaapvaal Craton, Mantle
DS1997-1104
1997
Gibson, R.L.Stevens, G., Gibson, R.L., Droop, G.T.R.Mid-crustal granulite facies metamorphism in the Central Kaapvaal Craton:Bushveld Complex connectionPrecambrian Research, Vol. 82, No. 1-2, March 1, pp. 113-32South AfricaCraton - Kaapvall, Bushveld Complex, layered intrusion
DS1997-1105
1997
Gibson, R.L.Stevens, G., Gibson, R.L., Droop, G.T.R.Mid crustal granulite facies metamorphism in the Central Kaapvaal craton:Bushveld Complex connectionPrecambrian Research, Vol. 82, No. 1-2, March pp. 113-132South Africametamorphism, Bushveld Complex
DS1998-0181
1998
Gibson, R.L.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
DS1998-0505
1998
Gibson, R.L.Gibson, R.L., Reimold, W.U., Stevens, G.Thermal metamorphic signature of an impact event in the Vredefort dome, South AfricaGeology, Vol. 26, No. 9, Sept. pp. 787-90South AfricaVredefort Dome, Geothermometry
DS1998-0758
1998
Gibson, R.L.Kisters, A.F.M., Gibson, R.L., Anhaeusser, C.R.The role of strain localization in the segregation and ascent of anatecticmelts, Namaqualand, South AfricaJournal of Struct. Geol, Vol. 20, No. 2-3, Feb.1, pp. 229-42South AfricaTectonics
DS2002-0566
2002
Gibson, R.L.Gibson, R.L., Jones, MQW.Late Archean to Paleoproterozoic geotherms in the Kaapvaal Craton, South Africa: constraints on the thermal evolution of the Witwatersrand Basin.Basin Research, Vol.14,2, pp.169-82.South AfricaTectonics, Georthermometry
DS2003-0181
2003
Gibson, R.L.Buick, I.S., Williams, I.S., Gibson, R.L., Cartwright, I., Miller, J.A.Carbon and U Pb evidence for a Paleoproterozoic crustal component in the CentralJournal of the Geological Society of London, Vol. 160, 4, pp. 601-12.South AfricaGeochronology, Mobile belt - not specific to diamonds
DS2003-0771
2003
Gibson, R.L.Lana, C., Gibson, R.L., Kisters, A.F., Reimold, W.U.Archean crustal structure of the Kaapvaal Craton, South Africa - evidence from theEarth and Planetary Science Letters, Vol. 206, 1-2, pp. 133-44.South AfricaTectonics
DS200412-0238
2003
Gibson, R.L.Buick, I.S., Williams, I.S., Gibson, R.L., Cartwright, I., Miller, J.A.Carbon and U Pb evidence for a Paleoproterozoic crustal component in the Central Zone of the Limpopo Belt, South Africa.Journal of the Geological Society, Vol. 160, 4, pp. 601-12.Africa, South AfricaGeochronology Mobile belt - not specific to diamonds
DS200412-1082
2004
Gibson, R.L.Lana, C., Reimold, W.U., Gibson, R.L., Koeberl, C., Siegesmund, S.Nature of the Archean midcrust in the core of the Vredfort dome, Central Kaapvaal Craton, South Africa.Geochimica et Cosmochimica Acta, Vol. 68, 3, pp. 623-42.Africa, South AfricaCraton, not specific to diamonds
DS200612-0037
2006
Gibson, R.L.Armstrong, R.A., Lana, C., Reimold, W.U., Gibson, R.L.Shrimp zircon age constraints on Mesoarchean crustal development in the Vredefort dome, central Kaapvaal Craton, South Africa.Geological Society of America, Special Paper 405, pp. 233-254.Africa, South AfricaGeochronology
DS200612-1151
2006
Gibson, R.L.Reimold, W.U., Gibson, R.L., editorsProcesses on the Early Earth.Geological Society of America, Processes on the Earth, Special Paper 405,Africa, AustraliaPapers of interest identified by authors
DS1996-0835
1996
Gibson, S.Leonardos, O.H., Thompson, R.N., Fleicher, R., Gibson, S.The origin of diamonds in western Minas Gerais, Brasil. Comment andreply., ,by Gonzaga, Teixeira and Gaspar.Mineral Deposits, Vol. 31, No. 4, May pp. 343-347.BrazilDiamond genesis
DS200512-1104
2005
Gibson, S.Tuff, J., Takahashi, E., Gibson, S.Experimental constraints on the role of garnet pyroxenite in the genesis of high Fe mantle plume derived melts.Chapman Conference held in Scotland August 28-Sept. 1 2005, 1p. abstractMantleMantle plume, ferro-picrites
DS201702-0218
2016
Gibson, S.Jennings, E.S., Holland, T.J.B., Shorttle, O., Gibson, S.The composition of melts from a heterogeneous mantle and origin of ferropicrite: application of a thermodynamic model.Journal of Petrology, In press available 22p.MantleEclogite, melting

Abstract: Evidence for chemical and lithological heterogeneity in the Earth’s convecting mantle is widely acknowledged, yet the major element signature imparted on mantle melts by this heterogeneity is still poorly resolved. In this study, a recent thermodynamic melting model is tested on a range of compositions that correspond to potential mantle lithologies (harzburgitic to pyroxenitic), to demonstrate its applicability over this compositional range, in particular for pyroxenite melting. Our results show that, despite the model’s calibration in peridotitic systems, it effectively reproduces experimental partial melt compositions for both Si-deficient and Si-excess pyroxenites. Importantly, the model accurately predicts the presence of a free silica phase at high pressures in Si-excess pyroxenites, indicating the activation of the pyroxene-garnet thermal divide. This thermal divide has a dominant control on solidus temperature, melt productivity and partial melt composition. The model is used to make new inferences on the link between mantle composition and melting behaviour. In silica-deficient and low-pressure (olivine-bearing) lithologies, melt composition is not very sensitive to source composition. Linearly varying the source composition between peridotite and basaltic pyroxenite, we find that the concentration of oxides in the melt tends to be buffered by the increased stability of more fusible phases, causing partial melts of even highly fertile lithologies to be similar to those of peridotite. An exception to this behaviour is FeO, which is elevated in partial melts of silica-deficient pyroxenite even if the bulk composition does not have a high FeO content relative to peridotite. Melt Al2O3 and MgO vary predominantly as a function of melting depth rather than bulk composition. We have applied the thermodynamic model to test the hypothesis that Fe-rich mantle melts such as ferropicrites are derived by partial melting of Si-deficient pyroxenite at elevated mantle potential temperatures. We show that the conspicuously high FeO in ferropicrites at a given MgO content does not require a high-Fe mantle source and is indeed best matched by model results involving around 0-20% melting of silica-deficient pyroxenite. A pyroxenite source lithology also accounts for the low CaO content of ferropicrites, whereas their characteristic low Al2O3 is a function of their high pressure of formation. Phanerozoic ferropicrites are exclusively located in continental flood basalt (CFB) provinces and this model of formation confirms that lithological heterogeneity (perhaps recycled oceanic crust) is present in CFB mantle sources.
DS201709-2002
2017
Gibson, S.Jackson, C., Gibson, S.New insights into sulfur-rich mantle metasomatism at Bultfontein, Kimberley.Goldschmidt Conference, abstract 1p.Africa, South Africadeposit - Bultfontein

Abstract: Metasomatised regions of Earth’s sub-continental lithospheric mantle potentially represent a large volatile reservoir. Nevertheless, the mechanisms involved in the storage and upward transport of volatiles such as C and S, from the convecting mantle and/or subducting slabs, are poorly understood. We have carried out a systematic microanalytical study of a suite of sulfide-rich mantle peridotites from the Bultfontein diamond mine, Kimberley. EDS mapping of large (>2mm), interstitial base metal sulfides in the Bultfontein xenoliths has identified distinct Ni-rich regions (pentlandite). The Ni-rich sulfides are adjacent to olivine with Ni poor rims (<0.2 wt% NiO). Diffusion profiles between the protolith olivines and adjacent sulfides are used to estimate the timing of the S-rich metasomatic event. The presence of large unequilibrated olivine indicates that Nisulfides were introduced immediately prior to kimberlite emplacement. The calculated composition of melt in equilibrium with metasomatic clinopyroxenes in the Bultfontein sulphide-bearing peridotites shows a strong correlation to high-density carbonatitic fluids trapped in diamonds. This association is extended by the wealth of metasomatic sulfides in the Bultfontein xenoliths. Moreover, Ni-rich sulfides (~25 wt%) are the most common mineral inclusion in peridotitic diamonds, implying that diamonds crystallise from a S-saturated fluid. Many studies attribute the metasomatism at Bultfontein to silicate melts associated with the kimberlite, but we explore the possibility of metasomatism by reactive percolation of a volatile-rich agent with carbonatitic affinity. The S-rich nature of the metasomatism and the correlation with diamond high-density fluids has great implications for the transport of volatiles from the deep mantle to shallow regions of the craton.
DS1991-0572
1991
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leat, P.T., Morrison, M.A., HendryUltrapotassic magmas along the flanks of the oligo-miocene Rio Grande @Proceedings of Fifth International Kimberlite Conference held Araxa June, pp. 133-135Colorado PlateauTectonics, Kimberlites, minettes
DS1991-0573
1991
Gibson, S.A.Gibson, S.A., Thompson, R.N., Mitchell, J.G., Dickin, A.P.Geochemical and petrographic evidence for high magnesium-ultrapotassic magmas in southeast Colorado, USAProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 136-138ColoradoGeochemistry, Petrography, minettes
DS1991-1724
1991
Gibson, S.A.Thompson, R.N., Gibson, S.A.Subcontinental mantle plumes, hotspots and pre-existing thinspotsJournal of the Geological Society of London, Vol. 248, November pp. 973-977MantlePlumes, Hotspots
DS1991-1725
1991
Gibson, S.A.Thompson, R.N., Gibson, S.A., Leat, P.T.Overt and cryptic strongly potassic mafic liquids in the Neogene magmatism of the n.part of the Rio Grande Rift, USA: a lithospheric drip feed into asthenospheric soProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 420-422Arizona, Colorado PlateauPotassic lavas, basalts, Minette, Lamproite, Elkhead Mts.Leucite Hills
DS1992-0565
1992
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leat, P.T., Dickin, A.P., MorrisonAsthenosphere-derived magmatism in the Rio Grande rift, westerm USA:implications for continental break upGeological Society Special Publication Magmatism and the causes of the continental, No. 68, pp. 61-89Cordillera, Arizona, New MexicoTectonics, Rifting
DS1993-0540
1993
Gibson, S.A.Gibson, S.A., Leonardos, O.H., Thompson, R.N., Turner, S.E.O diatrema alcalino-ultrafico da Serra do Bueno, Alto Paranaiba MinasGerais. (in Portugese).Brasiliao Geologi do Diamante UFMT., Esp. 2/93, Cuabe, pp. 57-78.BrazilKimberlites, mafic ultrapotassic rocks, alkaline rocks, Serra do Bueno
DS1993-0541
1993
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leat, P.T., Morrison, M.A., HendryUltrapotassic magmas along the flanks of the Oligo-Miocene Rio GrandeJournal of Petrology, Vol. 34, No. 1, February pp. 187-228Mantle, Colorado PlateauUltrapotassic, Tectonics
DS1993-1569
1993
Gibson, S.A.Tallarico, F.H.B., Leonardos, O.H., Gibson, S.A., Meyer, H.O.A.Quimica mineral da intrusa o da mat a do lenco, Abadia dos Dourados, MinasGerais.(in Portugese).Brasiliao Geologi do Diamante UFMT., Esp. 2/93, Cuabe, pp. 114-128.BrazilDa Mata do Lenco, Kimberlitic intrusive
DS1994-0618
1994
Gibson, S.A.Gibson, S.A.Ultrapotassic magmatic key to interaction of Cretaceous mantle plumes with laterally heterogeneous South AmericanEos, Annual Meeting November 1, Vol. 75, No. 44, p.722. abstractBrazil, South AmericaUltrapotassic, Alkaline rocks
DS1994-0619
1994
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leonardo, O.H., Turner, S.The Serra do Bueno potassic diatreme - a possible hypabyssal equiv. of ultramafic alkaline volcanics.Mineralogical Magazine, Vol. 58, No. 392, Sept. 357-373.BrazilAlkaline rocks, Diatremes
DS1994-0620
1994
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leonardos, O.H., Dickin, A.The late Cretaceous impact of the Trindade plume: evidence from large volume mafic potassic magmatism.International Symposium Upper Mantle, Aug. 14-19, 1994, Extended abstracts pp. 56-58.BrazilMantle plume, Alkaline rocks
DS1994-1769
1994
Gibson, S.A.Thompson, R.N., Gibson, S.A.Magmatic expression of lithospheric thinning across continental riftsTectonophysics, Vol. 233, No. 1-2, May 15, pp. 41-68.MantleTectonics, Magma
DS1994-1770
1994
Gibson, S.A.Thompson, R.N., Gibson, S.A.Interplay between lithospheric and convecting mantle sources during continental rift related magmatism.International Symposium Upper Mantle, Aug. 14-19, 1994, pp. 115-117.United States, Colorado, New Mexico, East Africa, Russia, BaikalMantle, Tectonics, magma
DS1995-0630
1995
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leonardos, G.H., DickinThe late Cretaceous impact of the Trindade mantle plume; evidence from large volume, mafic potassic MagazineJournal of Petrology, Vol. 36, No. 1, February, pp. 189-229.BrazilMagmatism -potassic, Alkaline rocks
DS1995-0631
1995
Gibson, S.A.Gibson, S.A., Thompson, R.N., Leonardos, O.H., Dickin, A.P.The Late Cretaceous impact of the Trindada mantle plume: evidence large volume mafic potassic magmatismJournal of Petrology, Vol. 36, No. 1, Feb. pp. 189-230.BrazilMagmatism -potassic, Alkaline rocks
DS1995-1085
1995
Gibson, S.A.Leonardos, O.H., Carvalho, J.B., Gibson, S.A., ThompsonThe diamond potential of the late Cretaceous Alto Paranaiba igneousprovince, Brasil.Proceedings of the Sixth International Kimberlite Conference Abstracts, pp. 320-322.BrazilAlluvials, Deposit -Alto Paranaiba
DS1996-0522
1996
Gibson, S.A.Gibson, S.A., Thompson, R.N., Dickin, A.P., Leonardos, O.Erratum to High Ti and low Ti mafic potassic magmas: Key to plume lithosphere interactions and flood genesisEarth and Planetary Science Letters, Vol. 141, pp. 325-341Brazil, ParaguayMagmas, Lithosphere
DS1996-0523
1996
Gibson, S.A.Gibson, S.A., Thomspon, R.N., Leonardos, O.H.Erratun to high Ti and low Ti mafic potassic magmas: key to plume lithosphere interactions ...Earth and Planetary Science Letters, Vol. 141, No. 1-4, June 1, pp. 325-MantleAlkaline rocks, Plumes
DS1997-0399
1997
Gibson, S.A.Gibson, S.A., Thompson, R.N., Weska, R.K., Dickin, A.P.Late Cretaceous rift related upwelling and melting of the Trindade starting mantle plume head beneath Brasil.Contributions to Mineralogy and Petrology, Vol. 126, pp. 303-314.BrazilMantle plume, Tectonics
DS1997-0400
1997
Gibson, S.A.Gibson, S.A., Thompson, R.N., Weska, R.K., Dickin, A.P.Late Cretaceous rift related upwelling and melting of the Trindada starting mantle plume head western BrasilContributions to Mineralogy and Petrology, Vol. 126, pp. 303-314BrazilTrindade Mantle, Sao Francisco Craton
DS1998-0231
1998
Gibson, S.A.Chalapthi Rao, N.V., Gibson, S.A., Dickin, A.P.Contrasting isotopic mantle sources for Proterozoic lamproites And kimberlites Cuddapah Basin, Dharwar Craton #1Journal of Geological Society India, Vol. 52, No. 6, Dec. pp. 683-94.India, South IndiaGeochronology, ages, Phanerozoic mantle heterogeneity
DS1998-0506
1998
Gibson, S.A.Gibson, S.A., Thompson, R.N., Dickin, A.P.Subcontinental mantle plume impact and kimberlite genesis7th International Kimberlite Conference Abstract, pp. 250-2.Angola, Brazil, Namibia, ParaguayMantle plume, Deposit - Lunda area
DS1998-0531
1998
Gibson, S.A.Greenwood, J.C., Gibson, S.A., Thompson, R.N., WeskaPetrogenesis of Cretaceous kimberlites from the Paranatinga region, centralBrasil.7th International Kimberlite Conference Abstract, pp. 268-270.BrazilGeochemistry, petrology, Deposit - Paratinga
DS2000-0109
2000
Gibson, S.A.Brod, J.A., Gibson, S.A., Thompson, R., Junqueira-BrodMineral chemistry fingerprints of liquid immiscibility and fractionation in the Tapira alkaline - carbonatiteIgc 30th. Brasil, Aug. abstract only 1p.Brazil, Minas GeraisCarbonatite - Alto Paranaiba Igneous Province
DS2000-0110
2000
Gibson, S.A.Brod, J.A., Gibson, S.A., Thompson, R., Junqueira-BrodKamafugite affinity of the Tapira alkaline carbonatite complex (Minas Gerais, Brasil).Igc 30th. Brasil, Aug. abstract only 1p.Brazil, Minas GeraisCarbonatite - Araxa, Serra Negra, Salitre, Catalao, Kamafugites
DS2000-0336
2000
Gibson, S.A.Gibson, S.A., Thompson, Dickin, LeonardosCarbonatite and kimberlite magmatism asssociated wiht the impact of the Proto-Tristan plume.Igc 30th. Brasil, Aug. abstract only 1p.BrazilParan-Etendeka igneous
DS2000-0953
2000
Gibson, S.A.Thompson, R.N., Gibson, S.A.Transient high temperature in mantle plume heads inferred from magnesian olivines Phanerozoic picritesNature, Vol. 407, No. 6803, Sept. 28, pp. 502-5.MantlePlumes, hot spots, Picrites
DS2001-1155
2001
Gibson, S.A.Thompson, R.N., Gibson, S.A., Dickin, A.P., Smith, P.M.Early Cretaceous basalt and picrite dykes of southern Etendeka Province: windows into role Tristan mantle ...Jour. Petrol., Vol. 42, No. 11, pp. 2049-82.NamibiaPlume - Parana - Etendeka magmatism, Picrite dikes
DS2002-0567
2002
Gibson, S.A.Gibson, S.A.Major element heterogeneity in Archean to recent mantle plume starting headsEarth and Planetary Science Letters, Vol. 195, No. 1-2, pp. 59-74.South Africa, Ontario, Manitoba, SiberiaPicrites, komatiites, flood basalts, eclogite, Lithosphere
DS2003-0013
2003
Gibson, S.A.Anand, M., Gibson, S.A., Subbarao, K.V., Kelley, S.P., Dickin, A.P.Early Proterozoic melt generation processes beneath the intra-cratonic CuddapahJournal of Petrology, Vol. 44, 12, pp. 2139-2172.IndiaMetasomatism
DS2003-0168
2003
Gibson, S.A.Brod, J.A., Junqueira-Brod, T.C., Gaspar, J.C., Gibson, S.A., Thompson, R.N.Ti rich and Ti poor garnet from the Tapira carbonatite complex, SE Brazil: fingerprinting8 Ikc Www.venuewest.com/8ikc/program.htm, Session 7, POSTER abstractBrazil, Minas GeraisBlank
DS200412-0025
2003
Gibson, S.A.Anand, M., Gibson, S.A., Subbarao, K., Kelly, S.P., Dickin, A.P.Early Proterozoic melt generation processes beneath the intra cratonic Cuddapah Basin, southern India.Journal of Petrology, Vol. 44, pp. 2139-2171.IndiaCraton, melting
DS200412-0026
2003
Gibson, S.A.Anand, M., Gibson, S.A., Subbarao, K.V., Kelley, S.P., Dickin, A.P.Early Proterozoic melt generation processes beneath the intra-cratonic Cuddapah Basin, southern India.Journal of Petrology, Vol. 44, 12, pp. 2139-2172.IndiaMetasomatism
DS200412-0214
2003
Gibson, S.A.Brod, J.A., Junqueira-Brod, T.C., Gaspar, J.C., Gibson, S.A., Thompson, R.N.Ti rich and Ti poor garnet from the Tapira carbonatite complex, SE Brazil: fingerprinting fractional crystallization and liquid8 IKC Program, Session 7, POSTER abstractSouth America, Brazil, Minas GeraisKimberlite petrogenesis
DS200412-0304
2004
Gibson, S.A.Chalapathi Rao, N.V., Gibson, S.A., Pyle, D.M., Dickin, A.P.Petrogenesis of Proterozoic lamproites and kimberlites from the Cuddapah Basin and Dharwar Craton, southern India.Journal of Petrology, Vol. 45, 5, pp. 907-948.IndiaLamproites - Mahbubnagar, Anantapur, diamonds
DS200512-0480
2005
Gibson, S.A.Johnson, J.S., Gibson, S.A., Thompson, R.N., Nowell, G.M.Volcanism in the Vitim volcanic field, Siberia: geochemical evidence for a mantle plume beneath the Baikal Rift zone.Journal of Petrology, Vol. 46, 7, July pp. 1309-1344.Russia, SiberiaGeochemistry - Vitim
DS200512-0481
2005
Gibson, S.A.Johnson, J.S., Gibson, S.A., Thompson, R.N., NOwell, G.M.Volcanism in the Vitim volcanic field, Siberia: geochemical evidence for a mantle plume beneath the Baikal Rift Zone.Journal of Petrology, Vol. 46, pp. 1309-1344.Russia, SiberiaPlume
DS200512-1084
2005
Gibson, S.A.Thompson, R.N., Ottley, C.J., Smith, P.M., Pearson, D.G., Dickin, A.P., Morrison, M.A., Leat, P.T., Gibson, S.A.Source of the Quaternary alkalic basalts, picrites and basanites of the Potrillo volcanic field, New Mexico, USA: lithosphere or convecting mantle?Journal of Petrology, Vol. 46, 8, pp. 1603-1643.United States, New Mexico, Colorado PlateauConvection
DS200512-1085
2005
Gibson, S.A.Thompson, R.N., Ottley, C.J., Smith, P.M., Pearson, D.G., Dickin, A.P., Morrison, M.A., Leat, P.T., Gibson, S.A.Source of the Quaternary alkaline basalts, picrites and basanites of the Potrillo volcanic field, New Mexico, USA: lithosphere or convecting mantle?Journal of Petrology, Vol. 46, 8, pp. 1603-1643.United States, New Mexico, Colorado PlateauPicrite, basanites
DS200512-1105
2005
Gibson, S.A.Tuff, J., Takahashi, E., Gibson, S.A.Experimental constraints on the role of garnet pyroxenite in the genesis of high Fe mantle plume derived melts.Journal of Petrology, Vol. 46, 10, pp. 2023-2058.MantleMelting
DS200512-1106
2005
Gibson, S.A.Tuff, J., Takahasi, E., Gibson, S.A.Experimental constraints on the role of garnet pyroxenite in the genesis of high Fe mantle plume derived melts.Journal of Petrology, Vol. 46. 10, Oct. pp. 2023-2058.MantleGarnet pyroxenite melting
DS200612-1444
2006
Gibson, S.A.Tuff, J., Gibson, S.A.3-7 GPa trace element partitioning in Fe rich picrites.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 26, abstract only.MantlePicrite
DS200712-0360
2006
Gibson, S.A.Gibson, S.A., Thompson, R.N., Day, J.A.Timescales and mechanisms of plume-lithosphere interactions: Ar/Ar geochronology and geochemistry of alkaline igneous rocks from the Parana Etendeka igneousEarth and Planetary Science Letters, Vol. 251, 1-2, Nov. 15, pp. 1-17.South America, BrazilGeochronology
DS200712-1095
2007
Gibson, S.A.Tuff, J., Gibson, S.A.Trace element partioning between garnet, clinopyroxene and Fe rich picritic melts at 3 to 7 GPa.Contributions to Mineralogy and Petrology, Vol. 153, 4, pp. 369-387.TechnologyPicrite
DS200812-0408
2008
Gibson, S.A.Gibson, S.A., Malarkey, J., Day, J.A.Melt depletion and enrichment beneath the western Kaapvaal Craton: evidence from Finsch peridotite xenoliths.Journal of Petrology, Vol. 49, 10, pp. 1817-1852.Africa, South AfricaDeposit - Finsch
DS201312-0310
2013
Gibson, S.A.Gibson, S.A., McMahon, S.C., Day, J.A., Dawson, J.B.Highly refractory lithospheric mantle beneath the Tanzanian Craton: evidence from Lashaine pre-metasomatic garnet bearing peridotites.Journal of Petrology, Vol. 54, 8, pp. 1503-1546.Africa, TanzaniaLashaine peridotites
DS201412-0290
2014
Gibson, S.A.Gibson, S.A.Continental rifting and mantle exotica.Volcanic and Magmatic Studies Group meeting, Abstract only Held Jan. 6-8. See minsoc websiteMantleRifting
DS201412-0586
2014
Gibson, S.A.Miller, W.G.R., Holland, T.J.B., Gibson, S.A.Multiple reaction oxygen barometry for mantle peridotite: an internally consistent thermodynamic model for reactions and garnet solid-solutions, with applications to the oxidation state of lithospheric mantle.Volcanic and Magmatic Studies Group meeting, Poster Held Jan. 6-8. See minsoc websiteMantleThermobarometry
DS201412-0751
2014
Gibson, S.A.Rooks, E.E., Gibson, S.A.Evolution of the SCLM beneath Pali Aike from mantle xenoliths.Volcanic and Magmatic Studies Group meeting, Poster Held Jan. 6-8. See minsoc websiteSouth America, PatagoniaXenoliths
DS201605-0880
2016
Gibson, S.A.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.
DS201608-1424
2016
Gibson, S.A.Miller, W.G.R., Holland, T.J.B., Gibson, S.A.Garnet and spinel oxybarometers: new internally consistent multi-equilibration temperatures models with applications to the oxidation state of the lithospheric mantle.Journal of Petrology, Vol. 57, 6, pp. 1199-1222.MantleGeobarometry

Abstract: New thermodynamic data for skiagite garnet (Fe3Fe23+Si3O12) are derived from experimental phase-equilibrium data that extend to 10 GPa and are applied to oxybarometry of mantle peridotites using a revised six-component garnet mixing model. Skiagite is more stable by 12 kJ mol-1 than in a previous calibration of the equilibrium 2 skiagite = 4 fayalite + ferrosilite + O2, and this leads to calculated oxygen fugacities that are higher (more oxidized) by around 1-1•5 logfO2 units. A new calculation method and computer program incorporates four independent oxybarometers (including 2 pyrope + 2 andradite + 2 ferrosilite = 2 grossular + 4 fayalite + 3 enstatite + O2) for use on natural peridotite samples to yield optimum logfO2 estimates by the method of least squares. These estimates should be more robust than those based on any single barometer and allow assessment of possible disequilibrium in assemblages. A new set of independent oxybarometers for spinel-bearing peridotites is also presented here, including a new reaction 2 magnetite + 3 enstatite = 3 fayalite + 3 forsterite + O2. These recalibrations combined with internally consistent PT determinations for published analyses of mantle peridotites with analysed Fe2O3 data for garnets, from both cratonic (Kaapvaal, Siberia and Slave) and circumcratonic (Baikal Rift) regions, provide revised estimates of oxidation state in the lithospheric mantle. Estimates of logfO2 for spinel assemblages are more reduced than those based on earlier calibrations, whereas garnet-bearing assemblages are more oxidized. Importantly, this lessens considerably the difference between garnet and spinel oxybarometry that was observed with previous published calibrations.
DS201610-1875
2016
Gibson, S.A.Jennings, E.S., Gibson, S.A., Maclennan, J., Heinonen, J.S.Deep mixing of mantle melts beneath continental flood basalt provinces: constraints from olivine hosted melt inclusions in primitive magmas. Etendeka and KarooGeochimica et Cosmochimica Acta, in press availableAfrica, NamibiaPicrite, ferroPicrite

Abstract: We present major and trace element compositions of 154 re-homogenised olivine-hosted melt inclusions found in primitive rocks (picrites and ferropicrites) from the Mesozoic Paraná-Etendeka and Karoo Continental Flood Basalt (CFB) provinces. The major element compositions of the melt inclusions, especially their Fe/Mg ratios, are variable and erratic, and attributed to the re-homogenisation process during sample preparation. In contrast, the trace element compositions of both the picrite and ferropicrite olivine-hosted melt inclusions are remarkably uniform and closely reflect those of the host whole-rocks, except in a small subset affected by hydrothermal alteration. The Paraná-Etendeka picrites and ferropicrites are petrogenetically related to the more evolved and voluminous flood basalts, and so we propose that compositional homogeneity at the melt inclusion scale implies that the CFB parental mantle melts were well mixed prior to extensive crystallisation. The incompatible trace element homogeneity of olivine-hosted melt inclusions in Paraná-Etendeka and Karoo near primitive magmatic rocks has also been identified in other CFB provinces and contrasts with findings from studies of basalts from mid-ocean ridges (e.g. Iceland and FAMOUS on the Mid Atlantic Ridge), where heterogeneity of incompatible trace elements in olivine-hosted melt inclusions is much more pronounced. We suggest that the low variability in incompatible trace element contents of olivine-hosted melt inclusions in near-primitive CFB rocks, and also ocean island basalts associated with moderately thick lithosphere (e.g. Hawaii, Galápagos, Samoa) may reflect mixing along their longer transport pathways during ascent and/or a temperature contrast between the liquidus and the liquid when it arrives in the crust. These thermal paths promote mixing of mantle melts prior to their entrapment by growing olivine crystals in crustal magma chambers. Olivine-hosted melt inclusions of ferropicrites from the Paraná-Etendeka and Karoo CFB have the least variable compositions of all global melt inclusion suites, which may be a function of their unusually deep origin and low viscosity.
DS201611-2115
2016
Gibson, S.A.Jennings, E.S., Gibson, S.A., Maclennan, J., Heinonen, J.S.Deep mantle melts beneath continental flood basalt provinces: constraints from olivine hosted melt inclusions in primitive magmas.Geochimica et Cosmochimica Acta, Vol. 196, pp. 36-57.Africa, Namibia, AngolaParan-Etendeka, Karoo

Abstract: We present major and trace element compositions of 154 re-homogenised olivine-hosted melt inclusions found in primitive rocks (picrites and ferropicrites) from the Mesozoic Parana ´-Etendeka and Karoo Continental Flood Basalt (CFB) provinces. The major element compositions of the melt inclusions, especially their Fe/Mg ratios, are variable and erratic, and attributed to the re-homogenisation process during sample preparation. In contrast, the trace element compositions of both the picrite and ferropicrite olivine-hosted melt inclusions are remarkably uniform and closely re?ect those of the host whole-rocks, except in a small subset a?ected by hydrothermal alteration. The Parana ´-Etendeka picrites and ferropicrites are petrogenet- ically related to the more evolved and voluminous ?ood basalts, and so we propose that compositional homogeneity at the melt inclusion scale implies that the CFB parental mantle melts were well mixed prior to extensive crystallisation. The incompatible trace element homogeneity of olivine-hosted melt inclusions in Parana ´-Etendeka and Karoo primitive magmatic rocks has also been identi?ed in other CFB provinces and contrasts with ?ndings from studies of basalts from mid- ocean ridges (e.g. Iceland and FAMOUS on the Mid Atlantic Ridge), where heterogeneity of incompatible trace elements in olivine-hosted melt inclusions is more pronounced. We suggest that the low variability in incompatible trace element contents of olivine-hosted melt inclusions in near-primitive CFB rocks, and also ocean island basalts associated with moderately thick lithosphere (e.g. Hawaii, Gala ´pagos, Samoa), may re?ect mixing along their longer transport pathways during ascent and/or a temperature contrast between the liquidus and the liquid when it arrives in the crust. These thermal paths promote mixing of mantle melts prior to their entrapment by growing olivine crystals in crustal magma chambers. Olivine-hosted melt inclusions of ferropicrites from the Parana ´-Etendeka and Karoo CFB have the least variable compositions of all global melt inclusion suites, which may be a function of their unusually deep origin and low viscosity.
DS201704-0629
2017
Gibson, S.A.Jennings, E.S., Holland, T.J.B., Maclennan, J., Gibson, S.A.The composition of melts from a heterogeneous mantle and the origin of ferropicrite: application of a thermodynamic model.Journal of Petrology, Vol. 57, 11-12, pp. 2289-2310.MantleGeochemistry
DS201708-1570
2017
Gibson, S.A.Gibson, S.A.On the nature and origin of garnet in highly refractory Archean lithospheric mantle: constraints from garnet exsolved in Kaapvaal craton orthopyroxenes.Mineralogical Magazine, Vol. 81, 4, pp. 781-809.Africa, South Africagarnet

Abstract: The widespread occurrence of pyrope garnet in Archean lithospheric mantle remains one of the ‘holy grails’ of mantle petrology. Most garnets found in peridotitic mantle equilibrated with incompatible-trace-element-enriched melts or fluids and are the products of metasomatism. Less common are macroscopic intergrowths of pyrope garnet formed by exsolution from orthopyroxene. Spectacular examples of these are preserved in both mantle xenoliths and large, isolated crystals (megacrysts) from the Kaapvaal craton of southern Africa, and provide direct evidence that some garnet in the sub-continental lithospheric mantle initially formed by isochemical rather than metasomatic processes. The orthopyroxene hosts are enstatites and fully equilibrated with their exsolved phases (low-Cr pyrope garnet ±± Cr-diopside). Significantly, P-TP-T estimates of the post-exsolution orthopyroxenes plot along an unperturbed conductive Kaapvaal craton geotherm and reveal that they were entrained from a large continuous depth interval (85 to 175 km). They therefore represent snapshots of processes operating throughout almost the entire thickness of the sub-cratonic lithospheric mantle. New rare-earth element (REE) analyses show that the exsolved garnets occupy the full spectrum recorded by garnets in mantle peridotites and also diamond inclusions. A key finding is that a few low-temperature exsolved garnets, derived from depths of ~90 km, are more depleted in light REEs than previously observed in any other mantle sample. Importantly, the REE patterns of these strongly LREE-depleted garnets resemble the hypothetical composition proposed for pre-metasomatic garnets that are thought to pre-date major enrichment events in the sub-continental lithospheric mantle, including those associated with diamond formation. The recalculated compositions of pre-exsolution orthopyroxenes have higher Al22O33 and CaO contents than their post-exsolution counterparts and most likely formed as shallow residues of large amounts of adiabatic decompression melting in the spinel-stability field. It is inferred that exsolution of garnet from Kaapvaal orthopyroxenes may have been widespread, and perhaps accompanied cratonization at ~ 2.9 to 2.75 Ga. Such a process would considerably increase the density and stability of the continental lithosphere.
DS201709-1987
2017
Gibson, S.A.Gibson, S.A.On the nature and origin of garnet in highly refractory Archean lithospheric mantle: constraints from garnet exsolved in Kaapvaal craton orthopyroxenes.Mineralogical Magazine, Vol. 81, 4, pp. 781-809.Africa, South Africagarnet mineralogy

Abstract: The widespread occurrence of pyrope garnet in Archean lithospheric mantle remains one of the ‘holy grails’ of mantle petrology. Most garnets found in peridotitic mantle equilibrated with incompatible-trace-element-enriched melts or fluids and are the products of metasomatism. Less common are macroscopic intergrowths of pyrope garnet formed by exsolution from orthopyroxene. Spectacular examples of these are preserved in both mantle xenoliths and large, isolated crystals (megacrysts) from the Kaapvaal craton of southern Africa, and provide direct evidence that some garnet in the sub-continental lithospheric mantle formed initially by isochemical rather than metasomatic processes. The orthopyroxene hosts are enstatites and fully equilibrated with their exsolved phases (low-Cr pyrope garnet?±?Cr-diopside). Significantly, P-T estimates of the post-exsolution orthopyroxenes plot along an unperturbed conductive Kaapvaal craton geotherm and reveal that they were entrained from a large continuous depth interval (85 to 175 km). They therefore represent snapshots of processes operating throughout almost the entire thickness of the sub-cratonic lithospheric mantle. New rare-earth element (REE) analyses show that the exsolved garnets occupy the full spectrum recorded by garnets in mantle peridotites and also diamond inclusions. A key finding is that a few low-temperature exsolved garnets, derived from depths of ~90 km, are more depleted in light rare-earth elements (LREEs) than previously observed in any other mantle sample. Importantly, the REE patterns of these strongly LREE-depleted garnets resemble the hypothetical composition proposed for pre-metasomatic garnets that are thought to pre-date major enrichment events in the sub-continental lithospheric mantle, including those associated with diamond formation. The recalculated compositions of pre-exsolution orthopyroxenes have higher Al2O3 and CaO contents than their post-exsolution counterparts and most probably formed as shallow residues of large amounts of adiabatic decompression melting in the spinel-stability field. It is inferred that exsolution of garnet from Kaapvaal orthopyroxenes may have been widespread, and perhaps accompanied cratonization at ~2.9 to 2.75 Ga. Such a process would considerably increase the density and stability of the continental lithosphere.
DS201809-2026
2018
Gibson, S.A.Gibson, S.A., Richards, M.A.Delivery of deep sourced, volatile rich plume material to the global ridge system.Earth and Planetary Science Letters, Vol. 499, pp. 205-218.Oceanplumes, hotspots

Abstract: The global mid-ocean ridge (MOR) system represents a major site for outgassing of volatiles from Earth's mantle. The amount of H2O released via eruption of mid-ocean ridge basalts varies along the global ridge system and greatest at sites of interaction with mantle plumes. These deep-sourced thermal anomalies affect approximately one-third of all MORs - as reflected in enrichment of incompatible trace elements, isotope signatures and elevated ridge topography (excess melting) - but the physical mechanisms involved are controversial. The “standard model” involves solid-state flow interaction, wherein an actively upwelling plume influences the divergent upwelling generated by a mid-ocean ridge so that melting occurs at higher pressures and in greater amounts than at a normal spreading ridge. This model does not explain, however, certain enigmatic features including linear volcanic ridges radiating from the active plume to the nearby MOR. Examples of these are the Wolf-Darwin lineament (Galápagos), Rodrigues Ridge (La Réunion), Discovery Ridge (Discovery), and numerous smaller ridge-like structures associated with the Azores and Easter-Salas y Gómez hot spots. An important observation from our study is that fractionation-corrected MORB with exceptionally-high H2O contents (up to 1.3 wt.%) are found in close proximity to intersections of long-lived plume-related volcanic lineaments with spreading centres. New algorithms in the rare-earth element inversion melting (INVMEL) program allow us to simulate plume-ridge interactions by mixing the compositions of volatile-bearing melts generated during both active upwelling and passively-driven corner-flow. Our findings from these empirical models suggest that at sites of plume-ridge interaction, moderately-enriched MORBs (with 0.2-0.4 wt.% H2O) result from mixing of melts formed by: (i) active upwelling of plume material to minimum depths of ~35 km; and (ii) those generated by passive melting at shallower depths beneath the ridge. The most volatile-rich MORB (0.4-1.3 wt.% H2O) may form by the further addition of up to 25% of “deep” small-fraction plume stem melts that contain >3 wt.% H2O. We propose that these volatile-rich melts are transported directly to nearby MOR segments via pressure-induced, highly-channelised flow embedded within a broader “puddle” of mostly solid-state plume material, spreading beneath the plate as a gravity flow. This accounts for the short wavelength variability (over 10s of km) in geochemistry and bathymetry that is superimposed on the much larger (many 100s of km) “waist width” of plume-influenced ridge. Melt channels may constitute a primary delivery mechanism for volatiles from plume stems to nearby MORs and, in some instances, be expressed at the surface as volcanic lineaments and ridges. The delivery of small-fraction hydrous melts from plume stems to ridges via a two-phase (melt-matrix) regime implies that a parallel, bimodal transport system is involved at sites of plume-ridge interaction. We estimate that the rate of emplacement of deep-sourced volatile-rich melts in channels beneath the volcanic lineaments is high and involves 10s of thousands of km3/Ma. Since mantle plumes account for more than half of the melt production at MORs our findings have important implications for our understanding of deep Earth volatile cycling.
DS201810-2331
2018
Gibson, S.A.Jackson, C.G., Gibson, S.A.Preservation of systematic Ni and Cr heterogeneity in otherwise homogeneous mantle olivine: implications for timescales of post-metasomatism re-equilibration.Lithos, Vol. 318-319. pp. 448-463.Africa, South Africadeposit - Bultfontein

Abstract: The flux of elements into Earth's sub-continental lithospheric mantle is facilitated by the passage of small-fraction melts that either crystallise new phases or react with pre-existing minerals.Metasomatised peridotite records the end product of this exchange but rarely captures the process in the act due to subsolidus re-equilibration. We present the results of a systematic investigation of a metasomatic melt channel preserved in a mantle peridotite from the Late Cretaceous Bultfontein kimberlite (Kaapvaal craton) that shows rare direct evidence of the melt-rock reaction processes. We show that the metasomatic proto-kimberlite melt underwent variable crystallisation of clinopyroxene, sulfides, phlogopite, spinel and zircon together with interaction and diffusive exchange with the surrounding olivine-rich mantle. Element profiles across large olivine porphyroclasts (Fo88) show significant core-to-rim variations in Ni (NiO?=?0.18-0.32?wt%) and Cr (Cr?=?35-60?ppm), while concentrations of all other elements (e.g. Mg, Fe, Mn, Co, V)are remarkably homogeneous. Electron backscatter diffraction analysis shows that the disequilibrium of Ni and Cr is greatest where the crystal contains large components of the [100] and [010] axes. The disequilibrium is preserved in certain orientations because diffusion of Ni and Cr in olivine is more anisotropic than Fe-Mg and Mn, and slower in the [100] and [010] directions. We present the first observations of Ni and Cr decoupling from other elements in mantle olivine and suggest that this is a consequence of: (i)changing mineral-melt concentration gradients associated with the reactive percolation of a precursory kimberlite melt; and (ii) late-stage sulfide and spinel precipitation. We use the diffusion limited re-equilibration of Ni in olivine to quantify the timing of metasomatism prior to xenolith entrainment by the host kimberlite. Our modelling indicates that reactive percolation occurred on the order of 103-105?years prior to entrainment; this provides an additional line of support for the hypothesis that a period of metasomatism by proto-kimberlite melts precedes the final kimberlite ascent to the surface. The broader implication of our finding of variable rates of minor element diffusion in natural olivine is that it highlights the importance of anisotropy and the impact of changing local concentration gradients during subsolidus re-equilibration.
DS201812-2821
2018
Gibson, S.A.Jackson, C.G., Gibson, S.A.Preservation of systematic Ni and Cr heterogeneity in otherwise homogeneous mantle olivine: implications for timescales of post-metasomatism re-equilibrium.Lithos, Vol. 318-319, pp. 448-463.Africa, South Africadeposit - Bultfontein

Abstract: The flux of elements into Earth’s sub-continental lithospheric mantle is facilitated by the passage of small-fraction melts that either crystallise new phases or react with pre-existing minerals. Metasomatised peridotite records the end product of this exchange but rarely captures the process in the act due to subsolidus re-equilibration. We present the results of a systematic investigation of a metasomatic melt channel preserved in a mantle peridotite from the Late Cretaceous Bultfontein kimberlite (Kaapvaal craton) that shows rare direct evidence of the melt-rock reaction processes. We show that the metasomatic proto-kimberlite melt underwent variable crystallisation of clinopyroxene, sulfides, phlogopite, spinel and zircon together with interaction and diffusive exchange with the surrounding olivine-rich mantle. Element profiles across large olivine porphyroclasts (Fo88) show significant core-to-rim variations in Ni (NiO = 0.18-0.32 wt.%) and Cr (Cr = 35-60 ppm), while concentrations of all other elements (e.g. Mg, Fe, Mn, Co, V) are remarkably homogeneous. Electron backscatter diffraction analysis shows that the disequilibrium of Ni and Cr is greatest where the crystal contains large components of the [100] and [010] axes. The disequilibrium is preserved in certain orientations because diffusion of Ni and Cr in olivine is more anisotropic than Fe-Mg and Mn, and slower in the [100] and [010] directions. We present the first observations of Ni and Cr decoupling from other elements in mantle olivine and suggest that this is a consequence of: (i) changing mineral-melt concentration gradients associated with the reactive percolation of a precursory kimberlite melt; and (ii) late-stage sulfide and spinel precipitation. We use the diffusion limited re-equilibration of Ni in olivine to quantify the timing of metasomatism prior to xenolith entrainment by the host kimberlite. Our modelling indicates that reactive percolation occurred on the order of 103-105 years prior to entrainment; this provides an additional line of support for the hypothesis that a period of metasomatism by proto-kimberlite melts precedes the final kimberlite ascent to the surface. The broader implication of our finding of variable rates of minor element diffusion in natural olivine is that it highlights the importance of anisotropy and the impact of changing local concentration gradients during subsolidus re-equilibration.
DS201908-1815
2019
Gibson, S.A.Shu, Q, Brey, G.P., Pearson, G., Liu, J., Gibson, S.A., Becker, H.The evolution of the Kaapvaal craton: a multi-isotopic perspective from lithospheric peridotites from Finsch diamond mine.Precambrian Research, 105380, 21p. PdfAfrica, South Africadeposit - Finsch

Abstract: Accurately dating the formation and modification of Earth’s sub-cratonic mantle still faces many challenges, primarily due to the long and complex history of depletion and subsequent metasomatism of this reservoir. In an attempt to improve this, we carried out the first study on peridotites from the Kaapvaal craton (Finsch Mine) that integrates results from Re-Os, Lu-Hf, Sm-Nd and Sr-isotope systems together with analyses of major-, trace- and platinum-group elements. The Finsch peridotites are well-suited for such a study because certain compositional features reflect they were highly depleted residues of shallow melting (1.5?GPa) at ambient Archean mantle temperatures. Yet, many of them have overabundant orthopyroxene, garnet and clinopyroxene compared to expected modal amounts for residues from partial melting. Finsch peridotites exhibit a wide range of rhenium depletion ages (TRD) from present day to 2.7?Ga, with a prominent mode at 2.5?Ga. This age overlaps well with a Lu-Hf isochron of 2.64?Ga (eHf (t)?=?+26) which records silico-carbonatitic metasomatism of the refractory residues. This late Archean metasomatism is manifested by positive correlations of Pt/Ir and Pd/Ir with 187Os/188Os ratios and good correlations of modal amounts of silicates, especially garnet, with Os isotope ratios. These correlations suggest that the Highly Siderophile Elements (HSE) and incompatible element reenrichment and modal metasomatism result from one single major metasomatic event at late Archean. Our detailed study of Finsch peridotites highlights the importance of using multiple isotopic systems, to constrain the ages of events defining the evolution of lithospheric mantle. The Re-Os isotope system is very effective in documenting the presence of Archean lithosphere, but only the oldest TRD ages may accurately date or closely approach the age of the last major partial melting event. For a meaningful interpretation of the Re-Os isotope systematics the data must be combined with HSE patterns, trace-element compositions and ideally other isotopic systems, e.g. Lu-Hf. This is highlighted by the widespread evidence in Finsch peridotites of Pt, Pd and Re enrichment through significant Base Metal Sulfide (BMS) addition (mainly in the range of 0.002-0.08?wt%) that systematically shifts the mode of TRD model ages to younger ages.
DS201911-2512
2019
Gibson, S.A.Black, B.A., Gibson, S.A.Deep carbon and the life cycle of large igneous provinces.Elements, Vol. 15, pp. 319-324.Mantlecarbon

Abstract: Carbon is central to the formation and environmental impact of large igneous provinces (LIPs). These vast magmatic events occur over geologically short timescales and include voluminous flood basalts, along with silicic and low-volume alkaline magmas. Surface outgassing of CO2 from flood basalts may average up to 3,000 Mt per year during LIP emplacement and is subsidized by fractionating magmas deep in the crust. The large quantities of carbon mobilized in LIPs may be sourced from the convecting mantle, lithospheric mantle and crust. The relative significance of each potential carbon source is poorly known and probably varies between LIPs. Because LIPs draw on mantle reservoirs typically untapped during plate boundary magmatism, they are integral to Earth’s long-term carbon cycle.
DS202004-0515
2020
Gibson, S.A.Gibson, S.A., Rooks, E.E., Day, J.A., Petrone, C.M., Leat, P.T.The role of sub-continental mantle as both "sink" and "source" in deep Earth volatile cycles.Geochimica et Cosmochimica Acta, Vol. 275, pp. 140-162.Mantlecraton

Abstract: The extent to which Earth’s sub-continental lithospheric mantle modulates the flux of volatile elements from our planet’s deep interior to its atmosphere (via volcanism) is poorly constrained. Here, we focus on "off-craton" sub-continental lithospheric mantle because this long-lived reservoir potentially acts as both a volatile “sink” and “source” during major heating and rifting events. The sub-continental lithospheric mantle is primarily formed of peridotites with subordinate amounts of pyroxenites. While both lithologies are dominated by nominally-volatile-free mantle minerals, some of these phases have been shown to contain non-negligible amounts of H2O (e.g. 100’s of ppmw in clinopyroxene). Data for volatile elements other than Li are, however, limited. We present new, high-precision, in-situ Secondary Ion Mass Spectrometry analyses of H, F, Cl, Li and B in olivine and pyroxenes from well-characterised garnet- and spinel-bearing peridotites and pyroxenites (from southern Patagonia and the Antarctic Peninsula). Our study confirms that clinopyroxene is the main host of H2O and F. The maximum F contents we report (up to 154 ppmw) are higher than those in previous studies and occur in Ti-Cr diopsides in highly-metasomatised peridotites and Ti-Al augites from clinopyroxenite veins. Water contents of clinopyroxenes (up to 615 ppmw) are within the range previously published for continental mantle. Lithium concentrations are low (<5 ppmw) in all analysed phases and both Cl and B are below detection levels (14 ppmw and 0.03 ppmw, respectively). Unique to our study is the large variation in major- and trace-element concentrations of the clinopyroxenes, which allows us to place quantitative constraints on how volatiles are stored in the mantle. We demonstrate that: (i) F contents of clinopyroxenes closely correlate with Ti and (ii) and is systematic and inversely correlated with temperature. Despite the redistribution of volatiles during sub-solidus re-equilibration, we show that the first order control on the concentration of volatiles in clinopyroxene is the style of metasomatism, i.e. channellised flow versus reactive percolation. The mean bulk volatile contents of peridotites from Pali Aike and the Antarctic Peninsula (H2O?=?89?±?31 ppmw, F?=?16?±?11.2 ppmw and Li?=?2?±?0.7 ppmw) are within the range previously published for continental "off-craton" mantle. The pyroxenites have significantly higher mean bulk concentrations of H2O (260?±?59 ppmw), F (86?±?43 ppmw) and Li (1.0?±?0.35 ppmw). While the greater capacity of mantle pyroxenites to host H2O relative to the associated peridotites has previously been observed in global "off-craton" mantle xenolith suites (e.g. Oahu, Hawaii; eastern China and the Rio Grande Rift, SW USA), here we show for the first time that pyroxenites are also major hosts of F (but not Cl, Li or B). Because of their relatively low solidus temperatures, pyroxenites in "off-craton" settings will be readily re-mobilised during lithospheric extension (and heating). We suggest these pyroxene-rich mantle lithologies may be responsible for the elevated concentrations of H2O and F observed in basalts and volcanic gasses from major continental rift zones and flood basalt provinces, and hence an important consideration in models of global volatile cycles.
DS1860-0938
1896
Gibson, W.Gibson, W.The Geology of Africa in Relation to Its Mineral WealthInstitute Mining Engineering NEWCASTLE Transactions, Vol. 12, PP. 303-320.Africa, South AfricaDiamonds, Economics
DS1970-0820
1973
Gibson, W.M.Sellschop, J.P.F., Gibson, W.M.Studies of Ion Channeling and Surface Impurities in DiamondDiamond Research, VOLUME FOR 1973, PP. 32-39.GlobalDiamond Genesis
DS201112-1026
2011
GicquelTallaire, A., Barjon, J., Brinza, O., Achard, Silva, Mille, Issaoui, Tardieu, GicquelDislocations and impurities introduced from etch-pitts at the epitaxial growth resumption of diamond.Diamond and Related Materials, Vol. 20, 7, pp. 875-881.TechnologyDiamond morphology
DS200612-1508
2005
Gicquel, A.Wang, W., Tallaire, A., Hall, M.S., Moses, T.M., Achard, J., Sussmans, R.S., Gicquel, A.Experimental CVD synthetic diamonds form LIMPH-CNRD France.Gems & Gemology, Vol. 41, 3, Fall, pp. 234244.TechnologySynthetic diamonds
DS1970-0086
1970
Giddey, R.F.Giddey, R.F.Metallogenic Provinces in Southern AfricaPetros, Vol. 2, PP. 26-36.South AfricaMetallogeny, Genesis, Kimberlite
DS1995-0837
1995
Giddings, J.W.Idnurm, M., Giddings, J.W.Paleoproterozoic-Neoproterozoic North America-Australia link: new evidence from PaleomagnetismGeology, Vol. 23, No. 2, Feb. pp. 149-152Australia, North AmericaPaleomagnetism, Proterozoic
DS2000-1023
2000
Giddings, J.W.Wingate, M.T.D., Giddings, J.W.Age and paleomagnetism of the Mundine Well dyke swarm: implications for Australia-Laurentia connection 755 MaPrecambrian Research, Vol. 100, No. 1-3, pp. 335-57.AustraliaDyke swarm, Geophysics - paleomagnetics
DS201707-1326
2017
Giebel, R.J.Giebel, R.J., Gauert, C.D.K., Marks, M.A.W., Costin, G., Markl, G.Multi stage formation of REE minerals in the Palabora carbonatite complex, South Africa.American Mineralogist, Vol. 102, pp. 1218-1233.Africa, South Africacarbonatite - Palabora

Abstract: The 2060 Ma old Palabora Carbonatite Complex (PCC), South Africa, comprises diverse REE mineral assemblages formed during different stages and reflects an outstanding instance to understand the evolution of a carbonatite-related REE mineralization from orthomagmatic to late-magmatic stages and their secondary post-magmatic overprint. The 10 rare earth element minerals monazite, REE-F-carbonates (bastnäsite, parisite, synchysite), ancylite, britholite, cordylite, fergusonite, REE-Ti-betafite, and anzaite are texturally described and related to the evolutionary stages of the PCC. The identification of the latter five REE minerals during this study represents their first described occurrences in the PCC as well as in a carbonatite complex in South Africa. The variable REE mineral assemblages reflect a multi-stage origin: (1) fergusonite and REE-Ti-betafite occur as inclusions in primary magnetite. Bastnäsite is enclosed in primary calcite and dolomite. These three REE minerals are interpreted as orthomagmatic crystallization products. (2) The most common REE minerals are monazite replacing primary apatite, and britholite texturally related to the serpentinization of forsterite or the replacement of forsterite by chondrodite. Textural relationships suggest that these two REE-minerals precipitated from internally derived late-magmatic to hydrothermal fluids. Their presence seems to be locally controlled by favorable chemical conditions (e.g., presence of precursor minerals that contributed the necessary anions and/or cations for their formation). (3) Late-stage (post-magmatic) REE minerals include ancylite and cordylite replacing primary magmatic REE-Sr-carbonates, anzaite associated with the dissolution of ilmenite, and secondary REE-F-carbonates. The formation of these post-magmatic REE minerals depends on the local availability of a fluid, whose composition is at least partly controlled by the dissolution of primary minerals (e.g., REE-fluorocarbonates). This multi-stage REE mineralization reflects the interplay of magmatic differentiation, destabilization of early magmatic minerals during subsequent evolutionary stages of the carbonatitic system, and late-stage fluid-induced remobilization and re-/precipitation of precursor REE minerals. Based on our findings, the Palabora Carbonatite Complex experienced at least two successive stages of intense fluid–rock interaction.
DS201709-1988
2017
Giebel, R.J.Giebel, R.J., et al.Fluid mineral interaction and REE mineralization in the Palabora carbonatite complex.Goldschmidt Conference, abstract 1p.Africa, South Africacarbonatite, Palabora

Abstract: The Palabora Carbonatite Complex (PCC) in South Africa intruded at 2060 Ma into Archean basement. The tripartite pipe-like intrusion is represented by a northern and southern pyroxenite and the central Loolekop pipe. Carbonatites and phoscorites of the Loolekop pipe experienced at least 4 stages of mineralization, recrystallization and redistibution reflected by an (1) orthomagmatic, (2) late-magmatic, (3) sulphide and (4) post-magmatic phase (Giebel et al., 2017). These four stages exhibit considerable variability of REE mineralization and especially stages 2 and 4 show intense fluid-rock interaction textures. We present microtextural and compositional data on apatite and phlogopite along a 2 km depth profile through the Loolekop pipe and investigate how these data reflect fluidmineral interaction with depth during stage (2). A special focus lies on understanding the behaviour, sources and sinks of REE elements. While fluid-apatite interaction causes a dissolution of apatite coupled with a precipitation of monazite at apatite rims, the fluid-phlogopite interaction induces a chloritization of phlogopite and an occasional formation of britholite along strongly dissolved phlogopite rims. We suspect that REE are transported into the system by this late-magmatic fluid rather than being released by the dissolution of orthomagmatic REE-bearing minerals. Combining these observations with fluid inclusion textures and microthermometry, we will investigate the nature and composition of the involved fluids and will try to model REE mineralisation processes during late-magmatic fluidmineral ineraction
DS201812-2810
2019
Giebel, R.J.Giebel, R.J., Marks, M.A.W., Gauert, C.D.K., Markl, G.A model for the formation of carbonatite-phoscorite assemblages based on the compositional variations of mica and apatite from the Palabora carbonatite complex, South Africa.Lithos, Vol. 324-325, pp. 89-104.Africa, South Africadeposit - Palabora

Abstract: A detailed electron microprobe study has been carried out on the compositional variations of mica and apatite from carbonatites, phoscorites and associated pyroxenites (and fenites) of the Loolekop deposit, Palabora Carbonatite Complex (South Africa). Mica in pyroxenites and fenites is Mg-rich biotite, whilst micas in carbonatites and phoscorites are compositionally diverse including phlogopite, Ba-rich phlogopite (up to 30% kinoshitalite component), IVAl-rich phlogopite (up to 30% eastonite component) and tetraferriphlogopite. The various types of phlogopites are interpreted as orthomagmatic phases, whereas tetraferriphlogopite precipitation was a late-magmatic to hydrothermal process that additionally introduced REE into the system. Orthomagmatic apatite is generally REE- and Sr-poor fluorapatite and does not show large compositional differences between rock types. Apatite associated with the late-stage tetraferriphlogopite mineralization reaches higher levels of REE (up to 4.9?wt%), Si (up to 1.5?wt% SiO2), Sr (up to 2.6?wt% SrO) and Na (up to 1.0?wt% Na2O). The compositional variation of micas and apatites, which is affiliated with distinct rock types, reflects the multi-stage evolution of the Loolekop deposit and provides detailed insight into the relationships of the carbonatite-phoscorite assemblage. The obtained data support the separation of phoscorite and carbonatite by immiscibility from a common parental magma, which may happen due to a decrease of temperature and/or pressure during the ascent of the magma. This results in a density contrast between the carbonatitic and phoscoritic components that will lead to descending phoscorite accumulations at the outer zones of the magma channel and a jet-like ascent (further promoted by its extremely low viscosity) of the carbonatite magma. The genetic model deduced here explains the peculiar association of carbonatites, phoscorites and silicate rocks in many alkaline complexes worldwide.
DS201902-0273
2019
Giebel, R.J.Giebel, R.J., Marks, M.A.W., Gauert, C.K., Markl, G.A model for the formation of carbonatite-phoscorite assemblages based on the compositonal variations of mica and apatite from the Palabora carbonatite complex, South AfricaLithos, Vol. 324, pp. 68-73.Europe, Azoresdeposit - Palabora

Abstract: A detailed electron microprobe study has been carried out on the compositional variations of mica and apatite from carbonatites, phoscorites and associated pyroxenites (and fenites) of the Loolekop deposit, Palabora Carbonatite Complex (South Africa). Mica in pyroxenites and fenites is Mg-rich biotite, whilst micas in carbonatites and phoscorites are compositionally diverse including phlogopite, Ba-rich phlogopite (up to 30% kinoshitalite component), IVAl-rich phlogopite (up to 30% eastonite component) and tetraferriphlogopite. The various types of phlogopites are interpreted as orthomagmatic phases, whereas tetraferriphlogopite precipitation was a late-magmatic to hydrothermal process that additionally introduced REE into the system. Orthomagmatic apatite is generally REE- and Sr-poor fluorapatite and does not show large compositional differences between rock types. Apatite associated with the late-stage tetraferriphlogopite mineralization reaches higher levels of REE (up to 4.9?wt%), Si (up to 1.5?wt% SiO2), Sr (up to 2.6?wt% SrO) and Na (up to 1.0?wt% Na2O). The compositional variation of micas and apatites, which is affiliated with distinct rock types, reflects the multi-stage evolution of the Loolekop deposit and provides detailed insight into the relationships of the carbonatite-phoscorite assemblage. The obtained data support the separation of phoscorite and carbonatite by immiscibility from a common parental magma, which may happen due to a decrease of temperature and/or pressure during the ascent of the magma. This results in a density contrast between the carbonatitic and phoscoritic components that will lead to descending phoscorite accumulations at the outer zones of the magma channel and a jet-like ascent (further promoted by its extremely low viscosity) of the carbonatite magma. The genetic model deduced here explains the peculiar association of carbonatites, phoscorites and silicate rocks in many alkaline complexes worldwide.
DS201909-2041
2019
Giebel, R.J.Giebel, R.J., Marks, M.A.W., Gauert, C.D.K., Markl, G.A model for the formation of carbonatite-phoscorite assemblages.Goldschmidt2019, 1p. AbstractGlobalcarbonatite

Abstract: A detailed electron microprobe study has been carried out on the compositional variations of mica and apatite from carbonatites, phoscorites and associated pyroxenites (and fenites) of the Loolekop deposit, Palabora Carbonatite Complex (South Africa). Mica in pyroxenites and fenites is Mg-rich biotite, whilst micas in carbonatites and phoscorites are compositionally diverse including phlogopite, Ba-rich phlogopite (up to 30% kinoshitalite component), IVAl-rich phlogopite (up to 30% eastonite component) and tetraferriphlogopite. The various types of phlogopites are interpreted as orthomagmatic phases, whereas tetraferriphlogopite precipitation was a late-magmatic to hydrothermal process that additionally introduced REE into the system. Orthomagmatic apatite is generally REE- and Sr-poor fluorapatite and does not show large compositional differences between rock types. Apatite associated with the late-stage tetraferriphlogopite mineralization reaches higher levels of REE (up to 4.9?wt%), Si (up to 1.5?wt% SiO2), Sr (up to 2.6?wt% SrO) and Na (up to 1.0?wt% Na2O). The compositional variation of micas and apatites, which is affiliated with distinct rock types, reflects the multi-stage evolution of the Loolekop deposit and provides detailed insight into the relationships of the carbonatite-phoscorite assemblage. The obtained data support the separation of phoscorite and carbonatite by immiscibility from a common parental magma, which may happen due to a decrease of temperature and/or pressure during the ascent of the magma. This results in a density contrast between the carbonatitic and phoscoritic components that will lead to descending phoscorite accumulations at the outer zones of the magma channel and a jet-like ascent (further promoted by its extremely low viscosity) of the carbonatite magma. The genetic model deduced here explains the peculiar association of carbonatites, phoscorites and silicate rocks in many alkaline complexes worldwide.
DS201909-2042
2019
Giebel, R.J.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
Giebel, R.J.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
Giebel, R.J.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
Giebel, R.J.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.
DS202109-1494
2021
Giebel, R.J.Walter, B.F., Giebel, R.J., Steele-MacInnis, M., Marks, M.A., Kolb, J., Markl, G.Fluids associated with carbonatitic magmatism: a critical review and implications for carbonatite magma ascent.Earth Science Reviews , Vol. 215, 103509, 27p. PdfMantlemagmatism

Abstract: Carbonatites are formed from volatile-rich melts, commonly associated with a characteristic hydrothermal footprint. However, studies of their fluid inclusions are relatively scarce and heterogeneous in terms of detail and completeness of the data presented. Here, we review and discuss comprehensively the results of previous studies and derive a general model for the formation and properties of fluids associated with carbonatitic magmatism. Worldwide, four types of fluid inclusion occur in carbonatites: (type I/HS) vapour-poor H2O-NaCl fluids with up to 50 wt% salinity; (type II/HC) vapour-rich H2O-NaCl-CO2 fluids with <5 wt% salinity; (type III/DS) multi-component fluids with high salinity and without CO2; and (type IV/CDS) multi-component fluids with high salinity and high CO2. This global dataset suggests continuous fluid release from deep to shallow-level intrusions. Modelling of the liquidus surface indicates that carbonatite magmas generally exsolve a saline brine (type I/HS). This brine separates/evolves into a Na-K-sulfate-carbonate/bicarbonate-chloride brine with or without CO2 (types III/DS and IV/CDS), trapped together with low salinity CO2-rich fluids produced by immiscibility. Fluid immiscibility is related to rapid pressure release during fast, forceful and discontinuous magma ascent, which we envisage as a "pneumatic jackhammer" model for carbonatite ascent and emplacement. In this model, cyclic and progressive fluid flux via pressure build-up and subsequent catastrophic pressure release results in a self-sustaining crustal ascent of the buoyant, low-viscosity magma. This process allows for rapid and efficient magma ascent, in particular above the brittle-ductile transition zone, where pressures that prevailed during apatite crystallization have been estimated in numerous complexes. Moreover, this model provides an explanation for the apparent absence of shallow carbonatite magma chambers (in a classical sense) and identifies fenitization as a phenomenon induced by both fluids released during magma ascent and residual fluids.
DS1997-0401
1997
Giebovtsky, V.A.Giebovtsky, V.A.The Early Precambrian of Russia #1Gordon and Breach Publ, 979p. approx. $ 100 United StatesRussiaBook - ad, Precambrian
DS201112-0369
2011
Giehl, C.Giehl, C., Bellucci, P., Nguyen, H-T., Marks, M., Nowak, M.Experimental investigation of the differentiation of iron rich peralkaline magma.Peralk-Carb 2011, workshop held Tubingen Germany June 16-18, PosterTechnologyMagmatism
DS202007-1184
2020
Gielbel, R.J.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.
DS200412-0514
2004
Gierlotka, S.Ekimov, E.A., Sidorov, V.A., Melnik, N.N., Gierlotka, S., Presz, A.Synthesis of polycrystalline diamond in the boron carbide graphite and boron graphite systems under high pressure and temperaturJournal of Materials Research, Vol. 39, 15, pp. 4957-4960.TechnologyDiamond synthesis
DS1986-0288
1986
Gierth, E.Gierth, E., Goldman, D., Leonardos, O.H., Baecker, M.L.Main features of the paragenetic evolution of the Carbonatite complex of Catalao 1, GoiasBrasilIn: Symposium on Latin American Sciences, Vol. 1985 No. 9-10, pp. 1469-1475BrazilBlank
DS1989-0510
1989
Gierth, E.Gierth, E., Leonardos, O.H.Some characteristics of the niobium ores in the unweathered sections Of the carbonatite complexes Catalao I and II, Goias, Brasil79th. Annual Meeting Of The Geologische Vereinigung, Mineral, p. 1-2. (abstract.)BrazilCarbonatite
DS200812-0409
2008
Gies, J.Gies, J., Schreurs, G., Berger, A., Herweigh, M., Gnos, E.Indenter tectonics in central Madagascar.Geotectonic Research, Vol. 95, suppl. 1 pp. 51-53.Africa, MadagascarTectonics
DS2001-1285
2001
Giese, et al.Yliniemi, J., Tiira, T., Luosto, Komminaho, Giese, et al.EUROBRIDGE'95: deep seismic profiling within the East European CratonTectonophysics, Vol. 339, No. 1-2, pp. 153-75.EuropeGeophysics - seismics, Craton
DS1997-0871
1997
Giese, P.Okaya, N., Tawackoli, S., Giese, P.Area -balanced model of the late Cenozoic tectonic evolution of the central Andean arc and back arcGeology, Vol. 25, No. 4, April pp. 367-370Chile, BoliviaTectonics model, Volcanics
DS2002-0896
2002
Giese, R.Kozlovskaya, E., taran, L.N., Yliniemi, J., Giese, R., Karatayev, G.I.Deep structure of the crust along the Fennoscandia Sarmatia Junction Zone ( CentralTectonophysics, Vol. 358,1-4,pp. 97-120.Fennoscandia, Europe, UralsTectonics
DS1993-0542
1993
Giesecke, A.Giesecke, A.Carbonatites and kimberlites; keys for fissiogeneses, expensionism andgeodynamics. (in German)Mitt. Geologisch-Paleo. Hamburg, (in German), Vol. 69, pp. 229-250.GlobalAlkaline rocks, Kimberlites
DS1995-2108
1995
Gieskes, J.M.You, C.F., Spivack, A.J., Gieskes, J.M., RosenbauerExperimental study of boron geochemistry: implications for fluid processes in subduction zonesGeochimica et Cosmochimica Acta, Vol. 59, No. 12, pp. 2435-2442GlobalGeochemistry - experimental, Boron
DS2002-1252
2002
Giester, G.Petersen, O.V., Giester, G., Brandstatter, NiedermayrNabesite, new mineral species from Ilmaussaq alkaline complex, south GreenlandCanadian Mineralogist, Vol.40,1,Feb.pp. 173-81.GreenlandAlkaline rocks
DS201609-1729
2016
Giester, G.Lykova, I.S., Pekov, I.V., Chukanov, N.V., Belakovskiy, D.I., Yapaskurt, V.O., Zubkova, N.V., Britvin, S.N., Giester, G.Calciomurmanite a new mineral from the Lovozero and Khibiny alkaline complexes, Kola Peninsula.European Journal of Minerlogy, in press avaialbe 15p.RussiaMineralogy
DS200412-0662
2004
Giesting, P.A.Giesting, P.A., Hofmeister, A.M., Wopenka, B., Gwanmesia, G.D., Joliff, B.L.Thermal conductivity and thermodynamics of majoritic garnets: implications for the transition zone.Earth and Planetary Science Letters, Vol. 218, 1-2, Jan. 30, pp. 45-56.MantleGeothermometry, heat capacity, entropy
DS200612-0350
2006
Giffin, B.J.Downes, P.J., Wartho, J-A., Giffin, B.J.Magmatic evolution and ascent history of the Aries micaceous kimberlite, central Kimberley Basin, Western Australia: evidence from zoned phlogopite phenocrysts and UV laserJournal of Petrology, Vol. 47, 9, Sept. pp. 1751-1783.Australia, Western AustraliaGeochronology - UV laser, analysis phlogopite-biotite
DS1960-0146
1961
Gifford, A.C.Gifford, A.C.The Geology of Eastern Marangudzi, Southern RhodesiaLondon: Ph.d. Thesis, University London., 171P.ZimbabweRegional Studies
DS1960-0847
1967
Gifford, A.C.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
DS201012-0490
2010
Gifford, J.Meert, J.G., Pandit, M.K., Pradhan, V.R., Banks, J., Sirianni, R., Stroud, M., Newstead, B., Gifford, J.Precambrian crustal evolution of Peninsular India: a 3.0 billion year odyssey.Journal of Asian Earth Sciences, Vol. 39, 6, pp. 483-515.IndiaGeodynamics, tectonics
DS201412-0291
2014
Gifford, J.N.Gifford, J.N., Mueller, P.A., Foster, D.A., Mogk, D.W.Precambrian crustal evolution in the Great Falls Tectonic Zone: insights from xenoliths from the Montana alkali province.Journal of Geology, Vol. 122, 5, pp. 531-548.United States, MontanaAlkalic
DS201502-0057
2014
Gifford, J.N.Gifford, J.N., Mueller, P.A., Foster, D.A, Mogk, D.W.Precambrian crustal evolution in the Great Falls Tectonic Zone: insights from xenoliths from the Montana Alkali province.Journal of Geology, Vol. 122, Sept. pp. 531-548.United States, MontanaAlkalic
DS201809-2027
2018
Gifford, J.N.Gifford, J.N., Mueller, P.A., Foster, D.A., Mogk, D.W.Extending the realm of Archean crust in the Great Falls tectonic zone: evidence from the Little Rocky Mountains, Montana.Precambrian Research, Vol. 315, pp. 264-281.United States, Montanacraton

Abstract: Two prominent features separate the Archean Wyoming and Hearne cratons: the Paleoproterozoic Great Falls tectonic zone (GFTZ) and the Medicine Hat block (MHB), neither of which is well defined spatially because of Phanerozoic sedimentary cover. Based on limited data, the MHB is thought to be a structurally complex mix of Archean (2.6-3.1?Ga) and Proterozoic (1.75?Ga) crust, but is recognized primarily by its geophysical signature, and its influence on the geochemistry of younger igneous rocks. Similarly, the GFTZ was recognized on the basis of broad differences in geophysical patterns, isopachs of Paleozoic sedimentary sections, and lineaments; however, juvenile arc rocks in the Little Belt Mountains (LBM) and strongly overprinted Archean rocks in southwestern Montana show it to be a dominantly Paleoproterozoic feature. The Little Rocky Mountains (LRM) of Montana provide access to exposures of the northeastern-most Precambrian crust in the MHB-GFTZ region. U/Pb ages of zircons from Precambrian rocks of the LRM range from 2.4 to 3.3?Ga, with most ages between 2.6 and 2.8?Ga. Whole-rock analyses yield Sm-Nd TDM from 3.1 to 4.0?Ga and initial eNd(T) values calculated at U-Pb zircon crystallization ages range from -0.9 to -10.5, indicating significant contributions from older Archean crust. The high proportion of 2.6-2.8?Ga U/Pb ages differentiates LRM crust from arc-related Paleoproterozoic magmatic rocks exposed in the LBM to the southwest. The age and isotopic composition of the LRM gneisses are similar to crust in the northern Wyoming Province (2.8-2.9?Ga), but Paleoproterozoic K-Ar cooling ages suggest crust in the LRM experienced the Paleoproterozoic metamorphism and deformation that characterizes the GFTZ. Consequently, its history differs markedly from the adjacent Beartooth-Bighorn magmatic zone of the northern Wyoming Province, which does not record Paleoproterozoic tectonism, but has a strong correlation with the Montana metasedimentary terrane that was strongly overprinted during the Paleoproterozoic Great Falls orogeny that defines the GFTZ. The LRM, therefore, likely provides a unique, and perhaps the only, opportunity to characterize Archean crust of the MHB.
DS201811-2562
2018
Gifford, J.N.Craddock, J., Malone, D., Schmitz, M.D., Gifford, J.N.Strain variations across the Proterozoic Penokean Orogen, USA and Canada. Sudbury impact Precambrian Research, Vol. 318, pp. 25-69.United States, Canadaorogeny

Abstract: Strata in the Huron (2.5-2.0 Ga) and Animikie (2.2-1.85 Ga) basins were deposited on the southern margin of the Archean Superior province. These rocks were deformed during the Penokean orogeny (~1850 Ma) followed by subsequent accretionary orogens to the south at 1750 Ma (Yavapai) and 1630 Ma (Mazatzal). Strain patterns are unique to each orogenic belt with no far-field effect: Archean Wawa terrane rocks in the Penokean foreland preserve deformation associated with Archean accretion with no younger Penokean, Yavapai or Mazatzal strain overprint. The Penokean orogeny deformed Huron-Animikie basin sediments into a north-vergent fold-and-thrust belt with no Yavapai or Mazatzal strain overprint. Yavapai orogen strains (SW-NE margin-parallel shortening) are unique when compared to the younger Mazatzal shortening (N20°W) shortening, with no strain overprint. Penokean deformation is characterized by shortening from the south including uplifted Archean gneisses and a northerly thin-skinned fold-and-thrust belt, with north-vergent nappes and a gently-dipping foreland. Our study of finite and calcite twinning strains (n=60) along (~1500 km) and across (~200 km) the Penokean belt indicate that this orogeny was collisional as layer-parallel shortening axes are parallel across the belt, or parallel to the tectonic transport direction (~N-S). Penokean nappe burial near the margin resulted in vertical shortening strain overprints, some of which are layer-normal. The Sudbury impact layer (1850 Ma) is found across the Animikie basin and provides a widespread deformation marker with many local, unique strain observations. We also report new geochronology (U-Pb zircon and apatite) for the gneiss-mafic dike rocks at Wissota (Chippewa Falls, WI) and Arbutus (Black River Falls, WI) dams, respectively, which bears on Penokean-Yavapai deformation in the Archean Marshfield terrane which was accreted during the Penokean orogen. Pseudotachylite formation was common in the Superior province Archean basement rocks, especially along terrane boundaries reactivated by contemporaneous Penokean, Trans-Hudson, Cape Smith and New Quebec deformation. In the hinterland (south), the younger Yavapai orogen (1750 Ma; n=8) deformation is preserved as margin-parallel horizontal shortening (~SW-NE) in Yavapai crust and up to 200 km to the north in the Penokean thrust belt as a strain and Barrovian metamorphic overprint. Mazatzal deformation (1630 Ma; n=16) is preserved in quartzites on Yavapai and Penokean crust with layer-parallel and layer-normal shortening strains oriented N20°W.
DS201804-0693
2018
Gifillan, S.M.V.Gifillan, S.M.V., Ballentine, C.J.He, Ne and Ar 'snapshot' of the subcontinental lithospheric mantle from CO2 well gas.Chemical Geology, Vol. 480, pp. 116-127.Mantlechemistry

Abstract: The subcontinental lithospheric mantle (SCLM) constitutes a significant portion of the upper mantle sourcing magmatic volatiles to the continents above, yet its geochemical signature and evolution remain poorly constrained. Here we present new interpretation of noble gas datasets from two magmatic CO2 fields in the SW US, namely Bravo Dome and Sheep Mountain, which provide a unique insight into the volatile character of the SCLM sourcing the Cenozoic volcanism in the region. We identify that reduction of 3He/4Hemantle ratio within the Sheep Mountain CO2 field can be attributed to radiogenic production within the SCLM. Using a Reduced Chi-Squared minimisation on the variation of derived 4He/21Necrust ratios within samples from the Sheep Mountain field, combined with a radiogenically raised 21Ne/22Nemantle end member, we resolve 3He/4Hemantle ratios of 2.59 ± 0.15 to 3.00 ± 0.18 Ra. These values correspond with a 21Ne/22Nemantle value of 0.136. Using these 3He/4Hemantle end member values with 21Nemantle resolved from Ne three component analysis, we derive the elemental 3He/22Nemantle of 2.80 ± 0.16 and radiogenic 4He/21Ne*mantle range of 1.11 ± 0.11 to 1.30 ± 0.14. A second Reduced Chi-Squared minimisation performed on the variation of 21Ne/40Arcrust ratios has allowed us to also determine both the 4He/40Armantle range of 0.78 to 1.21 and 21Ne/40Armantle of 7.66 ± 1.62 to 7.70 ± 1.54 within the field. Combining these ratios with the known mantle production ranges for 4He/21Ne and 4He/40Ar allows resolution of the radiogenic He/Ne and He/Ar ratios corresponding to the radiogenically lowered 3He/4Hemantle ratios. Comparing these values with those resolved from the Bravo Dome field allows identification of a clear and coherent depletion of He to Ne and He to Ar in both datasets. This depletion can only be explained by partial degassing of small melt fractions of asthenospheric melts that have been emplaced into the SCLM. This is the first time that it has been possible to resolve and account for both the mantle He/Ne and He/Ar ratios within a SCLM source. The data additionally rule out the involvement of a plume component in the mantle source of the two gas fields and hence any plume influence on the Colorado Plateau Uplift event.
DS1985-0233
1985
Gifitullina, D.S.Gifitullina, D.S., Solodova, Y.P., Khaydarov, A.A.Impurities in Diamonds of Fibrous Structure.*rusDoklady Academy of Sciences Akademy Nauk SSSR, (Russian), Vol. 284, No. 6, pp. 1464-1466RussiaCrystallography, Diamond Morphology
DS1993-0386
1993
Gigante, M.A.Earnshow, R.A., Gigante, M.A., Jones, H.Virtual reality systemsAcademic Press, 327p. approx. $ 50.00GlobalBook -ad, Virtual reality systems
DS1992-0566
1992
Giggenbach, W.F.Giggenbach, W.F.Isotopic shifts in waters from geothermal and volcanic systems along convergent plate boundaries and their originEarth and Planetary Science Letters, Vol. 113, No. 4, November pp. 495-510GlobalGeothermal systems, Plate tectonics
DS200812-0786
2008
GiglerNasdala, L., Gigler, Wildner, Grambole, Zaitsev, Harris, Hofmeister, Milledge, SatitkuneAlpha radiation damage in diamond.Goldschmidt Conference 2008, Abstract p.A672.TechnologyDiamond morphology
DS201312-0637
2013
Gigler, A.M.Nasdala, L., Grambole, D., Wildner, M., Gigler, A.M., Hainschwang, T., Zaitsev, A.M., Harris, J.W., Milledge, J., Schulze, D.J., Hofmeister, W., Balmer, W.A.Radio-colouration of diamond: a spectroscopic study.Contributions to Mineralogy and Petrology, Vol. 165, pp. 843-861.Africa, South Africa, Democratic Republic of Congo, South America, Brazil, VenezuelaDiamond - colour
DS1992-0243
1992
Giglierano, J.Chen, Xingzhi, Giglierano, J.The extraction of structural lineaments using Land sat multispectral imagery and geophysical dat a for northeast IowaGeological Society of America (GSA) Abstract Volume, Vol. 24, No. 4, April p. 9. abstract onlyIowaGeophysics, Lineaments
DS200612-0458
2006
Gignac, C.Gignac, C.Trends and outlook for mining equities.Insight Mining Business and Investment Forum, Held June 5-6, Toronto, 28p. Xerox of slides onlyGlobalEconomics - not specific to diamonds
DS1997-0402
1997
Giguere, E.Giguere, E., Hebert, R., Sharma, K.N.M., Cimon, J.Les peridotites grenvilliennes de l'Ouest du Quebec et leur potentiel diamantifere.Quebec Department of Mines, DV 97-03, p. 39.QuebecExploration - assessment
DS1998-0507
1998
Giguere, E.Giguere, E., Hebert, R., Sharma, K.N.M., Cimon, J.Les roches ultramafiques de la region de Temiscamingue et Fort CoulongeQuebec Department of Mines, DV 98-05, p. 41.QuebecExploration - assessment
DS2002-0568
2002
Giguere, E.Giguere, E., Corriveau, L., Beaudoin, G.Occurrence of ultramafic massifs in the western Grenville: petrogenesis and potential for diamond expl.Gac/mac Annual Meeting, Saskatoon, Abstract Volume, P.39, p.39QuebecTemiscaming, Bryson intrusions
DS2002-0569
2002
Giguere, E.Giguere, E., Corriveau, L., Beaudoin, G.Occurrence of ultramafic massifs in the western Grenville: petrogenesis and potential for diamond expl.Gac/mac Annual Meeting, Saskatoon, Abstract Volume, P.39, p.39QuebecTemiscaming, Bryson intrusions
DS201912-2790
2019
Giguet-Covex, C.Jacq, K., Giguet-Covex, C., Sabatier, P., Perrette, Y., Fanget, B., Coquin, D., Debret, M., Arnaud, F.High resolution grain size distribution of sediment core with hyperspectral imaging. ( not specific to diamond)Sedimentary Geology, Vol. 393-394, pdfGlobalhyperspectral

Abstract: The study of sediment cores allows for the reconstruction of past climate and environment through physical-chemical analysis. Nevertheless, this interpretation suffers from many drawbacks that can be overcome with the newest technologies. Hyperspectral imaging is one of these and allows a fast, high resolution, and non-destructive analysis of sediment cores. In this study, we use visible and near-infrared hyperspectral imaging to predict particle size fractions and distribution (PSD) at a resolution of 200?µm on a previously well-studied sediment core taken from Lake Bourget (Western Alps, France). These predictions agree with previous studies on this core. Then, the PSD was used to estimate sedimentary deposit sources using the PSD unmixing algorithm AnalySize. It permitted estimation of the contribution of five sources (micrite, small and large bio-induced calcite crystals, diatom frustules, detrital particles), which had previously been characterized. The spatial dimension allowed for laminae to be discretized and counted, in agreement with the age-depth model previously established. We then evaluated the particle size and spectral signatures of each of these annual laminae, hence characterizing their physico-chemical composition. These high-resolution data also allowed for estimation of the accumulation rate (cm/year) of each of the main sources in the laminated unit and inferring the trophic status and the presence of instantaneous events of the lake.
DS1983-0494
1983
Gik, L.D.Orlov, YU.A., Gik, L.D., Bobrov, B.A., Kolobova, S.E.Modelling of the Effect of a Kimberlite Pipe on a Seismic Wave Field.Soviet Geology And Geophysics, Vol. 24, No. 3, PP. 88-94.RussiaKimberlite, Geophysics
DS1991-0949
1991
GilbertLambert, D.D., Shirey, S.B., Carlson, R.W., Weaver, B.L., GilbertRhenium- Osmium (Re-Os) and samarium-neodymium (Sm-Nd) isotopic systematics of lamproites and basalts from theEos Transactions, Vol. 72, No. 44, October 29, abstract p. 543Arkansas, MidcontinentLamproites, Geochemistry, geochronology
DS1990-0567
1990
Gilbert, A.E.Gilbert, A.E., Kozmenko, O.A., Shatskiy, V.S.Rare and rare earth elements in Kokchetau massif eclogitesGeochemistry International, Vol. 27, No. 8, pp. 133-136RussiaRare earths, Eclogites
DS1990-0568
1990
Gilbert, A.E.Gilbert, A.E., Kozmenko, O.A., Shatsky, V.S.Rare and rare earth elements in eclogites of the Kokchetav Massif.(Russian)Geochemistry International (Geokhimiya), (Russian), No. 1, January 1990, pp. 141-144RussiaEclogites, Rare earths
DS1993-0543
1993
Gilbert, C.Gilbert, C.Portable GPS systems for mapping features versus benefitsEarth Observation Magazine, Vol. 2, No. 9, October pp. 43, 44, 47, 48GlobalGlobal Positioning system
DS1993-0544
1993
Gilbert, C.Gilbert, C.Portable GPS systems for mapping features versus benefitsEarth Observation Magazine, Vol. 2, No. 9, October pp. 43, 44, 47, 48.GlobalGPS Systems -brief explanation, Global Positioning Systems
DS1996-0524
1996
Gilbert, C.Gilbert, C.Translating GPS dat a to a GIS, CAD system or dat abase format, part IIEom., Dec. pp. 34-35GlobalComputers, GIS, GPS
DS1996-0525
1996
Gilbert, C.Gilbert, C.Translating GPS dat a to a GIS, CAD system or dat abase formatEom., October pp. 38-39GlobalGIS, Database format
DS1996-0526
1996
Gilbert, C.Gilbert, C.Doing a differential correction by handEarth Observation Magazine, Sept. pp. 40-41GlobalGPS -corrections
DS1996-0527
1996
Gilbert, C.Gilbert, C.GPS to record dat a at a fixed location and a laptop recording dat a in thefield... difference for error?Earth Observation Magazine, Sept. pp. 43-45GlobalGPS -corrections
DS1996-0528
1996
Gilbert, C.Gilbert, C.Using GPS with offset information. Part 3 of 3Earth Observation Magazine, May pp. 38-40.GlobalGPS data collection
DS1996-0529
1996
Gilbert, C.Gilbert, C.Using GPS with offset informationEarth Observation Magazine, May, pp. 38-40GlobalGPS data collection
DS1996-0530
1996
Gilbert, C.Gilbert, C.Using GPS with offset information: Laser Rangefinders Part 2Earth Observation Magazine, April, pp. 30-32.GlobalGPS, Laser Rangefinders
DS1996-0531
1996
Gilbert, C.Gilbert, C.How is the accuracy of a GPS receiver described?Earth Observation Magazine, June pp. 44-45GlobalGPS, Accuracy
DS1997-0403
1997
Gilbert, C.Gilbert, C.Batch processing of GPS data, part 2 of 2Eom., March pp. 36-37GlobalComputer, GPS
DS1997-0404
1997
Gilbert, C.Gilbert, C.Select the best type of GPS dat a for your application. Part 2 of 2Eom., October pp. 25-27GlobalComputer, GPS
DS1997-0405
1997
Gilbert, C.Gilbert, C.Translating GPS dat a to GIS, CAD system or dat abase format, Part IIIEom., Jan. pp. 36-37GlobalComputers, GPS
DS1997-0406
1997
Gilbert, C.Gilbert, C.Batch processing of GPS data, part 1 of. 2Eom., Feb. pp. 35-36GlobalComputers, GPS data
DS1997-0407
1997
Gilbert, C.Gilbert, C.Selecting the best type of GPS dat a for your application Part 1 of 2Eom., July pp. 49-50GlobalComputers, GPS data
DS1997-0408
1997
Gilbert, C.Gilbert, C.The vertical components of GPSEom., May pp. 34-35GlobalGPS, Computers
DS1998-0508
1998
Gilbert, C.Gilbert, C.Evolution of GPS dat a collection for GISEom., Feb. pp. 27-28GlobalComputer, GIS data
DS200812-0410
2008
Gilbert, C.D.Gilbert, C.D., William-Jones, A.E.Vapour transport of rare earth elements ( REE) in volcanic gas: evidence from encrustations at Oldoinyo Lengai.Journal of Volcanology and Geothermal Research, Vol. 178, 4, Oct. 15, pp. 519-528.Africa, TanzaniaNatrocarbonatite
DS1987-0795
1987
Gilbert, C>M.Williams, H., Turner, F.J., Gilbert, C>M.Petrography - an introduction to the study of rocks in thin sectionsFreeman and Co, pp. 227-259GlobalLamprophyres, Alkalic Rocks
DS1975-0515
1977
Gilbert, E.Gilbert, E., et al.Neutron activation determination of noble metals for the analysis of technological and natural materials.Journal of Radioanalyt. Chem., Vol. 38, pp. 147-54.GlobalGeochemistry - Not Specific To Diamonds, Platinum Group
DS200712-0361
2007
Gilbert, H.Gilbert, H., Velasco, A.A., Zandt, G.Preservation of Proterozoic terrane boundaries within the Colorado Plateau and implications for its tectonic evolution.Earth and Planetary Science Letters, Vol. 256, 1-2, June 15, pp. 237-248.United States, Colorado PlateauTectonics
DS201706-1095
2017
Gilbert, H.Marshak, S., Domrois, S., Abert, C., Larson, T., Pavlis, G., Hamburger, M., Yang, X., Gilbert, H., Chen, C.The basement revealed: tectonic insight from a digital elevation model of the Great Unconformity, USA cratonic platform.Geology, Vol. 45, 5, pp. 391-394.United Statestectonics - Mid continent

Abstract: Across much of North America, the contact between Precambrian basement and Paleozoic strata is the Great Unconformity, a surface that represents a >0.4 b.y.-long hiatus. A digital elevation model (DEM) of this surface visually highlights regional-scale variability in the character of basement topography across the United States cratonic platform. Specifically, it delineates Phanerozoic tectonic domains, each characterized by a distinct structural wavelength (horizontal distance between adjacent highs) and/or structural amplitude (vertical distance between adjacent lows and highs). The largest domain, the Midcontinent domain, includes long-wavelength epeirogenic basins and domes, as well as fault-controlled steps. The pronounced change in land-surface elevation at the Rocky Mountain Front coincides with the western edge of the Midcontinent domain on the basement DEM. In the Rocky Mountain and Colorado Plateau domains, west of the Rocky Mountain Front, structural wavelength is significantly shorter and structural amplitude significantly higher than in the Midcontinent domain. The Bordering Basins domain outlines the southern and eastern edges of the Midcontinent domain. As emphasized by the basement DEM, several kilometers of structural relief occur across the boundary between these two domains, even though this boundary does not stand out on ground-surface topography. A plot of epicenters on the basement DEM supports models associating intraplate seismicity with the Midcontinent domain edge. Notably, certain changes in crustal thickness also coincide with distinct changes in basement depth.
DS2001-0381
2001
Gilbert, H.J.Gilbert, H.J., Sheehan, A.F., Webb, S.Upper mantle discontinuity structure in the region of the Tonga subductionzone.Geophysical Research Letters, Vol. 28, No. 9, May 1, pp. 1855-8.MantleSubduction
DS2003-0465
2003
Gilbert, H.J.Gilbert, H.J., Sheehan, A.F., Dueker, K.G., Molnar, P.Receiver functions in the western United States with implications for upper mantleJournal of Geophysical Research, Vol. 108, B5, May 1, 10.1029/2002JB001194.Colorado, WyomingGeophysics - seismics
DS2003-0466
2003
Gilbert, H.J.Gilbert, H.J., Sheehan, A.F., Dueker, K.G., Molnar, P.Receiver functions in the western United States, with implications for upper mantleJournal of Geophysical Research, Vol. 108, 5, ETG3 DOI 10.1029/2002JB001194.United States, Colorado, WyomingGeophysics - seismics
DS200412-0663
2004
Gilbert, H.J.Gilbert, H.J., Sheehan, A.F.Images of crustal variations in the intermountain west.Journal of Geophysical Research, Vol. 109, B3, 10.1029/2003JB002730TechnologyTomography
DS200412-0664
2003
Gilbert, H.J.Gilbert, H.J., Sheehan, A.F., Dueker, K.G., Molnar, P.Receiver functions in the western United States, with implications for upper mantle structure and dynamics.Journal of Geophysical Research, Vol. 108, 5, ETG3 DOI 10.1029/2002 JB001194.United States, Colorado PlateauGeophysics - seismics
DS1986-0289
1986
Gilbert, J.M.Gilbert, J.M., Park, C.F.Jr.Kimberlites-diamond and carbonatites-PalaboraIn: Geology of ore deposits, W.H. Freeman and Co, pp. 436-452South AfricaCarbonatite
DS1998-0509
1998
Gilbert, J.S.Gilbert, J.S.The physics of explosive volcanic eruptionsGeological Society of London Spec. Publishing, No. 145, 192p. $ 98.00 United StatesGlobalMagmas, fragmentation - not specific to diamonds
DS1998-0510
1998
Gilbert, J.S.Gilbert, J.S., Sparks, R.S.J.Future research directions on the physics of explosive volcanic eruptionsGilbert and Sparks, Geological Society of London, No. 145, pp. 1-7.GlobalVolcanic processes - not specific to diamonds
DS1998-1388
1998
Gilbert, J.S.Sparks, R.S.J., Gilbert, J.S.The physics of explosive volcanic eruptionsGeological Society of London Spec. Pub, No. 145, 192p. $ 98.00GlobalBook - ad, Magma, flow, fragmentation, phretomagmatic
DS1986-0290
1986
Gilbert, L.A.Gilbert, L.A., Foland, K.A.The Mont St. Hilaire plutonic complex: occurrence of excess 40Ar and short intrusion historyCanadian Journal of Earth Sciences, Vol. 23, No. 7, July pp. 948-958QuebecCarbonatite
DS1970-0818
1973
Gilbert, M.C.Sears, C.E., Gilbert, M.C.Petrography of the Mt. Horeb Virginia, PeridotiteGeological Society of America (GSA), Vol. 5, No. 5, P. 434. (abstract.).Appalachia, VirginiaPetrography
DS1975-0404
1976
Gilbert, M.C.Sears, C.E., Gilbert, M.C.Nature of Central Appalachian KimberlitesEos, Vol. 57, No. 10, P. 761. (abstract.).Appalachia, VirginiaKimberlite, Mt. Horeb, Heavy Minerals
DS1983-0253
1983
Gilbert, M.C.Gilbert, M.C.Timing and chemistry of igneous events associated with the southern Oklahoma aulocogen.Tectonophysics, Vol. 94, pp. 439-55.GlobalTectonics, Magmatism
DS1983-0254
1983
Gilbert, M.C.Gilbert, M.C.Timing and Chemistry of Igneous Events Associated with the Southern Oklahoma Aulacogen.Tectonophysics, Vol. 94, No. 1-4, PP. 439-455.OklahomaMid-continent
DS1986-0291
1986
Gilbert, M.C.Gilbert, M.C., McConnell, D.A.The southern margin of North American craton: problems and constraints on possible modelsGeological Society of America (GSA) Abstract Volume, Vol. 18, No. 6, p. 613. (abstract.)MidcontinentBlank
DS1989-0511
1989
Gilbert, M.C.Gilbert, M.C.Cambrian rifting in the southern Midcontinent of the United States: processes andconsequencesEos, Vol. 70, No. 43, October 24, p. 1343. AbstractMidcontinentTectonics, Rifting
DS1990-0569
1990
Gilbert, M.C.Gilbert, M.C.Southern midcontinent -Texas transect: overview and statement of the tectonic problemsGeological Society of America (GSA) Abstracts with programs, South-Central, Vol. 22, No. 1, p. 6GlobalMidcontinent, Tectonics
DS1990-1003
1990
Gilbert, M.C.McConnell, D.A., Gilbert, M.C.Cambrian extensional tectonics and magmatism within the Southern Oklohomaaulocogen.Tectonophysics, Vol. 174, pp. 147-57.GlobalMidcontinent Rifting, Tectonics
DS1998-0630
1998
Gilbert, M.C.Hogan, J.P., Price, J.D., Gilbert, M.C.Magma traps and driving pressure: consequences for pluton shape and emplacement in an extensional regime.Journal of Structural Geology, Vol. 20, No. 9/10, Sept. pp. 1155-68.GlobalTectonics, structure, Not specific to diamonds
DS200712-0192
2007
Gilbert, M.C.Cloos, M., Carlson, W.D., Gilbert, M.C., Liou, J.G., Sorensen, S.S.Convergent margin terranes and associated regions: a tribute to W.G. Ernst.Geological Society of America, Special Publication 419, 273p. $ 70.00GlobalConference book - geotectonics
DS201904-0715
2019
Gilbert, S.Armistead, S.E., Collins, A.S., Redaa, A., Gilbert, S., Jepson, G., Gillespie, J., Blades, M.L., Foden, J.D., Razakamana, T.Structural evolution and medium temperature thermochronology of central Madagascar: implications for Gondwana amalgamation.Journal of the Geological Society of London, in press available 25p.Africa, Madagascarthermochronology

Abstract: Madagascar occupied an important place in the amalgamation of Gondwana, and preserves a record of several Neoproterozoic events that can be linked to orogenesis of the East African Orogen. We integrate remote sensing and field data to unravel complex deformation in the Ikalamavony and Itremo domains of central Madagascar. The deformation sequence comprises a gneissic foliation (S1), followed by south to south-west directed, tight to isoclinal, recumbent folding (D2). These are overprinted by north-trending upright folds that formed during a ~E-W shortening event. Together these produced type 1 and type 2 fold interference patterns throughout the Itremo and Ikalamavony domains. Apatite U-Pb and muscovite and biotite Rb-Sr thermochronometers indicate that much of central Madagascar was thermally reset to at least ~500oC at c. 500 Ma. Deformation in west-central Madagascar occurred between c. 750 Ma and c. 550 Ma, and we suggest this deformation formed in response to the c. 650 Ma collision of Azania with Africa along the Vohibory Suture in southwestern Madagascar. In eastern Madagascar, deformation is syn- to post-550 Ma, which formed in response to the final closure of the Mozambique Ocean along the Betsimisaraka Suture that amalgamated Madagascar with the Dharwar Craton of India.
DS202010-1826
2020
Gilbert, S.Armistead, S.E., Collins, A.S., Redaa, A., Jepson, G., Gillespie, J., Gilbert, S., Blades, M.L., Foden, J.D., RazakMnN, T.Structural evolution and medium temperature thermochronology of central Madagascar: implications for Gondwana amalagamation.Journal of the Geological Society, Vol. 177, pp. 784-798.Africa, Madagascargeothermometry

Abstract: Madagascar occupied an important place in the amalgamation of Gondwana and preserves a record of several Neoproterozoic events that are linked to orogenesis of the East African Orogen. In this study, we integrate remote sensing, field data and thermochronology to unravel complex deformation in the Ikalamavony and Itremo domains of central Madagascar. The deformation sequence comprises a gneissic foliation (S1), followed by south- to SW-directed, tight to isoclinal, recumbent folding (D2). These are overprinted by north-trending upright folds that formed during an approximately east-west shortening event (D3). Together these produced type 1 and type 2 fold interference patterns throughout the Itremo and Ikalamavony domains. We show that the Itremo and Ikalamavony domains were deformed together in the same orogenic system, which we interpret as the c. 630 Ma collision of Azania with Africa along the Vohibory Suture in southwestern Madagascar. In eastern Madagascar, deformation is syn- to post-550 Ma, and probably formed in response to final closure of the Mozambique Ocean along the Betsimisaraka Suture that amalgamated Madagascar with the Dharwar Craton of India. Apatite U-Pb and novel laser ablation triple quadrupole inductively coupled plasma mass spectrometry (LA-QQQ-ICP-MS) muscovite and biotite Rb-Sr thermochronology indicates that much of central Madagascar cooled through c. 500°C at c. 500 Ma.
DS200512-0751
2004
GilbertsonMoses, T.M., Johnson, M.L., Green, B., Blodgett, Cino, Geurts, Gilbertson, hemphill, King, Kornylak, ReinitzA foundation for grading the overall cut quality of round brilliant cut diamonds.Gems & Gemology, Vol. 40, 3, Fall, pp. 202-228.Diamond cutting
DS200712-0362
2006
Gilbertson, A.Gilbertson, A.The evolution of the American round brilliant diamonds... 1860-1955.Gems & Gemology, 4th International Symposium abstracts, Fall 2006, p.133. abstract onlyTechnologyDiamond cutting
DS201012-0235
2009
Gilbertson, A.Gilbertson, A., Gudlewski, B., Jhonson, M., Maltezos, G., Scherer, A., Shigley, J.Cutting diffraction gratings to improve dispersion ( 'fire') in diamonds. A new process of plasma eteching diffraction patterns on diamond facets.Gems & Gemology, Vol. 45, 4, Winter pp. 260-270.TechnologyDiamond cutting
DS201212-0648
2012
Gilbertson, A.Shigley, J.E., Gilbertson, A., Eaton-Magana, S.Characteristics of colorless coated cubic zirconia ( Diamantine).Gems & Gemology, Vol. 48, 1, pp.TechnologyDiamantine
DS200912-0380
2008
Gilbertson, A.M.King, J.M., Geurts, R.H., Gilbertson, A.M., Shigley, J.E.Color grading 'D-to-Z' diamonds at the GIA laboratory.Gems & Gemology, Vol. 44, 4, pp. 296-321.TechnologyDiamond colours
DS201312-0307
2011
Gilbertson, A.M.Geurts, R.H., Reinitz, I.M., Blodgett, T., Gilbertson, A.M.GIA's symmetry grading boundaries for round brilliant cut diamonds.Gems & Gemology, Vol. 47, winter pp. 286-295.TechnologyDiamond cutting
DS1991-1182
1991
Gilbertson, J.P.Mooers, H.D., Hobbs, H.C., Gilbertson, J.P.Correlation of Late Wisconsin ice margins in MinnesotaGeological Society of America, Abstract Volume, Vol. 23, No. 3, March p. 50MinnesotaGeomorphology, Glacial
DS200812-0146
2008
Gilbertson, M.Brown, R.J., Field, M., Gernon, T., Gilbertson, M., Sparks, R.S.J.Problems with in vent column collapse model for the emplacement of massive volcaniclastic kimberlite. Discussion of Porritt - Fox kimberliteJournal of Volcanology and Geothermal Research, in press available 8p.Canada, Northwest territoriesFox kimberlite petrology
DS200812-1100
2007
Gilbertson, M.Sparks, R.S., Brown, R.J., Field, M., Gilbertson, M.Kimberlite ascent and eruption.Nature, Vol. 450, 7172, p. E21.TechnologyClassification
DS200612-0447
2006
Gilbertson, M.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
DS200812-0397
2008
Gilbertson, M.A.Gernon, T.M., Gilbertson, M.A., Sparks, R.S.J., Field, M.Gas fluidization in an experimental tapered bed: insights into processes in diverging volcanic conduits.Journal of Volcanology and Geothermal Research, Vol. 174, 1-3, pp. 49-56.TechnologyEmplacement, diatreme
DS200912-0248
2009
Gilbertson, M.A.Gernon, T.M., Gilbertson, M.A., Sparks, R.S.J., Field, M.The role of gas fluidization in the formation of massive volcanoclastic kimberlite.Lithos, In press available 33p.MantleFluidization
DS200612-0459
2006
Gilborn, R.Gilborn, R.Reasonable cause: policies to test employees for drug or alcohol use... legal minefields.Canadian Diamonds, Winter, p. 14,16,42,44.Canada, Northwest TerritoriesNews item - legal
DS1990-0570
1990
Gilchrist, A.R.Gilchrist, A.R., Summerfield, M.A.Differential denudation and flexural isostasy in formation of rifted marginupwarpsNature, Vol. 346, No. 6286, August 23, pp. 739-741GlobalTectonics, Rifted margins
DS1988-0255
1988
Gilchrist, I.C.R.Gilchrist, I.C.R., Hunt, M.S.The recovery of water from a colloidally stable kimberlite suspensionInternational Mine Water Congress, 3rd. AusIMM, pp. 131-145AustraliaWastewater, Mineral processing
DS1990-0571
1990
Gilchrist, I.C.R.Gilchrist, I.C.R.Clarification of Premier mine slimesInternational Deep Mining Conference, held Johannesburg Sept. 17-21, 1990. Sth. Afr., Vol. 1, pp. 73-80South AfricaMining - Premier, Mineral Processing
DS1900-0319
1905
Gilchrist, J.D.F.Flint, W., Gilchrist, J.D.F.Science in South Africa. a Handbook and ReviewCape Town: Maskew Miller., 505P.Africa, South AfricaHistory, Kimberley
DS1996-1587
1996
Gilder, S.A.Zhai, X., Coe, R.S., Gilder, S.A., Frost, G.M.Paleomagnetic constraints on the paleogeography of China: implications forGondwanaland.Australian Journal of Earth Sciences, Vol. 43, pp. 643-672.ChinaPaleomagnetism, Tectonics
DS1996-1603
1996
Gilder, S.A.Zhao, X., Coe, R.S., Gilder, S.A., Frost, G.M.Paleomagnetic constraints on the paeogeography of China: implications forGondwanalandAustralian Journal of Earth Sciences, Vol. 43, pp. 643-672Australia, ChinaPaleomagnetism, Tarim, Tectonics
DS200712-0767
2007
Gilder, S.A.Muundjua, M., Hart, R.J., Gilder, S.A., Carporzen, L., Galdeano, A.Magnetic imaging of the Vredefort impact crater, South Africa.Earth and Planetary Science Letters, Vol. 261, 3-4, pp. 456-468.Africa, South AfricaGeophysics
DS2002-0149
2002
Giles, D.Betts, P.G., Giles, D., Lister, G.S., Frick, L.R.Evolution of the Australian lithosphereAustralian Journal of Earth Sciences, Vol. 49,4,August pp. 661-96.AustraliaMantle - geodynamics
DS2002-0570
2002
Giles, D.Giles, D.Southward growth of Australia in the paleo and mesoproterozoic accretionary margin of pre-Rodinian supercontinent?Geological Society of America Annual Meeting Oct. 27-30, Abstract p. 559.AustraliaTectonics, Gondwana
DS2002-0571
2002
Giles, D.Giles, D., Betts, P., Lister, G.Far field continental backarc setting for the 1.80 - 1.67 Ga basins of northeastern Australia.Geology, Vol. 30,9,Sept. pp. 823-6.AustraliaTectonics - plates, Proterozoic
DS200712-0076
2007
Giles, D.Betts, P.G., Giles, D., SChaefer, B.F., Mark, G.1600 -1500 Ma hotspot track in eastern Australia: implications for Mesoproterozoic continental reconstruction.Terra Nova, Vol. 19, 6, pp. 496-501.AustraliaHotspots, plumes
DS201112-0086
2011
Giles, D.Betts, P.G., Giles, D., Aitken, A.Paleoproterozoic accretion processes of Australia and comparisons with Laurentia.International Geology Review, Vol. 53, no. 11-12, pp. 1357-1376.Australia, CanadaTectonics
DS201412-0292
2014
Giles, D.Giles, D., Hillis, R., Clverely, J.Deep exploration technologies provide the pathway to deep discovery.SEG Newsletter, No. 97, April pp. 1, 23-27.TechnologyNot specific to diamonds
DS201606-1078
2016
Giles, D.Betts, P.G., Armit, R.J., Stewart, J., Aitken, A.R.A., Aileres, L., Donchak, P., Hutton, L., Withnall, I., Giles, D.Australia and Nuna.Geological Society of London Special Publication Supercontinent Cycles through Earth History., Vol. 424, pp. 47-81.AustraliaSupercontinents

Abstract: The Australian continent records c. 1860-1800 Ma orogenesis associated with rapid accretion of several ribbon micro-continents along the southern and eastern margins of the proto-North Australian Craton during Nuna assembly. The boundaries of these accreted micro-continents are imaged in crustal-scale seismic reflection data, and regional gravity and aeromagnetic datasets. Continental growth (c. 1860-1850 Ma) along the southern margin of the proto-North Australian Craton is recorded by the accretion of a micro-continent that included the Aileron Terrane (northern Arunta Inlier) and the Gawler Craton. Eastward growth of the North Australian Craton occurred during the accretion of the Numil Terrane and the Abingdon Seismic Province, which forms part of a broader zone of collision between the northwestern margins of Laurentia and the proto-North Australian Craton. The Tickalara Arc initially accreted with the Kimberley Craton at c. 1850 Ma and together these collided with the proto-North Australian Craton at c. 1820 Ma. Collision between the West Australian Craton and the proto-North Australian Craton at c. 1790-1760 Ma terminated the rapid growth of the Australian continent.
DS200712-1025
2006
Giles, G.Spera, F.J., Yuen, D.A., Giles, G.Tradeoffs in chemical and thermal variations in the post perovskite phase transition: mixed phase regions in the deep lower mantle?Physics of the Earth and Planetary Interiors, Vol. 159, 3-4, Dec. pp. 234-246.MantleGeothermometry
DS1960-0147
1961
Giles, G.S.Giles, G.S.Diamond Mining Practice in South AfricaSouth African Institute of Mining and Metallurgy. Journal, Vol. 61, SEPT. PP. 839-850.South AfricaDiamond Mining Recovery, Kimberlite Pipes
DS1995-0632
1995
Giles, J.R.A.Giles, J.R.A.Geological dat a managementGeological Society Publishing House, GlobalData Management, Book -ad
DS1997-0063
1997
Giles, J.R.A.Bain, K.A., Giles, J.R.A.A standard model for storage of geological map dataComputers and Geosciences, Vol. 23, No. 6, pp. 613-620GlobalMapping, Computers - Program
DS1997-0409
1997
Giles, J.R.A.Giles, J.R.A., Lowe, D.J., Bain, K.A.Geological dictionaries - critical elements of every geological databaseComputers and Geosciences, Vol. 23, No. 6, pp. 621-26GlobalDictionary, Computers - Program
DS1960-1092
1969
Giletti, B.J.Damon, P.E., Giletti, B.J.The Age of the Basement Rocks of the Colorado Plateau and Adjacent Areas.New York Academy of Sciences Annual, Vol. 91, PP. 443-453.United States, Colorado PlateauBlank
DS1860-0143
1871
Gilfillan, G.F.Gilfillan, G.F.On the Diamond Districts of the Cape of Good HopeQuarterly Journal of Geological Society (London), Vol. 27, PT. 1, PP. 72-73. ALSO: 1871 Geology Magazine, Vol. 8, PPAfrica, South Africa, Cape Province, Vaal RiverGeology
DS1997-0410
1997
Gilfillan, J.Gilfillan, J.Reporting mineral resources and ore reserves - the ASX, the JORC codes And the AusIMM: are you a competent ..Australian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 5, Aug, pp. 23-24AustraliaEconomics, ore reserves, geostatistics, Legal, reporting
DS2000-0337
2000
Gilfillan, J.F.Gilfillan, J.F.Testing the dat a - the role of technical due diligenceMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 505-10.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS2000-0338
2000
Gilfillan, J.F.Gilfillan, J.F.The resource database auditMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 91-6.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS2000-0339
2000
Gilfillan, J.F.Gilfillan, J.F., Levy, I.W.Monitoring the reserveMin. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 537-44.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS2000-0932
2000
Gilfillan, J.F.Stoker, P.T., Gilfillan, J.F.The resource database audit.Min. Res. Ore Res. Est. AusIMM Guide, Mon. 23, pp. 31-6.AustraliaEconomics - geostatistics, ore reserves, exploration, Not specific to diamonds
DS201912-2784
2019
Gilfillan, S.M.V.Gilfillan, S.M.V., Gyore, D., Flude, S., Johnson, G., Bond, C.E., Hicks, N., Lister, R., Jones, D.G., Kremer, Y., Hazeldine, R.S., Stuart, F.M.Noble gases confirm plume related mantle degassing beneath southern Africa.Nature Communications, Vol. 10, 1, 10.1038/s41467-019-1244-6Africa, South Africaplumes

Abstract: Southern Africa is characterised by unusually elevated topography and abnormal heat flow. This can be explained by thermal perturbation of the mantle, but the origin of this is unclear. Geophysics has not detected a thermal anomaly in the upper mantle and there is no geochemical evidence of an asthenosphere mantle contribution to the Cenozoic volcanic record of the region. Here we show that natural CO2 seeps along the Ntlakwe-Bongwan fault within KwaZulu-Natal, South Africa, have C-He isotope systematics that support an origin from degassing mantle melts. Neon isotopes indicate that the melts originate from a deep mantle source that is similar to the mantle plume beneath Réunion, rather than the convecting upper mantle or sub-continental lithosphere. This confirms the existence of the Quathlamba mantle plume and importantly provides the first evidence in support of upwelling deep mantle beneath Southern Africa, helping to explain the regions elevation and abnormal heat flow.
DS1999-0011
1999
Gilg, H.A.Andrade, F.R.D., Moller, P., Gilg, H.A.Hydrothermal rare earth elements mineralization in the Barra do Itapirapuacarbonatite, trace elements and C, OChemical Geology, Vol. 155, No. 1-2, Mar. 1, pp. 91-114.Brazilrare earth elements (REE), inclusions, Carbonatite
DS201312-0615
2013
Gilg, H.A.Moteani, G., Kostitsyn, Y.A., Gilg, H.A., Preinfalk, C., Razakamanana, T.Geochemistry of phlogopite, diopside, calcite, anhydrite and apatite pegmatites and syenites of southern Madagascar: evidence for crustal silicocarbonatitic (CSC) melt formatio in a Panafrican collisional tectonic setting.International Journal of Earth Sciences, Vol. 102, 3, pp. 627-645.Africa, MadagascarCarbonatite
DS201704-0646
2017
Gilg, H.A.Schmetzer, K., Gilg, H.A., Vaupel, E.Synthetic emeralds grown by Richard Nacken in the mid-1920's: properties, growth technique, and historical account.Gems & Gemology, Vol. 52, 4, pp. 368-392.Europe, GermanySynthetic - emeralds

Abstract: Chemical and microscopic examination of the first gem-quality synthetic emeralds of facetable size proves that Prof. Richard Nacken grew two main types of emerald by flux methods in the mid-1920s. One of these two types, grown with colorless beryl seeds in molybdenum-bearing and vanadium-free fluxes, has not previously been mentioned in the literature and would appear to be unknown to gemologists. The other main type, which has already been described in gemological publications, was grown from molybdenum- and vanadium-bearing fluxes. In drawing these conclusions, rough and faceted synthetic emeralds produced by Nacken were available for study from two principal sources: the Deutsches Museum in Munich, to which Nacken had donated samples in 1961, and family members who had inherited such crystals. Chemical, morphological, and microscopic properties are given, and circumstances concerning the developmental history of the Nacken production, including the possibility of collaboration with IG Farben (a subject of past speculation), are discussed as well. The latter has recently been elucidated by the discovery of original documents from the IG Farben gemstone plant, preserved in the Archives of the German Federal State of Saxony-Anhalt.
DS201909-2023
2019
Gilholy, W.P.Bosco-Santos, A., Gilholy, W.P., Fouskas, F., Baldim, M., Oliveira, E.P.Ferruginous - euxinc - oxic: a three step redox change in the Neoarchean record.Goldschmidt2019, 1p. AbstractSouth America, Brazilcraton

Abstract: Much of the secular record of sulfur mass independet fractionation (S-MIF) is based on pyrites extracted from a limited number of formations from Western Australia and Southern Africa. Here we present multiproxy evidence for an episodic loss of S-MIF in sulfides from a 2.7 Ga sedimentary record in the São Francisco craton, Brazil. Based on combined proxies, we assigned three phases, in a continous drill core, that track evolving water column redox conditions and changes in ecology. In Phase-I, the stratigraphically older rocks, reactive iron ratios suggest ferruginous conditions. The pyrites have modest S-MIF values (D33S from -0.7 to 2.6‰) and the carbon isotope composition of the iron formations is indicative of carbon fixation by anoxygenic photosynthetic bacteria that oxidized Fe2+ (d13Corg from -27.7 to -17.5‰). Within Phase-II, an intermediate phase characterized by graphite schist, the iron ratios, expansion of the S-MIF (D33S from 2.15 to 3.4‰) and an excess of Mo relative to Corg suggest deposition in an anoxic environment with periodic development of euxinic conditions. Phase-III culminates in fully oxic conditions with a loss of S-MIF and emergence of sulfur mass dependent fractionation (S-MDF) with homogeneous d34S pyrite values (average = 3.3 ± 0.5‰). The loss of S-MIF in the Archean sulfides of Phase-III was interpreted as a response to increased oxygen levels that lead to an intensification of oxidative weathering. Based on the continous deposition within this drillcore, the development of more oxidizing conditions may have been relatively rapid, reinforcing the model that the transition from S-MIF to S-MDF can happen on rapid geological time scales and was recorded about 400 million years prior to the GOE in the Brazilian craton.
DS201708-1649
2017
Gilika, O.Gilika, O.Building a geometallurgical model for Orapa mine, Botswana.11th. International Kimberlite Conference, PosterAfrica, Botswanadeposit - Orapa
DS1984-0304
1984
Gilinskaya, L.G.Gilinskaya, L.G., Egorov, L.S.Esr Spectra of Apatites of the Maimecha Kotuj Ijolite Carbonatite Complex.Geochemistry International (Geokhimiya)., No. 12, DECEMBER PP. 1858-1866.RussiaCarbonatite
DS1985-0234
1985
Gilinskaya, L.G.Gilinskaya, L.G., Yegorov, L.S.Esr Spectra of Apatite from the Maymecha-kotuy IjolitecarbonatitecomplexGeochemistry International, Vol. 22, No. 5, pp. 1-8RussiaCarbonatite, Ijolite
DS201507-0313
2015
Gilio, M.Gilio, M., Clos, F., Van Roermund, H.L.M.The Frimingen garnet peridotite ( central Swedish Caledonides). A good example of the characteristic PTt path of a cold mantle wedge garnet peridotite.Lithos, Vol. 230, pp. 1-16.Europe, SwedenPeridotite
DS201212-0491
2012
Gilisovic, P.Morrow, E., Mitrovica, J.X., Forte, A.M., Gilisovic, P., Huybers, P.An enigma in estimates of the Earth's dynamic ellipticity.Geophysical Journal International, in press availableMantleGeodynamics
DS1998-0904
1998
GillLundstrom, C.C., Shaw, Ryerson, Williams, GillCrystal chemistry control of clinopyroxene melt partioning in the Di Ab Ansystem: implications for elemental fractionations in the depleted mantle.Geochimica et Cosmochimica Acta, Vol. 62, No. 16, pp. 2849-62.MantleGeochemistry
DS1997-0411
1997
Gill, C.Gill, C., Marrs, R.Detection of kimberlite pipes in the Colorado - Wyoming State Line District using AVARIS.Twelfth Geologic Remote Sensing, Nov. 17th., AbstractsColorado, WyomingGeophysics - remote sensing, AVARIS
DS1860-0104
1870
Gill, J.Gill, J.The Emigrant's Guide to the South African Diamond FieldsLondon: Sampson Low, Marsden., 16P.Africa, South Africa, Cape ProvinceGuidebook, History
DS201212-0105
2012
Gill, J.Campbell, I., Gill, J., Iizuka, T., Allen, C.What detrital zircons tell us about growth of the continental crust.Goldschmidt Conference 2012, abstract 1p.MantleGeochronology
DS1986-0862
1986
Gill, J.B.Williams, R.W., Gill, J.B., Bruland, K.W.Ra Th disequilibration temperatures systematics-timescale of carbonatite magma formation at Oldoiny Lengai volcano, TanzaniaGeochimica et Cosmochimica Acta, Vol. 50, No. 6, June pp. 1249-1259TanzaniaCarbonatite
DS1991-0574
1991
Gill, J.B.Gill, J.B., Pyle, D.M., Williams, R.W.Igneous rocksMineralogical Association of Canada -Short Course Handbook, Vol. 19, Chapter 9, pp. 287-335GlobalGeochronology, Magmatic evolution, volcanoes
DS1992-1670
1992
Gill, J.B.Williams, R.W., Collerson, K.D., Gill, J.B., Deniel, C.High Th/U ratios in subcontinental lithospheric mantle: mass spectrometric measurement of Th isotopes in Gaussberg lamproitesEarth and Planetary Science Letters, Vol. 111, No. 2-4, July pp. 257-268MantleGeochronology, Lamproites
DS200612-0460
2006
Gill, J.B.Gill, J.B., Tollstrup, D., Todd, E.Hf mobility and immobility in subduction zones.Geochimica et Cosmochimica Acta, Vol. 70, 18, 1, p. 17, abstract only.MantleSubduction
DS201312-0432
2013
Gill, J.B.Izuka, T., Campbell, I.H., Allen, C.M., Gill, J.B., Maruyama, S., Makota, F.Evolution of the African continental crust as recorded by U-Pb, Lu-Hf and O isotopes in detrital zircons from modern rivers.Geochimica et Cosmochimica Acta, Vol. Pp. 96-120.AfricaGeochronology, Comgo, Zambesi, Orange
DS1981-0180
1981
Gill, M.Gill, M.Ashton Reports Consistent on Sampling But Wide on ValueThe Age (melbourne), APRIL 16TH.Australia, Western Australia, Kimberley RegionSampling, Valuation, Cra, Pipe
DS200712-0668
2007
Gill, R.Maier, R., Heinson, G., Thiel, S., Selway, K., Gill, R., Scroggs, M.A 3D lithospheric resistivity model of the Gawler Craton: southern Australia.Transactions of the Institution of Mining and Metallurgy, Vol. 116, 1, pp. 13-21.AustraliaGeophysics - resistivity
DS200512-0337
2004
Gill, R.C.Gill, R.C., Aparicio, A., El Azzouzi, M., Hernandez, J., Thirlwall, M.F., Bourgois, J., Marriner, G.F.Depleted arc volcanism in the Alboran Sea and shoshonitic volcanism in Morocco: geochemical and isotopic constraints on Neogene tectonic processes.Lithos, Vol. 78, 4, pp. 363-388.Africa, MoroccoShoshonite
DS1992-0567
1992
Gill, R.C.O.Gill, R.C.O., Pedersen, A.K., Larsen, J.G.Tertiary picrites in West Greenland: melting at the periphery of a plume?Geological Society Special Publication, Magmatism and the Causes of Continental, No. 68, pp. 335-348GreenlandPicrites, Plume
DS1992-0721
1992
Gill, R.C.O.Holm, P.M., Gill, R.C.O., Pedersen, A.K., Larsen, J.G., Hald, N.The Icelandic mantle plume: compositional constraints from the West Greenland Tertiary picritesEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.336GreenlandPicrites, Mantle plume
DS1993-0694
1993
Gill, R.C.O.Holm, P.M., Gill, R.C.O., Pedersen, A.K., Larsen, J.G., Hald, N.The Tertiary picrites of West Greenland: contributions from Icelandic and other sourcesEarth and Planetary Science Letters, Vol. 115, No. 1-4, March pp. 227-244GreenlandPicrites, Alkaline rocks
DS1995-0633
1995
Gill, R.C.O.Gill, R.C.O., Holm, NielsenWas a short lived Baffin Bay plume active prior to initiation of present Icelandic plume? clues from high magnesium picrites of west Greenland.L.Lithos, Vol. 34, pp. 27-39.GlobalMantle - plumes, Picrites
DS1995-0634
1995
Gill, R.C.O.Gill, R.C.O., Holm, P.M., Nielsen, T.F.D.Was a short lived Baffin Bay plume active prior to initiation of the present Icelandic plume? Clues ..Lithos, Vol. 34, No. 1-3, Jan. pp. 27-40GreenlandPicrite -magnesiuM., Plume
DS200812-0297
2008
Gill, T.I.Doyle, B.J., Gill, T.I., Thompson, V.The discovery of the Dharma kimberlite complex: evidence for a previously unknown Archean terrain north of Great Bear Lake.Northwest Territories Geoscience Office, p. 21. abstractCanada, Northwest TerritoriesBrief overview - Sanatana, Kennecott
DS200412-0741
2004
Gillan, M.Gubbins, D., Alfe, D., Masters, G., Price, G.D., Gillan, M.Gross thermodynamics of two component core convection.Geophysical Journal International, Vol. 157, 3, pp. 1407-1414.MantleConvection
DS2002-0020
2002
Gillan, M.J.Alfe, D., Gillan, M.J., Price, G.D.Composition and temperature of the Earth's core constrained by combining ab initio calculations/seismicEarth and Planetary Science Letters, Vol. 195, No. 1-2, pp. 91-8.MantleGeophysics - seismics, Geochemistry
DS2003-0007
2003
Gillan, M.J.Alfe, D., Gillan, M.J., Price, G.D.Thermodynamics from first principles: temperature and composition of the Earth's coreMineralogical Magazine, Vol. 67, 1, pp. 113-24.MantleGeothermometry
DS2003-0008
2003
Gillan, M.J.Alfe, D., Gillan, M.J., Price, G.D.Thermodynamics from first principles: temperature and composition of the Earth's coreMineralogical Magazine, Vol. 67, 1, Feb. pp. 113-124.MantleGeothermometry
DS201912-2833
2019
Gillander, A.Welsh, M., Gillander, A.Diamond policy framework.Yellowknife Forum NWTgeoscience.ca, abstract volume p. 97.Canada, Northwest Territorieslegal

Abstract: Established in 1999, the Diamond Policy Framework (DPF) was designed to facilitate the development of a diamond manufacturing industry in the Northwest Territories (NWT). In addition, agreements with NWT diamond producers were established which required them to offer 10 percent of their production, by value, to Approved NWT Diamond Manufacturers (ANDM) for manufacturing in the NWT. The NWT is the most expensive jurisdiction in which to operate a manufacturing facility and despite some early success, the policy was not successful in creating an operating environment for the secondary industry to flourish. In 2018, ITI commissioned a review of the DPF that sought recommendations on how to make this industry more attractive to investors. The report contained a detailed review of the global diamond market. It also presented a series of cost per carat analyses of NWT production costs versus costs in other diamond manufacturing regions. Policy recommendations included adopting an export provision for NWT rough diamonds (and making that export volume contingent on their investment in the NWT), permitting the development of a facility for high-skill planning and lasering services, and generally ensuring that the policy supported the acceptance of innovative business plans. In 2018, The Department of Industry, Tourism and Investment (ITI) amended the DPF. Accordingly, a new approach to the utilization of rough diamonds was developed to realize maximum economic benefits for the NWT and its residents. The amended DPF now has provisions that allow an ANDM to export a portion of their allocation based on their business proposal and an ANDM is no longer required to complete the entire manufacturing process in the NWT. To be eligible to export rough diamonds, ANDM applicants must provide a comprehensive business plan that outlines investment details. Business plans are reviewed and scored based on a comprehensive matrix that determines the export volume.
DS1997-0984
1997
Gillen, C.Rundqvist, D.V., Gillen, C.Precambrian ore deposits of the East European and Siberian CratonsElsevier, 470pRussia, Baltic States, Kola, AldanBook - ad, Mineral deposits
DS1995-0635
1995
Gillespie, A.Gillespie, A., Molnar, P.Asynchronous maximum advances of mountain and continental glaciersReviews of Geophysics, Vol. 33, No. 3, August pp. 311-364.GlobalGeomorphology, Glaciation patterns
DS200612-0975
2006
Gillespie, A.Nichols, K.K., Bierman, P.R., Fonini, W.R., Gillespie, A., Caffee, M., Finkel, R.Dates and rates of arid region geomorphic process.GSA Today, August pp. 4- 11.United States, California, ArizonaGeomorphology, desert landscapes
DS201904-0715
2019
Gillespie, J.Armistead, S.E., Collins, A.S., Redaa, A., Gilbert, S., Jepson, G., Gillespie, J., Blades, M.L., Foden, J.D., Razakamana, T.Structural evolution and medium temperature thermochronology of central Madagascar: implications for Gondwana amalgamation.Journal of the Geological Society of London, in press available 25p.Africa, Madagascarthermochronology

Abstract: Madagascar occupied an important place in the amalgamation of Gondwana, and preserves a record of several Neoproterozoic events that can be linked to orogenesis of the East African Orogen. We integrate remote sensing and field data to unravel complex deformation in the Ikalamavony and Itremo domains of central Madagascar. The deformation sequence comprises a gneissic foliation (S1), followed by south to south-west directed, tight to isoclinal, recumbent folding (D2). These are overprinted by north-trending upright folds that formed during a ~E-W shortening event. Together these produced type 1 and type 2 fold interference patterns throughout the Itremo and Ikalamavony domains. Apatite U-Pb and muscovite and biotite Rb-Sr thermochronometers indicate that much of central Madagascar was thermally reset to at least ~500oC at c. 500 Ma. Deformation in west-central Madagascar occurred between c. 750 Ma and c. 550 Ma, and we suggest this deformation formed in response to the c. 650 Ma collision of Azania with Africa along the Vohibory Suture in southwestern Madagascar. In eastern Madagascar, deformation is syn- to post-550 Ma, which formed in response to the final closure of the Mozambique Ocean along the Betsimisaraka Suture that amalgamated Madagascar with the Dharwar Craton of India.
DS202010-1826
2020
Gillespie, J.Armistead, S.E., Collins, A.S., Redaa, A., Jepson, G., Gillespie, J., Gilbert, S., Blades, M.L., Foden, J.D., RazakMnN, T.Structural evolution and medium temperature thermochronology of central Madagascar: implications for Gondwana amalagamation.Journal of the Geological Society, Vol. 177, pp. 784-798.Africa, Madagascargeothermometry

Abstract: Madagascar occupied an important place in the amalgamation of Gondwana and preserves a record of several Neoproterozoic events that are linked to orogenesis of the East African Orogen. In this study, we integrate remote sensing, field data and thermochronology to unravel complex deformation in the Ikalamavony and Itremo domains of central Madagascar. The deformation sequence comprises a gneissic foliation (S1), followed by south- to SW-directed, tight to isoclinal, recumbent folding (D2). These are overprinted by north-trending upright folds that formed during an approximately east-west shortening event (D3). Together these produced type 1 and type 2 fold interference patterns throughout the Itremo and Ikalamavony domains. We show that the Itremo and Ikalamavony domains were deformed together in the same orogenic system, which we interpret as the c. 630 Ma collision of Azania with Africa along the Vohibory Suture in southwestern Madagascar. In eastern Madagascar, deformation is syn- to post-550 Ma, and probably formed in response to final closure of the Mozambique Ocean along the Betsimisaraka Suture that amalgamated Madagascar with the Dharwar Craton of India. Apatite U-Pb and novel laser ablation triple quadrupole inductively coupled plasma mass spectrometry (LA-QQQ-ICP-MS) muscovite and biotite Rb-Sr thermochronology indicates that much of central Madagascar cooled through c. 500°C at c. 500 Ma.
DS1999-0251
1999
Gillespie, M.R.Gillespie, M.R., Styles, M.T.Rock classification, igneous rocksBritish Geological Survey, No. 99-06, 52p.GlobalClassification - igneous rocks
DS200412-0665
1999
Gillespie, M.R.Gillespie, M.R., Styles, M.T.Rock classification, igneous rocks.British Geological Survey, No. 99-06, 52p.TechnologyClassification - igneous rocks
DS200712-0956
2007
Gillespie, M.R.Schofield, D.I., Gillespie, M.R.A tectonic interpretation of Eburean terrane outliers in the Reguelen Shield, Mauritania.Journal of African Earth Sciences, Vol. 49, 4-5, pp. 179-186.Africa, MauritaniaTectonics
DS2002-0906
2002
GilletKunz, M., Gillet, Fiquet, Sautter, Graafsma, ConradCombined in situ x-ray diffraction and raman spectroscopy on majoritic garnet inclusions in diamondsEarth and Planetary Science Letters, Vol.198,3-4,pp.485-93., Vol.198,3-4,pp.485-93.GlobalSpectroscopy, Diamond inclusions
DS2002-0907
2002
GilletKunz, M., Gillet, Fiquet, Sautter, Graafsma, ConradCombined in situ x-ray diffraction and raman spectroscopy on majoritic garnet inclusions in diamondsEarth and Planetary Science Letters, Vol.198,3-4,pp.485-93., Vol.198,3-4,pp.485-93.GlobalSpectroscopy, Diamond inclusions
DS1992-0568
1992
Gillet, P.Gillet, P., Fiquet, G., Malesieux, J-M., Geiger, C.A.high pressure and high temperature Raman spectroscopy of end membergarnets: pyrope, grossular and andraditeEuropean Journal of Mineralogy, Vol. 4, No. 4, pp. 651-664GlobalMineralogy, Garnets
DS1992-0569
1992
Gillet, P.Gillet, P., Fiquet, G., Malezieux, J.M., Geiger, C.A.high pressure and high temperature Raman spectroscopy of end-member garnets-pyrope, grossular and andraditeEuropean Journal of Mineralogy, Vol. 4, No. 4, July-August pp. 651-664GlobalMineralogy, Garnets
DS1993-0121
1993
Gillet, P.Biellmann, C., Gillet, P., Guyot, F., Peyronneau, J., Reynard, B.Experimental evidence for carbonate stability in the earth's lower mantleEarth and Planetary Science Letters, Vol. 118, pp. 31-41MantleCarbon, Diamond inclusions
DS1993-0545
1993
Gillet, P.Gillet, P.Water in the mantle of the earth. (in French)Recherche, (in French), Vol. 24, No. 255, June pp. 676-685MantleComposition
DS1994-1530
1994
Gillet, P.Sautter, V., Gillet, P.Les diamants, messagers de profondeurs de la terre.(in French)La Recherche, (in French), Vol. 25, Dec. 21, pp. 1238-45.GlobalDiamond genesis -overview
DS1995-0636
1995
Gillet, P.Gillet, P.Mineral physics, mantle mineralogy and mantle dynamicsComptes Rendus de'l Academie Des Sciences Serie II , *in Eng., Vol. 320, No. 5, March 2, pp. 341-356.MantleReview -geophysics mantle, Geodynamics
DS1996-0938
1996
Gillet, P.McMillan, P.F., Hemley, R.J., Gillet, P.Vibrational spectroscopy of mantle mineralsIn: Mineral spectroscopy edited by Dyar, pp. 175-214.MantleMineral spectroscopy
DS1998-0511
1998
Gillet, P.Gillet, P., Hemley, R.J., McMillan, P.F.Vibrational properties at high pressures and temperaturesReviews in Mineralogy, Vol. 37, pp. 525-90.MantleMineralogy, Petrology - experimental
DS1998-0680
1998
Gillet, P.Jambon, A., Gillet, P., Chamorro, ColticeHelium and argon poor magmas from the under gassed mantleMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 705-6.Hawaii, Mantlehelium, Geodynamics
DS2002-0105
2002
Gillet, P.Barrat, J.A., Jambon, A., Bohn, M., Gillet, P., Sautter, V., Gopei, C., Lesourd, M.Petrology and chemistry of the picritic shergottite north west AfricaGeochimica et Cosmochimica Acta, Vol.66, 19, pp.3505-18.West AfricaPicrites
DS2002-0572
2002
Gillet, P.Gillet, P., Sautter, V., Harris, Reynard, Harte, KunzRaman spectroscopic study of garnet inclusions in diamonds from the mantle transition zone.American Mineralogist, Vol.87, 2-3, pp. 312-17.BrazilSpectroscopy - majoritic content, Deposit - Sao Luiz
DS2002-1100
2002
Gillet, P.Mostefaoui, S., El Goresy, A., Hopper, P., Gillet, P., Ott, U.Mode of occurrence , textural settings and nitrogen isotopic compositions of in situEarth and Planetary Science Letters, Vol. 204, No. 1-2, pp. 89-100.GlobalMeteorites - diamonds, geochronology
DS2003-0379
2003
Gillet, P.El Goresy, A., Dubrovinsky, L.S., Gillet, P., Mostefaoul, S., Graup, G.A new natural super hard transparent polymorph of carbon from the Popigai impactComptes Rendus Geosciences, IN FRENCH, Vol. 335, 12, Oct. pp. 889-898.RussiaBlank
DS200412-0515
2003
Gillet, P.El Goresy, A., Dubrovinsky, L.S., Gillet, P., Mostefaoul, S., Graup, G., Drakopoulos, M., Simionovici, A.S.A new natural super hard transparent polymorph of carbon from the Popigai impact crater, Russia.Comptes Rendus Geoscience, Vol. 335, 12, Oct. pp. 889-898.RussiaLonsdaleite, graphite, mineralogy
DS200612-0623
2006
Gillet, P.Ionov, D.A., Hofmann, A.W., Merlet, C., Gurenko, A.A., Hellebrand, E., Montagnac, G., Gillet, P., PrikhodkoDiscovery of whitlockite in mantle xenoliths: inferences for water and halogen poor fluid and trace element residence in the terrestrial upper mantle.Earth and Planetary Science Letters, Vol. 244, 1-2, Apr. 15, pp. 201-207.MantleXenolith - mineralogy
DS200712-0315
2007
Gillet, P.Fiquet, G., Coltice, N.,Guyot, F., Gillet, P.Potassium content in the Earth's core: a high pressure and high temperature study of the Fe K system.Plates, Plumes, and Paradigms, 1p. abstract p. A279..MantleCore, mantle boundary
DS201412-0222
2003
Gillet, P.El Goresy, A., Dubrovinsky, L.S., Gillet, P., Mostefaoui, S., Graup, G., Drakopoulos, M., Simionovici, A.S., Swamy, V., Masaitis, V.L.A new natural, super-hard, transparent polymorph of carbon from the Popigai impact crater, Russia.Comptes Rendus Geoscience, Vol. 335, pp. 889-898.Russia, YakutiaMeteorite
DS201506-0284
2015
Gillet, P.Miyahara, M., Ohtani, E., El Goresy, A., Lin, Y., Feng, L.,Zhang, J-C., Gillet, P., Nagase, T., Muto, J., Nishijima, M.Unique large diamonds in a urelilite from Almahat a Sitta TC3, asteroid.Geochimica et Cosmochimica Acta, Vol. 163, pp. 14-26.TechnologyUrelilite
DS201611-2131
2016
Gillet, P.Piet, H., Badro, J., Nabiei, F., Gillet, P.Spin and valence dependence of iron partitioning in Earth's deep mantle.Proceedings of National Academy of Science USA, Vol. 113, 40, pp. 11127-11130.MantleIron

Abstract: We performed laser-heated diamond anvil cell experiments combined with state-of-the-art electron microanalysis (focused ion beam and aberration-corrected transmission electron microscopy) to study the distribution and valence of iron in Earth’s lower mantle as a function of depth and composition. Our data reconcile the apparently discrepant existing dataset, by clarifying the effects of spin (high/low) and valence (ferrous/ferric) states on iron partitioning in the deep mantle. In aluminum-bearing compositions relevant to Earth’s mantle, iron concentration in silicates drops above 70 GPa before increasing up to 110 GPa with a minimum at 85 GPa; it then dramatically drops in the postperovskite stability field above 116 GPa. This compositional variation should strengthen the lowermost mantle between 1,800 km depth and 2,000 km depth, and weaken it between 2,000 km depth and the D” layer. The succession of layers could dynamically decouple the mantle above 2,000 km from the lowermost mantle, and provide a rheological basis for the stabilization and nonentrainment of large low-shear-velocity provinces below that depth.
DS201701-0026
2016
Gillet, P.Piet, H., Badro, J., Nabiel, F., Dennenwaldt, T., Shim, S-H., Cantoni, M., Hebert, C., Gillet, P.Spin and valence dependence on iron partitioning in Earth's deep mantle.Proceedings of National Academy of Science USA, Vol. 113, no. 40, pp. 11127-11130.MantleUHP

Abstract: We performed laser-heated diamond anvil cell experiments combined with state-of-the-art electron microanalysis (focused ion beam and aberration-corrected transmission electron microscopy) to study the distribution and valence of iron in Earth's lower mantle as a function of depth and composition. Our data reconcile the apparently discrepant existing dataset, by clarifying the effects of spin (high/low) and valence (ferrous/ferric) states on iron partitioning in the deep mantle. In aluminum-bearing compositions relevant to Earth's mantle, iron concentration in silicates drops above 70 GPa before increasing up to 110 GPa with a minimum at 85 GPa; it then dramatically drops in the postperovskite stability field above 116 GPa. This compositional variation should strengthen the lowermost mantle between 1,800 km depth and 2,000 km depth, and weaken it between 2,000 km depth and the D" layer. The succession of layers could dynamically decouple the mantle above 2,000 km from the lowermost mantle, and provide a rheological basis for the stabilization and nonentrainment of large low-shear-velocity provinces below that depth.
DS201804-0686
2018
Gillet, P.Dorfman, S.M., Badro, J., Nabiel, F., Prakapenka, V.B., Cantoni, M., Gillet, P.Carbonate stability in the reduced lower mantle.Earth and Planteray Science Letters, Vol. 489, pp. 84-91.Mantlecarbonate

Abstract: Carbonate minerals are important hosts of carbon in the crust and mantle with a key role in the transport and storage of carbon in Earth's deep interior over the history of the planet. Whether subducted carbonates efficiently melt and break down due to interactions with reduced phases or are preserved to great depths and ultimately reach the core-mantle boundary remains controversial. In this study, experiments in the laser-heated diamond anvil cell (LHDAC) on layered samples of dolomite (Mg,?Ca)CO3 and iron at pressure and temperature conditions reaching those of the deep lower mantle show that carbon-iron redox interactions destabilize the MgCO3 component, producing a mixture of diamond, Fe7C3, and (Mg,?Fe)O. However, CaCO3 is preserved, supporting its relative stability in carbonate-rich lithologies under reducing lower mantle conditions. These results constrain the thermodynamic stability of redox-driven breakdown of carbonates and demonstrate progress towards multiphase mantle petrology in the LHDAC at conditions of the lowermost mantle.
DS201805-0964
2018
Gillet, P.Nabiel, F., Badro, J., Dennenwaldt, T., Oveisi, E., Cantoni, M., Hebert, C., El Goresy, A., Barrat, J-A., Gillet, P.A large planetary body inferred from diamond inclusions in a urelite metorite.Nature Communications, doe:10.1038/ s41467-018- 030808-6 6p. PdfTechnologyureilite

Abstract: Planetary formation models show that terrestrial planets are formed by the accretion of tens of Moon- to Mars-sized planetary embryos through energetic giant impacts. However, relics of these large proto-planets are yet to be found. Ureilites are one of the main families of achondritic meteorites and their parent body is believed to have been catastrophically disrupted by an impact during the first 10 million years of the solar system. Here we studied a section of the Almahata Sitta ureilite using transmission electron microscopy, where large diamonds were formed at high pressure inside the parent body. We discovered chromite, phosphate, and (Fe,Ni)-sulfide inclusions embedded in diamond. The composition and morphology of the inclusions can only be explained if the formation pressure was higher than 20?GPa. Such pressures suggest that the ureilite parent body was a Mercury- to Mars-sized planetary embryo.
DS202009-1624
2020
Gillet, P.Dorfman, S.M., Potapkin, V., Lv, M., Greenberg, E., Kupenko, I., Chumakov, A.I., Bi, W., Alp, E.E., Liu, J., Magrez, A., Dutton, S.E., Cava, R.J., McCammon, C.A., Gillet, P.Effects of composition and pressure on electronic states of iron in bridgmanite.American Mineralogist, Vol. 105, pp. 1030-1039. pdfMantleredox

Abstract: Electronic states of iron in the lower mantle's dominant mineral, (Mg,Fe,Al)(Fe,Al,Si)O3 bridgmanite, control physical properties of the mantle including density, elasticity, and electrical and thermal conductivity. However, the determination of electronic states of iron has been controversial, in part due to different interpretations of Mössbauer spectroscopy results used to identify spin state, valence state, and site occupancy of iron. We applied energy-domain Mössbauer spectroscopy to a set of four bridgmanite samples spanning a wide range of compositions: 10-50% Fe/total cations, 0-25% Al/total cations, 12-100% Fe3+/total Fe. Measurements performed in the diamond-anvil cell at pressures up to 76 GPa below and above the high to low spin transition in Fe3+ provide a Mössbauer reference library for bridgmanite and demonstrate the effects of pressure and composition on electronic states of iron. Results indicate that although the spin transition in Fe3+ in the bridgmanite B-site occurs as predicted, it does not strongly affect the observed quadrupole splitting of 1.4 mm/s, and only decreases center shift for this site to 0 mm/s at ~70 GPa. Thus center shift can easily distinguish Fe3+ from Fe2+ at high pressure, which exhibits two distinct Mössbauer sites with center shift ~1 mm/s and quadrupole splitting 2.4-3.1 and 3.9 mm/s at ~70 GPa. Correct quantification of Fe3+/total Fe in bridgmanite is required to constrain the effects of composition and redox states in experimental measurements of seismic properties of bridgmanite. In Fe-rich, mixed-valence bridgmanite at deep-mantle-relevant pressures, up to ~20% of the Fe may be a Fe2.5+ charge transfer component, which should enhance electrical and thermal conductivity in Fe-rich heterogeneities at the base of Earth's mantle.
DS1998-0512
1998
Gillet, Ph.Gillet, Ph., Matas, Fiquet, Chamorro, Maryinez, JambonVolatiles in the Earth's mantle: insights from mineral and melt physicsMineralogical Magazine, Goldschmidt abstract, Vol. 62A, p. 521-2.MantleMagnesite, noble gases, volcanism.
DS1994-0705
1994
Gillies, A.D.S.Hancock, G.E., Gillies, A.D.S.Issues in Australasian mining taxation: the arguments for and against resource rent taxationAustralian Institute of Mining and Metallurgy (AusIMM) Bulletin, No. 4, July pp. 11, 13-17AustraliaLegal, Mining taxation
DS201609-1706
2016
Gilligan, A.Boyce, A., Bastow, I.D., Darbyshire, F.A., Ellwood, A.G., Gilligan, A., Levin, V., Menke, W.Subduction beneath Laurentia modifies the eastern North American cratonic edge: evidence from P wave and S wave tomography.Journal of Geophysical Research,, Vol. 121, 7, pp. 5013-5030.CanadaSubduction

Abstract: The cratonic cores of the continents are remarkably stable and long-lived features. Their ability to resist destructive tectonic processes is associated with their thick (~250 km), cold, chemically depleted, buoyant lithospheric keels that isolate the cratons from the convecting mantle. The formation mechanism and tectonic stability of cratonic keels remains under debate. To address this issue, we use P wave and S wave relative arrival-time tomography to constrain upper mantle structure beneath southeast Canada and the northeast USA, a region spanning three quarters of Earth's geological history. Our models show three distinct, broad zones: Seismic wave speeds increase systematically from the Phanerozoic coastal domains, through the Proterozoic Grenville Province, and to the Archean Superior craton in central Québec. We also recover the NW-SE trending track of the Great Meteor hot spot that crosscuts the major tectonic domains. The decrease in seismic wave speed from Archean to Proterozoic domains across the Grenville Front is consistent with predictions from models of two-stage keel formation, supporting the idea that keel growth may not have been restricted to Archean times. However, while crustal structure studies suggest that Archean Superior material underlies Grenvillian age rocks up to ~300 km SE of the Grenville Front, our tomographic models show a near-vertical boundary in mantle wave speed directly beneath the Grenville Front. We interpret this as evidence for subduction-driven metasomatic enrichment of the Laurentian cratonic margin, prior to keel stabilization. Variable chemical depletion levels across Archean-Proterozoic boundaries worldwide may thus be better explained by metasomatic enrichment than inherently less depleted Proterozoic composition at formation.
DS201711-2524
2017
Gilligan, A.Liddell, M.V., Bastow, I., Darbyshire, F., Gilligan, A., Pugh, S.The formation of Laurentia: evidence from shear wave splitting.Earth and Planetary Science Letters, Vol. 479, pp. 170-178.Canada, Nunavut, Baffin Islandgeophysics - seismics

Abstract: The northern Hudson Bay region in Canada comprises several Archean cratonic nuclei, assembled by a number of Paleoproterozoic orogenies including the Trans-Hudson Orogen (THO) and the Rinkian-Nagssugtoqidian Orogen. Recent debate has focused on the extent to which these orogens have modern analogues such as the Himalayan-Karakoram-Tibet Orogen. Further, the structure of the lithospheric mantle beneath the Hudson Strait and southern Baffin Island is potentially indicative of Paleoproterozoic underthrusting of the Superior plate beneath the Churchill collage. Also in question is whether the Laurentian cratonic root is stratified, with a fast, depleted, Archean core underlain by a slower, younger, thermally-accreted layer. Plate-scale process that create structures such as these are expected to manifest as measurable fossil seismic anisotropic fabrics. We investigate these problems via shear wave splitting, and present the most comprehensive study to date of mantle seismic anisotropy in northern Laurentia. Strong evidence is presented for multiple layers of anisotropy beneath Archean zones, consistent with the episodic development model of stratified cratonic keels. We also show that southern Baffin Island is underlain by dipping anisotropic fabric, where underthrusting of the Superior plate beneath the Churchill has previously been interpreted. This provides direct evidence of subduction-related deformation at 1.8 Ga, implying that the THO developed with modern plate-tectonic style interactions.
DS201809-2058
2018
Gilligan, A.Liddell, M.V., Bastow, I., Rawlinson, N., Darbyshire, F., Gilligan, A., Watson, E.Precambrian plate tectonics in northern Hudson Bay: evidence from P and S Wave Seismic tomography and analysis of source side effects in relative arrival-time dat a sets.Journal of Geophysical Research, Vol. 123, 7, pp. 5690-5709.Canada, NunavutGeophysics - seismic

Abstract: The geology of northern Hudson Bay, Canada, documents more than 2 billion years of history including the assembly of Precambrian and Archean terranes during several Paleoproterozoic orogenies, culminating in the Trans-Hudson Orogen (THO) ~1.8 Ga. The THO has been hypothesized to be similar in scale and nature to the ongoing Himalaya-Karakoram-Tibetan orogen, but the nature of lithospheric terrane boundaries, including potential plate-scale underthrusting, is poorly understood. To address this problem, we present new P and S wave tomographic models of the mantle seismic structure using data from recent seismograph networks stretching from northern Ontario to Nunavut (60-100°W and 50-80°N). The large size of our network requires careful mitigation of the influence of source side structure that contaminates our relative arrival time residuals. Our tomographic models reveal a complicated internal structure in the Archean Churchill plate. However, no seismic wave speed distinction is observed across the Snowbird Tectonic Zone, which bisects the Churchill. The mantle lithosphere in the central region of Hudson Bay is distinct from the THO, indicating potential boundaries of microcontinents and lithospheric blocks between the principal colliders. Slow wave speeds underlie southern Baffin Island, the leading edge of the generally high wave speed Churchill plate. This is interpreted to be Paleoproterozoic material underthrust beneath Baffin Island in a modern-style subduction zone setting.
DS202004-0529
2020
Gilligan, A.Petrescu, L., Bastow, I.D., Darbyshire, F.A., Gilligan, A., Bodin, T., Menke, W., Levin, V.Three billion years of crustal evolution in eastern Canada: constraints from receiver functions.Journal of Geophysical Research: Solid Earth, in press available, 24p. PdfCanadageophysics - seismics

Abstract: The geological record of SE Canada spans more than 2.5Ga, making it a natural laboratory for the study of crustal formation and evolution over time. We estimate the crustal thickness, Poisson's ratio, a proxy for bulk crustal composition, and shear velocity (Vs) structure from receiver functions at a network of seismograph stations recently deployed across the Archean Superior craton, the Proterozoic Grenville and the Phanerozoic Appalachian provinces. The bulk seismic crustal properties and shear velocity structure reveal a correlation with tectonic provinces of different ages: the post-Archean crust becomes thicker, faster, more heterogenous and more compositionally evolved. This secular variation pattern is consistent with a growing consensus that crustal growth efficiency increased at the end of the Archean. A lack of correlation among elevation, Moho topography, and gravity anomalies within the Proterozoic belt is better explained by buoyant mantle support rather than by compositional variations driven by lower crustal metamorphic reactions. A ubiquitous ~20km thick high-Vs lower-crustal layer is imaged beneath the Proterozoic belt. The strong discontinuity at 20km may represent the signature of extensional collapse of an orogenic plateau, accommodated by lateral crustal flow. Wide anorthosite massifs inferred to fractionate from a mafic mantle source are abundant in Proterozoic geology and are underlain by high Vs lower crust and a gradational Moho. Mafic underplating may have provided a source for these intrusions and could have been an important post-Archean process stimulating mafic crustal growth in a vertical sense.
DS1989-1447
1989
Gilligan, J.M.Starling, A., Gilligan, J.M., Carter, A.H.C., Foster, R.P.Experimental evidence for very low solubility of rareearth elements inCO2 rich fluids at mantle conditions #2Nature, Vol.340, No. 6231, July 27, pp. 298-300GlobalRare earth, Mantle
DS1980-0142
1980
Gilligan, L.B.Gilligan, L.B., Lishmund, S.R.Mineral Resources of the Orana RegionNew South Wales Open File., No. GS 1980-098, 15P. UNPUBL.Australia, New South WalesMineral Occurrences, Gemstones, Diamonds
DS1960-0243
1962
Gilliland, W.N.Gilliland, W.N.Possible Continuation of the Mendocino Fracture ZoneScience., Vol. 137, PP. 685-686.GlobalMid-continent
DS200512-0338
2005
Gillin, P.Gillin, P.Nunavut's first diamond mine - the Jericho project.British Columbia & Yukon Mineral Exploration Roundup, Jan.24-27th., p. 84-5.Canada, NunavutNews item - brief overview, Tahera
DS200612-0461
2006
Gillin, P.Gillin, P.Developing Nunavut's first diamond mine. JerichoRoundup 06, Abstract p.74.Canada, NunavutNews item - Tahara
DS1997-0412
1997
Gillin, R.P.Gillin, R.P.Equity risk assessmentInsight Press, CanadaEconomics, Eguity markets
DS1999-0252
1999
Gillin, R.P.Gillin, R.P., Armstrong, J.M.Financing the mining industry: techniques, trends and outlookNorth Atlantic Mineral Symposium, Sept., abstracts pp. 180-82.GlobalEconomics - techniques, brief overview, Financing - not specific to diamonds
DS2001-0382
2001
Gillis, K.M.Gillis, K.M.Nature and origin of the oceanic lithosphere: some insights from past ocean drilling and plans for future.Geoscience Canada, Vol. 28, No. 4, Dec. pp. 163-9.MantleLithological zones - not specific to diamonds
DS1860-0294
1878
Gillmore, P.Gillmore, P.The Diamond Fields. Great Thirst LandLondon:, PP. 444-466.Africa, South AfricaHistory
DS201911-2527
2019
Gilloly, T.Gilloly, T., Coltice, N., Wolf, C.An anticipation experiment for plate tectonics. Boundaries.Tectonics, in press availableMantleplate tectonics

Abstract: Although plate tectonics has pushed the frontiers of geosciences in the past 50 years, it has legitimate limitations and among them we focus on both the absence of dynamics in the theory, and the difficulty of reconstructing tectonics when data is sparse. In this manuscript, we propose an anticipation experiment, proposing a singular outlook on plate tectonics in the digital era. We hypothesize that mantle convection models producing self-consistently plate-like behavior will capture the essence of the self-organisation of plate boundaries. Such models exist today in a preliminary fashion and we use them here to build a database of mid-ocean ridge and trench configurations. To extract knowledge from it we develop a machine learning framework based on Generative Adversarial Networks (GANs) that learns the regularities of the self-organisation in order to fill gaps of observations when working on reconstructing a plate configuration. The user provides the distribution of known ridges and trenches, the location of the region where observations lack, and our digital architecture proposes a horizontal divergence map from which missing plate boundaries are extracted. Our framework is able to prolongate and interpolate plate boundaries within an unresolved region, but fails to retrieve a plate boundary that would be completely contained inside of it. The attempt we make is certainly too early because geodynamic models need improvement and a larger amount of geodynamic model outputs, as independent as possible, is required. However, this work suggests applying such an approach to expand the capabilities of plate tectonics is within reach.
DS1998-0941
1998
Gillou-Frottier, L.Mareschal, J.C., Gillou-Frottier, L., Cheng, L.Z.Heat flow in the Trans Hudson OrogenGeological Association of Canada (GAC)/Mineralogical Association of Canada (MAC) Abstract Volume, p. A117. abstract.ManitobaGeothermometry - heat flow, Trans Hudson Orogen
DS2002-0573
2002
Gilman, J.J.Gilman, J.J.Why diamond is very hardPhilosophical Magazine, A., (ingenta 1022994847), Vol.82, 10,pp. 1811-20.GlobalMineralogy
DS1970-0645
1973
Gilmer, T.H.Chase, C.G., Gilmer, T.H.Precambrian Plate Tectonics- the Mid-continent Gravity HighEarth And Planetary Letters, Vol. 21, No. 1, PP. 70-78.GlobalMid-continent
DS200612-0462
2005
Gilmore, E.Gilmore, E., Gleditsch, N.P., Lujala, P., Rod, J.K.Conflict diamonds: a new dataset. Primary deposits have low probability of being the object of conflict.Conflict Management and Peace Science, Vol. 22, 3, pp. 257-272.GlobalLegal - conflict diamonds
DS200612-0463
2005
Gilmore, E.Gilmore, E., Nils, G., Paivi, R.J.Conflict diamonds: a new dataset.Conflict Management and Peace Science , Vol. 22, 3, Fall, pp. 257-272.AfricaConflict diamonds
DS1980-0302
1980
Gilmore, J.L.Sendlein, L.V.A., Gilmore, J.L.Bedrock Topography of Southwest IowaUnited States Geological Survey (USGS) miscellaneous INVEST. MAP, I-1222, 1: 125, 000.GlobalMid-continent
DS1997-0413
1997
Gilmore, T.J.Gilmore, T.J., Clayton, E.A.Mapping the top of the permafrost using direct current resistivity surveyEnvironmental Geology, Vol. 30, No. 1-2, March 1, pp. 29-33GlobalEnvironment, Permafrost, Geophysics
DS1997-0610
1997
GilmourKoeberl, C., Masaitis, V.L., Shafranovsky, GilmourDiamonds from the Popigal impact structure, RussiaGeology, Vol. 25, No. 11, Nov. pp. 967-970.Russia, SiberiaMineralogy impact diamonds, Sample techniques
DS1990-1584
1990
Gilmour, I.Wright, I.P., Gilmour, I.Meteorites: origin of organic materialsNature, Vol. 345, No. 6271, May 10, p. 110GlobalMeteorites, Organics
DS1992-0570
1992
Gilmour, I.Gilmour, I., Russell, S.S., Arden, J.W., Lee, M.R., Franchi, I.A.Terrestrial carbon and nitrogen isotopic ratios from Cretaceous-Tertiary boundary nanodiamondsScience, Vol. 258, December 4, pp. 1624-1626GlobalGeochronology, Nanodiamonds
DS1995-0823
1995
Gilmour, I.Hough, R.M., Gilmour, I., Pillinger, C.T., Arden, H.J.Diamond and silicon carbide in impact melt rock from the Ries impactcrater.Nature, Vol. 378, No. 6552, Nov. 2, pp. 41-44.GlobalDiamond, SIC., Deposit -Ries crater
DS1997-0523
1997
Gilmour, I.Hough, R.M., Gilmour, I., Pillinger, C.T., LangenhorstDiamonds from the iridium rich K-T boundary layer at Arroyo el Mimbral, Tamaulipas, Mexico.Geology, Vol. 25, No. 11, Nov. pp. 1019-22.MexicoK-T boundary, Diamonds - mineralogy, techniques
DS2002-0574
2002
Gilmour, J.Gilmour, J.Partnering for sustainability - an NGO perspectiveAustralian Institute of Mining and Metallurgy, No. 3/2002, pp.185-7.GlobalMining - environmental agreement, socioeconomic
DS200512-0339
2005
Gilmour, J.D.Gilmour, J.D., Verchocsky, A.B., Fisenko, A.V., Holland, G., Turner, G.Xenon isotopes in size separated nanodiamonds from Efremovka: 129 Xe, Xe-P3 and Xe-P6.Geochimica et Cosmochimica Acta, Vol. 69, 16, Aug.15, pp. 4133-4148.TechnologyNanodiamonds, geochronology, degassing events
DS1995-0637
1995
Gilmour, W.R.Gilmour, W.R.Metallic and industrial mineral assessment report on the results for diamond exploration north of Hinton.Alberta Geological Survey, MIN 19950017AlbertaExploration - assessment, Montello Resources Ltd.
DS201312-0311
2013
Gilotti, J.Gilotti, J.Continental crust at mantle depths.Elements, Vol. 9, 4, pp. 255-260.MantleCoesite
DS201312-0349
2013
Gilotti, J.Hacker, B.R., Gerya, T.V., Gilotti, J.Formation and exhumation of ultrahigh pressure terranes.Elements, Vol. 9, 4, pp. 289-293.MantleUHP
DS1992-0571
1992
Gilotti, J.A.Gilotti, J.A., Friderichsen, J.D., Higgins, A.K., Steenfelt, A.A new eclogite province in the Arctic Caledonides, southeast Greenland 77to 78 degGeological Society of America (GSA) Abstract Volume, Vol. 24, No. 3, March p. 23. abstractGreenlandEclogite, Xenoliths
DS1994-0621
1994
Gilotti, J.A.Gilotti, J.A.Eclogites and related high-pressure rocks from north-east GreenlandGronlands Geol. Unders. Rapp., No. 162, pp. 77-90.GreenlandEclogites, Websterite bodies
DS1996-0532
1996
Gilotti, J.A.Gilotti, J.A., Elevold, S.Partial eclogization of igneous protoliths from northeastern Greenland and exlogite province...Geological Society of America, Abstracts, Vol. 28, No. 7, p. A-358.GreenlandEclogites, Caledonides
DS1998-0174
1998
Gilotti, J.A.Brueckner, H.K., Gilotti, J.A., Nutman, A.Caledonian eclogite- facies metamorphism of Early Proterozoic protoliths from northeast Greenland eclogite...Contributions to Mineralogy and Petrology, Vol. 130, No. 2, pp. 103-120.GreenlandEclogite province, Regional geology
DS2000-0267
2000
Gilotti, J.A.Elevevold, S., Gilotti, J.A.Pressure temperature evolution of retrogressed kyanite eclogites Weinschenk Island, Greenland Caledonides.Lithos, Vol. 53, No. 2, Aug. pp.127-48.GreenlandEclogites, metamorphism
DS2002-0575
2002
Gilotti, J.A.Gilotti, J.A., Krogh Ravna, E.J.First evidence for ultrahigh pressure metamorphism in the north east Greenland Caledonides.Geology, Vol. 30,6, June,pp. 551-4.GreenlandEclogite, coesite, pseudomorph, UHP
DS200412-0666
2004
Gilotti, J.A.Gilotti, J.A., Nutman, A.P., Brueckner, H.K.Devonian to Carboniferous in the Greenland Caledonides: U Pb zircon and Sm Nd ages of high pressure and ultrahigh pressure metamContributions to Mineralogy and Petrology, Vol. 148, 2, pp. 215-235.Europe, GreenlandUHP, geochronology
DS200612-0886
2006
Gilotti, J.A.McClelland, W.C., Power, S.E., Gilotti, J.A., Mazdab, F.K., Wopenka, B.U Pb SHRIMP geochronology and trace element geochemistry of coesite bearing zirocons, north east Greenland Caledonides.Geological Society of America, Special Paper, No. 403, pp. 23-44.Europe, GreenlandCoesite
DS1990-0572
1990
Gilruth, P.T.Gilruth, P.T., Hutchinson, C.F.Assessing deforestation in the Guinea Highlands of West Africa using RemotesensingPhotogrammetric Eng. and Remote Sensing, Vol. 56, No. 10, October pp. 1375-1382GuineaRemote sensing, General interest applicat
DS1999-0047
1999
Gilson, E.Bauman, P., Kellett, R., Sharma, A., Gilson, E.Three innovative geophysical techniques for the sterilization of diamond prospects in Alberta.The Canadian Mining and Metallurgical Bulletin (CIM Bulletin) ., Vol. 92, No. 1028, Mar. p. 95-6, abstractAlbertaGeophysics
DS202108-1279
2021
Gimenez, M.E.Dragone, G.N., Bologna, M.S., Ussami, N., Gimenez, M.E., Alvarez, O., Klinger, F.G.L., Correa-Otto, S.Lithosphere of South American intracratonic basins: electromagnetic and potential field data reveal cratons, terranes, and sutures.Tectonophysics, Vol. 811, 13p. PdfSouth America, Argentinacratons

Abstract: A magnetotelluric survey comprising 18 broadband stations disposed along a 450 km-long profile was carried out at the transition between the Chaco-Paraná (CPB) and the Paraná (PB) intracratonic basins in northeastern Argentina. Three-dimensional inversions of the responses show that the CPB and southern PB lithospheres are resistive (~103 O m) down to 120 km, but with distinct crustal and upper mantle electrical properties. Also, Bouguer gravity and density anomalies are positive at CPB, whereas they are negative at PB. We associate the CPB lithosphere with the Paleoproterozoic Rio Tebicuary craton and the southern PB lithosphere with an ancient and buried piece of craton, the Southern Paraná craton. Geochemical data of mantle xenoliths from the Cenozoic alkaline/carbonatitic province within the Rio Tebicuary craton suggest a subcontinental lithospheric mantle affected by metasomatic processes, which explains its lower resistivity (reaching values as low as 300 O m) and higher density (#Mg = 0.87). In contrast, the Southern Paraná craton is more resistive (>103 O m) and less dense, suggesting a de-hydrated, depleted, and thicker craton. These cratons are separated by a crustal conductor (15 to 20 km depth; 1-10 O m) that we interpret as a southward continuation of a linear anomaly (Paraná Axial Anomaly) defined in former induction studies within the PB in Brazil. Hence, we redefined the trace of this conductive lineament: instead of bending towards the Torres Syncline, it continues inside the CPB. We propose the lineament to be an Early Neoproterozoic suture zone that controlled the location of maximum subsidence in the intracratonic basins during the Paleozoic. In the Early Cretaceous, the Paraná Axial Anomaly was the site of maximum extrusion and deposition of Serra Geral basalts. This anomaly separates compositionally distinct cratonic lithospheres along its path. Melting of this heterogeneous and enriched mantle created the Paraná igneous province.
DS1983-0255
1983
Ginger, D.Ginger, D.The Kimberlites of the Noenieput District of Northwest Cape Province, South Africa.Bsc. Thesis, University Leeds, UNKNOWN.South AfricaGeochemistry, Geophysics, Kimberlite
DS2002-1439
2002
Gingerich, J.C.Seigel, H.O., Gingerich, J.C., Kostlin, E.O.Explore or acquire? The dilemmaC.i.m. Bulletin, Vol.95,1058,Feb.pp.9.62-GlobalEconomics - ore reserves, exploration, discoveries
DS201906-1299
2019
Gingerich, T.Hagedorn, G., Ross, M., Paulen, R., Smith, R., Neudorf, C., Gingerich, T., Lian, O.Ice-flow and deglacial history of the Laurentide Ice sheet in the southwestern Great Slave Lake area.GAC/MAC annual Meeting, 1p. Abstract p. 102.Canada, Northwest Territoriesgeomorphology

Abstract: Limited field studies and sparse chronological constraints in the southwestern Great Slave Lake area creates uncertainties about the Laurentide Ice Sheet (LIS) flow history and deglacial chronology. Improved understanding of the western LIS ice-margin morphology and retreat history is required to refine larger ice-sheet interpretations and timing for northwest drainage of glacial Lake McConnell. Using new field observations and geochronology we establish ice-flow history and better constrain regional deglaciation. Paleo-ice flow indicators (n = 66) show an oldest southwestern flow (230°), an intermediate northwesterly flow (305°), and a youngest westerly flow (250°). Till samples bulk sediment and matrix properties (n = 160) allowed identification of two till units. A lower grey till sourced mainly from local Paleozoic sediments produced clast fabrics indicating a southwesterly flow direction, overlain by a brown till that contained an increased Canadian Shield content with lodged elongate boulders a-axes and boulder-top striation orientations indicating a west to northwest ice-flow direction. Ice-flow results show a clockwise shift in direction interpreted as evidence for ice-divide migration followed by topographically controlled deglacial westward flow influenced by the Mackenzie River valley. Minimum deglacial timing estimates were constrained through optical dating of fine-sand deposits in a well-developed strandline (n = 2) and seven aeolian dunes; ages range from 9.9 ± 0.6 to 10.8 ± 0.7 ka BP. These ages are from dunes located below glacial Lake McConnell maximum water level and may thus provide new local lake level age constraints. Ice retreat is informed by a newly-mapped segment of the Snake River moraine, which is an understudied feature in the region. New ice-flow history and ice-margin retreat interpretations will be integrated into the larger body of work on the western LIS providing more confident conclusions on ice-sheet evolution and meltwater drainage pathways, specifically in the southwestern Great Slave Lake area.
DS1998-0047
1998
Ginibre, C.Arndt, N., Ginibre, C., Chauvel, Albaraede, CheadleWere komatiites wet?Geology, Vol. 26, No. 8, Aug. pp. 739-42GlobalMelting hydrous mantle, spiniflex textures, Magmatic volatiles
DS2003-0467
2003
Ginnermann, J.Ginnermann, J., Kusaka, K., Harris, J.W.Oriented graphite single crystal inclusions in diamondZeitschrift fur Kristallographie, Vol. 218, 11, pp. 733-739.GlobalDiamond - inclusions
DS200412-0667
2003
Ginnermann, J.Ginnermann, J., Kusaka, K., Harris, J.W.Oriented graphite single crystal inclusions in diamond.Zeitschrift fur Kristallographie, Vol. 218, 11, pp. 733-739.TechnologyDiamond - inclusions
DS1991-0575
1991
Ginsberg, D.W.Ginsberg, D.W., Whiten, W.J.Cluster analysis for mineral processing applicationsInstitute of Mining and Metallurgy, Vol. 100, Sept-Dec. pp. C 139-146GlobalComputer, Program -Cluster analysis
DS1992-0572
1992
Ginsberg, D.W.Ginsberg, D.W., Whiten W.J.Application of clustering in the analysis and control of mineral processingplantsAusIMM Proceedings, Vol. 297, No. 2, October pp. 9-17GlobalMineral processing, Cluster analysis, computers
DS1981-0181
1981
Ginzburg, A.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
DS1982-0494
1982
Ginzburg, A.Peters, D., Mooney, W.D., Andrews, M.C., Ginzburg, A.The Deep Crustal Structure of the Northern Mississippi Embayment.Eos, Vol. 63, No. 45, P. 1118. (abstract.).GlobalMid-continent
DS1983-0256
1983
Ginzburg, A.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
DS1988-0486
1988
Ginzburg, I.V.Morimoto, N., Fabries, J., Ferguson, A.K., Ginzburg, I.V., et al.Nomenclature of pyroxenes. ... new classification and recommendations based on crystal chemistryMineralogy and Petrology, Vol. 39, pp. 55-76. Database # 17362GlobalRock classification, Mineralogy - pyroxenes
DS1988-0362
1988
Ginzburg, L.N.Kogan, B.S., Ginzburg, L.N., Burenkov, E.K.Investigation of the spatial structures of geochemical fields for prospecting purposesInternational Geology Review, Vol. 30, No. 10, October pp. 1141-1146. Database # 1787RussiaComputer, Program -GEOSCAN Geochemistry
DS1989-1555
1989
Gioan, P.Vicat, J-P., Gioan, P., Albouy, Y., Cornacchia, M., Giorgi, L.Evidence of Upper Proterozoic rifts buried under the Phanerozoic of the Zaire basin on the western border of the Congo craton.(in French)Comptes Rendus, (in French), Vol. 309, No. 11, pp. 1207-1214Democratic Republic of CongoTectonics, Craton
DS1991-1080
1991
Gioan, P.Maurin, J-C., Boudzoumou, F., Diama, L-M., Gioan, P., Michard, A.The Proterozoic of west Congolian belt and its foreland in Congo: newC.r. Academy Of Science Paris, Ser. Ii, Vol. 312, No. ser II, pp. 1327-1334Central Africa, CongoGeochronology, Structure
DS200412-0456
2004
Giordano, D.Dingwell, D.B., Courtial, P., Giordano, D., Nichols, A.R.I.Viscosity of peridotite liquid.Earth and Planetary Science Letters, Vol. 226, 1-2, Sept. 30, pp.127-138.MantleGlass transition, calorimetry
DS200412-0457
2004
Giordano, D.Dingwell, D.B., Giordano, D., Courtial, P., Nichols, A.Viscosity of molten peridotite.Lithos, ABSTRACTS only, Vol. 73, p. S26. abstractMantleGeodynamics
DS200612-1187
2006
Giordano, D.Russell, J.K., Giordano, D., Kopylova, M., Moss, S.Transport properties of kimberlite melt.Emplacement Workshop held September, 5p. abstractGlobalMelting - composition
DS200812-0411
2008
Giordano, D.Giordano, D., Russell, J.K., Dingwell, D.B.Viscosity of magmatic liquids: a model.Earth and Planetary Science Letters, Vol. 271, 1-4, pp. 123-134.MantleMagmatism
DS200812-0412
2008
Giordano, D.Giordano, D., Russell, J.K., Dingwell, D.B.Viscosity of magmatic liquids: a model.Earth and Planetary Science Letters, Vol. 271, 1-4, pp. 123-134.TechnologyMagmatism
DS201610-1863
2016
Giordano, D.Giordano, D., Russell, J.K.The heat capacity of hydrous multicomponent natural melts and glasses.Chemical Geology, In press available 30p.MantleMelting

Abstract: The thermophysical properties of silicate melts and glasses are of fundamental importance for the characterization of the dynamics and energetics of silicate melts on Earth and terrestrial planets. The heat capacity of silicate melts is of particular importance because of its implications for the temperature dependencies of melt enthalpy and entropy and for the potential relationship to melt structure and transport properties. Currently, there are reliable models for predicting the heat capacity of simple and multicomponent silicate glasses (Cpglass) as a function of composition and temperature. Recent differential scanning calorimetry (DSC) measurements of heat capacity for multicomponent silicate liquid (Cpliquid), however, have shown that published models do not accurately reproduce heat capacity measurements on some silicate melts. Here, we have compiled a database of heat capacity values for hydrous and anhydrous multicomponent natural samples. The measurements are on pairs of glasses and melts over the compositional range (wt%) of: SiO2 (44-79), Al2O3 (5-35), TiO2 (0-3), FeOtot (0 - 11); Na2O + K2O (0-27); CaO + MgO (0-39), H2O (0-6.3) and minor oxides. The compiled data show strong correlations between silica content (XSiO2) and the configurational heat capacity (Cpconfig) defined as Cpliquid - Cpglass measured across the glass transition temperature (Tg). This correlation is used to establish an empirical model for predicting Cpliquid as a function of melt composition (i.e. SiO2 content) and values of Cpglass measured at the onset of the glass transition: Cpliquid=52.6-55.88XSiO2+CpglassCpliquid=52.6-55.88XSiO2+Cpglass. The model reproduces values of Cpliquid to within an average relative error of ~ 2.4%. Published models for the heat capacities of silicate melts (e.g., Stebbins, 1984; Richet and Bottinga, 1985; Lange and Navrotsky, 1992) applied to the same dataset have average relative errors in excess of 5.5%.
DS201810-2322
2018
Giordano, D.Giordano, D., Russell, J.K.Towards a structural model for the viscosity of geological melts.Earth and Planetary Science Letters, Vol. 501, pp. 202-212.Mantlemelting

Abstract: The viscosity of silicate melts is the most important physical property governing magma transport and eruption dynamics. This macroscopic property is controlled by composition and temperature but ultimately reflects the structural organization of the melt operating at the microscale. At present, there is no explicit relationship connecting viscosity to silicate melt structure and vice versa. Here, we use a single Raman spectroscopic parameter, indicative of melt structure, to accurately forecast the viscosity of natural, multicomponent silicate melts from spectroscopic measurements on glasses preserved on Earth and other planets. The Raman parameter is taken as the ratio of low and high frequency vibrational bands from the silicate glass by employing a green source laser wavelength of 514.5 nm (R514.5). Our model is based on an empirical linkage between R514.5 and coefficients in the Vogel-Fulcher-Tammann function for the temperature dependence of melt viscosity. The calibration of the Raman-based model for melt viscosity is based on 413 high-temperature measurements of viscosity on 23 melt compositions for which published Raman spectra are available. The empirical model obviates the need for chemical measurement of glass compositions, thereby, providing new opportunities for tracking physical and thermochemical properties of melts during igneous processes (e.g., differentiation, mixing, assimilation). Furthermore, our model serves as a milepost for the future use of Raman spectral data for predicting transport (and calorimetric) properties of natural melts at geological conditions (e.g., volatiles and pressure) and production.
DS201812-2811
2018
Giordano, D.Giordano, D., Russell, J.K.Towards a structural model for the viscosity of geological melts.Earth and Planetary Science Letters, Vol. 501, pp. 202-212.Mantlemelting

Abstract: The viscosity of silicate melts is the most important physical property governing magma transport and eruption dynamics. This macroscopic property is controlled by composition and temperature but ultimately reflects the structural organization of the melt operating at the microscale. At present, there is no explicit relationship connecting viscosity to silicate melt structure and vice versa. Here, we use a single Raman spectroscopic parameter, indicative of melt structure, to accurately forecast the viscosity of natural, multicomponent silicate melts from spectroscopic measurements on glasses preserved on Earth and other planets. The Raman parameter is taken as the ratio of low and high frequency vibrational bands from the silicate glass by employing a green source laser wavelength of 514.5 nm (R514.5). Our model is based on an empirical linkage between R514.5 and coefficients in the Vogel-Fulcher-Tammann function for the temperature dependence of melt viscosity. The calibration of the Raman-based model for melt viscosity is based on 413 high-temperature measurements of viscosity on 23 melt compositions for which published Raman spectra are available. The empirical model obviates the need for chemical measurement of glass compositions, thereby, providing new opportunities for tracking physical and thermochemical properties of melts during igneous processes (e.g., differentiation, mixing, assimilation). Furthermore, our model serves as a milepost for the future use of Raman spectral data for predicting transport (and calorimetric) properties of natural melts at geological conditions (e.g., volatiles and pressure) and production.
DS201903-0541
2019
Giordano, D.Roverato, M., Giordano, D., Giovanardi, T., Juliani, C., Polo, L.The 2.0-1.88 Ga Paleoproterozoic evolution of the southern Amazonian Craton ( Brazil): an interpretation inferred by lithofaciological, geochemical and geochronological data.Gondwana Research, Vol. 70, pp. 1-24. doi:10.1016/ j.gr.2018.12.005South America, Brazilcraton

Abstract: The study of Paleoproterozoic rocks is crucial for understanding Earth's tectonic evolution during the time when most of the modern crust and ore deposits were formed. The rocks of the Brazilian Amazonian Craton record some of the most-complete and best-preserved Paleoproterozoic magmatic and volcanic episodes on Earth. Following previous investigations, we present new lithofaciological and stratigraphic records of the felsic rocks of the Tapajós Mineral Province (TMP) (~2-1.88?Ga) and the São Felix do Xingú region (SFX) (~1.88?Ga) which, combined with new petrological and geochronological data, help providing a more complete understanding of the tectonic, magmatic and volcanological evolution of the Amazonian Craton. This magmatism/volcanism is thought to be formed in a late-/post-orogenic to extentional regime confirmed by the new geochemical data presented here. The transition from late-convergent to extensional tectonic setting could register the beginning of the taphrogenesis that marked the Amazonian Craton throughout the Mesoproterozoic. The volcanological approach of this contribution can serve as a strategy for the modelling of the evolution of Precambrian volcano-sedimentary basins around the world. The large amount of rocks analyzed are divided into primary and secondary volcaniclastic products depending on if they resulted from a direct volcanic activity (pyroclastic) or processes that reworked pyroclastic fragments. Furthermore, the deposits are subdivided into massive and stratified, depending on their primary mechanisms of transport and emplacement. By confirming the results from previous studies, our study permits to depict a more precise paleo-environmental picture of the processes that occurred in the Amazonian Craton during the Late-Paleoproterozoic. In particular, the presence of large regional-scale fissural systems and caldera collapses produced large silicic explosive volcanic eruptions, also accompanied by the emission of large volume effusive products. Although studies on the Amazonian Craton are still scarce and controversial, the present study provides new evidence that this volcanism may have formed one of the largest Silicic Large Igneous Provinces (SLIP) on earth. Our data also confirm that at least two major Paleoproterozoic periods of formation of volcanic rocks exist in the Amazonian craton. This point is of great relevance for any future interpretation of the geological evolution of this craton.
DS201905-1074
2019
Giordano, D.Roverato, M., Giordano, D., Giovanardi, T., Juliani, C., Polo, L.The 2.0-1.88 Ga Paleoproterozoic evolution of the southern Amazonian Craton ( Brazil): an interpretation inferred by lithofaciological, geochemical and geochronological data.Gondwana Research, Vol. 70, pp. 1-24.South America, Brazilcraton

Abstract: The study of Paleoproterozoic rocks is crucial for understanding Earth's tectonic evolution during the time when most of the modern crust and ore deposits were formed. The rocks of the Brazilian Amazonian Craton record some of the most-complete and best-preserved Paleoproterozoic magmatic and volcanic episodes on Earth. Following previous investigations, we present new lithofaciological and stratigraphic records of the felsic rocks of the Tapajós Mineral Province (TMP) (~2-1.88?Ga) and the São Felix do Xingú region (SFX) (~1.88?Ga) which, combined with new petrological and geochronological data, help providing a more complete understanding of the tectonic, magmatic and volcanological evolution of the Amazonian Craton. This magmatism/volcanism is thought to be formed in a late-/post-orogenic to extentional regime confirmed by the new geochemical data presented here. The transition from late-convergent to extensional tectonic setting could register the beginning of the taphrogenesis that marked the Amazonian Craton throughout the Mesoproterozoic. The volcanological approach of this contribution can serve as a strategy for the modelling of the evolution of Precambrian volcano-sedimentary basins around the world. The large amount of rocks analyzed are divided into primary and secondary volcaniclastic products depending on if they resulted from a direct volcanic activity (pyroclastic) or processes that reworked pyroclastic fragments. Furthermore, the deposits are subdivided into massive and stratified, depending on their primary mechanisms of transport and emplacement. By confirming the results from previous studies, our study permits to depict a more precise paleo-environmental picture of the processes that occurred in the Amazonian Craton during the Late-Paleoproterozoic. In particular, the presence of large regional-scale fissural systems and caldera collapses produced large silicic explosive volcanic eruptions, also accompanied by the emission of large volume effusive products. Although studies on the Amazonian Craton are still scarce and controversial, the present study provides new evidence that this volcanism may have formed one of the largest Silicic Large Igneous Provinces (SLIP) on earth. Our data also confirm that at least two major Paleoproterozoic periods of formation of volcanic rocks exist in the Amazonian craton. This point is of great relevance for any future interpretation of the geological evolution of this craton.
DS201908-1808
2019
Giordano, D.Roverato, M., Giordano, D., Giovanardi, T., Juliani, C., Polo, L.The 2.0-1.88 Ga Paleoproterozoic evolution of the southern Amazonian craton ( Brazil): an interpretation inferred by lithofaciological, geochemical and geochronological data.Gondwana Research, Vol. 70, pp. 1-24.South America, Braziltectonics

Abstract: The study of Paleoproterozoic rocks is crucial for understanding Earth's tectonic evolution during the time when most of the modern crust and ore deposits were formed. The rocks of the Brazilian Amazonian Craton record some of the most-complete and best-preserved Paleoproterozoic magmatic and volcanic episodes on Earth. Following previous investigations, we present new lithofaciological and stratigraphic records of the felsic rocks of the Tapajós Mineral Province (TMP) (~2-1.88?Ga) and the São Felix do Xingú region (SFX) (~1.88?Ga) which, combined with new petrological and geochronological data, help providing a more complete understanding of the tectonic, magmatic and volcanological evolution of the Amazonian Craton. This magmatism/volcanism is thought to be formed in a late-/post-orogenic to extentional regime confirmed by the new geochemical data presented here. The transition from late-convergent to extensional tectonic setting could register the beginning of the taphrogenesis that marked the Amazonian Craton throughout the Mesoproterozoic. The volcanological approach of this contribution can serve as a strategy for the modelling of the evolution of Precambrian volcano-sedimentary basins around the world. The large amount of rocks analyzed are divided into primary and secondary volcaniclastic products depending on if they resulted from a direct volcanic activity (pyroclastic) or processes that reworked pyroclastic fragments. Furthermore, the deposits are subdivided into massive and stratified, depending on their primary mechanisms of transport and emplacement. By confirming the results from previous studies, our study permits to depict a more precise paleo-environmental picture of the processes that occurred in the Amazonian Craton during the Late-Paleoproterozoic. In particular, the presence of large regional-scale fissural systems and caldera collapses produced large silicic explosive volcanic eruptions, also accompanied by the emission of large volume effusive products. Although studies on the Amazonian Craton are still scarce and controversial, the present study provides new evidence that this volcanism may have formed one of the largest Silicic Large Igneous Provinces (SLIP) on earth. Our data also confirm that at least two major Paleoproterozoic periods of formation of volcanic rocks exist in the Amazonian craton. This point is of great relevance for any future interpretation of the geological evolution of this craton.
DS201312-0172
2013
Giordano, G.Contincelli, S., Avanzinelli, R., Poli, G., Braschi, E., Giordano, G.Shift from lamproite-like to leucitic rocks: Sr-Nd-Pb isotope dat a from the Monte Cimino volcanic complex vs the Vico stratovolcano, central Italy.Chemical Geology, Vol. 353, pp. 246-266.Europe, ItalyLeucites
DS201312-0194
2013
Giordano, G.Conticelli, S., Avanzinelli, R., Poli, G., Braschi, E., Giordano, G.Shift from lamproite-like to leucitic rocks: Sr-Nd-Pb isotope dat a from the Monte Cimino volcanic complex vs the Vico stratovolcano, central Italy.Chemical Geology, Vol. 353, pp. 246-266.Europe, ItalyLamproite
DS201412-0103
2014
Giordano, G.Cashman, K.V., Giordano, G.Calderas and magma reservoirs. ReviewJournal of Volcanology and Geothermal Research, Vol. 288, pp. 28-45.GlobalCalderas - review
DS1989-1555
1989
Giorgi, L.Vicat, J-P., Gioan, P., Albouy, Y., Cornacchia, M., Giorgi, L.Evidence of Upper Proterozoic rifts buried under the Phanerozoic of the Zaire basin on the western border of the Congo craton.(in French)Comptes Rendus, (in French), Vol. 309, No. 11, pp. 1207-1214Democratic Republic of CongoTectonics, Craton
DS200512-0194
2005
Giorgia, D.Cosca, M.A., Giorgia, D., Rumble, D., Liou, J.G.Limiting effect of UHP metamorphism on length scales of oxygen, hydrogen and argon isotope exchange: an example from the Qinglongshan UHP eclogites, Sulu Terrain.International Geology Review, Vol. 47, 7, pp. 716-749.Asia, ChinaUHP
DS2000-0340
2000
Giorgis, D.Giorgis, D., Cosca, M., Li, S.Distribution and significance of extraneous argon in ultra high pressure (UHP) eclogite Sulu Terrain: UV laser ablation analysis.Earth and Planetary Science Letters, Vol.181, No.4, Sept.30, pp.605-15.ChinaEclogites, ultra high pressure (UHP), Dabie Shan
DS200512-0340
2004
Giorgis, S.Giorgis, S., Markley, M., Tikoff, B.Vertical axis rotation of rigid crustal blocks driven by mantle flow.Geological Society of London Special Paper, No. 226, pp. 83-100.MantleTectonics
DS1998-0513
1998
Giorgobiani, T.V.Giorgobiani, T.V., Basheleishvili, ZakariaThe northward drift of the Gondwanian lithospheric plates and geodynamics of formation of Caucasian OrogenJournal of African Earth Sciences, Vol. 27, 1A, p. 88. AbstractGondwana, Europe, RussiaTectonics, Geodynamics
DS1993-1656
1993
Giorgoni, C.Venturelli, G., Salvioli-Mariani, E., Toscani, L., Barbieri, M., Giorgoni, C.Post-magmatic apatite + hematite + carbonate assemblage in the Jumillalamproites. a fluid inclusion and isotope study.Lithos, Vol. 30, pp. 139-150.GlobalLamproites, Geochronology
DS201705-0830
2017
Giovanardi, T.Giovanardi, T., Girardi, V.A.V., Correia, C.T., Sinigoi, S., Tassinari, C.C.G., Mazzucchelli, M.The growth and contamination mechanism of the Cana Brava layered mafic-ultramafic complex: new field and geochemical evidences.Mineralogy and Petrology, in press available 24p.South America, BrazilGeochemistry

Abstract: The Cana Brava complex is the northernmost of three layered complexes outcropping in the Goiás state (central Brasil). New field and geochemical evidences suggest that Cana Brava underwent hyper- to subsolidus deformation during its growth, acquiring a high-temperature foliation that is generally interpreted as the result of a granulite-facies metamorphic event. The increase along the stratigraphy of the incompatible elements abundances (LREE, Rb, Ba) and of the Sr isotopic composition, coupled with a decrease in eNd(790), indicate that the complex was contaminated by the embedded xenoliths from the Palmeirópolis Sequence. The geochemical data suggest that the contamination occurred along the entire magma column during the crystallization of the Upper Mafic Zone, with in situ variations determined by the abundance and composition of the xenoliths. These features of the Cana Brava complex point to an extremely similarity with the Lower Sequence of the most known Niquelândia intrusion (the central of the three complexes). This, together with the evidences that the two complexes have the same age (c.a. 790 Ma) and their thickness and units decrease northwards suggests that Cana Brava and Niquelândia are part of a single giant Brasilia body grown through several melt impulses.
DS201903-0541
2019
Giovanardi, T.Roverato, M., Giordano, D., Giovanardi, T., Juliani, C., Polo, L.The 2.0-1.88 Ga Paleoproterozoic evolution of the southern Amazonian Craton ( Brazil): an interpretation inferred by lithofaciological, geochemical and geochronological data.Gondwana Research, Vol. 70, pp. 1-24. doi:10.1016/ j.gr.2018.12.005South America, Brazilcraton

Abstract: The study of Paleoproterozoic rocks is crucial for understanding Earth's tectonic evolution during the time when most of the modern crust and ore deposits were formed. The rocks of the Brazilian Amazonian Craton record some of the most-complete and best-preserved Paleoproterozoic magmatic and volcanic episodes on Earth. Following previous investigations, we present new lithofaciological and stratigraphic records of the felsic rocks of the Tapajós Mineral Province (TMP) (~2-1.88?Ga) and the São Felix do Xingú region (SFX) (~1.88?Ga) which, combined with new petrological and geochronological data, help providing a more complete understanding of the tectonic, magmatic and volcanological evolution of the Amazonian Craton. This magmatism/volcanism is thought to be formed in a late-/post-orogenic to extentional regime confirmed by the new geochemical data presented here. The transition from late-convergent to extensional tectonic setting could register the beginning of the taphrogenesis that marked the Amazonian Craton throughout the Mesoproterozoic. The volcanological approach of this contribution can serve as a strategy for the modelling of the evolution of Precambrian volcano-sedimentary basins around the world. The large amount of rocks analyzed are divided into primary and secondary volcaniclastic products depending on if they resulted from a direct volcanic activity (pyroclastic) or processes that reworked pyroclastic fragments. Furthermore, the deposits are subdivided into massive and stratified, depending on their primary mechanisms of transport and emplacement. By confirming the results from previous studies, our study permits to depict a more precise paleo-environmental picture of the processes that occurred in the Amazonian Craton during the Late-Paleoproterozoic. In particular, the presence of large regional-scale fissural systems and caldera collapses produced large silicic explosive volcanic eruptions, also accompanied by the emission of large volume effusive products. Although studies on the Amazonian Craton are still scarce and controversial, the present study provides new evidence that this volcanism may have formed one of the largest Silicic Large Igneous Provinces (SLIP) on earth. Our data also confirm that at least two major Paleoproterozoic periods of formation of volcanic rocks exist in the Amazonian craton. This point is of great relevance for any future interpretation of the geological evolution of this craton.
DS201904-0740
2019
Giovanardi, T.Giovanardi, T., Girardi, V.A.V., Teixeira, W., Mazzucchelli, M.Mafic dyke swarms at 1882, 535 and 200 Ma in the Carajas region Amazonian Craton: Sr-Nd isotopy, trace element geochemistry and inferences on their origin and geological settings.Journal of South American Earth Sciences, Vol. 92, pp. 197-208.South America, Brazilcraton

Abstract: The Carajás-Rio Maria region, together with the Rio Maria domain of the Central Amazonian province, comprises the eastern margin of the Amazonian Craton with the Neoproterozoic Araguaia belt. This region hosts several basaltic dyke swarms whose UPb baddeleyite ages highlighted three intrusive events at 1882, 535 and 200?Ma. New geochemical and SrNd isotopic data were obtained for the different groups of the Carajás dykes allowing new insights on i) the mantle source composition beneath the Carajás region through time and ii) the geodynamic setting of the intrusive events. The 1882?Ma swarm is coeval to the Uatumã SLIP event which is one of the oldest intraplate events of the proto-Amazonian craton. Trace elements and isotopic values suggest that the dyke parent melt for those dykes have a crustal component derived from a sedimentary source similar to GLOSS (GLObal Subducting Sediment compositions). This is consistent with the emplacement of the dykes in a supra-subduction setting or in a post-collisional setting. Trace and isotopic values of the 535?Ma dyke swarm are consistent with an enriched mantle source from EMII component. These geochemical features suggest an enrichment of the mantle from an oceanic lithosphere poor in sediments, different to that of the 1882?Ma source. The age of this swarm matches magmatic activity during a post-collisional extensive-transtensive event recorded in the marginal Araguaia belt after the amalgamation of the Amazonian Craton to the Western Gondwana during Neoproterozoic. The 200?Ma dyke swarm which is related to the CAMP (Central Atlantic Magmatic Province) and opening of the Atlantic Ocean shows trace element composition similar to Atlantic E-MORB. The coupled isotopic values are consistent with an enriched mantle source with EMII component. These particular geochemical features suggest that the plume activity responsible for the CAMP near the rifting zone has not affected the mantle beneath the Carajás region.
DS201905-1074
2019
Giovanardi, T.Roverato, M., Giordano, D., Giovanardi, T., Juliani, C., Polo, L.The 2.0-1.88 Ga Paleoproterozoic evolution of the southern Amazonian Craton ( Brazil): an interpretation inferred by lithofaciological, geochemical and geochronological data.Gondwana Research, Vol. 70, pp. 1-24.South America, Brazilcraton

Abstract: The study of Paleoproterozoic rocks is crucial for understanding Earth's tectonic evolution during the time when most of the modern crust and ore deposits were formed. The rocks of the Brazilian Amazonian Craton record some of the most-complete and best-preserved Paleoproterozoic magmatic and volcanic episodes on Earth. Following previous investigations, we present new lithofaciological and stratigraphic records of the felsic rocks of the Tapajós Mineral Province (TMP) (~2-1.88?Ga) and the São Felix do Xingú region (SFX) (~1.88?Ga) which, combined with new petrological and geochronological data, help providing a more complete understanding of the tectonic, magmatic and volcanological evolution of the Amazonian Craton. This magmatism/volcanism is thought to be formed in a late-/post-orogenic to extentional regime confirmed by the new geochemical data presented here. The transition from late-convergent to extensional tectonic setting could register the beginning of the taphrogenesis that marked the Amazonian Craton throughout the Mesoproterozoic. The volcanological approach of this contribution can serve as a strategy for the modelling of the evolution of Precambrian volcano-sedimentary basins around the world. The large amount of rocks analyzed are divided into primary and secondary volcaniclastic products depending on if they resulted from a direct volcanic activity (pyroclastic) or processes that reworked pyroclastic fragments. Furthermore, the deposits are subdivided into massive and stratified, depending on their primary mechanisms of transport and emplacement. By confirming the results from previous studies, our study permits to depict a more precise paleo-environmental picture of the processes that occurred in the Amazonian Craton during the Late-Paleoproterozoic. In particular, the presence of large regional-scale fissural systems and caldera collapses produced large silicic explosive volcanic eruptions, also accompanied by the emission of large volume effusive products. Although studies on the Amazonian Craton are still scarce and controversial, the present study provides new evidence that this volcanism may have formed one of the largest Silicic Large Igneous Provinces (SLIP) on earth. Our data also confirm that at least two major Paleoproterozoic periods of formation of volcanic rocks exist in the Amazonian craton. This point is of great relevance for any future interpretation of the geological evolution of this craton.
DS201908-1808
2019
Giovanardi, T.Roverato, M., Giordano, D., Giovanardi, T., Juliani, C., Polo, L.The 2.0-1.88 Ga Paleoproterozoic evolution of the southern Amazonian craton ( Brazil): an interpretation inferred by lithofaciological, geochemical and geochronological data.Gondwana Research, Vol. 70, pp. 1-24.South America, Braziltectonics

Abstract: The study of Paleoproterozoic rocks is crucial for understanding Earth's tectonic evolution during the time when most of the modern crust and ore deposits were formed. The rocks of the Brazilian Amazonian Craton record some of the most-complete and best-preserved Paleoproterozoic magmatic and volcanic episodes on Earth. Following previous investigations, we present new lithofaciological and stratigraphic records of the felsic rocks of the Tapajós Mineral Province (TMP) (~2-1.88?Ga) and the São Felix do Xingú region (SFX) (~1.88?Ga) which, combined with new petrological and geochronological data, help providing a more complete understanding of the tectonic, magmatic and volcanological evolution of the Amazonian Craton. This magmatism/volcanism is thought to be formed in a late-/post-orogenic to extentional regime confirmed by the new geochemical data presented here. The transition from late-convergent to extensional tectonic setting could register the beginning of the taphrogenesis that marked the Amazonian Craton throughout the Mesoproterozoic. The volcanological approach of this contribution can serve as a strategy for the modelling of the evolution of Precambrian volcano-sedimentary basins around the world. The large amount of rocks analyzed are divided into primary and secondary volcaniclastic products depending on if they resulted from a direct volcanic activity (pyroclastic) or processes that reworked pyroclastic fragments. Furthermore, the deposits are subdivided into massive and stratified, depending on their primary mechanisms of transport and emplacement. By confirming the results from previous studies, our study permits to depict a more precise paleo-environmental picture of the processes that occurred in the Amazonian Craton during the Late-Paleoproterozoic. In particular, the presence of large regional-scale fissural systems and caldera collapses produced large silicic explosive volcanic eruptions, also accompanied by the emission of large volume effusive products. Although studies on the Amazonian Craton are still scarce and controversial, the present study provides new evidence that this volcanism may have formed one of the largest Silicic Large Igneous Provinces (SLIP) on earth. Our data also confirm that at least two major Paleoproterozoic periods of formation of volcanic rocks exist in the Amazonian craton. This point is of great relevance for any future interpretation of the geological evolution of this craton.
DS201906-1271
2019
Giovannelli, D.Barry, P.H., de Moor, J.M., Giovannelli, D., Schrenk, M., Hummer, D.R., Lopez, T., Pratt, C.A., Alpizar Segua, Y., Battaglia, A., Beaudry, A., Bini, G., Cascante, M., d'Errico, G., di Carlo, M., Fattorini, D., Fullerton, K., H+Gazel, E., Gonzalez, G., HalForearc carbon sink reduces long term volatile recycling into the mantle.Nature , 588, 7753, p. 487.Mantlecarbon

Abstract: Carbon and other volatiles in the form of gases, fluids or mineral phases are transported from Earth’s surface into the mantle at convergent margins, where the oceanic crust subducts beneath the continental crust. The efficiency of this transfer has profound implications for the nature and scale of geochemical heterogeneities in Earth’s deep mantle and shallow crustal reservoirs, as well as Earth’s oxidation state. However, the proportions of volatiles released from the forearc and backarc are not well constrained compared to fluxes from the volcanic arc front. Here we use helium and carbon isotope data from deeply sourced springs along two cross-arc transects to show that about 91 per cent of carbon released from the slab and mantle beneath the Costa Rican forearc is sequestered within the crust by calcite deposition. Around an additional three per cent is incorporated into the biomass through microbial chemolithoautotrophy, whereby microbes assimilate inorganic carbon into biomass. We estimate that between 1.2 × 108 and 1.3 × 1010 moles of carbon dioxide per year are released from the slab beneath the forearc, and thus up to about 19 per cent less carbon is being transferred into Earth’s deep mantle than previously estimated.
DS202009-1614
2020
Giovannelli., D.Brovarone, A.V., Butch, C.J., Ciappa, A., Cleaves, H.J., Elmaleh, A., Faccenda, M., Feineman, M., Hermann, J., Nestola, F., Cordone, A., Giovannelli., D.Let there be water: how hydration/dehydration reactions accompany key Earth and life processes.American Mineralogist, Vol. 105, pp. 1152-1160. pdfMantlecarbon

Abstract: Water plays a key role in shaping our planet and making life possible. Given the abundance of water on Earth's surface and in its interior, chemical reactions involving water, namely hydration and dehydration reactions, feature prominently in nature and are critical to the complex set of geochemical and biochemical reactions that make our planet unique. This paper highlights some fundamental aspects of hydration and dehydration reactions in the solid Earth, biology, and man-made materials, as well as their connections to carbon cycling on our planet.
DS201712-2725
2017
Giovannini, A.L.Rossoni, M.B., Bastos Neto, A.C., Souza, V.S., Marquea, J.C., Dantas, E., Botelho, N.F., Giovannini, A.L., Pereira, V.P.U-Pb zircon geochronological investigation on the Morro dos Seis Lagos carbonatite complex and associated Nb deposit ( Amazonas, Brazil).Journal of South American Earth Sciences, Vol. 80, pp. 1-17.South America, Brazilcarbonatite

Abstract: We present results of U-Pb dating (by MC-ICP-MS) of zircons from samples that cover all of the known lithotypes in the Seis Lagos Carbonatite Complex and associated lateritic mineralization (the Morro dos Seis Lagos Nb deposit). The host rock (gneiss) yielded an age of 1828 ± 09 Ma interpreted as the crystallization time of this unit. The altered feldspar vein in the same gneiss yielded an age of 1839 ± 29 Ma. Carbonatite samples provided 3 groups of ages. The first group comprises inherited zircons with ages compatible with the gneissic host rock: 1819 ± 10 Ma (superior intercept), 1826 ± 5 Ma (concordant age), and 1812 ± 27 Ma (superior intercept), all from the Orosirian. The second and the third group of ages are from the same carbonatite sample: the superior intercept age of 1525 ± 21 Ma (MSWD ¼ 0.77) and the superior intercept age of 1328 ± 58 Ma (MSWD ¼ 1.4). The mineralogical study indicates that the ~1.3 Ga zircons have affinity with carbonatite. It is, however, a tendence rather than a well-defined result. The data allow state that the age of 1328 ± 58 Ma represents the maximum age of the carbonatite. Without the same certainty, we consider that the data suggest that this age may be the carbonatite age, whose emplacement would have been related to the evolution of the K'Mudku belt. The best age obtained in laterite samples (a superior intercept age of 1828 ± 12 Ma) is considered the age of the main source for the inherited zircons related to the gneissic host rock.
DS202004-0516
2020
Giovannini, A.L.Giovannini, A.L., Mitchell, R.H., Bastos Neto, A.C., Moura, C.A.V., Pereira, V.P., Porto, C.G.Mineralogy and geochemistry of the Morro dos Seis Lagos siderite carbonatite, Amazonas, Brazil.Lithos, vol. 360-361, 105433 20p. PdfSouth America, Brazil, Amazonascarbonatite

Abstract: The Morro dos Seis Lagos niobium rare earth element, Ti-bearing lateritic deposit (Amazonas, Brazil) is derived from a primary siderite carbonatite. The complex is the only example of a Nb deposit in which Nb-rich rutile is the main Nb ore mineral. Apart from the laterites, at the current level of exposure the complex consists only of siderite carbonatite; silicate rocks are absent. Three types of siderite carbonatite are recognized: (1) a brecciated and oxidized core siderite carbonatite consisting of up to 95 vol% siderite together with: hematite; pyrochlore; Nb-brookite; Ti-maghemite; and thorobastnäsite; (2) a REE- and P-rich variety of the core siderite carbonatite consisting of siderite (up to 95 vol%), hematite, minor pyrochlore, monazite and bastnäsite; (3) a border hydrothermal siderite carbonatite with ~70 vol% siderite, barite (~15 vol%), gorceixite (~7 vol%) and minor rhabdophane and pyrochlore. The country rock gneiss in which the carbonatite was emplaced was affected by potassic fenitization, with the formation of phlogopite and orthoclase together with monazite, fluorapatite and bastnäsite. The siderite carbonatites exhibit a wide variation of d13C (-5.39‰ to -1.40‰), accompanied by a significant variation in d18O (17.13‰ to 31.33‰), especially in the REE-rich core siderite carbonatite, and are explained as due to the presence of both H2O and CO2 in the magma. The core siderite carbonatite is the richest in Fe (48.64-70.85 wt% Fe2O3) and the poorest in Ca (up 0.82 wt% CaO) example of a siderite carbonatite yet recognized The ferrocarbonatite has significant contents of Mn, Ba, Th, Pb and LREE, and a very high Nb (up to 7667 ppm) content due to the presence of Nb-brookite. The substitution 3Ti4+ = Fe2+ + 2Nb5+ recognized in Nb-rich brookite explains enrichment of Nb in the core siderite carbonatite and indicates formation in a reducing environment. The high Nb/Ta ratio (1408-11,459) of the carbonatite is compatible with residual liquids derived by fractional crystallization. The 87Sr/86Sr (0.70411-0.70573) and 144Nd/143Nd (0.512663-0.512715) isotopic data suggest the carbonatite is mantle-derived with essentially no crustal contamination and is younger than the maximum age of 1328 ± 58 Ma (UPb in zircon). We suggest that the Morro dos Seis Lagos carbonatite complex represents the upper-most parts of a differentiated carbonatite magmatic system, and that the siderite carbonatite is related to late-magmatic-to-carbo-hydrothermal processes.
DS202107-1099
2021
Giovannini, A.L.Giovannini, A.L., Bastos Neto, A.C., Porto, C.G., Takehara, L., Pereira, V.P., Bidone, M.H.REE mineralization (primary, supergene and sedimentary) associated to the Morro dos Seis Lagos Nb( REE, Ti) deposit (Amazonas, Brazil).Ore Geology Reviews, doi.org/10.1016/ j.oregeorev. 2021.104308 59p. PdfSouth America, BrazilREE

Abstract: In the Morro dos Seis Lagos Nb (Ti, REE) deposit (MSLD), Amazonas state, Brazil, there are four types of REE mineralization: primary, associated to siderite carbonatite; supergene, associated to laterite profile; and sedimentary (detrital and authigenic). The mineralogical and geochemical evolutions of the REE in these domains are integrated into a comprehensible metallogenic model. The main primary ore in the core siderite carbonatite is 52 m thick with 1.47 wt% REE2O3 mainly in monazite-(Ce) and bastnäsite. However, considering the entire section intersected in the core siderite carbonatite, the average grade drops to 0.7 wt% REE2O3 mainly contained in thorbastnasite. In the border siderite carbonatite, the REE mineralization is hydrothermal [rhabdophane-(Ce) and REE-rich gorceixite]. The LREE and phosphates are concentrated at the reworked laterites from where the HREE were leached. With the advance of lateritization, pyrochlore was completely decomposed. The final secondary Ce-pyrochlore was progressively enriched in Ce4+ with loss in REE3+, resulting in the breakdown of the structure and release Ce under strongly oxidizing conditions (high Ce4+/Ce3+) thus forming extremely pure cerianite-(Ce). This mineral occurs intercalated with goethite bands in the lower part of the weathering profile, represented by the brown laterite, and forms intergrowth with hollandite in the manganiferous laterite, formed in a more alkaline environment closer to the water table. The brown laterite has 1.30 wt% REE2O3, the manganese laterite has 1.54 wt% REE2O3, of which 1.42 wt% is Ce2O3. Tectonic and karstic processes over the carbonatite formed several sedimentary basins. In the Esperança Basin, the sedimentary record (233 m thick) shows the whole evolution of the MSLD. The base of the basin (layer 5) is formed by abundant carbonatite fragments, have florencite-(Ce) mineralization with 1.07 wt% REE2O3; layer 4 is formed by carbonatite fragments interbedded with clayey bed; layer 3 is a rhythmite deposited in a lacustrine environment, with clasts of ferruginous materials related to early stages of carbonatite alteration; layer 2 is made up by clays, is rich in organic matter, has authigenic florencite-(Ce), florencite-(La) and base metals. This layer marks the inversion of the relief and the input into the basin of REE leached from the upper laterites, carried by the groundwater flow; layer 1 was formed by the oxidation of the upper part of layer 2. Layers 1 + 2 have 73 m thick and average of 1.72 wt% REE2O3.
DS1982-0616
1982
Gippius, A.A.Vavilov, V.S., Gippius, A.A., Dravin, V.A., Zajeev, A.M., Zakup.Cathodluminescence of Natural Diamond Associated with Implanted Impurities.Soviet Physics of Semi-conductors, Vol. 16, No. 11, PP. 1288-1290.RussiaBlank
DS200612-1164
2006
Giradri, V.A.V.Rivalenti, G., Zanetti, A., Giradri, V.A.V., Mazzucchelli, M., Tassinari, C.G., Bertotto, G.W.The effect of the Fernando de Noronha plume on the mantle lithosphere in north eastern Brazil.Lithos, in press available,South America, BrazilXenoliths, alkali basalts, geochemistry
DS1989-0512
1989
GirardGirard, J-P, Deynoux, M., Nahon, D.Diagenesis of the upper Proterozoic siliciclastic sediments of the Taoudeni basin, West Africa, and relation to diabase emplacementJournal of Sedimentary Petrology, Vol. 59, No. 2, March pp. 233-248. Database # 17951West AfricaProterozoic, Diagenesis
DS2002-0353
2002
Girard, F.Davaille, A., Girard, F., Le Bars, M.How to anchor hotspots in a convecting mantle?Earth and Planetary Science Letters, Vol. 203, 3, pp. 621-34.MantleHot spots, Convection - model
DS202007-1174
2020
Girard, G.Rooney, T., Girard, G., Tappe, S.The impact on mantle olivine resulting from carbonated silicate melt interaction. Allikite Superior cratonContributions to Mineralogy and Petrology, Vol. 175, 15p. Canadaolivine

Abstract: Interactions between carbonated ultramafic silicate magmas and the continental lithospheric mantle results in the formation of dunite—a ubiquitous xenolith type in kimberlites and aillikites. However, whether this process dominantly occurs in the mantle source region or by subsequent interactions between lithospheric mantle fragments and transporting silica-undersaturated magmas during ascent remains debated. Aillikite magmas, which are derived from the fusion of carbonate-phlogopite metasomes under diamond-stability field upper mantle conditions, have a mineralogically more complex source than kimberlites, providing an opportunity to more fully constrain the origin of dunite xenoliths in such deeply sourced carbonated silicate magmas. Here we present a major and trace element study of olivine occurring in xenoliths and as phenocrysts in an aillikite dike located on the southern Superior Craton. We show that olivine within the dunite microxenoliths exhibits extreme enrichment in Al, Cr, Na, and V when compared to equivalent xenoliths carried by kimberlites. We interpret these results as evidence for the presence of carbonate-phlogopite metasomes left residual in the cratonic mantle source during aillikite magma formation. Our results are inconsistent with models of dunite formation through orthopyroxene dissolution upon kimberlite/aillikite magma ascent, supporting an origin for such dunites that is more closely linked to primary melt generation at the base of relatively thick continental lithosphere. Our work demonstrates that it is possible to constrain the precursor composition of cratonic mantle dunite at depth, thereby facilitating the further exploration of how carbonated silicate magmas modify and weaken continental lithospheric roots.
DS201112-0175
2011
Girard, J.Chen, J., Liu, H., Girard, J.Comparative in situ x-ray diffraction study of San Carlos olivine: influence of water on the 410 km seismic velocity jump in Earth's mantle.American Mineralogist, Vol. 96, pp. 697-702.MantleSubduction
DS201602-0205
2015
Girard, J.Girard, J., Amulele, G., Farla, R., Mohiuddin, A., Karato, S-i.Shear deformation of bridgmanite and magnesiowustite aggregates at lower mantle conditions.Science, Vol. 351, 6269, pp. 144-147.MantleRheology

Abstract: Rheological properties of the lower mantle have strong influence on the dynamics and evolution of Earth. By using the improved methods of quantitative deformation experiments at high pressures and temperatures, we deformed a mixture of bridgmanite and magnesiowüstite under the shallow lower mantle conditions. We conducted experiments up to about 100% strain at a strain rate of about 3 × 10(-5) second(-1). We found that bridgmanite is substantially stronger than magnesiowüstite and that magnesiowüstite largely accommodates the strain. Our results suggest that strain weakening and resultant shear localization likely occur in the lower mantle. This would explain the preservation of long-lived geochemical reservoirs and the lack of seismic anisotropy in the majority of the lower mantle except the boundary layers.
DS202002-0208
2020
Girard, J.Mohiuddin, A., Karto, S-i., Girard, J.Slab weakening during the olivine to ringwoodite transition in the mantle.Nature Geoscience, doi: 10.1038/s41561-019-0523Mantlesubduction

Abstract: The strength of subducted slabs in the mantle transition zone influences the style of mantle convection. Intense deformation is observed particularly in relatively old subducted slabs in the deep mantle transition zone. Understanding the cause of this regional and depth variation in slab deformation requires constraint of the rheological properties of deep mantle materials. Here, we report results of in situ deformation experiments during the olivine to ringwoodite phase transformation, from which we infer the deformation process under the conditions of cold slabs deep in the mantle transition zone. We find that newly transformed fine-grained ringwoodite deforms by diffusion creep and that its strength is substantially smaller than that of coarser-grained minerals but increases with time. Scaling analysis, based on a model of transformation kinetics and grain-size evolution during a phase transformation, suggests that a cold slab will be made of a mixture of weak, fine-grained and strong, coarse-grained materials in the deep transition zone, whereas a warm slab remains strong because of its large grain size. We propose that this temperature dependence of grain size may explain extensive deformation of cold slabs in the deep transition zone but limited deformation of relatively warm slabs.
DS202003-0351
2020
Girard, J.Mohiuddin, A., Karato, S., Girard, J.Slab weakening during olivine to ringwoodite transition in the mantle.Nature Geoscience, Vol. 13, pp. 170-174.Mantleolivine

Abstract: The strength of subducted slabs in the mantle transition zone influences the style of mantle convection. Intense deformation is observed particularly in relatively old subducted slabs in the deep mantle transition zone. Understanding the cause of this regional and depth variation in slab deformation requires constraint of the rheological properties of deep mantle materials. Here, we report results of in situ deformation experiments during the olivine to ringwoodite phase transformation, from which we infer the deformation process under the conditions of cold slabs deep in the mantle transition zone. We find that newly transformed fine-grained ringwoodite deforms by diffusion creep and that its strength is substantially smaller than that of coarser-grained minerals but increases with time. Scaling analysis, based on a model of transformation kinetics and grain-size evolution during a phase transformation, suggests that a cold slab will be made of a mixture of weak, fine-grained and strong, coarse-grained materials in the deep transition zone, whereas a warm slab remains strong because of its large grain size. We propose that this temperature dependence of grain size may explain extensive deformation of cold slabs in the deep transition zone but limited deformation of relatively warm slabs.
DS1990-1532
1990
Girard, J.P.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
DS1997-0414
1997
Girard, J.P.Girard, J.P., Razandranorosoa, D., Freyssinet, P.Laser oxygen isotope analysis of weathering goethite from the lateritic profile of Yaou: paleoclimatic..Applied Geochemistry, Vol. 12, No. 2, March, 1, pp. 163-174French GuianaLaterites, Geochronology
DS1989-0410
1989
Girard, M.C.Escadafel, R., Girard, M.C., Courault, D.Munsell soil color and soil reflectance in the visible spectral bands ofLand sat Multispectral Scanner and Thematic Mapper dataRemote Sensing of Environment, Vol. 27, No. 1, January pp. 37-46GlobalRemote Sensing, Soils
DS1992-0125
1992
Girard, R.Birkett, T.C., Girard, R., Moorhead, J., Marchilfon, N.Carte geologique de la Province Grenville a l'est de l'axe LouvicourtVald'Or Senneterre.Quebec Department of Mines, MB 92-15, 15p.QuebecMap - geology
DS1992-0573
1992
Girard, R.Girard, R.Spreadsheet routine for the management of structural dat a with amicrocomputerComputers and Geosciences, Vol. 18, No. 1, pp. 29-46GlobalComputer, Program -Spreadsheet routine
DS1993-0546
1993
Girard, R.Girard, R.Petrographie mineralogie et potential diamantifere de l'intrusion ultramafique brechique KNG du Lac KenogamiExploration Diabior Inc., 49p.QuebecExploration - assessment, Jonquiere Township
DS1993-0547
1993
Girard, R.Girard, R.Etude petrographique et mineralogique de l'intersection de kimberlite du forage AI 93-01 Diatac Ress. WilliamsQuebec Department of Mines, GM 52925, 40p.QuebecExploration - assessment, William Ressources
DS1993-0548
1993
Girard, R.Girard, R., Birkett, T., Moorhead, J., Marchildon, N.Geologie de la region de Press ClovaQuebec Department of Mines, MB 93-04, 54p.QuebecGeology
DS1993-0954
1993
Girard, R.Madore, L., Girard, R.Etude petrographique et recommendations de travaux dans le cadre de l'exploracion pour le diamant.. Castignon.La Societe Miniere Ecudor Inc., Ressources KWG Inc., 37p.QuebecExploration - assessment, KWG Resources
DS1993-1069
1993
Girard, R.Moorhead, J., Girard, R., Boudreau, M-A.Circular aeromagnetic anomalies possibly related to kimberlite intrusions in northwest Quebec.Quebec Department of Mines preliminary promotion document, handout at PDA, 25p. 5 p. text and listing of anomalies by locationQuebecGeophysics, Aeromagnetic anomalies
DS1994-0622
1994
Girard, R.Girard, R.Echantillonnage et evaluation des roches sources diamantiferes.(in French)Seventh Colloque Annuel en Ressources Minerales, Universite du Quebec a, p.8-10. abstract in FrenchQuebecSampling
DS1994-0623
1994
Girard, R.Girard, R.Petrographie et mineralogie des intrusions lamprophyriques et des tuffs a lapilli du secteur du lac Hematite, Fosse du Labrador.Gestion STG Inc. et Ressources KWG In., 96p.Quebec, Ungava, LabradorExploration - assessment, KWG Resources Inc.
DS1994-0624
1994
Girard, R.Girard, R.Petrographie et mineralogie des intrusions lamprophyriques et des tufs a lapilli du secteur du lac Hematite, Fosse du Labrador.Gestion STG Inc. et Ressources KWG In., 96p.Quebec, Ungava, LabradorExploration - assessment, KWG Resources Inc.
DS1996-0990
1996
Girard, R.Moorhead, J., Girard, R., Boudreau, M.A.Anomalies aeromagnetic circulars possiblement reliees a des intrusions de kimberlite dans le nord ouest QuebecQuebec Department of Mines, MB 93-49, 23p.Quebec, Ungava, LabradorGeophysics - magnetics
DS2001-0383
2001
Girard, R.Girard, R.Characterisation de l'intrusion kimberlitique du lac Beaver, petrograhie et mineralogieQuebec Ministere des Resources Naturelles, (FRE), ME-08, 82p.QuebecPetrology
DS2003-0468
2003
Girard, R.Girard, R., Moorhead, J., Marchand, P.Kimberlites in Quebec: current statusQuebec Exploration Conference, Nov. 25-27, 1p. abstractQuebecBrief overview
DS2003-0972
2003
Girard, R.Moorhead, J., Beaumier, M., Girard, R., Heaman, L.Distribution, structural controls and ages of kimberlite fields in the Superior Province of8 Ikc Www.venuewest.com/8ikc/program.htm, Session 8, POSTER abstractQuebecGeochronology, tectonics
DS200412-0668
2003
Girard, R.Girard, R., Moorhead, J., Marchand, P.Kimberlites in Quebec: current status.Quebec Exploration Conference, Nov. 25-27, 1p. abstractCanada, QuebecBrief overview
DS200412-0669
2004
Girard, R.Girard, R., Parent,M., Aubin, A., Belley, J.M., Lalancette, J.Glacial dispersion of lithological indicators in the Otish Mountain area.Quebec Exploration Conference, Canada, Quebec, Otish MountainsGeochemistry, geomorphology
DS200412-1362
2003
Girard, R.Moorhead, J., Beaumier, M., Girard, R., Heaman, L.Distribution, structural controls and ages of kimberlite fields in the Superior Province of Quebec.8 IKC Program, Session 8, POSTER abstractCanada, QuebecDiamond exploration Geochronology, tectonics
DS200412-1499
2004
Girard, R.Parent, M., Beaumier, M., Girard, R., Paradis, S.J.Diamond exploration in the Archean craton of northern Quebec, kimberlite indicator minerals in eskers of the Saindon-Cambrien coQuebec Exploration Conference, MB 2004-02, 15p.Canada, QuebecOverview
DS2002-1399
2002
GirardeauSantos, J.F., Scharer, U., Ibarguchi, J.I.G., GirardeauGenesis of pyroxenite rich peridotite at Cabo Ortegal : geochemical and Pb Sr Nd isotope data.Journal of Petrology, Vol. 43, No. 1, pp. 17-44.SpainPyroxenite, lead, strontium, neodynium, Petrology
DS1989-0137
1989
Girardeau, J.Boillot, G., Feraud, G., Recq, M., Girardeau, J.Undercrusting by serpentinite beneath rifted marginsNature, Vol. 341, October 12, pp. 523-525. Database # 18207SpainTectonics, Mantle
DS2000-0864
2000
Girardeau, J.Scharer, U., Girardeau, J., Cornen, G., Boillot, G.138-121 Ma asthenospheric magmatism prior continental breakup in the North Atlantic geodynamic implications.Earth and Planetary Science Letters, Vol.181, No.4, Sept.30, pp.555-72.GlobalMagmatism, Tectonics - rifting, continental margin
DS2003-1368
2003
GirardiTeixeira, W., Pinese, J.P.P., Iacumin, V.V., Girardi, Piccirillo, Echevests, RibotCalc alkaline and tholeiitic dyke swarms of Tandilia, Rio de la Plat a Craton, Argentina:Precambrian Research, Vol. 119, 1-4, Dec. 20, pp. 329-353.ArgentinaTrans Amazonian Orogeny
DS1996-0533
1996
Girardi, A.Girardi, A., Mazzucchelli, M., Correia, C.T.Petrology and geochemistry of the mafic dyke swarm of the Treinte Y Tresregion, northeast Uruguay.Journal of South American Earth Sciences, Vol. 9, No. 3/4, pp. 243-250.UruguayDike swarm, Petrology
DS201804-0748
2018
Girardi, A.V.Teixeira, W., Hamilton, M.A., Girardi, A.V., Faleiros, F.M.U Pb baddeleyite ages of key dyke swarms in the Amazonian craton ( Carajas/Rio Maria and Rio Apa areas): tectonic implications for events at 1880, 1110 Ma, 535 Ma and 200 Ma.Precambrian Research, in press available 19p.South Americacraton - Amazonian

Abstract: U-Pb baddeleyite ages for key mafic dykes of the Amazonian Craton reveal four significant intraplate episodes that allow connections with global igneous activity through time and supercontinent cycles. The oldest dykes (Carajás-Rio Maria region) are diabases with ages of 1880.2 ± 1.5 Ma and 1884.6 ± 1.6 Ma, respectively, corresponding with the Tucumã swarm which crops out to the west and is age-equivalent. The magmatic activity has a genetic link with the ca. 1.88 Ga Uatumã Silicic Large Igneous Province (SLIP), characterized by felsic plutonic-volcanic rocks. There is an age correlation with LIP events (ca. 1880 Ma) in the Superior, Slave, Indian and other cratons. This magmatism could be derived from significant perturbations of the upper mantle during the partial assembly of Columbia. Gabbronorite of the Rio Perdido Suite (Rio Apa Terrane) crystallized at 1110.7 ± 1.4 Ma, and is identical to that of the Rincón del Tigre-Huanchaca LIP event of the Amazonian Craton. This event was synchronous with the initiation of Keweenawan magmatism of central Laurentia (Midcontinent Rift) and also with coeval units in the Kalahari, Congo and India cratons. The two youngest U-Pb dates (535 and 200 Ma) occur in the Carajás region. Diabase of the Paraupebas swarm yields an age of 535.1 ± 1.1 Ma, which may be correlative with the giant Piranhas swarm located ca. 900 km apart to the west. The Paraupebas swarm is correlative with post-collisional plutonism within the Araguaia marginal belt. Therefore, the Cambrian dykes may reflect reactivation of cooled lithosphere, due to crustal extension/transtension active along the craton’s margin during assembly of West Gondwana. This magmatism is also contemporaneous with the 539-530 Ma Wichita LIP of southern Laurentia. The youngest studied Carajás region dyke was emplaced at ca. 200 Ma, corresponding with 40Ar/39Ar ages for the Periquito dykes west of Carajás and with most K-Ar ages of the giant Cassiporé swarm, located north of the study area. The newly dated ca. 200 Ma dyke fits well into the known, brief span of ages for the CAMP Large Igneous Province event, around the present central and northern Atlantic Ocean.
DS201012-0472
2010
Girardi, J.D.Manthei, C.D., Ducea, M.N., Girardi, J.D., Patchett, P.Isotopic and geochemical evidence for a recent transition in mantle chemistry beneath the western Canadian Cordillera.Journal of Geophysical Research, Vol. 115, B2, B202204.Canada, Alberta, saskatchewan, Northwest TerritoriesGeochemistry
DS201312-0199
2013
Girardi, V.De Min, A., Hendriks, B., Siejko, F., Comin-Chiaramonti, P., Girardi, V., Ruberti, E., Gomes, C.B., Neder, R.D., Pinho, F.C.Age of ultramafic high K rocks from Planalto da Serra ( Mato Grosso, Brazil).Journal of South American Earth Sciences, Vol. 41, pp. 57-64.South America, BrazilGeochronology
DS1980-0326
1980
Girardi, V.A.V.Svisero, D.P., Haralyi, N.L.E., Girardi, V.A.V.Geology of the Limeira 1, Limeira 2 and Indaia Kimberlites, douradoquara Minas Gerais.Anais Do Congresso, 31st., Vol. 3, PP. 1789-1801.BrazilGeology, Geophysics
DS1986-0292
1986
Girardi, V.A.V.Girardi, V.A.V., Rivalent, G., Sinigoli, S.The petrogenesis of the Niquelandia layered basic ultrabasiccomplex, central Goias, BrasilJournal of Petrology, Vol. 27, No. 3, June pp. 715-744BrazilBlank
DS1989-1278
1989
Girardi, V.A.V.Rivalenti, G., Girardi, V.A.V., Coltorti, M., Correira, C.T.Geochemical models for the petrogenesis of komatiites from the Hidrolina greenstone belt, Central Goias, BrasilJournal of Petrology, Vol. 30, No. 1, pp. 175-197BrazilGreenstone belt, Komatiite
DS200612-0301
2006
Girardi, V.A.V.Da Costa, P.C.C., Girardi, V.A.V., Teixeira, W.40 Ar 39Ar and Rb Sr geochronology of the Goias Crixas dike swarm, central Brazil: constraints on the Neoarchean Paleoproterozoic tectonic boundary...International Geology Review, Vol. 48, 6, pp. 547-560.South America, BrazilGeochronology, subcontinental mantle
DS200712-0897
2006
Girardi, V.A.V.Rivalenti, G., Zanetti, A., Girardi, V.A.V., Mazzucchelli, M., Colombo, C.G., Bertotto, G.W.The effect of the Fernando de Noronha plume on the mantle lithosphere in north eastern Brazil.Geochimica et Cosmochimica Acta, In press availableSouth America, BrazilXenolith - alkali basalt
DS200912-0123
2009
Girardi, V.A.V.Comin-Chiaramonti, P., Lucassen, P., Girardi, V.A.V., De Min, A., Gomes, C.B.Lavas and their mantle xenoliths from intracratonic eastern Paraguay( South American Platform) and Andean domain NW Argentina: a comparative review.Mineralogy and Petrology, in press availableSouth America, Paraguay, ArgentinaXenoliths
DS201012-0044
2010
Girardi, V.A.V.Beatriz de Menezes Leal, A., Canabrava Brito, D., Girardi, V.A.V., Correa-Gomes, L.C., Cerqueira Cruz, S., Bastos Leal, L.R.Petrology and geochemistry of the tholeiitic mafic dykes from the Chapada Diamantina, northeastern Sao Francisco Craton, Brazil.International Dyke Conference Held Feb. 6, India, 1p. AbstractSouth America, BrazilGeochemistry
DS201012-0116
2009
Girardi, V.A.V.Comin-Chiaramonti, P., Lucassen, F., Girardi, V.A.V., De Min, A., Gomes, C.B.Lavas and their mantle xenoliths from intracratonic Eastern Paraguay ( South American Platform) and Anean Domain, NW Argentina: a comparative review.Mineralogy and Petrology, Vol. 98, 1-4, pp. 143-165.South America, Paraguay, ArgentinaXenoliths
DS201612-2342
2016
Girardi, V.A.V.Teixeira, W., Girardi, V.A.V., Mazzucchelli, M., Oliveira, E.P., Correa da Costa, P.C.Precambrian dykes in the Sao Francisco craton revisited: geochemical-isotopic signatures and tectonic significance.Acta Geologica Sinica, Vol. 90, July abstract p. 26-27.South America, Brazil, DiamantinaGeochronology
DS201705-0830
2017
Girardi, V.A.V.Giovanardi, T., Girardi, V.A.V., Correia, C.T., Sinigoi, S., Tassinari, C.C.G., Mazzucchelli, M.The growth and contamination mechanism of the Cana Brava layered mafic-ultramafic complex: new field and geochemical evidences.Mineralogy and Petrology, in press available 24p.South America, BrazilGeochemistry

Abstract: The Cana Brava complex is the northernmost of three layered complexes outcropping in the Goiás state (central Brasil). New field and geochemical evidences suggest that Cana Brava underwent hyper- to subsolidus deformation during its growth, acquiring a high-temperature foliation that is generally interpreted as the result of a granulite-facies metamorphic event. The increase along the stratigraphy of the incompatible elements abundances (LREE, Rb, Ba) and of the Sr isotopic composition, coupled with a decrease in eNd(790), indicate that the complex was contaminated by the embedded xenoliths from the Palmeirópolis Sequence. The geochemical data suggest that the contamination occurred along the entire magma column during the crystallization of the Upper Mafic Zone, with in situ variations determined by the abundance and composition of the xenoliths. These features of the Cana Brava complex point to an extremely similarity with the Lower Sequence of the most known Niquelândia intrusion (the central of the three complexes). This, together with the evidences that the two complexes have the same age (c.a. 790 Ma) and their thickness and units decrease northwards suggests that Cana Brava and Niquelândia are part of a single giant Brasilia body grown through several melt impulses.
DS201904-0740
2019
Girardi, V.A.V.Giovanardi, T., Girardi, V.A.V., Teixeira, W., Mazzucchelli, M.Mafic dyke swarms at 1882, 535 and 200 Ma in the Carajas region Amazonian Craton: Sr-Nd isotopy, trace element geochemistry and inferences on their origin and geological settings.Journal of South American Earth Sciences, Vol. 92, pp. 197-208.South America, Brazilcraton

Abstract: The Carajás-Rio Maria region, together with the Rio Maria domain of the Central Amazonian province, comprises the eastern margin of the Amazonian Craton with the Neoproterozoic Araguaia belt. This region hosts several basaltic dyke swarms whose UPb baddeleyite ages highlighted three intrusive events at 1882, 535 and 200?Ma. New geochemical and SrNd isotopic data were obtained for the different groups of the Carajás dykes allowing new insights on i) the mantle source composition beneath the Carajás region through time and ii) the geodynamic setting of the intrusive events. The 1882?Ma swarm is coeval to the Uatumã SLIP event which is one of the oldest intraplate events of the proto-Amazonian craton. Trace elements and isotopic values suggest that the dyke parent melt for those dykes have a crustal component derived from a sedimentary source similar to GLOSS (GLObal Subducting Sediment compositions). This is consistent with the emplacement of the dykes in a supra-subduction setting or in a post-collisional setting. Trace and isotopic values of the 535?Ma dyke swarm are consistent with an enriched mantle source from EMII component. These geochemical features suggest an enrichment of the mantle from an oceanic lithosphere poor in sediments, different to that of the 1882?Ma source. The age of this swarm matches magmatic activity during a post-collisional extensive-transtensive event recorded in the marginal Araguaia belt after the amalgamation of the Amazonian Craton to the Western Gondwana during Neoproterozoic. The 200?Ma dyke swarm which is related to the CAMP (Central Atlantic Magmatic Province) and opening of the Atlantic Ocean shows trace element composition similar to Atlantic E-MORB. The coupled isotopic values are consistent with an enriched mantle source with EMII component. These particular geochemical features suggest that the plume activity responsible for the CAMP near the rifting zone has not affected the mantle beneath the Carajás region.
DS201904-0718
1991
Girardi, V.V.Bossi, J., Campal, N., Civetta, L., Demarchi, G., Girardi, V.V., Mazzucchelli, M., Piccirillo, E.M., Rivalenti, G., Sinigol, S., Teixeira, W., Fragoso-Cesar, A.R.Petrological and geochronological aspects of the Precambrian mafic dyke swarm of Uruguay. IN: Eng. Note Date****BOL.IG-USP, Publ.Esp., Vol. 10, pp. 35-42.South America, Uruguaydykes

Abstract: The subparallel maflc dykes of the Aorida-Durazno-S.José region (SW Uruguay) trend N60-80W and vary in thickness from 0.6 to 50 m. They are part of the mafic dyke swarms intrudlng granitic-gnelssic basement that were mappecl by BOSSI et ai. (1989), In an ares approximately 200 km In length and 100 km in bresdth. Plagioclass, augite, subcalclc augite (plgeonite) and opaques are the maln components of the dykes. Orthopyroxene and oIlvine are very rare. Blotite and homblende are secondary minerais. Quartz-feldspar Intergrowths occur In the coarser gralnecl dykes. The characterlstlc textures are subophitic and intersertal.
DS1998-0066
1998
Girardin, N.Babuska, V., Montagner, J.P., Girardin, N.Age dependent large scale fabric of the mantle lithosphere as derived from surface wave velocity...Pure and Applied Geophys., Vol. 151, No. 2-4, Mar. 1, pp. 257-280.MantleGeophysics - seismics, Tectonics
DS201711-2534
2017
Giraud, G.Vidal, O., Rostom, F., Francois, C., Giraud, G.Global trends in metal consumption and supply: the raw material-energy nexus.Elements, Vol. 13, pp. 319-324.Globalresources

Abstract: The consumption of mineral resources and energy has increased exponentially over the last 100 years. Further growth is expected until at least the middle of the 21st century as the demand for minerals is stimulated by the industrialization of poor countries, increasing urbanization, penetration of rapidly evolving high technologies, and the transition to low-carbon energies. In order to meet this demand, more metals will have to be produced by 2050 than over the last 100 years, which raises questions about the sustainability and conditions of supply. The answers to these questions are not only a matter of available reserves. Major effort will be required to develop new approaches and dynamic models to address social, economic, environmental, geological, technological, legal and geopolitical impacts of the need for resources.
DS1975-0083
1975
Girdler, R.W.Girdler, R.W.The Great Negative Bouguer Gravity Anomaly over AfricaEos, Vol. 50, AUGUST PP. 516-519.AfricaGeotectonics, Geophysics
DS1975-0084
1975
Girdler, R.W.Girdler, R.W.The Great Negative Bouger Gravity Anomaly over AfricaEos, Vol. 56, No. 8, PP. 516-519.Africa, South Africa, BotswanaGeophysics
DS1990-0573
1990
Giresse, P.Giresse, P.Paleoclimatic and structural environment at the end of the Cretaceous along the western flank of the Congo Basin, with application of undergroundmicrodiamonds.Journal of African Earth Sciences, Vol. 10, No. 1/2. pp. 399-408GlobalPaleoclimate, alluvials, Microdiamonds
DS2001-0788
2001
GiretMoine, B., Gregoire, Cottin, Sheppard, O'Reilly, GiretVolatile bearing ultramafic to mafic xenoliths from the Kerugelen Archipelago: evidence for carbonatites...Journal of South African Earth Sciences, Vol. 32, No. 1, p. A 25. (abs)Indian Ocean, mantleCarbonatite, Kerugelen Archipelago
DS200412-1349
2004
GiretMoine, B.N., Gregoire, M., O'Reilly, S.Y., Delpech, G., Sheppard, S.M.F., Lorand, J.P., Renac, Giret, CottinCarbonatite melt in oceanic upper mantle beneath the Kerguelen Archipelago.Lithos, Vol. 75, pp. 239-252.Kerguelen IslandsCarbonatite, harzburgite, metasomatism
DS1985-0070
1985
Giret, A.Bonin, B., Giret, A.Clinopyroxene Compositional Trends in Over saturated and Undersaturated Alkaline Ring Complexes.Journal of African Earth Sciences, Vol. 3, No. 1-2, PP. 175-183.Africa, South AfricaBlank
DS1985-0071
1985
Giret, A.Bonin, B., Giret, A.Contrasting Roles of Rock Forming Minerals in Alkaline Ringcomplexes.Journal of African Earth Sciences, Vol. 3, No. 1-2, PP. 41-49.South Africa, AfricaBlank
DS1985-0235
1985
Giret, A.Giret, A.Alkaline Volcano Plutonic Complexes in Kerguelen Islands, Southern Indian Ocean.Conference Report On The Meeting of The Volcanics Studies Gr, 1P. ABSTRACT.GlobalAlkaline Ring Complexes
DS1989-0847
1989
Giret, A.Lameyre, J., Black, R., Giret, A.Le magmatism alcalin: donnees geologiques sur quelques provinces oceaniques et continentales.(in French)Geological Association of Canada (GAC) Annual Meeting Program Abstracts, Vol. 14, p. A49. (abstract.)West Africa, NigeriaAlkaline rocks
DS1994-0182
1994
Giret, A.Bonin, B., Bardintzeff, J-M., Giret, A.The distribution of felsic rocks within the alkaline igneous complexMem. Soc. Geol. France, No. 166, pp. 9-24.GlobalAlkaline rocks
DS1996-0155
1996
Giret, A.Bonin, B., Bardintzeff, J-M., Giret, A.The distribution of felsic rocks within the alkaline igneous centresMem. Soc. Geol. France, Vol. No. 166 pp. 9-24GlobalMagmatic suites, Alkaline rocks
DS1996-0906
1996
Giret, A.Mattielli, N., Weis, D., Giret, A.Kerguelen basic and ultrabasic xenoliths: evidence for hotspot activityLithos, Vol. 37, No. 2/3, April pp. 261-GlobalGeodynamics, Hotspots
DS200412-0437
2004
Giret, A.Delpech, G., Gregoire, M., O'Reilly, S.Y., Cottin, J.Y., Moine, B., Michon, G., Giret, A.Feldspar from carbonate rich silicate metasomatism in the shallow oceanic mantle under Kerguelen Islands ( South Indian Ocean).Lithos, Vol. 75, 1-2, July pp. 209-237.Kerguelen IslandsMetasomatism, trace element fingerprinting, petrogeneti
DS202008-1377
2020
Giri, R.K.Chalapathi Rao, N.V., Giri, R.K., Pandey, A.Kimberlites, lamproites and lamprophyres from the Indian shield: highlights of researches during 2016-2019.Proceedings Natural Science Academy, Vol. 86, 1, pp. 301-311.Indiakimberlite, lamproites

Abstract: Highlights of researches on kimberlites, lamproites and lamprophyres (and their entrained xenoliths) during 2016-2019 from the Indian context are presented. A few previously unknown occurrences have been brought to light, and a wealth of petrological, geochemical and isotopic data on these rocks became available. All these studies provided new insights into the nomenclatural as well as geodynamic aspects such as subduction-tectonics, mantle metasomatism, lithospheric thickness, supercontinent amalgamation, and break-up and nature of the sub-continental lithospheric mantle from the Indian shield.
DS202008-1431
2020
Giri, R.K.Pankaj, P., Giri, R.K., Chalapathi Rao, N.V., Charabarti, R., Raghuvanshi, S.Mineralogy and petrology of shoshonitic lamprophyre dykes from the Sivarampeta area, diamondiferous Wajrakarur kimberlite field, eastern Dharwar craton, southern India.Journal of Mineralogical and petrological Sciences, Vol. 115, 2, pp. 202-215. pdfIndiadeposit - Wajrakarur

Abstract: Petrology and geochemistry (including Sr and Nd isotopes) of two lamprophyre dykes, intruding the Archaean granitic gneisses at Sivarampeta in the diamondiferous Wajrakarur kimberlite field (WKF), eastern Dharwar craton, southern India, are presented. The Sivarampeta lamprophyres display porphyritic-panidiomorphic texture comprising macrocrysts/phenocrysts of olivine, clinopyroxene (augite), and mica set in a groundmass dominated by feldspar and comprising minor amounts of ilmenite, chlorite, carbonates, epidote, and sulphides. Amphibole (actinolite-tremolite) is essentially secondary in nature and derived from the alteration of clinopyroxene. Mica is compositionally biotite and occurs as a scattered phase throughout. Mineralogy suggests that these lamprophyres belong to calc-alkaline variety whereas their bulk-rock geochemistry portrays mixed signals of both alkaline as well as calc-alkaline (shoshonitic) variety of lamprophyres and suggest their derivation from the recently identified Domain II (orogenic-anorogenic transitional type mantle source) from eastern Dharwar craton. Trace element ratios imply melt-derivation from an essentially the garnet bearing-enriched lithospheric mantle source region; this is further supported by their 87Sr/86Srinitial (0.708213 and 0.708507) and ‘enriched’ eNdinitial (-19.1 and -24.2) values. The calculated TDM ages (2.7-2.9 Ga) implies that such enrichment occurred prior to or during Neoarchean, contrary to that of the co-spatial and co-eval kimberlites which originated from an isotopically depleted mantle source which was metasomatized during Mesoproterozoic. The close association of calc-alkaline shoshonitic lamprophyres, sampling distinct mantle sources, viz., Domain I (e.g., Udiripikonda) and Domain II (Sivarampeta), and kimberlites in the WKF provide further evidence for highly heterogeneous nature of the sub-continental lithospheric mantle beneath the eastern Dharwar craton.
DS202009-1618
2020
Giri, R.K.Chalapathi Rao, N.V., Giri, R.K., Sharma, A., Pandey, A.Lamprophyres from the Indian shield: a review of their occurrence, petrology, tectonomagmatic significance and relationship with the kimberlites and related rocks.Episodes, Vol. 43, 1, pp. 231-248.Indialamprophyres

Abstract: Lamprophyres are some of the oldest recognized alkaline rocks and have been studied for almost the last 150 years. Known for hosting economic minerals such as gold, diamond and base metals, they are also significant in our understanding of the deep-mantle processes (viz., mantle metasomatism and mantleplume-lithosphere interactions) as well as large-scale geodynamic processes (viz., subduction-tectonics, supercontinent amalgamation and break-up). The Indian shield is a collage of distinct cratonic blocks margined by the mobile belts and manifested by large igneous provinces (LIPs) such as the Deccan. A plethora of lamprophyres, varying in age from the Archaean to the Eocene, with diverse mineralogical and geochemical compositions, are recorded from the Indian shield and played a key role in clarifying the tectonic processes, especially during the Paleo- and Mesoproterozoic and the Late Cretaceous. A comprehensive review of the occurrence, petrology, geochemistry and origin of the Indian lamprophyres is provided here highlighting their tectonomagmatic significance. The relationship of the lamprophyres to the Kimberlite clan rocks (KCRs), focusing on the Indian examples, is also critically examined.
DS202106-0947
2021
Giri, T.K.Kumar, S., Kumar, D., Sengupta, K., Giri, T.K.Impact of community based business model and competitive advantage on exports: evidence from diamond industry.Competitive Review, Vol. 31, 2, pp. 276-296. pdfGlobalmarkets

Abstract: his study aims to examine the altering paradigms for two specific characteristics of the international diamond industry: community-based business model and competitive advantage and their impact and interaction effect.
DS1996-1349
1996
Girnia, A.V.Solovova, I.P., Girnia, A.V., Ryabchikov, I.D.Inclusions of carbonate and silicate melts in minerals of alkali basaltoids from the East Pamirs.Petrology, Vol. 4, No. 2, pp. 339-363.Russia, PamirAlkalic rocks, Basaltoids -potassic
DS1991-0576
1991
Girnis, A.Girnis, A., Solovova, I., Ryabchikov, I., Kogarko, L.Petrogenesis of Prairie Creek lamproites: constraints from melt inclusion sand high pressure experimentsProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, p. 513ArkansasLamproite, Deposit -Prairie Creek
DS1991-1634
1991
Girnis, A.Solovova, I., Girnis, A., Kogarko, L., Ryabchikov, I.A study of Micro inclusions in minerals of Spanish lamproitesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, p. 564GlobalLamproite, Melt inclusions
DS1991-1635
1991
Girnis, A.Solovova, I., Girnis, A., Naumov, V., Guzhova, A.Immiscible salt and silicate melts: dat a from Micro inclusions in minerals of alkali basaltsEuropean Current Research Fluid Inclusions, Firenze, Italy April 10-12, Abstracts, ECROFI XI, p. 205RussiaCarbonatite, Fluid inclusions
DS1992-1453
1992
Girnis, A.Solovova, I., Girnis, A., Ryabchikov, D.Fluid regime of highly potassic mafic-ultramafic magmasProceedings of the 29th International Geological Congress. Held Japan August 1992, Vol. 1, abstract p. 195Arkansas, AustraliaLamproites, Carbon dioxide
DS1995-0441
1995
Girnis, A.Dreibus, G., Brey, G., Girnis, A.The role of carbon dioxide in the generation and emplacement of kimberlitemagmas: new exp. dat a on CO2Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 138-40.GlobalPetrology -experimental -CO2, Kimberlite magmas
DS2003-0158
2003
Girnis, A.Brey, G.P., Bulatov, V., Girnis, A., Harris, J., Stachel, T.Ferropericlase - a lower mantle phase in the upper mantle8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, AbstractGuineaMantle petrology
DS2003-0469
2003
Girnis, A.Girnis, A., Grutter, H.S.Thermobarometry of mantle peridotites: calibration based on experimental and natural8 Ikc Www.venuewest.com/8ikc/program.htm, Session 6, POSTER abstractGlobalBlank
DS200412-0205
2003
Girnis, A.Brey, G.P., Bulatov, V., Girnis, A., Harris, J., Stachel, T.Ferropericlase - a lower mantle phase in the upper mantle.8 IKC Program, Session 6, AbstractAfrica, GuineaMantle petrology
DS200412-0206
2004
Girnis, A.Brey, G.P., Bulatov, V., Girnis, A., Harris, J.W., Stachel, T.Ferropericlase - a lower mantle phase in the upper mantle.Lithos, Vol. 77, 1-4, Sept. pp. 655-663.South America, BrazilUHP, diamond inclusions, olivine, San Luiz
DS200412-0670
2003
Girnis, A.Girnis, A., Grutter, H.S.Thermobarometry of mantle peridotites: calibration based on experimental and natural data.8 IKC Program, Session 6, POSTER abstractTechnologyMantle petrology
DS200612-0172
2006
Girnis, A.Brey, G., Bulatov, V., Girnis, A.Redox melting and composition of near liquidus melts of C O H bearing peridotite.Geochimica et Cosmochimica Acta, Vol. 70, 18, p. 1, abstract only.MantleRedox melting
DS200912-0712
2009
Girnis, A.Solovova, I., Girnis, A., Kopylova, M.Fluid and melt inclusions in minerals of West Greenland lamprophyres. Maniitsoq areaalkaline09.narod.ru ENGLISH, May 10, 2p. abstractEurope, GreenlandChemistry
DS201012-0739
2010
Girnis, A.Solovova, I., Girnis, A.Potassium rich carbonatite magma: mechanism of formation and mineralogy as a result of examination melt inclusions (eastern Pamir).International Mineralogical Association meeting August Budapest, abstract p. 577.Russia, PamirCarbonatite
DS1989-1227
1989
Girnis, A.V.Plaksenko, A.N., Girnis, A.V., Bocharov, V.L.Crystallization conditions of the gabbro-norite of the Yelan nickel bearing plutonInternational Geology Review, Vol. 31, No. 5, May pp. 502-505RussiaPseudobrookite-lamproite association
DS1991-0577
1991
Girnis, A.V.Girnis, A.V., Plaksenko, A.N., Ryabchikov, I.D., Suddaby, P.Geochemical features of ultramafic xenoliths from norite intrusions in the Voronezh crystalline massifGeochemistry International, Vol. 28, No. 11, pp. 1-9RussiaGeochemistry, norite, Komatiites
DS1992-0574
1992
Girnis, A.V.Girnis, A.V., Ryabchikov, I.D.Model of samarium-neodymium (Sm-Nd) isotope evolution of a depleted mantleDoklady Academy of Science USSR, Earth Science Section, Vol. 312, No. 1-3, June pp. 243-246RussiaGeochronology, Mantle
DS1992-0575
1992
Girnis, A.V.Girnis, A.V., Solova, I.P., Ryabchikov, I.D., Guzhova, A.V.high pressure experiments on the conditions of generation of the Prairie Creek lamproite magmaGeochemistry International, Vol. 29, No. 4, pp. 94-102ArkansasLamproite, Experimental petrology
DS1992-1211
1992
Girnis, A.V.Plaksenko, A.N., Girnis, A.V., Isaichkin, A.A., Frolov, S.M.A harzburgite xenolith from the Voronezh crystalline massif PrecambriannoritesGeochemistry International, Vol. 29, No. 2, pp. 146-RussiaXenolith, Harzburgite
DS1993-0723
1993
Girnis, A.V.Isaichkin, A.A., Plaksenko, A.N., Girnis, A.V.Petrology of harzburgite xenoliths from Voronezh crystalline massif norite-diorite intrusions.Geochemistry International, Vol. 30, No. 8, pp. 66-76.RussiaXenoliths
DS1995-0231
1995
Girnis, A.V.Bulatov, V.K., Girnis, A.V., Brey, G.P.Anhydrous partial melting of spinel lherzolites from 3.5 to 20 KBAR:composition of partial melts.Proceedings of the Sixth International Kimberlite Conference Extended Abstracts, p. 80-82.RussiaLherzolites
DS1995-0638
1995
Girnis, A.V.Girnis, A.V., Brey, G.P., Ryabchikov, I.D.Origin of Group 1a kimberlites: fluid saturated melting experiments at45-55 kbar.Earth and Planetary Science Letters, Vol. 134, No. 3-4, Sept. 1, pp. 283-296.South AfricaKimberlites, Petrochemistry
DS1997-0285
1997
Girnis, A.V.Doroshev, A.M., Brey, G.P., Girnis, A.V., Turkin, A.I.Pyrope - knorringite garnets in the Earth's mantle: experimental in the MgOAl2O3 SiO2 Cr2O3 systemRussian Geology and Geophysics, Vol. 38, No. 2, pp. 559-586.MantleGarnets, Petrochemistry
DS1998-0514
1998
Girnis, A.V.Girnis, A.V., Stachel, T., Brey, G., Harris, J., PhilipInternally consistent geothermobarometers for garnet harzburgites7th International Kimberlite Conference Abstract, pp. 253-5.GlobalGeothermometry, Garnet harzburgite compositions
DS1999-0100
1999
Girnis, A.V.Bulatov, V.K., Girnis, A.V., Brey, G.P.Experimental melting of spinel lherzolites and the problem of the primary magma genesis of oceanic basaltsPetrology, Vol. 7, No. 1, Jan-Feb. pp. 21-31.MantleMagma, Lherzolite - experimental petrology
DS2002-0222
2002
Girnis, A.V.Bulatov, V.K., Girnis, A.V., Brey, G.P.Experimental melting of a modally heterogeneous mantleMineralogy and Petrology, Vol.75,3-4, pp.131-52.MantleMelt
DS2003-0470
2003
Girnis, A.V.Girnis, A.V.Olivine orthopyroxene melt equilibrium as a thermobarometer for mantle derivedPetrology, Vol. 11, 2, pp. 101-113.MantleMagmatism - melting
DS2003-0471
2003
Girnis, A.V.Girnis, A.V.Olivine orthopyroxene melt equilibrium as a thermometer for mantle derived magmasPetrology, Vol. 11, 2, pp. 101-113.MantleMagmatism, geothermometry
DS2003-1311
2003
Girnis, A.V.Solovova, I.P., Girnis, A.V.Extraction of ore components from mafic magmas by immiscible carbonate and saltin Mineral Exploration and Sustainable Development Vol. 1, eds. Eliopoulos et al., Ore forming processes associated with mafic and ultramafic rockseast Greenlandalkaline igneous complex, Verknedunkeldykskii massif, Gardiner massif
DS200412-0671
2003
Girnis, A.V.Girnis, A.V.Olivine orthopyroxene melt equilibrium as a thermobarometer for mantle derived magmas.Petrology, Vol. 11, 2, pp. 101-113.MantleMagmatism - melting
DS200512-0341
2005
Girnis, A.V.Girnis, A.V., Bulatov, V.K., Brey, G.P.Transition from kimberlite to carbonatite melt under mantle parameters: an experimental study.Petrology, Vol. 13, 1, pp. 1-15.Melting - kimberlite/carbonatite
DS200512-1024
2003
Girnis, A.V.Solova, I.P., Girnis, A.V., Rass, I.T., Keller, J., Kononkova, N.N.Different styles of evolution of CO2 rich alkaline magmas: the role of melt composition in carbonate silicate liquid immiscibility. ( Mahlberg)Periodico di Mineralogia, (in english), Vol. LXX11, 1. April, pp. 87-93.Europe, GermanyMagmatism
DS200612-0464
2006
Girnis, A.V.Girnis, A.V., Bulatov, V.K., Lahaye, Y., Brey, G.P.Partitioning of trace elements between carbonate silicate melts and mantle minerals: experiment and petrological consequences.Petrology, Vol. 14, 5, pp. 492-514.MantleMelts
DS200612-0465
2005
Girnis, A.V.Girnis, A.V., Ryabchikov, I.D.Conditions and mechanisms of generation of kimberlite magmas.Geology of Ore Deposits, Vol. 47, 6, pp. 476-487.RussiaMagmatism
DS200612-0739
2006
Girnis, A.V.Kovalenko, V.I., Naumov, V.B., Girnis, A.V., Dorofeeva, V.A., Yarmolyuk, V.V.Composition and chemical structure of oceanic mantle plumes.Petrology, Vol. 14, 5, pp. 452-476.MantleGeochemistry - hot spots
DS200612-1193
2005
Girnis, A.V.Ryabchikov, I.D., Girnis, A.V.Genesis of low calcium kimberlite magmas.Russian Geology and Geophysics, Vol. 46, 12, pp. 1202-1212.MantleMagmatism
DS200612-1334
2005
Girnis, A.V.Solovova, I.P., Girnis, A.V., Kogarko, L.N., Kononkova, N.N., Stoppa, F., Rosaatelli, G.Compositions of magma and carbonate silicate liquid immiscibility in the Vulture alkaline igneous complex, Italy.Lithos, Vol. 85, 1-4, Nov-Dec. pp. 113-128.Europe, ItalyCarbonatite
DS200612-1335
2006
Girnis, A.V.Solovova, I.P., Girnis, A.V., Ryabchikov, I.D., Simakin, S.G.High temperature carbonatite melts and its inter relations with alkaline magmas of the Dundel'dyk complex, southeastern Pamirs.Doklady Earth Sciences, Vol. 410, no. 7 July-August, pp. 1148-51.RussiaCarbonatite
DS200712-0578
2007
Girnis, A.V.Kovalenko, V.I., Naumov, V.B., Girnis, A.V., Dorofeeva, V.A., Yarmoluk, V.V.Average contents of incompatible and volatile components in depleted, oceanic plume, and within plate continental mantle types.Doklady Earth Sciences, Vol. 445, 6, pp. DOI:10.1134/S1028334 X07060116MantleGeochemistry - plumes
DS200812-0139
2007
Girnis, A.V.Brey, G.P., Bulatov, V.K., Girnis, A.V.Geobarometry for peridotites: experiments in simple and natural systems from 6 to 10 GPa.Journal of Petrology, Vol. 49, 1, pp. 3-24.TechnologyGarnet
DS200812-0140
2008
Girnis, A.V.Brey, G.P., Bulatov, V.K., Girnis, A.V.Experimental melting of magnesite bearing peridotite with H2O and F at 6 - 10 GPa, and implications for the genesis of kimberlites.9IKC.com, 3p. extended abstractMantleMelting
DS200812-0141
2008
Girnis, A.V.Brey, G.P., Bulatov, V.K., Girnis, A.V., Lahaye, Y.Experimental melting of carbonated peridotite at 6-10 GPa.Journal of Petrology, Vol. 49, 4, pp. 797-821.MantleMelting
DS200912-0075
2009
Girnis, A.V.Brey, G.P., Bulato, V.K., Girnis, A.V.Influence of water and fluorine on melting of carbonated peridotite at 6 and 10 GPa.Lithos, In press availableMantleMelting
DS200912-0084
2009
Girnis, A.V.Bulatov, V.K., Girnis, A.V., Brey, G.P.Experimental melting of carbonated K rich garnet harzburgite and origin of kimberlite melts.alkaline09.narod.ru ENGLISH, May 10, 2p. abstractTechnologyMelting
DS200912-0252
2009
Girnis, A.V.Girnis, A.V., Bulatov, V.K., Brey, G.P.Influence of melt compositions on Fe, Mn and Ni partitioning between carbonate silicate melts and mantle minerals: experiments and applications.....alkaline09.narod.ru ENGLISH, May 10, 2p. abstractTechnologyGenesis of kimberlites and inclusions in diamonds
DS201012-0409
2009
Girnis, A.V.Kovalenko, V.I., Naumov, V.B., Girnis, A.V., Dorofeeva, V.A., Yarmolyuk, V.V.Average compositions of magmas and mantle sources of Mid-Ocean Ridges and intraplate Oceanic and Continental settings estimated from the dat a of melt inclusionsDeep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., p.35-78,MantleGlasses of basalts
DS201012-0740
2009
Girnis, A.V.Solovova, I.P., Girnis, A.V., Ryabchikov, I.D., Kononkova, N.N.Mechanisms of formation of barium rich phlogopite and strontium rich apatite during the final stages of alkaline magma evolution.Geochemistry International, Vol. 47, 6, June, pp. 578-591.MantleMagmatism
DS201112-0110
2011
Girnis, A.V.Brey, G.P., Bulatov, V.K., Girnis, A.V.Melting of K rich carbonated peridotite at 6 - 10 GPa and the stability of K phases in the upper mantle.Chemical Geology, Vol. 281, 3-4, pp. 333-342.MantleCratonic geothermometry
DS201112-0370
2011
Girnis, A.V.Girnis, A.V.Peridotite melting experiments.Australian Journal of Earth Sciences, in press available 42p.TechnologyPeridotite
DS201112-0371
2011
Girnis, A.V.Girnis, A.V., Bulatov, V.K., Brey, G.P.Formation of primary kimberlite melts - constraints from experiments at 6-12 GPa and variable CO2/H2O.Lithos, In press available, 42p.TechnologyMelting
DS201112-0372
2011
Girnis, A.V.Girnis, A.V., Bulatov, V.K., Brey, G.P.Formation of primary kimberlite melts - constraints from experiments at 6-12 GPa and variable CO2/H2O.Lithos, Vol. 127, 3-4, Dec. pp. 401-413.TechnologyMelting
DS201112-0549
2010
Girnis, A.V.Kovalenko, V.I., Naumov, V.B., Girnis, A.V., Dorofeeva, V.A., Yarmolyuk, V.V.Average composition of basic magmas and mantle sources of island arcs and active continental margins estimated from the dat a on melt inclusions and quenched glassesVladykin, N.V., Deep Seated Magmatism: its sources and plumes, pp. 22-53.MantlePetrology
DS201112-0726
2011
Girnis, A.V.Naumov, V.B., Kovanenko, V.I., Dorofeeva, V.A., Girnis, A.V., Yarmolyuk,V.V.Average compositions of igneous melts from main geodynamic settings according to the investigation of melt inclusions in minerals& quenched glasses of rocks.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., pp. 171-204.MantleMelt inclusion database
DS201112-0984
2011
Girnis, A.V.Solovova, I.P., Girnis, A.V., Kogarko, L.N., Kononkova, N.N.Compositions of magmas and carbonate silicate liquid immiscibility in the Vulture alkaline igneous complex, Italy.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., pp. 150-170.Europe, ItalyCarbonatite
DS201212-0690
2012
Girnis, A.V.Solovoa, I.P., Girnis, A.V.silicate carbonate liquid immiscibility and crystallization of carbonate and K rich basaltic magma: insights from melt and fluid inclusions.Mineralogical Magazine, Vol. 76, 2, pp. 411-439.MantleCarbonatite, melting
DS201212-0691
2012
Girnis, A.V.Solovova, I.P., Ohnenstetter, D., Girnis, A.V.Melt inclusions in olivine from boninites of New Caledonia: postentrapment melt modification and estimation of primary magma compositions.Petrology, Vol. 20, 6, pp. 529-544.AsiaBoninites
DS201312-0312
2013
Girnis, A.V.Girnis, A.V., Bulatov, V.K., Brey, G.P., Gerdes, A., Hofer, H.E.Trace element partitioning between mantle minerals and silico-carbonate melts at 6-12 Gpa and applications to mantle metasomatism and kimberlite genesis.Lithos, Vol. 160-161, pp. 183-200.MantleKimberlite genesis, melting
DS201312-0868
2012
Girnis, A.V.Solovova, I.P., Girnis, A.V., Kononkova, N.N.Relationships of carbonate and K rich basaltoid magmas: insight from melt and fluid inclusions.Vladykin, N.V. ed. Deep seated magmatism, its sources and plumes, Russian Academy of Sciences, pp. 164-203.MantleMetasomatism
DS201412-0868
2014
Girnis, A.V.Solovova, I.P., Girnis, A.V.Behavior of F and Cl in agpaitic acid melts.Deep Seated Magmatism, its sources and plumes, Ed. Vladykin, N.V., pp. 155-159.TechnologyMelting
DS201509-0386
2015
Girnis, A.V.Brey, G.P., Girnis, A.V., Bulatov, V.K., Hofer, H.E., Gerdes, A., Woodland, A.B.Reduced sediment melting at 7.5-12 Gpa: phase relations, geochemical signals and diamond nucleation.Contributions to Mineralogy and Petrology, Vol. 170, 25p.TechnologyExperimental petrology

Abstract: Melting of carbonated sediment in the presence of graphite or diamond was experimentally investigated at 7.5–12 GPa and 800–1600 °C in a multianvil apparatus. Two starting materials similar to GLOSS of Plank and Langmuir (Chem Geol 145:325–394, 1998) were prepared from oxides, carbonates, hydroxides and graphite. One mixture (Na-gloss) was identical in major element composition to GLOSS, and the other was poorer in Na and richer in K (K-gloss). Both starting mixtures contained ~6 wt% CO2 and 7 wt% H2O and were doped at a ~100 ppm level with a number of trace elements, including REE, LILE and HFSE. The near-solidus mineral assemblage contained a silica polymorph (coesite or stishovite), garnet, kyanite, clinopyroxene, carbonates (aragonite and magnesite-siderite solid solution), zircon, rutile, bearthite and hydrous phases (phengite and lawsonite at <9 GPa and the hydrous aluminosilicates topaz-OH and phase egg at >10 GPa). Hydrous phases disappear at ~900 °C, and carbonates persist up to 1000-1100 °C. At temperatures >1200 °C, the mineral assemblage consists of coesite or stishovite, kyanite and garnet. Clinopyroxene stability depends strongly on the Na content in the starting mixture; it remains in the Na-gloss composition up to 1600 °C at 12 GPa, but was not observed in K-gloss experiments above 1200 °C. The composition of melt or fluid changes gradually with increasing temperature from hydrous carbonate-rich (<10 wt% SiO2) at 800-1000 °C to volatile-rich silicate liquids (up to 40 wt% SiO2) at high temperatures. Trace elements were analyzed in melts and crystalline phases by LA ICP MS. The garnet-melt and clinopyroxene-melt partition coefficients are in general consistent with results from the literature for volatile-free systems and silicocarbonate melts derived by melting carbonated peridotites. Most trace elements are strongly incompatible in kyanite and silica polymorphs (D < 0.01), except for V, Cr and Ni, which are slightly compatible in kyanite (D > 1). Aragonite and Fe-Mg carbonate have very different REE partition coefficients (D Mst-Sd/L ~ 0.01 and D Arg/L ~ 1). Nb, Ta, Zr and Hf are strongly incompatible in both carbonates. The bearthite/melt partition coefficients are very high for LREE (>10) and decrease to ~1 for HREE. All HFSE are strongly incompatible in bearthite. In contrast, Ta, Nb, Zr and Hf are moderately to strongly compatible in ZrSiO4 and TiO2 phases. Based on the obtained partition coefficients, the composition of a mobile phase derived by sediment melting in deep subduction zones was calculated. This phase is strongly enriched in incompatible elements and displays a pronounced negative Ta-Nb anomaly but no Zr-Hf anomaly. Although all experiments were conducted in the diamond stability field, only graphite was observed in low-temperature experiments. Spontaneous diamond nucleation and the complete transformation of graphite to diamond were observed at temperatures above 1200-1300 °C. We speculate that the observed character of graphite-diamond transformation is controlled by relationships between the kinetics of metastable graphite dissolution and diamond nucleation in a hydrous silicocarbonate melt that is oversaturated in C.
DS201805-0945
2018
Girnis, A.V.Girnis, A.V., Brey, G.P., Bulatov, V.K., Hofer, H.E., Woodland, A.B.Graphite to diamond transformation during sediment-peridotite interaction at 7.5 and 10.5 Gpa.Lithos, in press available 42p.Mantleperidotites

Abstract: Diamond nucleation and growth were investigated experimentally at 7.5 and 10.5?GPa and temperatures up to 1500?°C. Samples consisted of two layers: i) H2O- and CO2-bearing model sediment and ii) graphite-bearing garnet harzburgite comprising natural minerals. Two experimental series were conducted, one under a controlled temperature gradient with the sedimentary layer usually in the cold zone and the other under isothermal conditions. In the latter case, diamond seeds were added to the sedimentary mixture. During the experiments, the sedimentary layer partially or completely melted, with the melt percolating and interacting with the adjacent harzburgite. The graphite-to-diamond transition in the peridotite was observed above 1300?°C at 7.5?GPa and 1200?°C at 10.5?GPa in the temperature-gradient experiments, and at temperatures ~100?°C lower in the isothermal experiments with diamond seeds. Newly formed diamond occurs mostly as individual grains up to 10?µm in size and is separate from graphite aggregates. In some cases, an association of diamond with magnesite was observed. Diamond nucleation occurs in hydrous and CO2-bearing silicate melt following graphite dissolution and recrystallization. In the case of the diamond-magnesite association, diamond was probably formed through carbonate reduction coupled with graphite oxidation. The composition of the melts ranged from “carbonatitic” with ~10?wt% SiO2 and?>?50?wt% volatiles to hydrous silicate with ~40?wt% SiO2 and?
DS202103-0381
2021
Giro, J.P.Giro, J.P., Almeida, J., Guedes, E., Bruno, H.Tectonic inheritances in rifts: the meaning of NNE lineaments in the continental rift of SE Brazil.Journal of South American Earth Sciences, Vol. 108, 103255. 17p. PdfSouth America, Brazillineaments, tectonics

Abstract: The effect of previous structures inheritance is known to be important in the development of tectonic rifts. A series of overlapping structures generally can be represented by lineaments marking the successive tectonic events. We studied the NNE structural lineaments corridor in the central region of the Ribeira Belt. We used a digital elevation model (DEM) and new and previous fieldwork data to investigate the structural control of such lineaments and their relevance for the Brazilian continental margin. Our results suggest that the NNE direction is a crustal weakness zone characterising corridors of intense ductile and brittle deformation which was recurrently reactivated. Aligned NNE Neoproterozoic-Ordovician ductile and brittle structures as foliations, shear zones, lithological boundaries, and fractures filled by pegmatitic veins coincide with the lineaments. During the Cretaceous rift, a transtensional sinistral regime generated NNE T-fractures filled by mafic dykes. In the Cenozoic, the NNE direction is represented by transfer and domino faults developed within a mega accommodation zone in an intracontinental rift system. Our results suggest that the NNE direction was active in this region throughout the Phanerozoic and has high relevance for the structural development of the continental margin of southeastern Brazil.
DS1960-0827
1967
Girod, M.Girod, M.Donnees Petrographiques sur des Pyroxenolites a Grenat En Enclaves dans des Basaltes du Hoggar ( Sahara Central ).Soc. Franc. Min. Cristall. Bulletin., Vol. 90, PP. 202-213.GlobalBlank
DS2000-0898
2000
Giroola, H.Simmons, N.A., Giroola, H.Multiple seismic discontinuities near the base of the transition zone in the Earth's mantle.Nature, Vol. 405, No. 6786, June 1, pp. 559-61.MantleGeophysics - seismics, Discontinuity
DS1999-0768
1999
Giroux, J.F.Veillette, J.J., Giroux, J.F.The enigmatic rings of the James Bay Lowland, Ontario and Quebec: aprobable geological origin.Geological Survey of Canada (GSC), Open file 3708 $ 12.00Ontario, QuebecStructure, Rings
DS201706-1075
2017
Giruts, M.V.Gordadze, G.N., Kerimov, V.Yu., Gaiduk, A.V., Giruts, M.V., Lobusev, M.A., Serov, S.G., Kuznetsov, N.B., Romanyuk, T.V.Hydrocarbon biomarkers and diamondoid hydrocarbons from Late Precambrian and Lower Cambrian rocks of the Katanga Saddle ( Siberian Platform).Geochemistry International, Vol. 55, 4, pp. 360-366.Russia, Siberiadiamondoid

Abstract: A broad suite of geological materials were studied a using a handheld laser-induced breakdown spectroscopy (LIBS) instrument. Because LIBS is simultaneously sensitive to all elements, the full broadband emission spectrum recorded from a single laser shot provides a ‘chemical fingerprint’ of any material - solid, liquid or gas. The distinguishing chemical characteristics of the samples analysed were identified through principal component analysis (PCA), which demonstrates how this technique for statistical analysis can be used to identify spectral differences between similar sample types based on minor and trace constituents. Partial least squares discriminant analysis (PLSDA) was used to distinguish and classify the materials, with excellent discrimination achieved for all sample types. This study illustrates through four selected examples involving carbonate minerals and rocks, the oxide mineral pair columbite-tantalite, the silicate mineral garnet and native gold how portable, handheld LIBS analysers can be used as a tool for real-time chemical analysis under simulated field conditions for element or mineral identification plus such applications as stratigraphic correlation, provenance determination and natural resources exploration.
DS1997-0415
1997
GIS ProceedingsGIS ProceedingsExpanding boundaries: geoscience information for earth system scienceGis Proceedings 32 Annual, Vol. 27, approx. $ 40.00GlobalBook - table of contents, Geoscience information
DS200512-0862
2005
Gisbert, P.E.Pla Cid, J., Stoll Nardi, L.V., Gisbert, P.E., Merlet, C., Boyer, B.SIMS analyses on trace and rare earth elements in coexisting clinopyroxene and mica from minette mafic enclaves in potassic syenites crystallized under high pressure.Contributions to Mineralogy and Petrology, Vol. 148, 6, pp. 675-688.UHP - minettes
DS201312-0634
2013
Gisbert, P.E.Nardi, L.V.S., Pla Cid, J., Pla Cid, C.C., Gisbert, P.E., Balzaretti, N.M.Granite compositions in a veined flower mantle, as indicated by mineral inclusions in diamonds from Juin a deposits, Brazil.Goldschmidt 2013, AbstractSouth America, BrazilDeposit - Juina
DS201412-0691
2014
Gisbert, P.E.Pla Cid, J., Nardi, L.V.S., Pla Cid, C., Gisbert, P.E., Balzaretti, N.M.Acid composition in a veined lower mantle, as indicated by inclusions of ( K, Na) - hollandite + SiO2 in diamonds.Lithos, Vol. 196-197, pp. 42-53.South America, BrazilDeposit - Juina area
DS201412-0692
2014
Gisbert, P.E.Pla Cid, J., Nardi, L.V.S., Pla Cid, C., Gisbert, P.E., Balzaretti, N.M.Acid compositions in a veined lower mantle, as indicated by inclusions of ( K, Na)- Hollandite + SiO2 in diamonds.Lithos, Vol. 196-197, pp. 42-53.South America, BrazilDeposit - Juina
DS2002-0576
2002
Gislason, S.R.Gislason, S.R., Oelkers, E.H., Bruno, J.Geochemistry of crustal fluids: an Andalusian perspectiveChemical Geology, Vol. 190, 1-4, pp.MantleGeochemistry
DS202007-1158
2020
GITLeelawatanasuk, T., Atichat, W., Pisutha-Arnond, V., Sutthirat, C., Jakkawanvibul, J., GITTwo decades of GIT's ruby and sapphire color standards.incolorMagazine.com, Vol. winter pp. 96-103.Asia, Thailandsapphire colour
DS2002-0577
2002
Gitelson, A.A.Gitelson, A.A., Stark, R., Grits, U., et al.Vegetation and soil lines in visible spectral space: a concept and technique for remote estimation of vegetation fraction.International Journal of Remote Sensing, Vol.23,No.13, July 20, pp. 2537-62.GlobalRemote sensing - not specific to diamonds, Techniques
DS1960-0666
1966
Gittins, J.Gittins, J.Summaries and Bibliographies of Carbonatite ComplexesInterscience Publishing, PP. 417-540.United States, Gulf Coast, Arkansas, Rocky Mountains, Montana, ColoradoBibliography
DS1970-0087
1970
Gittins, J.Gittins, J.Carbonatites- Nature and OriginReprint of A Paper., 14P.Canada, Tanzania, Russia, South Africa, Sweden, East AfricaOverview, Classification, Geophysics
DS1970-0693
1973
Gittins, J.Gittins, J., Hewins, R.H., Laurin, A.F.Kimberlitic Carbonatitic Dikes of the Saguenay River ValleyProceedings of First International Kimberlite Conference, EXTENDED ABSTRACT PP. 127-130.Canada, QuebecOccurrences
DS1970-0898
1974
Gittins, J.Cooper, A.F., Gittins, J.Shortite in Kimberlite from the Upper Canada Gold Mine, Ontario: Discussion.Journal of GEOLOGY, Vol. 82, No. 5, PP. 667-669.Canada, OntarioBlank
DS1975-0085
1975
Gittins, J.Gittins, J., Hewins, R.H., Laurin, A.F.Kimberlitic and Carbonatitic Dykes of the Saguenay River Valley, Quebec, Canada.Physics and Chemistry of the Earth., Vol. 9, PP. 137-148.Canada, QuebecRelated Rocks, Carbonatite, Kimberlite, Arvida
DS1975-0748
1978
Gittins, J.Gittins, J.Some Observations on the Present State of Carbonatite StudieI Symposio International De Carbonatitos, Pocos De Caldas, Brasil, PP. 107-115.GlobalGeochronology, Mineral Composition, Mineral Chemistry
DS1975-1034
1979
Gittins, J.Gittins, J.Problems Inherent in the Application of Calcite-dolomite Geothermometry to Carbonatites.Contributions to Mineralogy and Petrology, Vol. 69, PP. 1-4.GlobalGenesis
DS1980-0143
1980
Gittins, J.Gittins, J., Fawcett, J.J., Brooks, C.K., Rucklidge, J.C.Intergrowths of Nepheline Potassium Feldspar and Kalsilite Potassium Feldspar: a Re-examination of the Pseudo-leucite Problem.Contributions to Mineralogy and Petrology, Vol. 73, PP. 119-126.Greenland, BatbjergRelated Rocks, Leucite, Mineral Chemistry
DS1981-0102
1981
Gittins, J.Brooks, C.K., Fawcett, J.J., Gittins, J., Rucklidge, J.C.The Batbjerb Complex, East Greenland: a Unique Ultrapotassic Caledonian Intrusion.Canadian Journal of Earth Sciences, Vol. 18, No. 2, PP. 274-285.GreenlandLeucite
DS1985-0688
1985
Gittins, J.Twyman, J.D., Gittins, J.Alkalic Carbonatite Magmas: Parental or Derivative? #2Conference Report of A Meeting of The Volcanics Studies Grou, 1P. ABSTRACT.TanzaniaOldoinyo Lengai
DS1986-0161
1986
Gittins, J.Currie, K.L., Eby, G.N., Gittins, J.The petrology of the Mont Saint Hilaire complex, southernQuebec: an alkaline gabbro peralkaline syenite associationLithos, Vol. 19, No. 1, pp. 65-81QuebecAlkaline rocks
DS1986-0293
1986
Gittins, J.Gittins, J.Genesis and evolution of carbonatite magmasGeological Association of Canada (GAC) Annual Meeting, Vol. 11, p. 73. (abstract.)GlobalCarbonatite
DS1987-0754
1987
Gittins, J.Twyman, J.D., Gittins, J.Alkalic carbonatite magmas: parental or derivative? #1in: Fitton and Upton, Alkaline igneous rocks, Blackwell publ, pp. 85-94GlobalBlank
DS1988-0256
1988
Gittins, J.Gittins, J.Comment on 'Ra-Th disequilibration temperatures systematics: timescale of carbonatite magma formation at Oldoinyo Langai volcano, TanzaniaGeochimica et Cosmochimica Acta, Vol. 52, p. 957TanzaniaBlank
DS1989-0513
1989
Gittins, J.Gittins, J.Carbonatite origin and diversity. Reply to commentsNature, Vol. 338, No. 6216, p. 548GlobalCarbonatite
DS1989-0514
1989
Gittins, J.Gittins, J.The origin and evolution of carbonatite magmasCarbonatites -Genesis and Evolution, Ed. K. Bell Unwin Hyman Publ, pp. 580-600GlobalCarbonatite-genesis, Magma evolution
DS1989-0515
1989
Gittins, J.Gittins, J., Jago, B.C.Calcitic carbonatite lavas reinterpreted; their significance for magmagenesisNew Mexico Bureau of Mines Bulletin., Continental Magmatism Abstract Volume, Held, Bulletin. No. 131, p. 108. AbstractGlobalCarbonatite
DS1989-0788
1989
Gittins, J.Kjarsgaard, B., Hamilton, D.L., Gittins, J.Carbonatite origin and diversity.. discussion and replyNature, Vol. 338, No. 6216, April 13, pp. 547-548GlobalCarbonatite, Genesis
DS1990-0574
1990
Gittins, J.Gittins, J., Beckett, M.F., Jago, B.C.Composition of the fluid phase accompanying carbonatite magma: a criticalexaminationAmerican Mineralogist, Vol. 75, No. 9-10. Sept.-Oct. pp. 1106-1109QuebecOka, Husereau Hill, Carbonatite
DS1990-0575
1990
Gittins, J.Gittins, J., Jago, B.C.Carbonatite lavas: the role of fluorine, chlorine and water in carbonatitemagmasTerra, Abstracts of Experimental mineralogy, petrology and, Vol. 2, December abstracts p. 76GlobalCarbonatite, Experimental petrology
DS1990-0751
1990
Gittins, J.Jago, B.C., Gittins, J.Comparative roles of fluorine and water in carbonatite magma evolutionTerra, Abstracts of Experimental mineralogy, petrology and, Vol. 2, December abstracts p. 82GlobalExperimental Petrology, Carbonatite
DS1991-0578
1991
Gittins, J.Gittins, J., Jago, B.C.Extrusive carbonatites: their origins reappraised in the light of new experimental dataGeological Magazine, Vol. 128, No. 4, July pp. 301-305GlobalExperimental petrology, Carbonatite
DS1991-0782
1991
Gittins, J.Jago, B.C., Gittins, J.The role of fluorine in the crystallization of niobium and phosphorous ores in carbonatitesProceedings of Fifth International Kimberlite Conference held Araxa June 1991, Servico Geologico do Brasil (CPRM) Special, pp. 193-195GlobalPyrochlore, apatite, Experimental petrology
DS1991-0783
1991
Gittins, J.Jago, B.C., Gittins, J.The role of fluorine in carbonatite magma evolutionNature, Vol. 349, No. 6304, January 3, pp. 56-58TanzaniaCarbonatite, Oldoinyo Lengai -fluorine
DS1992-0576
1992
Gittins, J.Gittins, J., Beckett, M.F., Jago, B.C.Composition of the fluid phase accompanying carbonatite magmas: acritical examination- replyAmerican Mineralogist, Vol. 77, No. 5, 6, May-June pp. 666-667GlobalCarbonatite, Petrology
DS1992-0577
1992
Gittins, J.Gittins, J., Jago, B.C.The role of fluorine in the crystallization and evolution of carbonatitemagmasEos Transactions, Vol. 73, No. 14, April 7, supplement abstracts p.349GlobalCarbonatite, Fluorine
DS1993-0734
1993
Gittins, J.Jago, B.C., Gittins, J.Pyrochlore crystallization in carbonatites: the role of fluorineSouth African Journal of Geology, Vol. 96, No. 3, Sept. pp. 149-159.TanzaniaCarbonatite -pyrochlore, Petrology -experimental
DS1994-0823
1994
Gittins, J.Jago, B.C., Gittins, J.Solubility of water in carbonatite magmas and partitioning of Fluorine and Chlorine between magma and aequeous fluid.Geological Association of Canada (GAC) Abstract Volume, Vol. 19, p.GlobalCarbonatite, Petrology -experimental
DS1995-0639
1995
Gittins, J.Gittins, J., Harmer, R.E.The origin of periclase bearing carbonatitesGeological Society Africa 10th. Conference Oct. Nairobi, p. 112-3. AbstractTanzaniaCarbonatite -periclase, Deposit -Kerimasi
DS1995-0640
1995
Gittins, J.Gittins, J., Harmer, R.E.Evolutionary paths of carbonatite magmasGeological Society Africa 10th. Conference Oct. Nairobi, p. 111-2. AbstractTanzaniaCarbonatite, Calcite or dolomite Carbonatite
DS1995-0751
1995
Gittins, J.Harmer, R.E., Gittins, J.Carbonatites: primary or secondary magma types?Geological Society Africa 10th. Conference Oct. Nairobi, p. 110. AbstractSouth Africa, TanzaniaCarbonatite
DS1997-0416
1997
Gittins, J.Gittins, J.Discussion on carbonatites: where do we go from here?Geological Association of Canada (GAC) Abstracts, GlobalCarbonatite
DS1997-0417
1997
Gittins, J.Gittins, J., Harmer, R.E.What is a ferrocarbonatite? A revised classificationJournal of African Earth Sciences, Vol. 25, No. 1, July pp. 159-GlobalCarbonatite, Ferrocarbonatite - definition
DS1997-0418
1997
Gittins, J.Gittins, J., Harmer, R.E.Dawson Oldoinyo Lengai calciocarbonatite - a magmatic sovite or an extremely altered natrocarbonatite.Mineralogical Magazine, Vol. 61, No. 3, June pp. 351-355.TanzaniaCarbonatite
DS1997-0476
1997
Gittins, J.Harmer, R.E., Gittins, J.Dolomitic carbonatite parental magmasGeological Association of Canada (GAC) Abstracts, GlobalCarbonatite, Magma - genesis
DS1997-0477
1997
Gittins, J.Harmer, R.E., Gittins, J.The origin of dolomitic carbonatites: field and experimental constraintsJournal of African Earth Sciences, Vol. 25, No. 1, July pp. 5-28.South AfricaCarbonatite
DS1998-0515
1998
Gittins, J.Gittins, J., Jago, B.C.Differentiation of natrocarbonatite magma at Oldoinyo Lengai volcano, Tanzania.Mineralogical Magazine, Vol. 62, No. 6, Dec. 1, pp. 759-68.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS1998-0583
1998
Gittins, J.Harmer, R.E., Gittins, J.The case for primary, mantle derived carbonatite magmaJournal of Petrology, Vol. 39, No. 11-12, Nov-Dec. pp. 1895-04.AfricaCarbonatite, Napak, Kerimasi, Shombole, Dorova, Shawa, Magmatism, Spiskop
DS1999-0331
1999
Gittins, J.Jago, B.C., Gittins, J.Manganese and Fluorine bearing rasvumite in natrocarbonatite at Oldoinyo Lengai Tanzania.Mineralogical Magazine, Vol. 63, No. 1, pp. 53-5.TanzaniaCarbonatite, Deposit - Oldoinyo Lengai
DS2000-0390
2000
Gittins, J.Harmer, R.E., Hayward, G., Siegfried, P., Gittins, J.The geology and economic potential of the Xiluvo carbonatite complex, Mozambique.Igc 30th. Brasil, Aug. abstract only 1p.GlobalCarbonatite, Deposit - Xiluvo
DS2001-0384
2001
Gittins, J.Gittins, J., Harmer, R.E.The carbonatite alkalic silicate igneous rock association: an unfortunate and misleading assumption.Journal of South African Earth Sciences, Vol. 32, No. 1, p. A 16 (abs)Zimbabwe, South AfricaCarbonatite, Genesis
DS200512-0342
2003
Gittins, J.Gittins, J., Harmer, R.E.Myth and reality in the carbonatite silicate rock association.Periodico di Mineralogia, Vol. LXX11, 1. April, pp. 19-26.Field relations, geochronology
DS200512-0343
2005
Gittins, J.Gittins, J., Harmer, R.E., Barker, D.S.The bimodal composition of carbonatites: reality or misconception?Lithos, Advanced in press,Carbonatite, mineralogy
DS200612-0466
2005
Gittins, J.Gittins, J., Harmer, R.E., Barker, D.S.The bimodal composition of carbonatites: reality or misconception?Lithos, Vol. 85, 1-4, Nov-Dec. pp. 129-139.Carbonatite, genesis
DS201607-1318
2016
Gittins, J.Viladkar, S.G., Gittins, J.Trace element and REE geochemistry of Siriwasan carbonatite, Chhota Udaipur, Gujarat.Journal of the Geological Society of India, Vol. 87, 6, pp. 709-715.IndiaCarbonatite

Abstract: The Siriwasan carbonatite-sill along with associated alkaline rocks and fenites is located about 10 km north of the well-known Amba Dongar carbonatite-alkaline rocks diatreme, in the Chhota Udaipur carbonatite-alkaline province. Carbonatite has intruded as a sill into the Bagh sandstone and overlying Deccan basalt. This resulted in the formation of carbonatite breccia with enclosed fragments of basement metamorphics, sandstone and fenites in the matrix of ankeritic carbonatite. The most significant are the plugs of sovite with varied mineralogy that include pyroxene, amphibole, apatite, pyrochlore, perovskite and sphene. REE in sovites is related to the content of pyrochlore, perovskite and apatite. The carbon and oxygen isotopic compositions of some sovite samples and an ankeritic carbonatite plot in the "mantle box" pointing to their mantle origin. However, there is also evidence for mixing of the erupting carbonatite magma with the overlying Bagh limestone. The carbonatites of Siriwasan and Amba Dongar have the same Sr and Nd isotopic ratios and radiometric age, suggesting the same magma source. On the basis of available chemical analyses this paper is aimed to give some details of the Siriwasan carbonatites. The carbonatite complex has good potential for an economic mineral deposit but this is the most neglected carbonatite of the Chhota Udaipur province.
DS1960-0828
1967
Gittins, J.G.Gittins, J.G., Macintyre, R.M., Yorck, D.The Ages of Carbonatite Complexes in Eastern CanadaCanadian Journal of Earth Sciences, Vol. 4, PP. 651-655.Canada, QuebecRelated Rocks
DS2001-1289
2001
GittsovichZaitseva, T.S., Goncharov, G.N., Gittsovich, SemenovCrystal chemistry of chromium spinel from Imandra Layered pluton, Kola PeninsulaGeochemistry International, Vol. 39, No. 5, pp. 479-81.Russia, Kola PeninsulaSpinels
DS202008-1383
2020
Giuiani, A.Dalton, H., Giuiani, A., Phillips, D., Hergt, J., Maas, R., Woodhead, J., Matchan, E., O'Brien, H.Kimberlite magmatism in Finland: distinct sources and links to the breakup of Rodinia.Goldschmidt 2020, 1p. AbstractEurope, Finlanddeposit - Kuusamo

Abstract: The Karelian Craton in Finland is host to (at least) two distinct pulses of kimberlite magmatism. Twenty kimberlite occurrences have so far been discovered on the southwest margin of the craton at Kaavi-Kuopio and seven kimberlites are located in the Kuusamo area within the core of the craton. Comprehensive radiometric age determinations (U-Pb, Ar- Ar and Rb-Sr) reveal that all kimberlite activity was restricted to the Proterozoic. The Kaavi-Kuopio field was emplaced over a protracted period from ~610 to 550 Ma and is predated by the Kuusamo cluster that represents a relatively short pulse of magmatism at ~750 to 730 Ma. The emplacement of kimberlites globally has recently been linked to supercontinent reorganisation and we propose a similar scenario for these Finnish occurrences which, at the time of kimberlite emplacement, were situated on the Baltica paleo-continent. This land mass was contiguous with Laurentia in the Proterozoic and together formed part of Rodinia. The breakup of Rodinia is considered to have commenced at ~750 Ma and initiation of the opening of the Iapetus ocean at ~615 Ma. Contemporaneous with Kaavi-Kuopio magmatism, this latter period of Neoproterozoic crustal extension also includes the emplacement of kimberlites and related rocks in areas that were linked with Baltica as part of Rodinia - West Greenland and eastern North America. Both the initial and final periods of Rodinia’s breakup have been linked to mantle upwellings from the core-mantle boundary. We suggest that kimberlite magmatism in Finland was promoted by the influx of heat from mantle upwellings and lithospheric extension associated with the demise of Rodinia. Although both magmatic episodes are potentially linked to the breakup of Rodinia, whole-rock and perovskite radiogenic isotope compositions for the Kuusamo kimberlites (eNd(i) +2.6 to +3.3, eHf(i) +3.1 to +5.6) are distinct from the Kaavi-Kuopio kimberlites (eNd(i) -0.7 to +1.8, eHf(i) -6.1 to +5.2). The spread in Hf isotope compositions for the Kaavi-Kuopio magmas may be linked to variable assimilation of diverse mantle lithologies.
DS202003-0341
2019
Giuilani, G.Groat, L.A., Giuilani, G.,, Stone-Sundberg, J., Sun, Z., Renfro, N.D., Palke, A.C.A review of analytical methods used in geographic origin determination of gemstones.Gems & Gemology, Vol. 55, 4, pp. 512-535.Globalemerald, sapphire

Abstract: Origin determination is of increasing importance in the gem trade. It is possible because there is a close relationship between the geological environment of formation and the physical and chemical properties of gemstones, such as trace element and isotopic compositions, that can be measured in the laboratory using combinations of increasingly sophisticated instrumentation. Origin conclusions for ruby, sapphire, and emerald make up the bulk of demand for these services, with growing demand for alexandrite, tourmaline, and spinel. However, establishing origin with a high degree of confidence using the capabilities available today is met with varying degrees of success. Geographic origin can be determined with a high level of confidence for materials such as emerald, Paraíba-type tourmaline, alexandrite, and many rubies. For some materials, especially blue sapphire and some rubies, the situation is more difficult. The main problem is that if the geology of two deposits is similar, then the properties of the gemstones they produce will also be similar, to the point where concluding an origin becomes seemingly impossible in some cases. Origin determination currently relies on a combination of traditional gemological observations and advanced analytical instrumentation.
DS201608-1418
2016
Giuillong, 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;
DS201212-0243
2012
Giulani, A.Giulani, A., Kamenetsky, V.S., Phillips, D., Wyatt, B.A., Hutchinson, G.Alkali-carbonate fluids in the lithospheric mantle.10th. International Kimberlite Conference Feb. 6-11, Bangalore India, AbstractMantleCarbonatite
DS201912-2807
2019
Giulani, A.Mitchell, R.H., Giulani, A., O'Brien, H.What is a kimberlite? Petrology and mineralogy of hypabyssal kimberlite.Elements, Vol. 15, 6, pp.Mantlediamond genesis

Abstract: Hypabyssal kimberlites are subvolcanic intrusive rocks crystallised from mantle-derived magmas poor in SiO2 and rich in CO2 and H2O. They are complex, hybrid rocks containing significant amounts of mantle-derived fragments, primarily olivine with rare diamonds, set in a matrix of essentially magmatic origin. Unambiguous identification of kimberlites requires careful petrographic examination combined with mineral compositional analyses. Melt inclusion studies have shown that kimberlite melts contain higher alkali concentrations than previously thought but have not clarified the ultimate origin of these melts. Because of the hybrid nature of kimberlites and their common hydrothermal alteration by fluids of controversial origin (magmatic and/or crustal), the composition of primary kimberlite melts remains unknown.
DS201812-2856
2019
Giuli, G.Nazzarini, S., Nestola, F., Zanon, V., Bindi, L., Scricciolo, E., Petrelli, M., Zanatta, M., Mariotto, G., Giuli, G.Discovery of moissanite in a peralkaline syenite from the Azores Islands.Lithos, Vol. 324-325, pp. 68-73.Europe, Portugal, Azoresmoissanite

Abstract: Our discovery of moissanite grains in a peralkaline syenite from the Água de Pau Volcano (São Miguel, Azores Islands, Portugal) represents the first report of this mineral in present day oceanic geodynamic settings. Raman spectroscopy and single-crystal X-ray diffraction show the presence of both the 6H and 4H polytypes with the predominance of the first one. The distribution of trace elements is homogeneous, except for Al and V. Azorean moissanite often hosts rounded inclusions of metallic Si and other not yet identified metallic alloys. A process involving a flushing of CH4-H2 ultra-reducing fluids in the alkaline melts might be considered as a possible mechanism leading to the formation of natural SiC, thus calling for strongly reducing conditions that were locally met in the crust-mantle beneath the São Miguel Island.
DS201902-0302
2019
Giuli, G.Nazzarini, S., Nestola, F.,Zanon, V., Bindi, L., Giuli, G.Discovery of moissanite in a peralkaline syenite from the Azores Islands.Lithos, Vol. 324, pp. 68-73.Europe, Portugal, Azoresmoissanite

Abstract: Our discovery of moissanite grains in a peralkaline syenite from the Água de Pau Volcano (São Miguel, Azores Islands, Portugal) represents the first report of this mineral in present day oceanic geodynamic settings. Raman spectroscopy and single-crystal X-ray diffraction show the presence of both the 6H and 4H polytypes with the predominance of the first one. The distribution of trace elements is homogeneous, except for Al and V. Azorean moissanite often hosts rounded inclusions of metallic Si and other not yet identified metallic alloys. A process involving a flushing of CH4-H2 ultra-reducing fluids in the alkaline melts might be considered as a possible mechanism leading to the formation of natural SiC, thus calling for strongly reducing conditions that were locally met in the crust-mantle beneath the São Miguel Island.
DS202007-1178
2020
GiulianiSoltys, A., Giuliani, A,m Phillips, D., Kamenetsky, V.S.Kimberlite metasomatism of the lithosphere and the evolution of olivine in carbonate rich melts evidence from the Kimberley kimberlites ( South Africa).Journal of Petrology, 10.1093/petrology /egaa062/5857610 90p. PdfAfrica, South Africadeposit - Kimberley

Abstract: Olivine is the most abundant phase in kimberlites and is stable throughout most of the crystallisation sequence, thus providing an extensive record of kimberlite petrogenesis. To better constrain the composition, evolution, and source of kimberlites we present a detailed petrographic and geochemical study of olivine from multiple dyke, sill, and root zone kimberlites in the Kimberley cluster (South Africa). Olivine grains in these kimberlites are zoned, with a central core, a rim overgrowth, and occasionally an external rind. Additional ‘internal’ and ‘transitional’ zones may occur between the core and rim, and some samples of root zone kimberlites contain a late generation of high-Mg olivine in cross-cutting veins. Olivine records widespread pre-ascent (proto-)kimberlite metasomatism in the mantle including: (a) Relatively Fe-rich (Mg# <89) olivine cores interpreted to derive from the disaggregation of kimberlite-related megacrysts (20% of cores); (b) Mg-Ca-rich olivine cores (Mg# >89; >0.05?wt.% CaO) suggested to be sourced from neoblasts in sheared peridotites (25% of cores); (c) transitional zones between cores and rims probably formed by partial re-equilibration of xenocrysts (now cores) with a previous pulse of kimberlite melt (i.e., compositionally heterogeneous xenocrysts); and (d) olivine from the Wesselton water tunnel sills, internal zones (I), and low-Mg# rims, that crystallised from a kimberlite melt that underwent olivine fractionation within the shallow lithospheric mantle. Magmatic crystallisation begins with internal olivine zones (II), which are common but not ubiquitous in the Kimberley olivine. These zones are euhedral, contain rare inclusions of chromite, and have a higher Mg# (90.0 ± 0.5), NiO, and Cr2O3 contents, but are depleted in CaO compared to the rims. Internal olivine zones (II) are interpreted to crystallise from a primitive kimberlite melt during its ascent and transport of olivine toward the surface. Their compositions suggest assimilation of peridotitic material (particularly orthopyroxene) and potentially sulfides prior to or during crystallisation. Comparison of internal zones (II) with liquidus olivine from other mantle-derived carbonate-bearing magmas (i.e., orangeites, ultramafic lamprophyres, melilitites) show that low (100×) Mn/Fe (~1.2), very low Ca/Fe (~0.6), and moderate Ni/Mg ratios (~1.1) appear to be the hallmarks of olivine in melts derived from carbonate-bearing garnet-peridotite sources. Olivine rims display features indicative of magmatic crystallisation, which are typical of olivine rims in kimberlites worldwide - i.e. primary inclusions of chromite, Mg-ilmenite and rutile, homogeneous Mg# (88.8 ± 0.3), decreasing Ni and Cr, increasing Ca and Mn. Rinds and high-Mg olivine are characterised by extreme Mg-Ca-Mn enrichment and Ni depletion, and textural relationships indicate these zones represent replacement of pre-existing olivine, with some new crystallisation of rinds. These zones likely precipitated from evolved, oxidised, and relatively low-temperature kimberlite fluids after crustal emplacement. In summary, this study demonstrates the utility of combined petrography and olivine geochemistry to trace the evolution of kimberlite magmatic systems from early metasomatism of the lithospheric mantle by (proto-)kimberlite melts, to crystallisation at different depths en route to surface, and finally late-stage deuteric/hydrothermal fluid alteration processes after crustal emplacement.
DS201212-0244
2012
Giuliani, A.Giuliani, A., Kamenetsky, V.S., Kendrick, M.A., Phillips, D., Goemann, K.Nickel rich metasomatism of the lithospheric mantle by pre-kimberlitic alkali S Cl rich C-O-H fluids.Contributions to Mineralogy and Petrology, in press availableAfrica, South AfricaDeposit - Bultfontein
DS201212-0245
2012
Giuliani, A.Giuliani, A., Kamenetsky, V.S., Phillips, D., Kendrick, M.A., Wyatt, B.A., Goemann, K.Nature of alkali-carbonate fluids in the sub-continental lithospheric mantle.Geology, Vol. 40, 11, pp. 967-970.Mantle, RussiaDeposit - Udachnaya
DS201212-0246
2012
Giuliani, A.Giuliani, A.,Kamenetsky, V.S., Lendrick, M.A., Phillips, D., Goemann, K.Nickel-rich metasomatism of the lithospheric mantle by pre-kimberlitic alkali-S-Cl-rich C-O-H fluids.Contributions to Mineralogy and Petrology, in press available 17p.MantleMetasomatism
DS201312-0313
2013
Giuliani, A.Giuliani, A., Kamenetsky, V.S., Kendrick, M.A., Phillips, D., Wyatt, B.A., Maas, R.Oxide, sulphide and carbonate minerals in a mantle polymict breccia: metasomatism by proto-kimberlite magmas, and relationship to the kimberlite megacrystic suite.Chemical Geology, Vol. 353, pp. 4-18.Africa, South AfricaKimberley district
DS201312-0314
2013
Giuliani, A.Giuliani, A., Phillips, D., Kendrick, M.K., Maas, R., Greig, A., Armstrong, R., Felgate, M.R., Kamenetsky, V.S.Dating mantle metasomatism: a new tool ( U/PB LIMA Titanate) and an imposter ( 40Ar/39Ar phlogopite).Goldschmidt 2013, AbstractMantleMetasomatism
DS201412-0293
2014
Giuliani, A.Giuliani, A., Phillips, D., Kamenetsky, V.S., Fiorentini, M.L., Farqukar, J., Kendrick, M.A.Stable isotope ( C,O,S) compositions of volatile rich minerals in kimberlites: a review.Chemical Geology, Vol. 374-375, pp. 61-83.Africa, South Africa, Canada, Northwest Territories, RussiaDeposit - Kimberley, Lac de Gras, Udachnaya
DS201412-0294
2014
Giuliani, A.Giuliani, A., Phillips, D., Kamenetsky, V.S., Kendrick, M.A., Wyatt, B.A., Goemann, K., Hutchinson, G.Petrogenesis of mantle polymict breccias: insights into mantle processes coeval with kimberlite magmatism.Journal of Petrology, Vol. 55, 4, pp. 831-858.Africa, South AfricaDeposit - Bultfontein
DS201412-0438
2014
Giuliani, A.Kamenetsky, V.S., Belousova, E.A., Giuliani, A., Kamenetsky, M.B., Goemann, K., Griffin, W.L.Chemical abrasion of zircon and ilmenite megacrysts in the Monastery kimberlite: implications for the composition of kimberlite melts.Chemical Geology, Vol. 383, pp. 76-85.Africa, South AfricaDeposit - Monastery
DS201412-0439
2014
Giuliani, A.Kamenetsky, V.S., Golovin, A.V., Maas, R., Giuliani, A., Kamenetsky, M.B., Weiss, Y.Towards a new model for kimberlite petrogenesis: evidence from unaltered kimberlites and mantle minerals. Earth Science Reviews, Vol. 139, pp. 145-151.Russia, YakutiaDeposit - Udachnaya
DS201509-0405
2015
Giuliani, A.Kamenetsky, V.S., Mitchell, R.H., Maas, R., Giuliani, A., Gaboury, D., Zhitova, L.Chlorine in mantle derived carbonatite melts revealed by halite in the St. Honore intrusion ( Quebec, Canada).Geology, Vol. 43, 8, pp. 687-690.Canada, QuebecCarbonatite

Abstract: Mantle-derived carbonatites are igneous rocks dominated by carbonate minerals. Intrusive carbonatites typically contain calcite and, less commonly, dolomite and siderite as the only carbonate minerals. In contrast, lavas erupted by the only active carbonatite volcano on Earth, Oldoinyo Lengai, Tanzania, are enriched in Na-rich carbonate phenocrysts (nyerereite and gregoryite) and Na-K halides in the groundmass. The apparent paradox between the compositions of intrusive and extrusive carbonatites has not been satisfactorily resolved. This study records the fortuitous preservation of halite in the intrusive dolomitic carbonatite of the St.-Honoré carbonatite complex (Québec, Canada), more than 490 m below the present surface. Halite occurs intergrown with, and included in, magmatic minerals typical of intrusive carbonatites; i.e., dolomite, calcite, apatite, rare earth element fluorocarbonates, pyrochlore, fluorite, and phlogopite. Halite is also a major daughter phase of melt inclusions hosted in early magmatic minerals, apatite and pyrochlore. The carbon isotope composition of dolomite (d13C = –5.2‰) and Sr-Nd isotope compositions of individual minerals (87Sr/86Sri = 0.70287 in apatite, to 0.70443 in halite; eNd = +3.2 to +4.0) indicate a mantle origin for the St.-Honoré carbonatite parental melt. More radiogenic Sr compositions of dolomite and dolomite-hosted halite and heavy oxygen isotope composition of dolomite (d18O = +23‰) suggest their formation at some time after magma emplacement by recrystallization of original magmatic components in the presence of ambient fluids. Our observations indicate that water-soluble chloride minerals, common in the modern natrocarbonatite lavas, can be significant but ephemeral components of intrusive carbonatite complexes. We therefore infer that the parental magmas that produce primary carbonatite melts might be enriched in Na and Cl. This conclusion affects existing models for mantle source compositions, melting scenarios, temperature, rheological properties, and crystallization path of carbonatite melts.
DS201601-0018
2016
Giuliani, A.Giuliani, A., Phillips, D., Kamenetsky, V.S., Goemann, K.Constraints on kimberlite ascent mechanisms revealed by phlogopite compositions in kimberlites and mantle xenoliths.Lithos, Vol. 240, pp. 189-201.Africa, South AfricaDeposit - Bultfontein

Abstract: Kimberlite magmas are of economic and scientific importance because they represent the major host to diamonds and are probably the deepest magmas from continental regions. In addition, kimberlite magmas transport abundant mantle and crustal xenoliths, thus providing fundamental information on the composition of the sub-continental lithosphere. Despite their importance, the composition and ascent mechanism(s) of kimberlite melts remain poorly constrained. Phlogopite is one of the few minerals that preserves a history of fluid migration and magmatism in the mantle and crust and is therefore an invaluable petrogenetic indicator of kimberlite magma evolution. Here we present major and trace element compositional data for phlogopite from the Bultfontein kimberlite (Kimberley, South Africa; i.e. the kimberlite type-locality) and from entrained mantle xenoliths. Phlogopite macrocrysts (~ > 0.3-0.5 mm) and microcrysts (between ~ 0.1 and 0.3 mm) in the Bultfontein kimberlite display concentric compositional zoning patterns. The cores of these phlogopite grains exhibit compositions typical of phlogopite contained in peridotite mantle xenoliths. However, the rims of some grains show compositions analogous to kimberlite groundmass phlogopite (i.e. high Ti, Al and Ba; low Cr), whereas other rims and intermediate zones (between cores and rims) exhibit unusually elevated Cr and lower Al and Ba concentrations. The latter compositions are indistinguishable from matrix phlogopite in polymict breccia xenoliths (considered to represent failed kimberlite intrusions) and from Ti-rich overgrowth rims on phlogopite in other mantle xenoliths. Consequently, it is likely that these phlogopite grains crystallized from kimberlite melts and that the high Ti-Cr zones originated from earlier kimberlite melts at mantle depths. We postulate that successive pulses of ascending kimberlite magma progressively metasomatised the conduit along which later kimberlite pulses ascended, producing progressively decreasing interaction with the surrounding mantle rocks. In our view, these processes represent the fundamental mechanism of kimberlite magma ascent. Our study also indicates that, in addition to xenoliths/xenocrysts and magmatic phases, kimberlite rocks incorporate material crystallized at various mantle depths by previous kimberlite intrusions (mantle-derived ‘antecrysts’).
DS201606-1119
2016
Giuliani, A.Soltys, A., Giuliani, A., Phillips, D., Kamenetsky, V.S., Maas, R., Woodhead, J., Rodemann, T.In-situ assimilation of mantle minerals by kimberlitic magmas - direct evidence from a garnet wehrlite xenolith entrained in the Bultfontein kimberlite ( Kimberley, South Africa).Lithos, Vol. 256-257, pp. 182-196.Africa, South AfricaDeposit - Bultfontein

Abstract: The lack of consensus on the possible range of initial kimberlite melt compositions and their evolution as they ascend through and interact with mantle and crustal wall rocks, hampers a complete understanding of kimberlite petrogenesis. Attempts to resolve these issues are complicated by the fact that kimberlite rocks are mixtures of magmatic, xenocrystic and antecrystic components and, hence, are not directly representative of their parental melt composition. Furthermore, there is a lack of direct evidence of the assimilation processes that may characterise kimberlitic melts during ascent, which makes understanding their melt evolution difficult. In this contribution we provide novel constraints on the interaction between precursor kimberlite melts and lithospheric mantle wall rocks. We present detailed textural and geochemical data for a carbonate-rich vein assemblage that traverses a garnet wehrlite xenolith [equilibrated at ~ 1060 °C and 43 kbar (~ 140-145 km)] from the Bultfontein kimberlite (Kimberley, South Africa). This vein assemblage is dominated by Ca-Mg carbonates, with subordinate oxide minerals, olivine, sulphides, and apatite. Vein phases have highly variable compositions indicating formation under disequilibrium conditions. Primary inclusions in the vein minerals and secondary inclusion trails in host wehrlite minerals contain abundant alkali-bearing phases (e.g., Na-K bearing carbonates, Mg-freudenbergite, Na-bearing apatite and phlogopite). The Sr-isotope composition of vein carbonates overlaps those of groundmass calcite from the Bultfontein kimberlite, as well as perovskite from the other kimberlites in the Kimberley area. Clinopyroxene and garnet in the host wehrlite are resorbed and have Si-rich reaction mantles where in contact with the carbonate-rich veins. Within some veins, the carbonates occur as droplet-like, globular segregations, separated from a similarly shaped Si-rich phase by a thin meniscus of Mg-magnetite. These textures are interpreted to represent immiscibility between carbonate and silicate melts. The preservation of reaction mantles, immiscibility textures and disequilibrium in the vein assemblage, suggests quenching, probably triggered by entrainment and rapid transport toward the Earth's surface in the host kimberlite magma. Based on the Sr-isotope systematics of vein carbonate minerals, and the close temporal relationship between carbonate-rich metasomatism and kimberlite magmatism, we suggest that the carbonate-rich vein assemblage was produced by the interaction between a melt genetically related to the Bultfontein kimberlite and wehrlitic mantle wall rock. If correct, this unique xenolith sample provides a rare snapshot of the assimilation processes that might characterise parental kimberlite melts during their ascent through the lithospheric mantle.
DS201610-1838
2016
Giuliani, A.Abersteiner, A., Giuliani, A., Kamenetsky, V.S., Phillips, D.Petrographic and melt inclusion constraints on the petrogenesis of a magmaclast from the Venetia kimberlite cluster, South Africa.Chemical Geology, in press available 11p.Africa, South AfricaDeposit - Venetia

Abstract: Kimberlitic magmaclasts are discrete ovoid magmatic fragments that formed prior to emplacement from disrupted kimberlite magma. To provide new constraints on the origin and evolution of the kimberlite melts, we document the mineralogy and petrography of a magmaclast recovered from one of the ca. 520 Ma Venetia kimberlites, South Africa. The sample (BI9883) has a sub-spherical shape and consists of a ~ 10 mm diameter central olivine macrocryst, surrounded by porphyritic kimberlite. The kimberlitic material consists of concentrically aligned, altered olivine phenocrysts, set in a crystalline groundmass of calcite, chromite, perovskite, phlogopite, apatite, ilmenite, titanite, sulphides, rutile and magnetite along with abundant alteration phases (i.e. serpentine, talc and secondary calcite). These features are typical of archetypal hypabyssal kimberlites. We examined primary fluid/melt inclusions in chromite, perovskite and apatite containing a diversity of daughter phases. Chromite and perovskite host polycrystalline inclusions containing abundant alkali-carbonates (i.e. enriched in K, Na, Ba, Sr), phosphates, Na-K chlorides, sulphides and equal to lesser quantities of olivine, phlogopite and pleonaste. In contrast, apatite hosts polycrystalline assemblages with abundant alkali-carbonates and Na-K chlorides and lesser amounts of olivine, monticellite and phlogopite. Numerous solid inclusions of shortite (Na2Ca2(CO3)3), Na-Sr-carbonates and apatite occur in groundmass calcite along with fluid inclusions containing daughter crystals of Na-carbonates and Na-chlorides. The primary inclusions in chromite, perovskite and apatite are considered to represent remnants of fluid(s)/melt(s) trapped during crystallisation of the host minerals, whereas the fluid inclusions in calcite are probably secondary in origin. The component proportions of these primary fluid/melt inclusions were estimated in an effort to constrain the composition of the evolving kimberlite melt. These estimates suggest melt evolution from a silicate-carbonate kimberlite melt that became increasingly enriched in carbonates, phosphates, alkalis and chlorides, in response to the fractional crystallisation of constituent minerals (i.e. olivine to apatite). The concentric alignment of crystals around the olivine kernel and ovoid shape of the magmaclast can be ascribed to the low viscosity of the kimberlite melt and rapid rotation whilst in a liquid or partial crystalline state, or to progressive layer-by-layer growth of the magmaclast. Although the mineralogy of our sample is similar to hypabyssal kimberlites worldwide, it differs from hypabyssal kimberlite units in the main Venetia pipes, which contain monticellite-phlogopite rich assemblages and segregationary matrix textures. Therefore magmaclast BI9883 probably originated from a batch of magma distinct from those that produced known hypabyssal units within the Venetia kimberlite cluster.-
DS201611-2110
2016
Giuliani, A.Giuliani, A., Soltys, A., Phillips, D., Kamenetsly, V.S., Maas, R., Geomann, K., Woodhead, J.D., Drysdale, R.N., Griffin, W.L.The final stages of kimberlite petrogenesis: petrography, mineral chemistry, melt inclusions and Sr-C-O isotope geochemistry of the Bultfontein kimberlite ( Kimberley, South Africa).Chemical Geology, in press available 15p.Africa, South AfricaDeposit - Bultfontein

Abstract: The petrogenesis of kimberlites commonly is obscured by interaction with hydrothermal fluids, including deuteric (late-magmatic) and/or groundwater components. To provide new constraints on the modification of kimberlite rocks during overprinting by such fluids and on the fractionation of kimberlite magmas during crystallisation, we have undertaken a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa).
DS201707-1299
2017
Giuliani, A.Abersteiner, A., Giuliani, A., Kamenetsky, V.S., Phillips, D.Petrographic and melt inclusion constraints on the petrogenesis of a magmaclast from the Venetia kimberlite cluster, South Africa.Chemical Geology, Vol. 455, pp. 331-341.Africa, South Africadeposit - Venetia

Abstract: Kimberlitic magmaclasts are discrete ovoid magmatic fragments that formed prior to emplacement from disrupted kimberlite magma. To provide new constraints on the origin and evolution of the kimberlite melts, we document the mineralogy and petrography of a magmaclast recovered from one of the ca. 520 Ma Venetia kimberlites, South Africa. The sample (BI9883) has a sub-spherical shape and consists of a ~ 10 mm diameter central olivine macrocryst, surrounded by porphyritic kimberlite. The kimberlitic material consists of concentrically aligned, altered olivine phenocrysts, set in a crystalline groundmass of calcite, chromite, perovskite, phlogopite, apatite, ilmenite, titanite, sulphides, rutile and magnetite along with abundant alteration phases (i.e. serpentine, talc and secondary calcite). These features are typical of archetypal hypabyssal kimberlites. We examined primary fluid/melt inclusions in chromite, perovskite and apatite containing a diversity of daughter phases. Chromite and perovskite host polycrystalline inclusions containing abundant alkali-carbonates (i.e. enriched in K, Na, Ba, Sr), phosphates, Na-K chlorides, sulphides and equal to lesser quantities of olivine, phlogopite and pleonaste. In contrast, apatite hosts polycrystalline assemblages with abundant alkali-carbonates and Na-K chlorides and lesser amounts of olivine, monticellite and phlogopite. Numerous solid inclusions of shortite (Na2Ca2(CO3)3), Na-Sr-carbonates and apatite occur in groundmass calcite along with fluid inclusions containing daughter crystals of Na-carbonates and Na-chlorides. The primary inclusions in chromite, perovskite and apatite are considered to represent remnants of fluid(s)/melt(s) trapped during crystallisation of the host minerals, whereas the fluid inclusions in calcite are probably secondary in origin. The component proportions of these primary fluid/melt inclusions were estimated in an effort to constrain the composition of the evolving kimberlite melt. These estimates suggest melt evolution from a silicate-carbonate kimberlite melt that became increasingly enriched in carbonates, phosphates, alkalis and chlorides, in response to the fractional crystallisation of constituent minerals (i.e. olivine to apatite). The concentric alignment of crystals around the olivine kernel and ovoid shape of the magmaclast can be ascribed to the low viscosity of the kimberlite melt and rapid rotation whilst in a liquid or partial crystalline state, or to progressive layer-by-layer growth of the magmaclast. Although the mineralogy of our sample is similar to hypabyssal kimberlites worldwide, it differs from hypabyssal kimberlite units in the main Venetia pipes, which contain monticellite-phlogopite rich assemblages and segregationary matrix textures. Therefore magmaclast BI9883 probably originated from a batch of magma distinct from those that produced known hypabyssal units within the Venetia kimberlite cluster.
DS201707-1327
2017
Giuliani, A.Giuliani, A., Soltys, A., Phillips, D., Kamenetsky, V.S., Maas, R., Goemann, K., Woodhead, J.D., Drysdale, R.N., Griffin, W.L.The final stages of kimberlite petrogenesis: petrography, mineral chemistry, melt inclusions and Sr-C-O isotope geochemistry of the Bultfontein kimberlite ( Kimberley, South Africa.Chemical Geology, Vol. 455, pp. 342-256.Africa, South Africadeposit - Bultfontein

Abstract: The petrogenesis of kimberlites is commonly obscured by interaction with hydrothermal fluids, including deuteric (late-magmatic) and/or groundwater components. To provide new constraints on the modification of kimberlite rocks during fluid interaction and the fractionation of kimberlite magmas during crystallisation, we have undertaken a detailed petrographic and geochemical study of a hypabyssal sample (BK) from the Bultfontein kimberlite (Kimberley, South Africa). Sample BK consists of abundant macrocrysts (> 1 mm) and (micro-) phenocrysts of olivine and lesser phlogopite, smaller grains of apatite, serpentinised monticellite, spinel, perovskite, phlogopite and ilmenite in a matrix of calcite, serpentine and dolomite. As in kimberlites worldwide, BK olivine grains consist of cores with variable Mg/Fe ratios, overgrown by rims that host inclusions of groundmass phases (spinel, perovskite, phlogopite) and have constant Mg/Fe, but variable Ni, Mn and Ca concentrations. Primary multiphase inclusions in the outer rims of olivine and in Fe-Ti-rich (‘MUM’) spinel are dominated by dolomite, calcite and alkali carbonates with lesser silicate and oxide minerals. Secondary inclusions in olivine host an assemblage of Na-K carbonates and chlorides. The primary inclusions are interpreted as crystallised alkali-Si-bearing Ca-Mg-rich carbonate melts, whereas secondary inclusions host Na-K-rich C-O-H-Cl fluids. In situ Sr-isotope analyses of groundmass calcite and perovskite reveal similar 87Sr/86Sr ratios to perovskite in the Bultfontein and the other Kimberley kimberlites, i.e. magmatic values. The d18O composition of the BK bulk carbonate fraction is above the mantle range, whereas the d13C values are similar to those of mantle-derived magmas. The occurrence of different generations of serpentine and occasional groundmass calcite with high 87Sr/86Sr, and elevated bulk carbonate d18O values indicate that the kimberlite was overprinted by hydrothermal fluids, which probably included a significant groundwater component. Before this alteration the groundmass included calcite, monticellite, apatite and minor dolomite, phlogopite, spinel, perovskite and ilmenite. Inclusions of groundmass minerals in olivine rims and phlogopite phenocrysts show that olivine and phlogopite also belong to the magmatic assemblage. We therefore suggest that the crystallised kimberlite was produced by an alkali-bearing, phosphorus-rich, silica-dolomitic melt. The alkali-Si-bearing Ca-Mg-rich carbonate compositions of primary melt inclusions in the outer rims of olivine and in spinel grains with evolved compositions (MUM spinel) support formation of these melts after fractionation of abundant olivine, and probably other phases (e.g., ilmenite and chromite). Finally, the similarity between secondary inclusions in kimberlite olivine of this and other worldwide kimberlites and secondary inclusions in minerals of carbonatitic, mafic and felsic magmatic rocks, suggests trapping of residual Na-K-rich C-O-H-Cl fluids after groundmass crystallisation. These residual fluids may have persisted in pore spaces within the largely crystalline BK groundmass and subsequently mixed with larger volumes of external fluids, which triggered serpentine formation and localised carbonate recrystallisation.
DS201708-1650
2017
Giuliani, A.Giuliani, A.Olivine zoning and the evolution of kimberlite systems.11th. International Kimberlite Conference, OralGlobalolivine
DS201708-1651
2017
Giuliani, A.Giuliani, A.Tracing mantle metasomatism using combined stable (S,O) and radiogenic (Sr, Nd, Hf, Pb) isotope geochemistry: case studies from mantle xenoliths of the Kimberley kimberlites.11th. International Kimberlite Conference, PosterAfrica, South Africadeposit - Kimberley Pool
DS201709-1989
2017
Giuliani, A.Giuliani, A., et al.Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to mantle upwelling in Angola. CatandaGoldschmidt Conference, abstract 1p.Africa, Angolacarbonatite, Catanda

Abstract: The origin of intraplate carbonatitic to alkaline volcanism in Africa is controversial. A tectonic control, i.e., decompression melting associated with far-field stress, is suggested by correlation with lithospheric sutures, repeated magmatic cycles in the same areas over several million years, synchronicity across the plate, and lack of clear age progression patterns. Conversely, a dominant role for mantle convection is supported by the coincidence of Cenozoic volcanism with regions of lithospheric uplift, positive free-air gravity anomalies, and slow seismic velocities. To improve constraints on the genesis of African volcanism, here we report the first radiometric and isotopic results for the Catanda complex, which hosts the only extrusive carbonatites in Angola. Apatite (U-Th-Sm)/He and phlogopite 40Ar/39Ar ages of Catanda aillikite lavas indicate eruption at ca. 500–800 ka, more than 100 m.y. after emplacement of abundant kimberlites and carbonatites in this region. The lavas share similar high-µ (HIMU)–like Sr-Nd-Pb-Hf isotope compositions with other young mantle-derived volcanics from Africa (e.g., Northern Kenya Rift; Cameroon Line). The position of the Catanda complex in the Lucapa corridor, a long-lived extensional structure, suggests a possible tectonic control for the volcanism. The complex is also located on the Bié Dome, a broad region of fast Pleistocene uplift attributed to mantle upwelling. Seismic tomography models indicate convection of deep hot material beneath regions of active volcanism in Africa, including a large area encompassing Angola and northern Namibia. This is strong evidence that intraplate late Cenozoic volcanism, including the Catanda complex, resulted from the interplay between mantle convection and preexisting lithospheric heterogeneities.
DS201801-0017
2017
Giuliani, A.Giuliani, A., Campeny, M., Kamenetsky, V.S., Afonso, J.C., Maas, R., Melgarejo, J.C., Kohn, B.P., Matchen, E.L., Mangas, J., Goncalves, A.O., Manuel, J.Southwestern Africa on the burner: Pleistocene carbonatite volcanism linked to deep mantle upwelling in Angola.Geology, Vol. 45, 11, pp. 971=974.Africa, Angolacarbonatite - Catanda

Abstract: The origin of intraplate carbonatitic to alkaline volcanism in Africa is controversial. A tectonic control, i.e., decompression melting associated with far-field stress, is suggested by correlation with lithospheric sutures, repeated magmatic cycles in the same areas over several million years, synchronicity across the plate, and lack of clear age progression patterns. Conversely, a dominant role for mantle convection is supported by the coincidence of Cenozoic volcanism with regions of lithospheric uplift, positive free-air gravity anomalies, and slow seismic velocities. To improve constraints on the genesis of African volcanism, here we report the first radiometric and isotopic results for the Catanda complex, which hosts the only extrusive carbonatites in Angola. Apatite (U-Th-Sm)/He and phlogopite 40Ar/39Ar ages of Catanda aillikite lavas indicate eruption at ca. 500-800 ka, more than 100 m.y. after emplacement of abundant kimberlites and carbonatites in this region. The lavas share similar high-µ (HIMU)-like Sr-Nd-Pb-Hf isotope compositions with other young mantle-derived volcanics from Africa (e.g., Northern Kenya Rift; Cameroon Line). The position of the Catanda complex in the Lucapa corridor, a long-lived extensional structure, suggests a possible tectonic control for the volcanism. The complex is also located on the Bié Dome, a broad region of fast Pleistocene uplift attributed to mantle upwelling. Seismic tomography models indicate convection of deep hot material beneath regions of active volcanism in Africa, including a large area encompassing Angola and northern Namibia. This is strong evidence that intraplate late Cenozoic volcanism, including the Catanda complex, resulted from the interplay between mantle convection and preexisting lithospheric heterogeneities.
DS201803-0450
2014
Giuliani, A.Giuliani, A., Phillips, D., Maas, R., Woodhead, J.D., Kendrick, M.A., Greig, A., Armstrong, R.A., Chew, D., Kamenetsky, V.S., Fiorentini, M.L.LIMA U-Pb ages link lithospheric mantle metasomatism to Karoo magmatism beneath the Kimberley region, South Africa.Earth and Planetary Science Letters, Vol. 401, pp. 132-147.Africa, South Africametasomatism

Abstract: The Karoo igneous rocks (174-185 Ma) of southern Africa represent one of the largest continental flood basalt provinces on Earth. Available evidence indicates that Karoo magmas either originated in the asthenosphere and were extensively modified by interaction with the lithospheric mantle prior to emplacement in the upper crust; or were produced by partial melting of enriched mantle lithosphere. However, no direct evidence of interaction by Karoo melts (or their precursors) with lithospheric mantle rocks has yet been identified in the suites of mantle xenoliths sampled by post-Karoo kimberlites in southern Africa. Here we report U-Pb ages for lindsleyite-mathiasite (LIMA) titanate minerals (crichtonite series) from three metasomatised, phlogopite and clinopyroxene-rich peridotite xenoliths from the ~84 Ma Bultfontein kimberlite (Kimberley, South Africa), located in the southern part of the Karoo magmatic province. The LIMA minerals appear to have formed during metasomatism of the lithospheric mantle by fluids enriched in HFSE (Ti, Zr, Hf, Nb), LILE (K, Ba, Ca, Sr) and LREE. LIMA U-Pb elemental and isotopic compositions were measured in situ by LA-ICP-MS methods, and potential matrix effects were evaluated by solution-mode analysis of mineral separates. LIMA minerals from the three samples yielded apparent U-Pb ages of , and (). A single zircon grain extracted from the ~190 Ma LIMA-bearing sample produced a similar U-Pb age of , within uncertainty of the LIMA ages. These data provide the first robust evidence of fluid enrichment in the lithospheric mantle beneath the Kimberley region at ~180-190 Ma, and suggest causation of mantle metasomatism by Karoo melts or their precursor(s). The results further indicate that U-Pb dating of LIMA minerals provides a new, accurate tool for dating metasomatic events in the lithospheric mantle.
DS201803-0451
2018
Giuliani, A.Giuliani, A., Woodhead, J.D., Phillips, D., Maas, R., Davies, G.R.Titanates of the lindsleyite mathiasite ( LIMA) group reveal isotope disequilibrium associated with metasomatism in the mantle beneath Kimberley ( South Africa).Earth and Planetary Science Letters, Vol. 482, pp. 253-264.Africa, South Africametasomatism

Abstract: Radiogenic isotope variations unrelated to radiogenic ingrowth are common between minerals found in metasomatised mantle xenoliths entrained in kimberlite, basalts and related magmas. As the metasomatic minerals are assumed to have been in isotopic equilibrium originally, such variations are typically attributed to contamination by the magma host and/or interaction with mantle fluids during or before xenolith transport to surface. However, the increasing evidence of metasomatism by multiple, compositionally distinct fluids permeating the lithospheric mantle, coeval with specific magmatic events, suggests that isotopic disequilibrium might be a consequence of discrete, though complex, metasomatic events. Here we provide clear evidence of elemental and Sr isotope heterogeneity between coeval Ti-rich LIMA (lindsleyite–mathiasite) minerals at the time of their formation in the mantle. LIMA minerals occur in close textural association with clinopyroxene and phlogopite in low-temperature (~800–900?°C), strongly metasomatised mantle xenoliths from the ~84 Ma Bultfontein kimberlite (South Africa). Previous U/Pb dating of the LIMA phases was used to argue that each xenolith recorded a single event of LIMA crystallisation at ~180–190 Ma, coeval with the emplacement of Karoo magmas. SEM imaging reveals that up to four types of LIMA phases coexist in each xenolith, and occasionally in a single LIMA grain. Major element and in situ Sr isotope analyses of the different LIMA types show that each phase has a distinct elemental composition and initial 87Sr/86Sr ratio (e.g., 0.7068–0.7086 and 0.7115–0.7129 for two LIMA types in a single xenolith; 0.7053-0.7131 across the entire sample suite). These combined age and isotopic constraints require that multiple fluids metasomatised these rocks at broadly the same time (i.e. within a few thousands to millions of years), and produced similar mineralogical features. Elemental and isotopic variations between different LIMA types could be due to interaction between one (or more) Karoo-related Ti-rich silicate melts and previously metasomatised, phlogopite-rich lithospheric mantle. This study demonstrates that mantle metasomatic assemblages seemingly generated in a single event may instead result from the infiltration of broadly coeval fluids with variable compositions. This in turn implies that the isotopic variations recorded in mantle rocks may be an inherent feature of metasomatism, and that hot fluids infiltrating a rock do not necessarily cause equilibration at the cm scale, as has been assumed previously. Simple modelling of solid-state diffusion in mantle minerals shows that isotopic disequilibrium may be preserved for up to hundreds of Myr at mantle lithosphere temperatures (=1100–1200?°C), unless subsequently affected by transient heating and/or fluid infiltration events. Radiogenic isotope disequilibrium associated with mantle metasomatism may therefore be a common feature of mantle xenoliths.
DS201803-0477
2018
Giuliani, A.Soltys, A., Giuliani, A., Phillips, D.A new approach to reconstructing the composition and evolution of kimberlite melts: a case study of the archetypal Bultfontein kimberlite ( Kimberley, South Africa).Lithos, in press available Africa, South Africadeposit - Bultfontein

Abstract: The compositions of kimberlite melts at depth and upon emplacement in the upper crust remain elusive. This can be attributed to the unquantified effects of multiple processes, such as alteration, assimilation, xenocryst contamination, and fractional crystallisation. The inability to accurately constrain the composition and physical properties of kimberlite melts prevents a comprehensive understanding of their petrogenesis. To improve constraints on the compositions of kimberlite melts, we have combined modal analysis including the discrimination of xenocrystic from magmatic phases, with mineral chemistry determinations to reconstruct a whole-rock composition. We apply this approach to a sample of “fresh” macrocrystic hypabyssal kimberlite (sample BK-1) from the Bultfontein mine (Kimberley, South Africa). The accuracy of this whole-rock reconstruction method is validated by the similarity between reconstructed and measured whole-rock compositions. A series of corrections are then applied to account for the effects of post-emplacement serpentinisation, pre-emplacement olivine crystallisation, and the inclusion and assimilation of mantle material. This approach permits discernment of melt compositions at different stages of kimberlite evolution. The primitive melt parental to the Bultfontein kimberlite is estimated to contain 17.4-19.0?wt% SiO2, 20.2-22.8?wt% MgO, 20.9-21.9?wt% CaO, 2.1-2.3?wt% P2O5, 1.2-1.4?wt% TiO2, 0.9-1.1?wt% Al2O3, and 0.6-0.7?wt% K2O, and has a Mg# of 83.4-84.4. Primary volatile contents (i.e., after an attempt to account for volatile loss) are tentatively estimated at ~2.1-2.2?wt% H2O and ~22.9-25.4?wt% CO2. This composition is deficient in SiO2, MgO and H2O, but enriched in CaO and CO2 compared with most previous estimates of primitive kimberlite melts. We suggest that the primitive melt parental to the Bultfontein kimberlite was a transitional silicate-carbonate melt, which was progressively enriched in SiO2, MgO, Al2O3, Cr2O3, and Na2O through the assimilation of lithospheric mantle material. Comparisons with experimentally produced low-degree melts of carbonated lherzolite indicate that the Bultfontein kimberlite could have formed by ~0.5% melting of asthenospheric mantle at ~6.0-8.6?GPa (i.e., ~190-285?km) and ~1400-1500?°C. The low calculated Na2O contents (<0.2?wt%), which are inconsistent with derivation from low-degree melting of lherzolite, suggest that an alkali-bearing, volatile-rich fluid was exsolved during ascent or released after emplacement, and subsequently removed.
DS201806-1223
2018
Giuliani, A.Fitzpayne, A., Giuliani, A., Phillips, D., Wu, N.Kimberlite related metasomatism recorded in Marid and PIC mantle xenoliths. Kimberlites and orangeitesMineralogy and Petrology, in press available, 14p.Africa, South Africadeposit - Bultfontein

Abstract: MARID (Mica-Amphibole-Rutile-Ilmenite-Diopside) and PIC (Phlogopite-Ilmenite-Clinopyroxene) xenoliths are thought to be formed by intense Bprimary^ mantle metasomatism. These rocks also display secondary features, such as cross-cutting veins and geochemical zonation of matrix minerals, which probably reflect latermetasomatic events. To investigate the nature and origin(s) of these secondary features, 28 MARID and PIC xenoliths from southern African kimberlites and orangeites have been studied. MARID-hosted veins contain both carbonate and Ti-rich phases (e.g., titanite, phlogopite), suggesting that they formed by the infiltration of a carbonated silicate melt. Elevated TiO2 contents in MARID matrix mineral rims are spatially associated with carbonate-dominated veins, suggesting a genetic relationship between vein formation and geochemical zonation. Spongy rims around primaryMARID and PIC clinopyroxene are depleted in Na2O andAl2O3 relative to their cores, possibly reflecting mineral dissolution in the xenoliths during ascent and emplacement of the entraining kimberlite. The preservation of compositional differences between primary and secondary phases in MARID and PIC xenoliths indicates that metasomatism occurred shortly before, or broadly coeval with, kimberlite/orangeite magmatism; otherwise, at typical mantle temperatures, such features would have quickly re-equilibrated. Increased Na2O in some mineral rims (e.g., K-richterite) may therefore reflect equilibration with a more Na-enriched primitive kimberlite melt composition than is commonly suggested. Vein-hosted clinopyroxene 87Sr/86Sri (0.70539 ± 0.00079) in one MARID sample is intermediate between primary clinopyroxene in the sample (0.70814 ± 0.00002) and the host Bultfontein kimberlite (0.70432 ± 0.00005), suggesting that vein minerals are derived from interactions between primary MARID phases and kimberlite-related melts/fluids. Sulfur isotope compositions of barite (d34SVCDT = +4.69 ‰) and sulfides (d34SVCDT = -0.69 ‰) in carbonate veins reflect equilibration at temperatures of 850-900 °C, consistent with sulfurrich melt/fluid infiltration in the lithospheric mantle. In contrast, vein carbonate C-O isotope systematics (d13CVPDB = -9.18 ‰ d18OVSMOW = +17.22‰) are not typical of kimberlites or other mantle carbonates (d13CVPDB = -3 to -8‰ d18OVSMOW = 6 to 9 ), and may represent post-emplacement hydrothermal interactions of the cooling kimberlite with crustal fluids. These constraints suggest protracted metasomatism of MARID rocks shortly before and during entrainment by the host kimberlite.
DS201807-1527
2018
Giuliani, A.Soltys, A., Giuliani, A., Phillips, D.Crystallisation sequence and magma evolution of the De Beers dyke ( Kimberley, South Africa).Mineralogy and Petrology, June 14, DOI:10.1007/ s00710-018 -0588-5, 16p.Africa, South Africadeposit - De Beers dyke

Abstract: We present petrographic and mineral chemical data for a suite of samples derived from the De Beers dyke, a contemporaneous, composite intrusion bordering the De Beers pipe (Kimberley, South Africa). Petrographic features and mineral compositions indicate the following stages in the evolution of this dyke: (1) production of antecrystic material by kimberlite-related metasomatism in the mantle (i.e., high Cr-Ti phlogopite); (2) entrainment of wall-rock material during ascent through the lithospheric mantle, including antecrysts; (3) early magmatic crystallisation of olivine (internal zones and subsequently rims), Cr-rich spinel, rutile, and magnesian ilmenite, probably on ascent to the surface; and (4) crystallisation of groundmass phases (i.e., olivine rinds, Fe-Ti-rich spinels, perovskite, apatite, monticellite, calcite micro-phenocrysts, kinoshitalite-phlogopite, barite, and baddeleyite) and the mesostasis (calcite, dolomite, and serpentine) on emplacement in the upper crust. Groundmass and mesostasis crystallisation likely forms a continuous sequence with deuteric/hydrothermal modification. The petrographic features, mineralogy, and mineral compositions of different units within the De Beers dyke are indistinguishable from one another, indicating a common petrogenesis. The compositions of antecrysts (i.e., high Cr-Ti phlogopite) and magmatic phases (e.g., olivine rims, magnesian ilmenite, and spinel) overlap those from the root zone intrusions of the main Kimberley pipes (i.e., Wesselton, De Beers, Bultfontein). However, the composition of these magmatic phases is distinct from those in ‘evolved’ intrusions of the Kimberley cluster (e.g., Benfontein, Wesselton water tunnel sills). Although the effects of syn-emplacement flow processes are evident (e.g., alignment of phases parallel to contacts), there is no evidence that the De Beers dyke has undergone significant pre-emplacement crystal fractionation (e.g., olivine, spinel, ilmenite). This study demonstrates the requirement for detailed petrographic and mineral chemical studies to assess whether individual intrusions are in fact ‘evolved’; and that dykes are not necessarily produced by differentiated magmas.
DS201808-1764
2018
Giuliani, A.Lim, E., Giuliani, A., Phillips, D., Goemann, K.Origin of complex zoning in olivine from diverse, Diamondiferous kimberlites and tectonic settings: Ekati ( Canada), Alto Paranaiba ( Brazil) and Kaalvallei ( South Africa).Mineralogy and Petrology, doi.org/10.1007/s00710-018-0607-6 16p.Canada, Northwest Territories, South America, Brazildeposit - Ekati, Grizzly, Kaola, Limpeza-18, Tres Ranchos-04, Kaalvallei, Samada, New Robinson

Abstract: Olivine in kimberlites can provide unique insights into magma petrogenesis, because it is the most abundant xenocrystic phase and a stable magmatic product over most of the liquid line of descent. In this study we examined the petrography and chemistry of olivine in kimberlites from different tectonic settings, including the Slave craton, Canada (Ekati: Grizzly, Koala), the Brasilia mobile belt (Limpeza-18, Tres Ranchos-04), and the Kaapvaal craton, South Africa (Kaalvallei: Samada, New Robinson). Olivine cores display a wide range of compositions (e.g., Mg#?=?78-95). The similarity in olivine composition, resorption of core zones and inclusions of mantle-derived phases, indicates that most olivine cores originated from the disaggregation of mantle peridotites, including kimberlite-metasomatised lithologies (i.e. sheared lherzolites and megacrysts). Olivine rims typically show a restricted range of Mg#, with decreasing Ni and increasing Mn and Ca contents, a characteristic of kimberlitic olivine worldwide. The rims host inclusions of groundmass minerals, which implies crystallisation just before and/or during emplacement. There is a direct correlation between olivine rim composition and groundmass mineralogy, whereby high Mg/Fe rims are associated with carbonate-rich kimberlites, and lower Mg/Fe rims are correlated with increased phlogopite and Fe-bearing oxide mineral abundances. There are no differences in olivine composition between explosive (Grizzly) and hypabyssal (Koala) kimberlites. Olivine in kimberlites also displays transitional zones and less common internal zones, between cores and rims. The diffuse transitional zones exhibit intermediate compositions between cores and rims, attributed to partial re-equilibration of xenocrystic cores with the ascending kimberlite melt. In contrast, internal zones form discrete layers with resorbed margins and restricted Mg# values, but variable Ni, Mn and Ca concentrations, which indicates a discrete crystallization event from precursor kimberlite melts at mantle depths. Overall, olivine exhibits broadly analogous zoning in kimberlites worldwide. Variable compositions for individual zones relate to different parental melt compositions rather than variations in tectonic setting or emplacement mechanism.
DS201809-2006
2018
Giuliani, A.Castillo-Oliver, M., Giuliani, A., Griffin, W.L., O'Reilly, S.Y.Characterisation of primary and secondary carbonates in hypabyssal kimberlites: an integrated compositional and Sr-isotopic approach. Mineralogy and Petrology, doi.org/10.1007/s00710-018-0626-3 13p.Africa, South Africa, Australia, Europe, Finland, Canada, Northwest Territoriesdeposit - Wesselton, De Beers, Bultfontein, Benfontein, Jagersfontein, Cullinan, Melita, Pipe 1, Grizzley, Koala

Abstract: Carbonates in fresh hypabyssal kimberlites worldwide have been studied to understand their origin [i.e. primary magmatic (high T) versus deuteric (‘low T’) versus hydrothermal/alteration (‘low T’)] and identify optimal strategies for petrogenetic studies of kimberlitic carbonates. The approach presented here integrates detailed textural characterisation, cathodoluminescence (CL) imaging, in situ major- and trace-element analysis, as well as in situ Sr-isotope analysis. The results reveal a wide textural diversity. Calcite occurs as fine-grained groundmass, larger laths, segregations, veins or as a late crystallising phase, replacing olivine or early carbonates. Different generations of carbonates commonly coexist in the same kimberlite, each one defined by a characteristic texture, CL response and composition (e.g., variable Sr and Ba concentrations). In situ Sr isotope analysis revealed a magmatic signature for most of the carbonates, based on comparable 87Sr/86Sr values between these carbonates and the coexisting perovskite, a robust magmatic phase. However, this study also shows that in situ Sr isotope analysis not always allow distinction between primary (i.e., magmatic) and texturally secondary carbonates within the same sample. Carbonates with a clear secondary origin (e.g., late-stage veins) occasionally show the same moderately depleted 87Sr/86Sr ratios of primary carbonates and coexisting perovskite (e.g., calcite laths-shaped crystals with 87Sr/86Sr values identical within uncertainty to those of vein calcite in the De Beers kimberlite). This complexity emphasises the necessity of integrating detailed petrography, geochemical and in situ Sr isotopic analyses for an accurate interpretation of carbonate petrogenesis in kimberlites. Therefore, the complex petrogenesis of carbonates demonstrated here not only highlights the compositional variability of kimberlites, but also raises concerns about the use of bulk-carbonate C-O isotope studies to characterise the parental melt compositions. Conversely, our integrated textural and in situ study successfully identifies the most appropriate (i.e. primary) carbonates for providing constraints on the isotopic parameters of parental kimberlite magmas.
DS201810-2315
2018
Giuliani, A.Fitzpayne, A., Giuliani, A., Hergt, J., Phillips, D., Janney, P.New geochemical constraints on the origins of MARID and PIC rocks: implications for mantle metasomatism and mantle -derived potassic magmatism.Lithos, Vol. 318-319, pp. 478-493.Mantlemetasomatism
DS201812-2771
2018
Giuliani, A.Abersteiner, A., Kamenetsky, V.S., Goemann, K., Giuliani, A., Howarth, G.H., Castillo-Oliver, M., Thomspon, J., Kamenetsky,M., Cherry, A.Composition and emplacement of the Benfontein kimberlite sill complex ( Kimberley, South Africa): textural, petrographic and melt inclusion constraints.Lithos, doi.org/10.1016 /jlithos.2018 .11.017 32p.Africa, South Africadeposit - Benfontein

Abstract: The Benfontein kimberlite is a renowned example of a sill complex and provides an excellent opportunity to examine the emplacement and evolution of intrusive kimberlite magmas. We have undertaken a detailed petrographic and melt inclusion study of the Benfontein Upper, Middle and Lower sills. These sills range in thickness from 0.25 to 5?m. New perovskite and baddeleyite U/Pb dating produced ages of 85.7?±?4.4?Ma and 86.5?±?2.6?Ma, respectively, which are consistent with previous age determinations and indicate emplacement coeval with other kimberlites of the Kimberley cluster. The Benfontein sills are characterised by large variations in texture (e.g., layering) and mineral modal abundance between different sill levels and within individual samples. The Lower Sill is characterised by carbonate-rich diapirs, which intrude into oxide