 | | Journal (article/letter/editorial) | | diamonds from the Jagersfontein and Koffiefontein kimberlite, South Africa PETER DEINES,’J. W. HARRIS,’ and...GURNEYS ‘Department of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA 2Department...Department, University of Cape Town, Rondebosch 7700, South Africa (Received September 19, 1990; accepted in revised...Abstract-Asthenospheric diamonds, from the Jagersfontein kimberlite, South Africa, have a 613Crange from - 18.9 to -24.4%0...4%0 vs. PDB. Deep diamonds from the nearby Koffiefontein mine have 613Cvalues between -2.9 and -6.1 %o |  | | Journal (article/letter/editorial) | | W. HARRIS~ of Geosciences, The Pennsylvania State University, University Park, PA 16802, USA ‘Department...mineral inclusions among diamond suites from Koffiefontein, Orapa, Premier, Roberts Victor, Jagersfontein...inclusions of the African diamonds (mostly from Koffiefontein) could have been in chemical equilibrium with...relative abundance of silicate inclusions in Koffiefontein diamonds (93% peridotitic, 7% eclogitic) and...differs among kimberlites, however, for each kimberlite sulfide and silicate inclusion containing diamonds |  | Naidoo, P., Stiefenhofer, J., Field, M., Dobbe, R. (2004) Recent advances in the geology of Koffiefontein Mine, Free State Province, South Africa. Lithos, 76 (1) 161-182 doi:10.1016/j.lithos.2004.04.032 | Journal (article/letter/editorial) | | advances in the geology of Koffiefontein Mine, $ Free State Province, South Africa P. Naidoo a,b,*, J. Stiefenhofer...Beers Koffiefontein Mine, South Africa De Beers Mineral Resource Management, CHQ, South Africa c De Beers...Beers Geoscience Centre, South Africa d De Beers Central Mines, South Africa e De Beers Mineral Resource...geology of the Koffiefontein pipe has contributed to the marginal nature of the mine. The key to this...xenoliths. Recent work indicates that the kimberlite pipe at Koffiefontein consists of precursor dykes (the West |  | | Journal (article/letter/editorial) | | with similar datasets available for Ekati and Koffiefontein kimberlites, suggest a general pattern of metasomatic...peridotitic garnet and pyroxenes is expected in local mantle segments during fibrous diamond production...diamonds from one kimberlite. Izraeli et al. (2004) analysed mineral inclusions in Koffiefontein diamonds (RSA...fibrous and non-fibrous diamonds at Panda (Ekati mine, Canada, Slave craton) and concluded that metasomatism...formation of fibrous diamond from a Diavik mine kimberlite (Slave craton) and a metaconglomerate of the |  | Meyer, Nicole A., Wenz, Michelle D., Walsh, James P.S., Jacobsen, Steven D., Locock, Andrew J., Harris, Jeffrey W. (2019) Goldschmidtite, (K,REE,Sr)(Nb,Cr)O3: A new perovskite supergroup mineral found in diamond from Koffiefontein, South Africa. American Mineralogist, 104 (9) 1345-1350 doi:10.2138/am-2019-6937 | Journal (article/letter/editorial) | | supergroup mineral found in diamond from Koffiefontein, South Africa Nicole A. Meyer1,*, Michelle D. Wenz2...an inclusion in a diamond from the Koffiefontein pipe in South Africa. In addition to the dark green and...peak at 815 cm–1, which is possibly a result of local ordering of Nb and Cr at the B site. The name goldschmidtite...niobium, mantle, diamond inclusion, new mineral, Koffiefontein, Kaapvaal Introduction Diamonds are carriers...deep-mantle regions. The Kaapvaal craton in South Africa is host to many diamondiferous kimberlites that |  | | Book | | D) World Production E) South African Diamond Occurrences 1. Large Kimberlite Mines 1.1 Venetia 1.2 Premier...1.4 Kimberley 1.5 Koffiefontein 2. Smaller mineralised kimberlites in South Africa 2.1 The Oaks 2.2 The...relative production contributions in South Africa were, primary (kimberlite) 8.63 million carats (89% of total)...Premier mine. The proportion of gems in the West Coast marine deposits is over 98%. The MIBA mine in the...the Congo and the Argyle mine in Australia have an average gem content of only 5%. The dispersal of diamonds |  | HANSON, E.K., MOORE, J.M., BORDY, E.M., MARSH, J.S., HOWARTH, G., ROBEY, J.V.A. (2009) CRETACEOUS EROSION IN CENTRAL SOUTH AFRICA: EVIDENCE FROM UPPER-CRUSTAL XENOLITHS IN KIMBERLITE DIATREMES. South African Journal of Geology, 112 (2) 125-140 doi:10.2113/gssajg.112.2.125 | Journal (article/letter/editorial) | | EROSION IN CENTRAL SOUTH AFRICA: EVIDENCE FROM UPPER-CRUSTAL XENOLITHS IN KIMBERLITE DIATREMES E.K. HANSON...Rhodes University, P.O. Box 94, Grahamstown, South Africa email: emilykhanson@gmail.com; j.moore@ru.ac...Kimberley, South Africa email: jock.robey@debeersgroup.com © 2009 June Geological Society of South Africa ABSTRACT...Group II and fourteen Group I kimberlite diatremes in central South Africa were examined for upper crustal...Supergroup in the main Karoo basin at times of kimberlite eruption, the Cretaceous erosional history of |  | | Journal (article/letter/editorial) | | mineral inclusions in cloudy diamonds from Koffiefontein, South Africa ELAD S. IZRAELI,1,* JEFFREY W. HARRIS...in microinclusions in cloudy diamonds from Koffiefontein. The silicates belong to either the eclogitic...the larger mineral inclusions found in other Koffiefontein diamonds and record similar pressures and temperatures...mineral phases that were not detected before in Koffiefontein: phlogopite, high-Si mica, an Al-Mg-rich phase...with the high proportion of cloudy diamonds in Koffiefontein, suggest that brine penetration into neighboring |  | | Journal (article/letter/editorial) | | N-δ13C-inclusion profiles of cloudy diamonds from Koffiefontein: Evidence for formation by continuous Rayleigh...N-δ13Cinclusion profiles of cloudy diamonds from Koffiefontein: Evidence for formation by continuous Rayleigh...N-δ13C-inclusion profiles of cloudy diamonds from Koffiefontein: evidence for formation by continuous Rayleigh...zone (‘cloudy diamonds’) from the Koffiefontein mine, South Africa, were investigated for N concentrations...indicate formation of diamond shortly before AN kimberlite eruption from a single fluid without a time gap |  | | Journal (article/letter/editorial) | | Microinclusions analyzed in a coated diamond from the Diavik mine in Canada comprise peridotitic minerals and fluids...brine found in cloudy octahedral diamonds from South Africa and carbonatitic melt analyzed in cubic diamonds...a mantle source not significantly influenced by local heterogeneities. D 2004 Elsevier B.V. All rights...with brine inclusions in cloudy diamonds from Koffiefontein. This, together with the evidence for metasomatism...one concentrically zoned diamond from the Diavik mine in Lac de Gras, Slave Craton, Canada. Microinclusions |  | Timmerman, Suzette, Honda, Masahiko, Phillips, David, Jaques, Alan L., Harris, Jeffrey W. (2018) Noble gas geochemistry of fluid inclusions in South African diamonds: implications for the origin of diamond-forming fluids. Mineralogy and Petrology, 112. 181-195 doi:10.1007/s00710-018-0603-x | Journal (article/letter/editorial) | | Noble gas geochemistry of fluid inclusions in South African diamonds: implications for the origin of...the Finsch (n = 3), DeBeers Pool (n = 7), and Koffiefontein (n = 3) mines on the Kaapvaal Craton. C isotope...the Finsch (n = 3), DeBeers Pool (n = 7) and Koffiefontein (n = 3) kimberlites. These kimberlites are located...Geological background The Finsch, DeBeers Pool and Koffiefontein kimberlites are located on the western margin...Kimberley Block in the Kaapvaal Craton, South Africa. The Finsch kimberlite has an eruption age of ca.118 Ma |  | | Journal (article/letter/editorial) | | Sulphide inclusions in diamonds from the Koffiefontein kimberlite, S Africa: constraints on diamond ages and...Department of Geological Sciences, Durham University, South Road, Durham DH1 3LE, UK Department of Terrestrial...(P-type) parageneses in diamonds from the Koffiefontein mine, South Africa have been analysed using a technique...host diamond, crystallised close to the time of kimberlite emplacement (90 Ma), in the Mesozoic. This is...diamonds; geochronology; sulfides; inclusions; kimberlite 1. Introduction Knowledge of diamond crystallisation |  | Aulbach, Sonja, Shirey, Steven B., Stachel, Thomas, Creighton, Steven, Muehlenbachs, Karlis, Harris, Jeff W. (2009) Diamond formation episodes at the southern margin of the Kaapvaal Craton: Re–Os systematics of sulfide inclusions from the Jagersfontein Mine. Contributions to Mineralogy and Petrology, 157 (4) 525-540 doi:10.1007/s00410-008-0350-9 | Journal (article/letter/editorial) | | systematics of sulfide inclusions from the Jagersfontein Mine Sonja Aulbach Æ Steven B. Shirey Æ Thomas Stachel...inclusions in diamonds from the 90-Ma Jagersfontein kimberlite, intruded into the southern margin of the Kaapvaal...hosts, thus preserving the composition, thermal state, and early modifications of the cratonic mantle...diamond hosts. The mantle beneath the Jagersfontein kimberlite is of particular interest because it is situated... 1 Map (after Pearson et al. 1998) of southern Africa with political boundaries showing the outline of |  | | Journal (article/letter/editorial) | | The role of swelling clay in kimberlite weathering J. Morkel* and M. K. G. Vermaak Weathering tests on...single most important aspect when considering kimberlite weathering is the presence of swelling clay....Weathering, Kimberlite, Smectite, Cation exchange capacity (CEC) Introduction Kimberlite weathering is...understanding of the kimberlite weathering mechanism. Research work on kimberlite weathering has been...on this topic. The question is what renders a kimberlite vulnerable to size degradation by weathering |  | | Journal (article/letter/editorial) | | the lithospheric seismic structure of Southern Africa Steven B. Shirey a,*, Jeffrey W. Harris b, Stephen... Rondebosch 7701, South Africa d Department of Geological Sciences, Arizona State University, Box 871404...Department of Mineral Sciences, The Pennsylvania State University, University Park, PA, USA g De Beers...GeoScience Centre, PO Box 82232, Southdale, 2135, South Africa Abstract The Archean lithospheric mantle beneath...beneath the Kaapvaal – Zimbabwe craton of Southern Africa shows F 1% variations in seismic P-wave velocity |  | | Journal (article/letter/editorial) | | the Precambrian mantle lithosphere of southern Africa Steven B. Shirey Department of Terrestrial Magnetism...Sciences, University of Cape Town Rondebosch 7701, South Africa, e-mail: shr@geology.uct.ac.za Jeffrey W. Harris...Geological Society of South Africa ABSTRACT Two decades of diamond research in southern Africa allow the age...diamonds from the Kimberley area kimberlites, Koffiefontein, Orapa and Jwaneng have Re-Os isotopic ages...of Archean lithosphere, particularly in southern Africa, is to relate lithospheric structure to the age |  | | Report (issue) | | high quality pink diamonds for which the Williamson mine is known and sold for US$15 million in FY 2016 ...Optimise recoveries Improving operating margins at each mine Drive efficiencies Maintaining a culture of effective...benefit of this work as we are in line to become free cashflow positive in H2, with our cashflow profile...Operational Review 32 Finsch 34 Cullinan 37 Koffiefontein 38 Combined Kimberley Operations 40 Williamson...Supplementary Information 5 Focused on Africa TANZANIA Africa produces 47% of the world’s diamonds by |  | | Journal (article/letter/editorial) | | peridotite/eclogite paragenesis 15 from Southern Africa (Koffiefontein, Letlhakane, Orapa) were studied for trace...constraints that are 97 greater than or equal to the kimberlite eruption age, suggest heterogeneity in the mantle...117 2. Methods 118 Ten GMC diamonds from Koffiefontein (n=3), Orapa (n=4) and Letlhakane (n=3) were...122 (2017). Carbon isotope values for the Koffiefontein diamonds were measured in this study, 123 ...individual spot analyses for each of the 125 Koffiefontein diamonds is provided in Table 1; the carbon |  | | Journal (article/letter/editorial) | | diamond-forming fluids in the metasomatic ‘cocktail’ of kimberlite sources Yaakov Weiss 1,2 & Steven L. Goldstein...between mantle metasomatism, diamond formation and kimberlite eruptions in intracratonic provinces. We have...microinclusion-bearing diamonds from the Finsch Group II kimberlite, South Africa, and identified two diamond populations:...young saline metasomatic event that preceded kimberlite eruption by ~50 kyr to 15 Myr. The possible timing...eclogites which were identified as metasomatised by kimberlite or high-Mg carbonatite; suggesting a possible |  | | Journal (article/letter/editorial) | | Sciences, University of Cape Town, Rondebosch 7701, South Africa c Division of Earth Sciences, University of...Abstract Two decades of diamond research in southern Africa allow the age, average N content and carbon composition...diamonds from the Kimberley area kimberlites, Koffiefontein, Orapa and Jwaneng have Re – Os isotopic ages...and the Limpopo mobile belt known as the Southern Africa Seismic Experiment (SASE; James et al., 2001; James...averaged. This cylinder is centered below each diamond mine and extends from 150 to 225 km depth. Seismic data |  | | Journal (article/letter/editorial) | | KESSON AND J.D. FITZ G E R A L D sent in its local environment. However, a suite of diamonds from one...crystallized at much greater depths in the mantle. Some South African and Brazilian diamonds contain syngenetic...inclusion-bearing diamonds from kimberlite dykes at Orrorroo in South Australia. Three of the inclusions...like the first, recovered from pristine stones, free of cracks or fractures. An epigenetic origin for...coexisting Orrorroo, South Australia 57.4 Mw Mw solitary inclusions Koffiefontein, South Africa 57.1 0.03 1 |  | | Journal (article/letter/editorial) | | Sciences, University of Cape Town, Rondebosch 7701, South Africa Department of Terrestrial Magnetism, Carnegie...inclusions in diamonds from the 240 Ma Jwaneng kimberlite has revealed the presence of at least two generations...grains may be captured by young (relative to kimberlite emplacement) diamond or zircon growth (e.g.,...following young diamond formation immediately before kimberlite emplacement. However, the possibility of recent...times to explain the typical nitrogen aggregation state of lithospheric diamonds (e.g., Richardson and Harris |  | | Journal (article/letter/editorial) | | extant at the time of emplacement of the host kimberlite or lamproite. Some inclusions record thermal...celui qui existait lors de la mise en place de la kimberlite ou la lamproïte hôte, voire même plus froid que...composition of the clinopyroxene in orthopyroxene-free assemblages would be little affected by a variation...lithospheric keels of cratons, both the orthopyroxene-free polymineralic inclusions and the isolated inclusions...and would therefore reflect the ambient thermal state of the mantle at the time of eruption. Taking into |  | | Journal (article/letter/editorial) | | inclusions from De Beers Pool diamonds, Kimberley, South Africa D. Phillips a,*, J.W. Harris b, K.S. Viljoen...Mines Ltd., P.O. Box 82232, Southdale, 2135, South Africa b Received 27 June 2003; accepted 14 December...important De Beers Pool kimberlites in Kimberley, South Africa, are characterised by harzburgitic compositions...re-equilibration in a cooling mantle ( f 1050 jC) prior to kimberlite eruption at f 85 Ma. Pressure estimates for touching...diamonds are significantly older than the host kimberlite/lamproite magma, with some retaining mantle signatures |  | | Journal (article/letter/editorial) | | and their bearing on the fluid composition in kimberlite magmas. Am. Mineral. 92, 1200–1212]. At diamond...Phase relations and second critical endpoint in a K-free eclogite at 700 to 1400 °C. Earth Planet. Sci. Lett...rate is the same in the kimberlitic melts with a free fluid phase and in a pure H2O or CO2 fluid, suggesting...fibrous dia- monds typically has a low aggregation state (a-centers) suggesting short mantle residence time...indeed yielded ages similar to that of the host kimberlite (Pearson et al., 1998; Burgess et al., 2002) |
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