 | | Journal (article/letter/editorial) | | bodies Roger N. Scoon PO Box 2461, Rivonia 2128, South Africa e-mail: rnscoon@iafrica.com Andrew A. Mitchell...4000, South Africa e-mail: mitchell@pixie.udw.ac.za Ā© 2004 Geological Society of South Africa ABSTRACT...are emplaced in the Upper Critical zone, the Onverwacht and Twyfelaar pipes occur in the Lower Critical...evaluation and mining of the Driekop, Mooihoek and Onverwacht pipes, which are among the oldest platinum mines...Cr-spinel. The magnesian dunite forms comparatively deep-rooted, stock-like bodies. At Onverwacht and |  | | Journal (article/letter/editorial) | | FROM THE ONVERWACHT AND TWEEFONTEIN ULTRAMAFIC PIPES, EASTERN BUSHVELD COMPLEX, SOUTH AFRICA FEDERICA...Witwatersrand, PO Wits 2050, South Africa ABSTRACT The ultramafic pipes of Onverwacht and Tweefontein, in the...the eastern part of the Bushveld Complex, in South Africa, contain small xenoliths of chromitite that...Complex, Republic of South Africa. SOMMAIRE Les pipes ultramafiques de Onverwacht et Tweefontein, dans...The Merensky Reef in the Bushveld Complex, in South Africa, was discovered at about the same time (1924) |  | | Report (issue) | | SURVEY OF SOUTH AFRICA COUNCIL FOR GEOSCIENCE GEOLOGICAL SURVEY OF SOUTH AFRICA MINERALOGY OF SOUTH AFRICA:... COUNCIL FOR GEOSCIENCE GEOLOGICAL SURVEY OF SOUTH AFRICA Scientific Editor R.D. Dixon Linguistic and...Council for Geoscience (Geological Survey of South Africa), 280 Pretoria Street, Silverton, Pretoria or........................... 69 5.1 Overview of South African Occurrences ..............................LAYEREDSUITE,BUSHVELDCOMPLEX.... 111 MINERALOGY OF SOUTH AFRICA: TYPE-MINERAL SPECIES AND TYPE-MINERAL NAMES |  | | Journal (article/letter/editorial) | | EUGENE N. CAMERON OF SOUTH AND No. 2 PEGMATITES THE BUSHVELD AFRICA GEORGE A. DESBOROUGH ABSTRACT...same origin. The outer forsteritic dunite of the Onverwacht platinum pipe has formed by replacementof bronzititesof...consistentwith structural relations of the core to the Steelpoort Main chromitite seam, as reportedby Wagner and...pegrnatitesin the easternpart of the BushveldComplexof South Africa have been known for many years. The pegmatitesare...pegmatiteare in the platinum-bearing pipes of Onverwacht,Mooihoek,and Driekop,minedchieflyin the 1920's |  | | Journal (article/letter/editorial) | | REPLACED MERENSKY REEF AT THE AMANDELBULT MINE, SOUTH AFRICA R.N. SCOON Department of Geology, Rhodes...Rhodes University, Grahamstown 6140, South Africa e-mail: rnscoon@iafrica.com A.A. MITCHELL School of Geological...4000, South Africa e-mail: mitchaa@mweb.co.za Ā© 2011 March Geological Society of South Africa ABSTRACT...in the eastern limb of the Bushveld Complex, South Africa, differ sufficiently from one another to warrant...In our previous contributions on the Driekop, Onverwacht, and Twyfelaar localities we noted that despite |  | | Journal (article/letter/editorial) | | hortonolitedunites, and dunite-bronzitites from the Onverwacht,Mooihoek,and Driekoppipesrevealedthe presenceof... mineralsof the pipes. the three dunRe pipes,Onverwacht,Mooihoek,and The unique geologicalpositionof...the Introduction ton Pt were encountered at Onverwacht and annual productionfrom the three pipeswason...pipeswason the order of 15,000 ozs. Driekop was the last mine to ceaseoperationsin 1961. The disappearanceof these...connection"implied magmaticassociation, it also, The pipesof Onverwacht,Mooihoek,and Driekop and even better, fits the |  | | Journal (article/letter/editorial) | | ROGER N. SCOONā P.O. Box 2461, Rivonia 2128, South Africa AND ANDREW A. MITCHELL School of Geology,...KwaZulu-Natal, Private Bag 54001, Durban 4000, South Africa Abstract Discordant ultramafic bodies are a...significant feature of the Bushveld Complex, South Africa. Many of these bodies form subvertical, cylindrical...assemblage of forsteritic olivine with accessory Cr spinel), together with an extensive rim of clinopyroxenite...magnesian dunite pipes were forsteritic olivine and Cr spinel. Crystallization of orthopyroxene and plagioclase |  | | Journal (article/letter/editorial) | | Metallurgy (NIM) Bon Accord Mpumalanga Province South Africa BRUCE CAIRNCROSS N Department of Geology University...PO Box 524, Auckland Park 2006 Johannesburg South Africa brucec@uj.ac.za IMITE, (Ni,Mg,Al)6(Si,Al)4O10(OH)8...Barberton greenstone belt, Mpumalanga Province, South Africa. Figure 1. Entrance to the Council for Mineral...of Johannesburg city center, in the Randburg municipality. Bruce Cairncross photo (February 2017). Volume...for Metallurgy (NIM) based in Johannesburg, South Africa, subsequently renamed in 1981 as MINTEK, the |  | | Journal (article/letter/editorial) | | of the discorthe famous Driekop, Mooihoek, and Onverwacht dant bodies of ultramarie rock have a detrimental...observed although hybrid chromite-Ti magnetite spinel may occur. The nature of the pyroxene(orthopyroxene...DISCORDANT BODIES 1113 To the north of the Steelpoort valley in the The platiniferouscore zone in the...iron-richultramaficpegmatiteare abun- Mooihoek, and Onverwacht, aswell as a subeconomic dant in the upper critical...bodies are particularly abundantin the that the Onverwacht pipe resulted from in situ areasadjacentto the |  | | Journal (article/letter/editorial) | | PIPE, EASTERN LIMB OF THE BUSHVELD COMPLEX, SOUTH AFRICA R.N. SCOON Postnet Suite 291, Private Bag X31...Durban 4000, South Africa e-mail: mitchaa@mweb.co.za Ā© 2009 June Geological Society of South Africa ABSTRACT...on the basis of detailed mapping and sampling of mine workings that are not generally accessible. The...at Driekop are distinguished by the absence of a spinel phase. The pipe crosscuts a thick sequence of leucocratic...through a vertical conduit. Magnesian olivine and Cr-spinel were the only liquidus phases during this phase |  | | Journal (article/letter/editorial) | | ultramafic pegmatite at the Amandelbult Platinum mine, northwestern Bushveld Complex R. N. SCOON1,* 1...2128, South Africa Department of Geology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa...pegmatite are described from the Amandelbult Platinum mine in the northwestern part of the Bushveld Complex...Ti-magnetite, disseminated Fe-Ti-Cr spinel and massive Fe-Ti-Cr spinel. The Fe-Ti-Cr spinels show a range...relationship was found between stratigraphic height and spinel-type, with the Fe-Ti-Cr spinels restricted to pegmatites |  | | Journal (article/letter/editorial) | | University of the Witwatersrand, PO Wits, 2050, South Africa e-mail: 065rgc@cosmos.wits.ac.za C. Harris Department... University of Cape Town, Rondebosch, 7700, South Africa F. J. Kruger Hugh Allsopp Laboratory of the...University of the Witwatersrand, PO Wits, 2050, South Africa Editorial responsibility: A. Hofmann pared...considered to have formed by replacement as a result of local migration of residual magma from the underlying...example, the platiniferous olivine-rich pipes of Onverwacht, Driekop and Mooihoek (Fig. 1b) have been mined |  | | Journal (article/letter/editorial) | | 155 THE PRINCIPAL GEOLOGICAL FEATURES OF THE ONVERWACHT PLATINIFEROUS DUNITE PIPE, EASTERN LIMB OF THE...Geology, Rhodes University, Grahamstown 6140, South Africa e-mail: rnscoon@iafrica.com A.A. MITCHELL Department...Durban 4000, South Africa e-mail: mitchaa@mweb.co.za Ā© 2010 June Geological Society of South Africa ABSTRACT...ABSTRACT The Onverwacht pipe, situated on the leasehold of Eastern Chrome mines in the eastern limb of the...as it is the site of the oldest platinum mine in South Africa. The central part of the pipe consists of |  | Toulkeridis, Theofilos, Goldstein, Steve L., Clauer, Norbert, Krƶner, Alfred, Todt, Wolfgang, Schidlowski, Manfred (1998) SmāNd, RbāSr and PbāPb dating of silicic carbonates from the early Archaean Barberton Greenstone Belt, South Africa. Precambrian Research, 92 (2) 129-144 doi:10.1016/s0301-9268(98)00071-0 | Journal (article/letter/editorial) | | the early Archaean Barberton Greenstone Belt, South Africa Evidence for post-depositional isotopic resetting...silicic carbonate sequences occurring in the Onverwacht Group (OG) and the overlying Fig Tree Group (FTG)...the early Archaean Barberton Greenstone Belt, South Africa, contain silicified dolomites with primary structures...rocks dated by single zircons. The associated Onverwacht felsic volcanics have an age of ~3440ā3416 Ma...carbonate rocks by various isotopic methods of the Onverwacht and Fig Tree Groups from the early Archaean Barberton |  | | Journal (article/letter/editorial) | | Complex, South Africa R.N. Scoon Department of Geology, Rhodes University, Grahamstown 6140, South Africa...Geology, Rhodes University, Grahamstown 6140, South Africa Department of Earth, Environmental and Planetary...Operations South Africa, Rustenburg, South Africa Ā© 2017 June Geological Society of South Africa Abstract...Abstract The 2055 Ma Bushveld Complex, South Africa, is well known for the occurrence of discordant bodies...Kennedy's Vale discordant body, situated in the Steelpoort Valley section of the Eastern Limb, has been |  | | Journal (article/letter/editorial) | | layers in the Barberton greenstone belt of southern Africa and one in the Pilbara greenstone belt of Western...preserved layers. Some spherules contain up to 40% spinel, which is often the only primary phase that crystallized...Closely associated komatiites in the underlying Onverwacht Group, both fresh and highly altered, have unaltered...and morphologies quite distinct from the impact spinel. Characteristics of spine1 preserved in these Archean...impact spine1 has higher Ni/Fe than Cenozoic impact spinel, though distinctly lower Fe+3/Fe+2, which probably |  | | Journal (article/letter/editorial) | | Petrogenesis of some Archaean Volcanic Rocks from Southern Africa by C. J. HAWKESWORTH 1 and R. K. O'NIONS 2 Department...from greenstone belts in Rhodesia (~2-6 by) and South Africa (~3-4 by). In Rhodesia two distinct series can...better documented greenstone belts in southern Africa, Western Australia and North America. A detailed... The Swaziland Sequence of South Africa (or at least the lower Onverwacht Series) appears to be older...a basal ARCHAEAN VOLCANIC ROCKS FROM SOUTHERN AFRICA 489 ANALYTICAL METHODS Si, Al, Fe, Mg, Ca, Mn |  | OāDriscoll, B., Clay, P. L., Cawthorn, R. G., Lenaz, D., Adetunji, J., Kronz, A. (2014) Trevorite: Ni-rich spinel formed by metasomatism and desulfurization processes at Bon Accord, South Africa?. Mineralogical Magazine, 78 (1) 145-163 doi:10.1180/minmag.2014.078.1.11 | Journal (article/letter/editorial) | | Ni-rich spinel formed by metasomatism and desulfurization processes at Bon Accord, South Africa? B. OāDRISCOLL1...University of the Witwatersrand, PO Wits, 2050 South Africa Dipartimento di Geoscienze, Trieste University...maļ¬cultramaļ¬c lavas of the Barberton Greenstone Belt (South Africa). Though now completely mined out, it comprised...WORDS : trevorite, spinel, metasomatism, desulfurization, Bon Accord, South Africa. Introduction TREVORITE...TREVORITE is a rare Ni-rich spinel (NiFe3+ 2 O4) endmember more commonly reported in meteorites than from |  | | Book | | Archaean Geology of the Kaapvaal Craton, Southern Africa Regional Geology Reviews Series editors Roland... Nelson Mandela University, Port Elizabeth, South Africa FranƧois M. Roure, Rueil-Malmaison, France ...Archaean Geology of the Kaapvaal Craton, Southern Africa 123 Editors Alfred Krƶner Institut fĆ¼r Geowissenschaften...Geology University of Johannesburg Auckland Park, South Africa ISSN 2364-6438 ISSN 2364-6446 (electronic)...continued interest. The Kaapvaal Craton of Southern Africa is featuring prominently in early Earth studies |  | Scoon, Roger N., Mitchell, Andrew A. (2019) Discussion of āOxygen isotope and trace element compositions of platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component?ā by GĆ¼nther, T., Haase, K.M., Junge, M., OberthĆ¼r, T., Woelki, D., and Krumm, S. Lithos, 324. 893-898 doi:10.1016/j.lithos.2018.09.023 | Journal (article/letter/editorial) | | platiniferous dunite pipes of the Bushveld complex, South Africa - Signals from a recycled mantle component?ā...platiniferous dunite pipes of the Bushveld complex, South Africa - Signals from a recycled mantle component?ā...platiniferous dunite pipes of the Bushveld Complex, South Africa - Signals from a recycled mantle component?ā...University, Grahamstown 6140, South Africa 2 PO Box 421, McGregor 6708, South Africa MA NU SC 1 TE D...platiniferous dunite pipes of the Bushveld Complex, South Africa in many respects. The attempt to suggest there |  | | Journal (article/letter/editorial) | | spherule beds in the Barberton Mountain Land, South Africa: no evidence for impact origin Christian Koeberl...spherule-rich layers in the Barberton Mountain Land, South Africa, which were previously inferred by Lowe and...(94)00099-9 in the Kaapvaal Craton of southern Africa (Fig. I). The stratigraphy consists of a lower...lower, predominantly volcanic, sequence, the Onverwacht Group, which is overlain by two mainly sedimentary...KILOMETERS - LOCALITY 5 ', BOTSWANA "" --'/ SOUTH - r._ ,,F: ( " Fig. 1. Geologicalmap of the |  | DZIGGEL, A., KNIPFER, S., KISTERS, A.F.M., MEYER, F.M. (2006) P-T and structural evolution during exhumation of high-T, medium-P basement rocks in the Barberton Mountain Land, South Africa. Journal of Metamorphic Geology, 24 (7) 535-551 doi:10.1111/j.1525-1314.2006.00653.x | Journal (article/letter/editorial) | | basement rocks in the Barberton Mountain Land, South Africa A . D Z I G G E L ,1 S . K N I P F E R ,1 A...Stellenbosch, Private Bag X1, Matieland 7602, South Africa ABSTRACT The PāT evolution of amphibolite...Paleo to MesoArchean Barberton greenstone belt, South Africa, has been reconstructed via detailed structural...c. 3550ā3100 Ma Barberton greenstone belt in South Africa is generally considered to be a remnant of an...shows location of the greenstone belt in southern Africa. Terrane is ļ¬anked by high-grade gneisses and |  | | Book | | APPRECIATION R. M. Shackleton THE STRUCTURAL FRAMEWORK OF AFRICA Xi 1 T. N. Clifford ARCHAEAN VULCANICITY AND...KIBARIDE AND KATANGIDE OROGENIC BELTS OF CENTRAL AFRICA 97 L. Cahen OROGENIC AND POST-OROGENIC PLUTONISM...SOUTHERN AFRICA 157 O. Von Knorring LATE PALAEOZOIC TO RECENT IGNEOUS ACTIVITY IN WEST AFRICA AND ITS...CONTENTS 12 VULCANICITY AND RirT TECTONICS IN EAST AFRICA B. C. King 13 TECTONIC AND MAGMATIC EVOLUTION...OF DYKES AND RELATED IRRUPTIVE ROCKS IN EASTERN AFRICA 337 \ J. R. Vail 17 GEOCHEMICAL VARIATIONS IN |  | | Journal (article/letter/editorial) | | zeh@kit.edu Ā© March 2019 Geological Society of South Africa Abstract Archean terrestrial-marine transitional...therein). Because of their important role in the SOUTH AFRICAN JOURNAL OF GEOLOGY 2019 ā¢ VOLUME 122.1 PAGE...Group of the Barberton Greenstone Belt (BGB), South Africa. Our data show an estuary fed by erosion from...Ga Barberton Greenstone Belt of northeastern South Africa and Eswatini (formerly Swaziland; Figure 1)...generally ļ¬ne-grained sedimentary rocks. The Onverwacht Group (3 570 to 3 260 Ma) mostly consists of |  | | Journal (article/letter/editorial) | | DISCUSSION Discussion of āThe Bushveld Complex, South Africa: formation of platinumāpalladium, chromeand...of Geology, Rhodes University, Grahamstown, South Africa e-mail: rnscoon@iafrica.com A. A. Mitchell School...KwaZulu-Natal, Private Bag X54001, Durban 4000, South Africa De Klerk, Canad Mineral 25:51ā77, 1987) and...from the Upper Critical Zone at the Amandelbult mine (32 samples), 2 magnesian dunite, Winnaarshoek pipe...are mistaken in this regard) with accessory Cr-spinel (Scoon and Mitchell 2004b). The mineralogy and |
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