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| Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa e-mail: David.R.Bell@asu.edu ...University of Cape Town, Rondebosch 7700, South Africa Email: © 2004 Geological Society of South Africa ABSTRACT...subcontinental lithospheric mantle of southern Africa, and may be used to probe its compositional structure...garnet megacrysts from 61 kimberlites in southern Africa define four broad arrays on the basis of Cr2O3...mantle. High-Cr megacrysts in kimberlites of the northern cratonic areas bear the influence of lithospheric |
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| Ultramafic nodules from the Kimberley pipes, South Africa F. R. BOYD Geophysical Laboratory, Carnegie...collected in a number of other areas in southern Africa in two important respects: (1) There are no sheared...mosaic-porphyroclastic. In most nodule suites from southern Africa and elsewhere in the world, these low-temperature...low-temperature. mainly coarse peridotite xenoliths from northern Lesotho and other areas. Abundant sheared dunites...origin for the garnet lherzolites and for the enstatite discrete nodules shows an inflected geotherm for_Kimberley |
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| 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 |
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| Kimberlite-hosted diamond deposits of southern Africa: A review Matthew Field a,⁎, Johann Stiefenhofer...Southdale, 2135, South Africa c De Beers Group Services, PO Box 47, Kimberley, South Africa d De Beers Canada...discovery of diamonds in river deposits in central South Africa in the mid nineteenth century, it was at Kimberley...economic and industrial development of southern Africa. Following the discoveries at Kimberley, even more...more valuable deposits were discovered in South Africa and Botswana in particular, but also in Lesotho |
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| S. R. Hart, I. D. MacGregor, R. H. Mitchell, D. Smith, J. Ro Smyth, H. Go Wilshire The MantleSample...development since the First Kimberlite Conference, held in Cape Town in 1973, has come in the interpretation of...Diamond-Graphite Ecologite From the Roberts Victor Mine, C. J. Hatton and John J. Gurney .................Granulites and Eclogites From Lesotho, Southern Africa, W. L. Griffin, D. A. Carswell, and P. H. Nixon...Garnet Harzburgite XenolithsFrom the Premier Mine, South Africa, R. V. Danchin ........................ |
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| Mitchell, A. Nicolas, D.J. Powell, A.M. Reid, J.V. Smith, N.V. Sobolev, W.E. Stephens, and P.J. Wyllie. In...John Gurney and Joe Smith with whose research groups at the universities of Cape Town and Chicago I have...collaboration. Much of my fieldwork in southern Africa has been carried out with the cooperation and assistance...7.3 2.8 2.9 Africa . . . . . . . . . . . . . . . . . . . . . . . . . . . . West Africa . . . . . . .... . . . . Central Africa. . . . . . . . . . . . . . . . . . . . . . . East Africa. . . . . . . . . . |
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| rise and development of the diamond mines of South Africa, from an historical, economic and technical...collect during my many visits to all parts of South Africa where kimberlite deposits occurred and the filing...was necessary to file * "The Diamond Mines of South Africa," by Gardner F. Williams. V . Vl l I I...my attention from the time of my arrival in South Africa was the accidental and cognate inclusions found...had collected specimens from various parts of South Africa for years, it has only been since the publication |
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| CLINOPYROXENE MEGACRYST FROM BELLSBANK KIMBERLITE (SOUTH AFRICA) KEN-ICHIRO AOKI and HIROKAZU FUJIMAKI Institute...clinopyroxene megacryst from Bellsbank kimberlite (South Africa). Chem. Geol., 45: 165-171. REE abundances of...of major elements among coexisting diopside, enstatite and garnet, which have exsolved from the megacryst...thin parallel lamellae composed of diopside, enstatite and garnet are observed megascopically on the...the host crystal. Under the microscope, thick enstatite lamellae are visible, exsolved parallel to the |
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| metamorphism, and metasomatism: The complex history of South African upper-mantle symplectites Stephen W. Field*...are found in the Horoman peridotite complex in northern Japan (Takahashi and Arai 1989), in ultramafic...recovered from mafic lavas in the American southwest (Smith 2000), and in xenoliths found in Siberian kimberlites...(Zuyev 1971). In a study of peridotites from South Africa (Field and Haggerty 1994), up to one third of...that spinel-enstatite-olivine symplectites were eutectic intergrowths. Dawson and Smith (1975) proposed |
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| 1981) indicates that the former A12O3 contents in enstatite are too high at any chosen P-T condition. This...data, it would appear that alumina contents in enstatite reported by Akella (1974) and Akella & Boyd (1974)...accumulated on xenolith suites in kimberlites from South Africa, U.S.S.R, North America, and Australia. Estimation...revised best-fit geotherm for xenoliths from southern Africa, illustrated here in Fig. 4. Arguments concerning...garnet lherzolite nodules from kimberlites of South Africa (A) and other areas (B). Pressures estimated |
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| PETROGRAPHICAL STUDY OF THE COGNATE INCLUSIONS OLIVINE ENSTATITE BRONZITE GARNET KELYPHITE - CHEMICAL COMPOSITION...DIAMOND-BEARING ALLUVIAL GRAVELS OF THE UNION OF SOUTH AFRICA DIAMOND-BEARING GRAVELS DRAINAGE WEATHERING...SYSTEMS THE ORIGIN OF THE ALLUVIAL DIAMONDS THE SOUTH-WEST AFRICA DIAMOND DEPOSITS THE VAAL RIVER ALLUVIAL GRAVELS...Plate No. 96. THIN SECTION (359, X 12) FONTEIN MINE BRONZITE PERIDOTITE FROM JAGERS facing page 368...following plate MINE THIN SECTION (8, x 12) BRONZITE PERIDOTITE FROM BuLTFONTEIN 98. MINE ,, ,, 99. THIN |
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| the palaeogeotherm in the upper mantle beneath northern Lesotho was inflected in late Cretaceous times...cratonic areas, including Lesotho, Premier, Frank Smith, Siberia. Non-inflected geotherms beneath stable...equilibration temperature of xenoliths from the amount of enstatite in solid solution in the diopside (B.T.e. * Originally...1975), Mothae (Nixon and Boyd, 1973a; Dawson and Smith, 1975; Mori, 1975), Thaba Putsoa (Nixon and Boyd...depth-temperature relationships in the upper mantle beneath northern Lesotho at late Cretaceous times (G.L. Davis et |
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| (megacrysts) from the Kaapvaal craton of southern Africa, and provide direct evidence that some garnet in...affected by exsolution of garnet from orthopyroxene (enstatite) remains enigmatic; much more widely reported...described in orthopyroxene found as megacrysts at Frank Smith and Bellsbank diamond mines in the classic Kimberley...HIGHLY-REFRACTORY ARCHEAN LITHOSPHERE (BD1366) from Monastery mine, Lesotho (Aoki et al., 1980; Dawson, 2004; Dawson...lamellae in a large porphyroclast of orthopyroxene (enstatite) or as a ‘necklace’ along orthopyroxene grain |
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| understand the nature of the upper mantle in southern Africa and the processes that have modified it, including...within or near the Kaapvaal craton 1 of southern Africa (Figure 1) and it is the study of the geological...ultradepleted nod ules have been described from northern Lesotho (Carswell et a11979) but they are much...documented from northern Lesotho (Nixon & Boyd 1973b), Jagersfontein (MacGregor 1975), and Frank Smith '(Boyd...harzburgite nodules from kimberJites in southern Africa. Pyrolite quoted from Ringwood (1975). Table 1 |
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| calcite, clay minerals and fragments of crustal and local host country-rock. At Lattavaram the kimberlite...temperature range 850 to 1450°C for the system enstatite-pyrope and in the pres¬ sure range 30 to 105 kbar...are shown in Figure 1. The solid solubility of enstatite in pyrope increases gradually to 140 kbar and...Iherzolite nodules in kimberlites(from Lesotho and South Africa) and were analysed for isotopic compositions...Extended Abstract, First Kimberlite Conference, Cape Town, 23. Basu, A. R. and Murthy, V. R.(1977) EPSL |
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| clinopyroxene rnegacrysts from the Frank Smith Mine, Cape Province, South Africa D. B. CLARKE & G. G. PE-PIPER...clinopyroxene meg~crysts from the Frank Smith Mine, Cape Province, South Africa. Litfios, Vol. 16, pp. 75-84...0024-4.937. Two dinopyroxene megacrysts from the Frank Smith kimberfite show multiple exsoluti~n of garneL...the surface ~s accidental xenocryst~ by the Frank Smith kimberl~te. D. 8. Clarke & G. G. Pe-Piper, Department...Aoki et al. (1980) in megacr;sts from the Frank Smith Mine. These discontinuous garnet-only lamellae |
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| Geological Sciences, University of Cape Town, Rondebosch 7700, South Africa Department of Earth, Atmospheric...and Proterozoic lithospheric terranes in southern Africa during the Mesozoic was evaluated by thermobarometry...day distribution of surface heat flow in southern Africa is related to this dynamic event and is not a direct...cratons, of which the Kaapvaal craton of southern Africa is a well-studied example (De Wit et al., 1992)...Pollack 1993). In the regional case of southern Africa, the difference is accentuated to the extent that |
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| 1990 Silicate-bearingrutile-dominatednodulesfrom South African kimberlites: Metasomatizedcumulates DaNrrr...Kampfersdam and Jagersfonteinkimberlite pipes in South Africa contain euhedral olivines and spinels,graphic...and ilmenite are graphically intergrown with enstatite. These are interpreted as having crystallized...Haggerty,1987),and Jagersfontein and Kampfersdam in South Africa (Haggerty, 1983; Schulze,1983; Tollo and Haggerty...1979; Smith and Dawson, 1975),peridotites(Smith and Dawson, 1975),and MARID rocks (Dawson and Smith, 1977) |
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| Geology Department, University o f Cape Town, Cape Town (South Africa) and J.J. GURNEY Geochemistry Department...Department, University o f Cape Town, Cape Town (South Africa) Received March 11, 1975 Sharp has proposed...kimberlites involving plate tectonics and has used South Africa as the main example. This hypothesis is open...tendency for it to rebound. (2) The concept of the Cape Fold Belt as representing a subduction zone is probably...incorrect. The belt resulted from the deformation of the Cape Karroo Trough which has a maximum sediment thickness |
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| mineral in many Group I kimberlites (defined by Smith 1983), occurring in a variety of different associations...kimberlites (e.g. Monastery (Gurney et al. 1979) and Frank Smith (Pasteris et al. 1979)). These large grains are...pyroxene-ilmenite xenolith from the Weltevreden mine, which they suggest is also genetically related...lamellar intergrowths with pyroxenes in the Frank Smith kimberlite (Pasteris et al. 1979). In contrast...ilmenites from the Mayeng Kimberlite Sills, South Africa (adapted from Apter et al. 1984). Solid circles |
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| from 16 intrusions in Lesotho, the Republic of South Africa, and Tanzania have been investigated. The following...bronzite that are found in the kimberlites of northern Lesotho also show some fractures and cracks (NlxoN...the abundance of zircon in the Kimberley and Frank Smith mines, he admitted that zircon may possibly be...intergrowths are particularly common at Monastery mine (WHITELOCK 1973). Among the inclusions in zircon...inclusion of phlogopite in zircon from the Monastery mine (Fig. 1). A semiquantitative analysis proved the |
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| in xenoliths in the Jagersfontein Kimberlite, South Africa. Harzburgites of olivine and high-A1 (1.9-3...6 wt%), Ca (0.6-0.9 wt%) and Cr (0.3~.9 wt%) enstatite contain symplectites of spinel and diopside, or...2 wt%), Ca (0.10.4 wt%) and Cr (0.02-0.8 wt%) enstatite. From textures and mineral chemistries these symplectites...unmixing and migration from A1-Ca-Cr discrete enstatite to adjoining mineral interfaces. Garnet harzburgites...wt%), Ca (0.1-0.5 wt%), and Cr (0.1 0.3 wt%) enstatite and smaller interstitial garnet, diopside, and |
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| Richterite Bearing Peridotite Xenoliths from South Africa Ken-ichiro Aoki Institute of Mineralogy,Petrologyand...granular type garnet peridotite xenoliths from South Africa and Lesotho, except for an abnormally high content...100 km suffered local introduction of a potash-rich fluid, and garnet and enstatite reacted with this...identified in four peridotites (Erlank, 1973) from South Africa and Lesotho. Recent highpressure experiments...derived from the upper mantle from kimberlites in South Africa and Lesotho. In the course of a petrological |
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| several other pairs from South African kimberlites for comparison. In the lunar and South African samples the...with enstatite contents ranging from 79 to 86%. The SkaerM~TiO3 (GEtKIELITE) 3 M~ISiO~ (ENSTATITE) 2...60016; 2 = Monastery Mine, South Africa [4]; 3 = Frank Smith Mine, South Africa [5]; 4 = Skaergaard intrusion...composed of cumulus ilmenite and orthopyroxene. Smith et al. [ 18] indicate that ilmenite orthopyroxene...extraordinary event. Accordingly, we prefer melting of a local il- menite-orthopyroxene cumulate in response to |
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| Exsolved garnet-bearing pyroxene megacrysts from some South African rnbedites KEN-ICHIRO AOKI, HIROKAZU FUJIMAKI...Exsolved garnet~bearing pyroxene megacr;sts from some South African kimberlites. Lithos 13, 269-279. Oslo. ISSN...exsolved phase are found rarely in kimberlites from Frank Smith and Bellsbank. Chemically the cfinopyroxenes...gran~ar-type garnet peridotite xenoliths in Lesotho and South African kimberfites. Mineralogy and chemistry indicate...peridotite and g~Lrnet pyroxenite xenoliths, South Africa (MacCiregor 1973; Boyd 1974), an orthopyroxene |
