.... Here we investigate the mantle carbon and nitrogen sources and growth patterns from selected diamonds mined from four kimberlites: macro-sized diamonds from River Ranch kimberlite in Zimbabwe and the Swartruggens and Klipspringer kimberlitic deposits from South Africa, and micro-sized diamonds from...

... of the Swartruggens Kimberlite Dike Swarm, South Africa. Deformation includes local fracturing and brecciation and is associated with relay zones between offset dike segments. Breccia zones indicate dilation and hydraulic fracturing, and some zones along the dikes were affected by chemical corrosion, forming fresh...

.... The Swartruggens kimberlite dike swarm, Helam Mine, South Africa, consists of three dikes, two kimberlites (Main and Changehouse dikes) and a lamprophyre (Muil dike). The dikes were intruded at the end of the Jurassic ( Allsopp and Barrett, 1975 ; Phillips, 1991 ; Gurney and Kirkley, 1996 ) and cut...

...E. Cotter Abstract Mid- to Upper Devonian strata of the lower Witteberg Group in the Cape Fold Belt of South Africa comprise three principal facies deposited in the shoreface and contiguous inner shelfalong a storm-dominated coastal zone. Weakly burrowed mudrock with variable minor proportions...

...Fig. 1. Location map of the Swartruggens and Star kimberlite dyke swarms, South Africa, in relation to the Kaapvaal Craton. ...

..., bedrock morphology, and controls on deposition. The forensics of the source regions is fascinating. Some interesting facts are sprinkled throughout the book. For example, whereas Premier (Cullinan) is the largest known kimberlite in South Africa (32 ha), small Swartruggens has reported locally...

..., South Africa , 545 – 549 . McKenna , N. ( 2001 ). A study of the diamonds, diamond inclusion minerals and other mantle minerals from the Swartruggens kimberlite, South Africa . M.Sc. Thesis (unpublished), University of Cape Town , South Africa , 289 pp. McKenzie , D. ( 1985...

... of Africa some 858, 171 of them including carbonatite. Nowhere else in the world are there such rich petrological pickings. Extrusive carbonatite is a newish topic, and of the 39 occurrences known worldwide, 24 are in Africa. Curiously, lamproites seem to be absent from Africa apart from a possible...

.... Hammond, R.H. Mitchell (2002) Accessory mineralogy of orangeite from Swartruggens, South Africa. Mineral. Petrology, 76, 1–19. The mineral occurs as euhedral grains, up to 60 μm across, that have a hexagonal habit and are dark reddish to purplish brown, almost opaque in thin section. The average...

... International Kimberlite Conference , Novosibirsk, Russia , 71 – 73 . De Bruin , D. ( 1998 ). Inclusion bearing Cr-poor and Cr-rich garnet megacrysts from the Group II Swartruggens kimberlite. Extended Abstracts, 7th International Kimberlite Conference , Cape Town, South Africa , 181 – 183...

.... PHN2751 is from Kampfersdam, South Africa. This rock consists almost entirely of phlogopite and would be referred to as a “glimmerite” by kimberlite petrologists. Minor diopside and ilmenite are also present. The mica is predominantly recrystallised in platelets (0.1 mm) but some porphyroclasts range up...

... varieties of hypabyssal facies kimberlite. As the Voorspoed kimberlite is located between the approximately 120 Ma Barkly West and the approximately 145 Ma Swartruggens kimberlites, accurate determination of an intrusion age is crucial to the evaluation of the Group II age progression across southern Africa...

... , 114 , 172 pp. De Bruin , D. ( 1998 ). Inclusion bearing Cr-poor and Cr-rich garnet megacrysts from the Group II Swartruggens kimberlite . Extended Abstracts, 7th International Kimberlite Conference, Cape Town, South Africa , 181 – 183 . De Bruin , D. ( 2000a ). The mineral...

.... and Ringwood , A.E. ( 1989 ). Slab-mantle interactions, 2. The formation of diamonds . Chemical Geology , 78 , 97 – 118 . Klump , J. ( 1995 ). A pilot study of the Swartruggens kimberlite dyke swarm . Unpublished B.Sc. Honours Thesis, University of Cape Town , South Africa , 33 pp...

...-octahedral diamonds have been reported in nature. Diamonds from the Swartruggens dike in the Helam Mine, South Africa, exhibit cubo-octahedral growth sectors ( McKenna et al., 2004 ). Octahedral diamonds from Yakutian kimberlites have cubo-octahedral growth bands ( Bulanova, 1995 ). This growth pattern can...

... to the Lebombo. After appropriate analysis, poles derived from Lesotho lavas, Karoo dolerite dykes and sills, Sabie River basalts, Mashikiri and Letaba lavas, and Jozini rhyolites, when averaged, yielded a palaeomagnetic (south) pole at: N = 6, latitude = -69.2, longitude = 98.3, alpha = 3.3. The sites...

... the absence of diamonds from Mesozoic kimberlites and Cainozoic fossils within the gravels support the conclusion that the runs are of Karoo age. e-mail: [email protected] © 2016 December Geological Society of South Africa 2016 Geological Society of South Africa Diamond-bearing gravels...

... , G. ( 2008 ) Petrogenesis of the Swartruggens and Star Group II kimberlite dyke swarms, South Africa: constraints from whole rock geochemistry . Contrib. Mineral. Petrol. v .v. 156 , pp. 627 – 652 . Dawson , J.B. ( 1980 ) Kimberlites and their xenoliths . Springer-Verlag , Berlin...