Back Karoo-supergroep Afrikaans Supergrup Karoo Catalan Karoo-Supergruppe German Supergrupo Karoo Spanish Supergroupe du Karoo French Supergruppo del Karoo Italian カルー超層群 Japanese Karoosupergroep Dutch Супергрупа Кару Ukrainian

Karoo Supergroup

Stratigraphy of the Karoo Supergroup in the Karoo Basin
Period Group Formation west of 24°E Formation east of 24°E Assemblage Zone
Jurassic Drakensberg Hiatus Drakensberg
Stormberg Clarens
Triassic Elliot
Molteno
Beaufort
Burgersdorp Cynognathus
Katberg Lystrosaurus
Balfour
Permian Dicynodon
Teekloof
Cistecephalus
Middleton
Tropidostoma
Pristerognathus
Abrahams-Kraal Abrahams-Kraal
Tapinocephalus
Eodicynodon
Ecca Waterford Waterford
Tierberg / Fort Brown Fort Brown
Laingsburg / Ripon Ripon
Collingham Collingham
Whitehill Whitehill
Prince Albert Prince Albert
Carboniferous Dwyka Elandsvlei Elandsvlei
References: Rubidge (2005),[1] Selden and Nudds (2011).[2]

The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Kalahari Desert. The supergroup consists of a sequence of units, mostly of nonmarine origin, deposited between the Late Carboniferous and Early Jurassic, a period of about 120 million years.[3]

In southern Africa, rocks of the Karoo Supergroup cover almost two thirds of the present land surface, including all of Lesotho, almost the whole of Free State, and large parts of the Eastern Cape, Northern Cape, Mpumalanga and KwaZulu-Natal Provinces of South Africa. Karoo supergroup outcrops are also found in Namibia, Eswatini, Zambia, Zimbabwe and Malawi, as well as on other continents that were part of Gondwana. The basins in which it was deposited formed during the formation and breakup of Pangea.[4][5] The type area of the Karoo Supergroup is the Great Karoo in South Africa, where the most extensive outcrops of the sequence are exposed.[3][6] Its strata, which consist mostly of shales and sandstones,[7] record an almost continuous sequence of marine glacial to terrestrial deposition from the Late Carboniferous to the Early Jurassic. These accumulated in a retroarc foreland basin called the "main Karoo" Basin.[4] This basin was formed by the subduction and orogenesis along the southern border of what eventually became Southern Africa, in southern Gondwana.[4] Its sediments attain a maximum cumulative thickness of 12 km, with the overlying basaltic lavas (the Drakensberg Group) at least 1.4 km thick.[8]

Fossils include plants (both macro-fossils and pollen), rare insects and fish, common and diverse tetrapods (mostly therapsid reptiles, temnospondyl amphibians, and in the upper strata dinosaurs), and ichnofossils. Their biostratigraphy has been used as the international standard for global correlation of Permian to Jurassic nonmarine strata.[9]

A timeline of the Earth's geological history, with an emphasis on events in Southern Africa. The green block labeled K indicates when the Karoo Supergroup was deposited, in relation to the Cape supergroup, C, immediately before it. The W indicates when the Witwatersrand supergroup was laid down, very much further in the past. The graph also indicates the period during which banded ironstone formations were formed on Earth, indicative of an oxygen-free atmosphere. The Earth's crust was wholly or partially molten during the Hadean Eon; the oldest rocks on Earth are therefore less than 4000 million years old. One of the first microcontinents to form was the Kaapvaal Craton, which forms the foundation of the north-eastern part of the country. The assembly and break-up of Gondwana are, in terms of the Earth's and South Africa's geological history, relatively recent events.
  1. ^ Rubidge, B.S. (2005). "Re-uniting lost continents – Fossil reptiles from the ancient Karoo and their wanderlust". South African Journal of Geology. 108 (1): 135–172. doi:10.2113/108.1.135.
  2. ^ Selden, P.; and Nudds, J. (2011). "Karoo". Evolution of Fossil Ecosystems (2 ed.). Manson Publishing. pp. 104–122. ISBN 9781840761603.
  3. ^ a b Schlüter, Thomas (2008). Geological Atlas of Africa: With Notes on Stratigraphy, Tectonics, Economic Geology, Geohazards and Geosites of Each Country (2nd ed.). Springer. pp. 26–28. ISBN 9783540763734.
  4. ^ a b c Catuneanu, O; Wopfner, H; Eriksson, P; Cairncross, B; Rubidge, B; Smith, R; Hancox, P (2005). "The Karoo basins of south-central Africa" (PDF). Journal of African Earth Sciences. 43 (1–3): 211. Bibcode:2005JAfES..43..211C. doi:10.1016/j.jafrearsci.2005.07.007.
  5. ^ McCarthy, T., Rubridge, B. (2005). The Story of Earth and Life. pp. 161, 187–241. Struik Publishers, Cape Town
  6. ^ Geological map of South Africa, Lesotho and Swaziland (1970). Council for Geoscience, Geological Survey of South Africa.
  7. ^ Hamilton, G.N.G. and Finlay, J.G. (1928). Outline of Geology for South African Students, Central News Agency Ltd., Johannesburg.
  8. ^ Adelmann, D. and Kerstin Fiedler, (1996). "Sedimentary development of the Upper Ecca and Lower Beaufort Groups (Karoo Supergroup) in the Laingsburg subbasin (SW Karoo Basin, Cape Province/South Africa)" Archived 2005-09-03 at the Wayback Machine, Schriftenreihe der Deutschen Geologischen Gesellschaft, 1: 88–89, Bonn.
  9. ^ Hancox, P. J. and Bruce S. Rubidge (1997). The role of fossils in interpreting the development of the Karoo basin, Palaeontologica Africana, 33: 41–54.
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