||It has been suggested that Karoo System be merged into this article. (Discuss) Proposed since May 2012.|
|Stratigraphy of the Karoo Supergroup in the Karoo Basin|
|Period||Group||Formation west of 24°E||Formation east of 24°E||Assemblage Zone|
|Tierberg / Fort Brown||Fort Brown|
|Laingsburg / Ripon||Ripon|
|White Hill||White Hill|
|Prince Albert||Prince Albert|
The Karoo Supergroup is the most widespread stratigraphic unit in Africa south of the Sahara 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.
In southern Africa, rocks of the Karoo Supergroup cover almost two thirds of the present land surface, including central Cape Province, almost all of Orange Free State, western Natal, much of south-east Transvaal, Zambia, Zimbabwe and Malawi. The basins in which it was deposited formed during the formation and breakup of Pangea.
Its strata, mostly shales and sandstones, 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. This basin was formed by the subduction and orogenesis along the boundary of Gondwana (the past African continent) and the Panthalassan Sea (paleo-Pacific). Its sediments attain a maximum cumulative thickness of 12 km, with the overlying basaltic lavas (the Drakensberg Group) at least 1.4 km thick.
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.
The type area for the Karoo Supergroup is the Great Karoo Basin in South Africa and Lesotho, where the sequence is exposed in outcrops. In the Great Karoo Basin, the Karoo Supergroup is divided into the following stratigraphic groups (from oldest to youngest):
- Dwyka Group, tillite and other glaciogenic deposits
- Ecca Group, clastic sedimentary rocks, including coal deposits
- Beaufort Group, terrestrial sedimentary rocks, largely of fluvial origin
- Stormberg Group, including and ending with the Drakensberg flood basalts
In Zambia, Zimbabwe and Mozambique the Karoo Supergroup is divided into (from oldest to youngest):
- Lower Karoo Group, comprising the Dwyka, Hwange (Zimbabwe) / Siankondobo (Zambia) and Madumabisa formations.
- Upper Karoo Group, comprising the Escarpment Grit formation (in the Mid-Zambezi and Limpopo basins) and the Angwa Sandstone Formation (in the Mana Pools and Cabora Bassa Basins), overlain by the Pebbly Arkose Formation and the Forest Sandstone Formation, capped by Batoka basalts.
- 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.
- Selden, P.; and Nudds, J. (2011). "Karoo". Evolution of Fossil Ecosystems (2 ed.). Manson Publishing. pp. 104–122. ISBN 9781840761603.
- 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.
- Catuneanu, O; Wopfner, H; Eriksson, P; Cairncross, B; Rubidge, B; Smith, R; Hancox, P (2005). "The Karoo basins of south-central Africa". Journal of African Earth Sciences 43 (1–3): 211. Bibcode:2005JAfES..43..211C. doi:10.1016/j.jafrearsci.2005.07.007.
- Hamilton, G.N.G. and Finlay, J.G. (1928), Outline of Geology for South African Students, Central News Agency Ltd., Johannesburg.
- 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), Schriftenreihe der Deutschen Geologischen Gesellschaft, 1: 88-89, Bonn.
- 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.
- Catuneanu, O.; Wopfner, H.; Eriksson, P.G.; Cairncross, B.,Rubidge, B.S., Smith, R.M.H.,Hancox, P.J. (2005). "The Karoo basins of south-central Africa". Journal of African Earth Sciences 43: 211–253. Bibcode:2005JAfES..43..211C. doi:10.1016/j.jafrearsci.2005.07.007.
- Nyambe, Imasiku A.; Utting, John (1997). "Stratigraphy and palynostratigraphy, Karoo Supergroup (Permian and Triassic), mid-Zambezi Valley, southern Zambia". Journal of African Earth Sciences 24 (4): 563. Bibcode:1997JAfES..24..563N. doi:10.1016/S0899-5362(97)00081-X.
- Bordy, Emese M.; Catuneanu, Octavian (2001). "Sedimentology of the upper Karoo fluvial strata in the Tuli Basin, South Africa". Journal of African Earth Sciences 33 (3–4): 605. Bibcode:2001JAfES..33..605B. doi:10.1016/S0899-5362(01)00090-2.
- d'Engelbronner, E.R. (1996). "New palynological data from Karoo sediments, Mana Pools basin, northern Zimbabwe". Journal of African Earth Sciences 23: 17. Bibcode:1996JAfES..23...17D. doi:10.1016/S0899-5362(96)00049-8.
- Jones, D. L.; Duncan, R. A.; Briden, J. C.; Randall, D. E.; MacNiocaill, C. (2001). "Age of the Batoka basalts, northern Zimbabwe, and the duration of Karoo Large Igneous Province magmatism". Geochemistry Geophysics Geosystems 2 (2). Bibcode:2001GGG.....2.1022J. doi:10.1029/2000GC000110.
- Ponomarenko A.G. & Mostovski M.B. 2005. New beetles (Insecta: Coleoptera) from the Late Permian of South Africa. African Invertebrates 46: 253-260.
- Sukatsheva I.D., Beattie R. & Mostovski M.B. 2007. Permomerope natalensis sp. n. from the Lopingian of South Africa, and a redescription of the type species of Permomerope (Insecta: Trichoptera). African Invertebrates 48 (2): 245-251.