Karoo Supergroup

The Karoo Supergroup is the largest stratigraphic unit in Southern Africa, covering 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.[1]

Its strata, mostly shales and sandstones,[2] record an almost continuous sequence of marine glacial to terrestrial deposition from the Late Carboniferous to the Early Jurassic, a period of about a hundred million years. These accumulated in a retroarc foreland basin called the "main Karoo" Basin.[1] This basin was formed by the subduction and orogenesis along the boundary of Gondwana (the past African continent) and the Panthalassan Sea (paleo-Pacific).[1] Its sediments attain a maximum cumulative thickness of 12 km, with the overlying basaltic lavas (the Drakensberg Group) at least 1.4 km thick.[3]

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.[4]

The Karoo Supergroup is divided into the following strata (from oldest to youngest):

See also

References

  1. ^ 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". Journal of African Earth Sciences 43 (1-3): 211. doi:10.1016/j.jafrearsci.2005.07.007. 
  2. ^ Hamilton, G.N.G. and Finlay, J.G. (1928), Outline of Geology for South African Students, Central News Agency Ltd., Johannesburg.
  3. ^ 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.
  4. ^ 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.