| 翻訳と辞書 |
| Karoo Supergroup ： ウィキペディア英語版 |
Karoo Supergroup
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 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, Swaziland, 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.〔McCarthy, T., Rubridge, B. (2005). ''The Story of Earth and Life.'' pp. 193-241. Struik Publishers, Cape Town〕 The type area of the Karoo Supergroup is the Great Karoo in South Africa, where the most extensive outcrops of the sequence are exposed.〔〔Geological map of South Africa, Lesotho and Swaziland (1970). Council for Geoscience, Geological Survey of South Africa.〕 Its strata, mostly shales and sandstones,〔Hamilton, G.N.G. and Finlay, J.G. (1928). ''Outline of Geology for South African Students'', Central News Agency Ltd., Johannesburg.〕 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 southern border of what eventually became Southern Africa, in southern Gondwana.〔 Its sediments attain a maximum cumulative thickness of 12 km, with the overlying basaltic lavas (the Drakensberg Group) at least 1.4 km thick.〔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.〕
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.〔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.〕
==Geological origin==
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
■ウィキペディアで「Karoo Supergroup」の詳細全文を読む
スポンサード リンク
| 翻訳と辞書 : 翻訳のためのインターネットリソース |
Copyright(C) kotoba.ne.jp 1997-2016. All Rights Reserved.
|
|