Karoo super group

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Stratigraphic structure of the main Karoo basin

The Karoo supergroup is a lithostratigraphic structural unit in Africa . It is made up of several sedimentary basins that occur mainly south of the equator .

Definition

The geological term "Karoo" was initially limited to the sedimentary structures of the Karoo Basin in South Africa. This was used to describe continental sediments that extend beyond the Karool landscape . As knowledge progressed, the term was mainly applied to all continental sediments that emerged from the extensional basin structures of Gondwana . Similar sedimentary basins from the Upper Carboniferous to the Jura have also been found in India, Antarctica and Australia.

geology

The Karoo supergroup comprises a succession of sediments formed over 100 million years. The thickness of the deposits in individual cases exceeds 10,000 meters. The Karoo supergroup is having a major impact on the landscape in many African countries.

The first sediment formation within this supergroup began in the Carboniferous , about 300 million years ago, with the glacial deposits of the Dwyka Group. It was followed by marine sediments in the period of the Ecca Group (Ecca Group). Later fluvial sediments of the Beaufort Group and Stormberg Group were deposited over it . In the most recent section (Drakensberg Formation) of the Karoo period, lava effusions penetrated and covered the existing sediments. The most important evidence of this Plutonic activity are the Drakensberg in Lesotho and South Africa . This concludes the Karoo super group in the Jura .

Typical rocks include sandstones , siltstones , slate clays and tillites . Tectonic activities have created magmatic intrusions in some basin structures, which are among the most recent formations in the Karoo supergroup. The Karoo dolerites are best known in southern Africa. In the Lebombo Mountains , the common border area of ​​South Africa and Mozambique , however, basalts , rhyolites , tuffs and ignimbrites occur.

Large structures

Important individual pelvic structures are:

Individual evidence

  1. ↑ JJ Lambiase: The framework of African rifting during the Phanerozoic . In: Journal of African Earth Sciences (8) 1989, pp. 183-190
  2. ^ Nick Norman, Gavin Whitefield: Geological Journeys . Cape Town (Struik Publishers) 2006, p. 166 ISBN 1-77007-062-1

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