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Part II: Applied thermochronology - long-term evolution studies |
1 Institute of Geology and Paleontology, Basel University, 4056 Basel, Switzerland
2 NGU, Geological Survey of Norway, 7491 Trondheim, Norway
3 AEON and Department of Geological Sciences, UCT, 7701 Rondebosch, South Africa
4 South African Nuclear Energy Corporation, PO Box 582, 0001 Pretoria, South Africa, and School of Geosciences, University of the Witwatersrand, Private Bag 3, 2050 Wits, South Africa
* Corresponding author (e-mail: a.kounov{at}unibas.ch)
Apatite fission-track (AFT) data from two traverses across the Great Escarpment of the western coast of South Africa are used to reconstruct the tectonic evolution and denudation history of this sector of the Atlantic passive margin. Fission-track ages range between 180 and 86 Ma. Modelling of this data identifies two distinct cooling events. The first event, between 160 and 138 Ma, is recorded only by the rocks above the escarpment in the Karoo area, and is tentatively linked to post-Karoo magmatism (c. 180 Ma) thermal relaxation. The second, between 115 and 90 Ma, results instead from a tectonically induced denudation episode responsible for the removal of up to 2.5 km of crust across the coastal zone in front of the escarpment and less than 1 km on the elevated interior plateau. Based on these results, it is suggested that the Cretaceous is the time when most of the elevated topography of Southern Africa was generated, with only a minor Cenozoic contribution.
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F. Lisker, B. Ventura, and U. A. Glasmacher Apatite thermochronology in modern geology Geological Society, London, Special Publications, 2009; 324: 1 - 23. [Abstract] [Full Text] [PDF] |
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