Geologists find out how over 2.6 Ga years old rocks were formed at Limpopo Complex

phys.org | 7/17/2018 | Staff
gbabii05 (Posted by) Level 3
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Cratons (from the Greek "power" or "might") are the areas of the oldest continental crust on Earth, and are preserved only in only a few places around the world. According to scientists, the Kaapvaal Craton in the South Africa and the Pilbara Craton in Australia (the most ancient of these structures) were the parts of Vaalbara, an Archean supercontinent.

The transformation of the lower parts of the cratons under the influence of heat emitted by the Earth's mantle may lead to the formation of rocks called granulites that frame cratons like belts. However, the processes that cause granulites to move upward from the lower part of the crust to the surface along the craton borders are still largely debatable. The oldest granulite belts were formed in the Archean (3 Ga years ago), which is only several hundred million years younger than the life on Earth. The youngest granulites are about 0.5 billion years old. One ancient (2.7 Ga) granulite belt is situated at the Kaapvaal Craton at the borders of South Africa, Zimbabwe, and Botswana, not far from the famous Limpopo River. The Limpopo Complex is considered as a natural laboratory for study of relations between the oldest tectonic structures in the continental crust and therefore is of great interest for geologists.

Time - Reasons - Magmas - Granulite - Complex

"For the first time, we have strong reasons to assume that granite magmas in the Neo-Archean granulite complex of Limpopo (South Africa) have been formed in the course of tectonic interaction of this complex with the rocks of the Kaapvaal Craton as the complex was rising from the lower part of the continental crust," says Oleg Safonov, a co-author of the work, Doctor of Geology and Mineralogy, Professor of the Petrology Department of the Geological Faculty, MSU, and Director of the Korzhinskii Institute of Experimental Mineralogy of the Russian Academy...
(Excerpt) Read more at: phys.org
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