Geological Framework

Chapter

Abstract

The geological framework of East Africa is comprised of three terranes: basement complexes, regional plateaus and the East African Rift System (EARS). The oldest of the basement complexes is the Archaean-age Lake Victoria Terrane, part of the extensive Central African craton which dominates the area between the Albertine and Gregory Rifts. The Lake Victoria Terrane includes greenstones, altered sedimentary and basaltic rocks, as well as large plutons of granite-gneiss. The Neoproterozoic-age Mozambique Belt is restricted to areas east of the craton and includes both metasedimentary rocks and granitic plutons. Preservation and exposure of these ancient, crystalline rocks is ascribed to cycles of uplift and erosion associated with the break up of the supercontinent of Gondwana. This process started during the Jurassic at approximately 180 Ma. The most pronounced phase of erosion produced the 70-Ma-old Cretaceous-age African Surface. The EARS commenced in Ethiopia in the Late Oligocene (at approximately 30 Ma) and propagated southwards reaching Kenya in the Miocene and northern Tanzania in the Pliocene. The principal manifestations of the EARS are well-defined, narrow, linear valleys enclosed by elevated rift platforms, together with intensive volcanism. Sedimentary basins are a localised feature of the EARS but are important as they may contain fossils of both hominins and extinct mammals. Hominins evolved during the Pliocene and Early Pleistocene of East Africa in epochs of intensive tectonism and volcanism. The Late Pleistocene of East Africa confirms that the Ice Ages were global phenomena. Homo sapiens have thrived in the Holocene, i.e. since 11,500 BP in an epoch of comparatively modest climatic cycles and less intense volcanism.

Keywords

African surface Basement complexes EARS Hominins Regional plateaus Volcanism 

Copyright information

© Springer International Publishing AG, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of GeologyRhodes UniversityGrahamstownSouth Africa

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