Post-Hercynian tectonics in Northern and Western Africa

Abstract

During the evolution of the Alpine fold belt in North Africa, important deformations occurred within the African plate. Precambrian/Palaeozoic fracture systems were reactivated as four major lineaments with trends close to East–West (from Guinea in North Africa to the Nubik Province, in Central Africa) and also north–south as megashears between 2° and 6° E. Magmatic activity, in part attributed to folding, and expressed as chains or roots of volcanoes with alkaline affinities, are considered to be related to major fault systems especially in the North Cameroon and Mamfe basins. In the Benue Trough an intracontinental chain with abundant igneous intrusions can be correlated with the opening of the Atlantic near the Gulf of Guinea. Intraplate deformation is linked to six major periods of tectonic activity identified as Lias, Aptian, Santonian, End Cretaceous, Upper Eocene, and Miocene. From the Aptian onwards, the stress regime remained relatively constant. Intraplate deformation is a consequence of both the plate collision between Africa and Europe and the opening of the Atlantic.