Late Permian to Recent magmatic activity on the African-Arabian margin of Tethys

Abstract

Abstract Magmatic activity on the African-Arabian margin of Tethys has fluctuated significantly during the past 250 Ma in response to major phases of mantle plume activity and to extensional stresses within the African plate related to periods of continental break-up. A series of maps have been compiled, based upon stratigraphic constraints and K-Ar and 40 Ar- 39 Ar age determinations, to illustrate the changing patterns of igneous activity since the Late Permian. These are divided into five stages: I, Late Permian (256 Ma)-Latest Triassic (208 Ma); II, Early Jurassic (208 Ma, Liassic)-Mid Jurassic (157 Ma, Dogger); III, Late Jurassic (157 Ma)-Earliest Aptian (120 Ma); IV, Mid Aptian (119 Ma)-Mid Eocene (42 Ma); V, Late Eocene (42 Ma)-Recent. Extensive tholeiitic basaltic magmatism at c. 200 Ma, preceding continental break-up in the Central Atlantic, is attributed to upwelling of the Cape Verde mantle plume beneath the West African craton. Contemporaneous magmatic activity in the Levant is related to the break-up of the Eastern Mediterranean margin. Early Cretaceous alkaline magmatism around the margins of the Equatorial Atlantic and within the Levant may also be plume related. During Neogene-Recent times there was a major change in the convection pattern within the upper mantle, generating extensive magmatism across the entire margin. Magmatism appears to be extremely long lived in a number of areas (e.g. Sudan, Air), with volcanic centres located along major basement fault zones, such as the Guinean-Nubian lineaments.