Chapter 33 - Late Mesozoic rifting in Africa

Abstract

Plate tectonic development of the Central, Equatorial and South Atlantic oceans during the late Mesozoic had a major influence on the development of sedimentary basins within Africa giving rise to a set of interconnecting rift basins spanning the continent from Nigeria to Kenya. Geophysical studies indicate these basins have gravitational expressions that can be described using the lithospheric extension model of McKenzie. The geometries of these rift basins show that large extensional basins have formed at the ends of major wrench and shear fault systems emanating from the Gulf of Guinea. Movement of these shear systems and opening of the rift basins are closely linked to the early opening of the South and Equatorial Atlantic oceans as well as to the subsequent differential opening of the Central and South Atlantic oceans in Cretaceous times. The crustal structure of the West and Central African rift system (WCARS) as deduced from geophysical studies is compatible with the crustal structure associated with the Atlantic type passive continental margins, in terms of its crustal attenuation and early geological history, to suggest that the WCARS is more typical of continental break up than the East African rift system (EARS).