The crustal structure and evolution of the continental margin off Senegal and the Gambia, from total-intensity magnetic anomalies

Abstract

Magnetic anomalies over the Cape Verde Basin and the continental margin off Senegal and The Gambia help define the boundary between oceanic crust and attenuated continental crust. Development of the Atlantic continental margin in the region through continental fragmentation, rifting, attenuation and subsidence began presumably in Early Mesozoic, or possibly in Palaeozoic time. Sea-floor spreading and formation of oceanic crust started in the Middle Jurassic. Later, during the Middle Tertiary, after initial uplift, the oceanic and transitional lithosphere off West Africa cracked into a set of fissures through which deep seated magmas intruded abundantly into overlying Mesozoic and Tertiary sediments and in places threw up substantial volcanic mounts. It is suggested that the origìn of the Cape Verde Rise and Cape Verde Islands is also due to this process, which is probably related to African and Eurasian plate collision.