A gravity study of the crust beneath the Adamawa fault zone, west central Africa

In this work, a regional-residual separation of the gravity anomalies on the southern part of the Adamawa plateau is undertaken. Analysis of the maps obtained show a N70°E oriented zone which coincides with the main direction of the fractures affecting the basement in the region. Three profiles were drawn on the residual anomaly map, and are interpreted using a gravity modelling program. They show an uplift of dense rocks in the granite-gneiss substratum, found at an average depth of about 8 km. This dense material, which runs parallel to the Foumban Shear Zone (FSZ), is interpreted as an igneous intrusion probably of basaltic composition, which may be associated with the Cameroon Volcanic Line (CVL). The ascent of the body may have been facilitated by the reactivation of the FSZ.