Gravity investigation of the Cameroon Volcanic Line in Adamawa region: Geothermal features and structural control

Abstract

The study area is located at the Adamawa region that belongs to the continental part of the Cameroon Volcanic Line (CVL). The active volcanic activities are represented by various thermal springs with temperatures reaching 74 °C notably in Woulndé locality. The region is investigated through 647 gravity data collected during the main geophysical surveys of Central Africa. The geophysical filtering applied in this study includes horizontal gradient, analytical signal, Euler deconvolution and modeling techniques. Bouguer anomaly values of the region range from −126 to −56 mGal. Faults and geological contacts highlighted through the density contrast of geological formations, extend up to 12 km depth. Moreover, this work reveals faults covered by lava flows suggesting a fissural volcanism in the region. The statistical analysis of geophysical lineaments shows that its major orientation is similar to the Central Cameroon shear zone as well as the N70° direction of the CVL in Adamawa region. The amplitude of analytic signal from the thermal springs zone is maximal. The findings of this work suggest that the geothermal gradient identified in the Adamawa region attests to the effectiveness of the influence of mantle convection in the nearby subsurface.