Bathymetry, microphysiography and reflectivity characteristics of the West African margin between Sierra Leone and Mauritania.

This report maps and analyzes the bathymetry and seafloor reflectivity characteristics along the NW African margin between 3o and 23oN. The bathymetric trends strongly suggest that the morphology associated with the mid-ocean ridge (MOR) spreading system strikes N throughout the area mapped (N of 10oN). The system of equatorial fracture zones defines a dominant E-W morphologic fabric in the SE portion of the map area, and appears to extend through the NE-trending Sierra Leone Rise in the SE part of the area. The Sierra Leone Rise is an aseismic system of plateaus probably formed at the MOR crest during a phase of excess basalt generation. The reflectivity characteristics and microphysiography show that both downslope processes (turbidity flows and sediment slides) and along-slope processes (geostrophic bottom currents) have been important in shaping the present morphology of the continental rise.-Authors