RECENT MORPHOSTRUCTURAL EVOLUTION OF THE WEST-RIFFIAN CONTINENTAL-SHELF (NORTH-ATLANTIC MOROCCO)

A 3.5 KHz high-resolution seismic survey carried out on the West-Riffi an continental shelf, between Cap Spartel and Rabat, has shown that th e morphostructural lineaments already identified on the continent, mai nly within the South-Riffian western basin and its margins, extends to wards the sea, on the continental shelf. These structures are related to stepped anticlinal flexures with a large curvature radius. The pale ozoic acoustic substratum to the south and the cenozoic to the north a re both characterised by a succession of abrupt erosion surfaces whose relatively constant bathymetric position could be attributed to paleo shorelines. We have also shown that the river mouth of Oued Sebou has changed position in the course of the Quaternary, under the influence of glacio-eustatic fluctuation as well as the substratum's structural configurations.