Mapping of seabed morphology and shallow sediment structure of the Mauritania continental margin, Northwest Africa: Some implications for geohazard potential

Seafloor mapping of the Mauritania margin by multibeam bathymetry as well as shallow and high-resolution seismics in combination with core data has revealed a wide variety of seafloor features, which are primarily generated by turbidity currents and landslides. The largest observed features in the study area are two submarine slides, which both have affected over 30,000 km' of seafloor. The Cap Blanc Slide is not considered to be a significant geohazard at the present day as it has a minimum age of 165 ka and shows no evidence of recent reactivation. In contrast, the complex Mauritania Slide Complex is characterized by a retrogressive failure style and has an age of only 10.5-10.9 cal. ka B.P. We found no indication for recent reactivation of this slide, but more data are needed to assess the present seafloor stability in this area. Turbidity current activity on the margin is evidenced by numerous gullies, canyons and channels. The largest of these is the >450 km-long meandering Cap Timiris Canyon. During the present Holocene sea-level highstand, however, terrigenous sediment supply to the modern outer shelf has been restricted and most of the conduits are therefore thought to be largely inactive, at least in terms of large sand-rich flows.