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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 km2 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. [ABSTRACT FROM AUTHOR]

Abstract: This study of sediments from the Cap Timiris Canyon demonstrates that geochemical data can provide reliable age-depth correlation even of highly turbiditic cores and attempts to improve our understanding of how turbidite emplacement is linked to climatic-related sea-level changes. The canyon incises the continental margin off NW Africa and is an active conduit for turbidity currents. In sediment cores from levee and intrachannel sites turbidites make up 6–42% of sediment columns. Age models were fitted to all studied cores by correlating downcore element data to dated reference cores, once turbidite beds had been removed from the dataset. These age models enabled us to determine turbidite emplacement times. The Cap Timiris Canyon has been active at least over the last 245kyr, with turbidite deposition seemingly linked to stage boundaries and glacial stages. The highly turbiditic core from the intrachannel site postdates to≈15kyr and comprises Holocene and late Pleistocene sediments. Turbidite deposition at this site was associated especially with the rapid sea-level rise at the Pleistocene/Holocene transition. During the Holocene, turbidity current activity decreased but did not cease. [Copyright &y& Elsevier]