Slumps, canyons and related features on the continental margin off East London, SE Africa (SW Indian Ocean)

Abstract

Bathymetric and seismic reflection surveys in the Natal Valley east of East London show that the most important factors in the Neogene development of the outer continental margin have been large-scale slumping and penecontemporaneous canyon formation. Slope wasting and allochthonous mass movements have shifted the foot of the continental slope up to 25 km basinward and have constructed extensive continental rise lobes. Shelf break breaching by canyon heads is considered an important factor in transferring sediment entrained in the Agulhas Current from the continental shelf to the deep ocean basin. A preliminary sediment budget suggests that the continental rise lobes could have been constructed during the last 2.69 m.y. following an episode of massive slumping.