The Cape Basin is located at a central location with respect to variouswater masses. The coldest and densest of these water masses is theLower Circumpolar Deep Water.The location and topography of the Agulhas Ridge effectively blocks itsnorthward flowing branches and deflects them into a south-westerndirection to follow the bathymetric contours of the Agulhas Ridge wheresuspended sediments accumulate in contourite drifts.Several hundred metres of sediments have accumulated since the onsetof Antarctic Bottom Water intrusion into the basins of the South Atlantic.A present day like bottom current following Agulhas Ridge contours existssince an erosional event in the Early Oligocene took place which markeda prominent change in sedimentation.Strong and varying currents in the Early Oligocene formed a sheet likedeposition at high sedimentation rates.The fluctuating types of sediments produce strong seismic reflections.It was followed by a very stable unidirectional bottom current with mainlymuddy sediments. This resulted in the formation of a more than 200 kmlong, approx. 30 km wide elongate contourite drift which shows fewinternal reflections on the seismic data. An increase of well-defined unitsis found after a period of non-deposition in the Middle Miocene.Still the build-up of the drift structure continued, but at places erosion isfound, especially in Quaternary sediments and probably in relation toglaciation cycles.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > MAR2-Palaeo Climate Mechanisms and Variability