The area south of South Africa is one of the most important seaways since there watermasses from the Atlantic and Indik-Pacific mix. This results in a very complex flow pattern which up to now has been known only in general terms. A set of seismic reflection lines from the southern Agulhas Plateau has been analysed with respect to sedimentary structures known as contourites. Those contourites were formed by the geostrophic currents active in this area and may shed light on the evolution of the current system.Strong indications for the effect of the contour currents in form of sediment drifts, channels, erosional unconformities and sediment waves were identified. Those observations were used to create a picture on the development of the currents on the southern Agulhas Plateau since Paleogene times. Three different currents could be identified. The oldest observed sets across the Agulhas Plateau from the southwestern tip to the northeast. It probably started along this path in Eocene times and is interpreted to be comprised of an Antarctic Bottomwater component derived from its source in the south.The eastern Agulhas Plateau is characterized by a southsetting current. This current has been active since Lower Oligocene and appears to have remained stationary within a distance of 10 km. The Agulhas Retroflection is considered as its source. The third current observed shows a path along the western flank of the plateau. It left its mark in sediments as old as Middle Miocene and probably results from an Antarctic Bottomwater component re-circulated via the Cape Basin.
Helmholtz Research Programs > MARCOPOLI (2004-2008) > POL-MARCOPOLI