Reconstruction of palaeo-currents via the investigation of sediment drifts

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The Argentine Basin represents an important path within the global conveyor belt. Cold Antarctic Bottom Water (AABW) takes a northward path as a western boundary current through this basin, and North Atlantic Deep Water (NADW) takes a southern route as a western boundary current. Antarctic Intermediate Water (AAIW) also sets towards the north along the Argentine continental margin (The_Open_University, 1999). The sedimentary sequences at the Argentine continental margin hence represent an important archive of the evolution of those water masses and their modifications (path, physical and chemical properties) e.g. they relate to plate tectonic events such as the opening of the Drake passage or the extensive emplacement of volcanic flows at the Rio Grande Rise/Walvis Ridge. The water masses formed sediment drifts, which document path and intensity of the flow. An identification and detailed analysis and mapping of the drift development in time will shed light on the evolution of the water masses. This in turn will lead to information on the climatic condition during formation. Up to now only the drifts in the central Argentine Basin (e.g. Zapiola Drift) have been investigated. We will concentrate on the continental margin and study long-term (Eocene to Holocene) interaction of the currents with sediment input. The Argentine Basin forms one of the four major basins of the South Atlantic. It opened in Early Cretaceous times (Hinz et al., 1999) and hence built up a long term but high resolution record of the oceanographic-climatic conditions. The proposed project thus ideally tackles the research goals (a) Structure and morphology of the continental margins and shelf areas, (b) The effects of the basin morphology of the Atlantic on the establishment of recent and palaeo-oceanic circulation patterns and climatefeedback, and (c) Erosion and sedimentation processes on- and offshore formulated within the research focus D ‘Sedimentary processes and fluid systems’ of the priority program. The project presented here further links tectonic reconstructions and climate/ocean current simulations.