Development of the Neogene current system in the Cape Basin as recorded in the seismostratigraphy
The sedimentary sequences of the continental margin off southwest Africa have been shaped by different currents. At the surface, the Benguela and Agulhas Currents are active, in greater depths the Antarctic Intermediate Water (AAIW), the North Atlantic Depth Water (NADW) and Antarctic Bottom Water (...
| Main Authors: | , |
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| Format: | Conference Object |
| Language: | unknown |
| Published: |
2003
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| Subjects: | |
| Online Access: | https://epic.awi.de/id/eprint/8631/ https://hdl.handle.net/10013/epic.19157 |
| Summary: | The sedimentary sequences of the continental margin off southwest Africa have been shaped by different currents. At the surface, the Benguela and Agulhas Currents are active, in greater depths the Antarctic Intermediate Water (AAIW), the North Atlantic Depth Water (NADW) and Antarctic Bottom Water (AABW) take effect. Our aim is to unravel the development and modifications of those current systems. Especially we want to concentrate on the onset of the Benguela Current Upwelling System, which represents one of the largest upwelling regions worldwide and is closely related to the developement of the climate in southern Africa. Significant events as incursions of warm or cold waters, terrigenous input, climate changes and slumpings are recorded in the deposited material. The sedimentary properties are expected to be reflected in the signal structure of the seismic data from this area.In this contribution we will present a seismic stratigraphy for the Neogene sedimentary layers in the entire Cape Basin on the base of results of the ODP Leg 175 Sites 1081-1087 which are correlated with seismic data. With a maximum depth of 610mbsf (Site 1085a) the sites span the time period between Holocene and late Miocene (0-15 Ma). Corelog parameters as for example velocity, density, lithostratigraphy, carbon and carbonate content are linked to the seismic sections via synthetic seismograms. This procedure enables an interpretation of the origin of reflectors and a spatial extrapolation of sites informations.The depositional enviroment in the Cape Basin can be divided roughly into three major areas and is reflected in a change in stratigraphy from north to south: Deposition in the northern regions is influenced by eroded sediments from the Walvis Ridge and by upwelling sediments. Sediments of the middle Cape Basin are dominated by the presumable most productive coastal upwelling cells. The depositions in the southern Cape Basin contain the most imprint of incursions from the south as the Agulhas Current.All seismic sections show a ... |
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