The SW African volcanic rifted margin and the initiation of the Walvis Ridge,South Atlantic |
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| Authors: | Gavin M Elliott Christian Berndt Lindsay M Parson |
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| Institution: | (1) Geology & Geophysics NSRD, National Oceanography Centre, European Way, Southampton, SO14 3ZH, UK;(2) Present address: Department of Earth Science & Engineering, Imperial College, Prince Consort Road, London, SW7 2BP, UK;(3) IfM-Geomar, Leibniz Institute for Marine Sciences, Kiel, Germany |
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| Abstract: | The continental margin of SW Africa is typical of a volcanic rifted margin associated with a hotspot trail characterized by a large volcanic ridge, the Walvis Ridge, defining the hotspot migration, and extensive extrusive volcanism that produced seaward-dipping reflectors (SDR). Previously unpublished seismic data show two significant anomalies of the SW African Margin when compared to other typical volcanic rifted margins: (1) Hyaloclastitic outer highs are rare, and (2) the SDR in the North dip towards the Walvis Ridge. We explain these anomalies by a major transform segment close to the centre of volcanism combined with pulsed volcanism. The Walvis Ridge represents an east-west striking extrusive centre which produced a SDR sequence. Following break-up the northern boundary of the Walvis Ridge became a left lateral transform fault. Our data support the idea that a transform fault system interacting with a ridge jump were responsible for the accretion of the São Paulo Plateau to the American plate. |
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