Deformation and syn-rift magmatism at the South Atlantic passive continental margin, Walvis Ridge area. A marine wide angle seismic and magnetotelluric experiment.

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The South Atlantic passive margin around the landfall of the Walvis Ridge hotspot track is a unique example of continental extension, breakup and oceanic basin development, assisted or dominated by hotspot-related magmatism. There is a prime opportunity to study the variation of the magmatic signal in space and time, and investigate the interrelation with rift-related deformation. A globally significant problem to be addressed here by observation of lithospheric structure, velocity and conductivity is whether magmatism drives continental deformation and breakup, or whether even rifting with copious hot-spot related magmatism is principally in response to crustal and lithospheric stretching. The approach is to quantify thickness and extent of dipping reflector sequences and interleaved sediments, identify deep fault zones, and characterize underplated magmatic rocks near the continent-ocean transition zone from a set of new set of wide angle seismic, magnetotelluric (MT), and supplementary gravity data. The funding requested is intended to support marine surveys of the Namibian margin where it is intersected by the Walvis Ridge, and to carry out post-cruise data processing. Our new integrated approach is geared towards achieving imaging of large magmatic bodies, of sediments interleaved in dipping reflector sequences, and large, potentially fluid filled fault zones. Data integration will be achieved through joint inversion of wide angle seismic, gravity and MT data. The project is part of a coordinated amphibian geophysical campaign within the SAMPLE program.