On/offshore deep electrical conductivity structure to investigate the Walvis Ridge magmatism and its interaction with the Kaoko Mobile Belt in northern Namibia

The breakup of the supercontinent Gondwana was accompanied by strong volcanic eruptions, which lead to the formation of Paraná-Etendeka flood basalts. This magmatism is associated with the Tristan da Cunha mantle plume and the formation of the Walvis Ridge and the Rio de Grande Rise - two volcanic seamount chains which connect the present position of the plume and the Paraná and Etendeka magmatic provinces in South America and Africa. Within the framework of the DFG-SPP SAMPLE project, key questions related to the observed magmatic activity, the pre- and post-breakup evolution of the passive continental margin are investigated using the magnetotelluric method. The magnetotelluric onshore data were acquired in Northern Namibia in October and November 2011, at 167 sites in a ~140 km wide and ~260 km long corridor, from the Atlantic Ocean across the main NNW striking Neoproterozoic shear zones and faults of the Kaoko Belt onto the Congo Craton. This onshore coverage is extended offshore by the Helmholtz Centre Kiel - GEOMAR along two transects, parallel and perpendicular, to the Walvis Ridge. Focus of the MT experiment is to gain a three dimensional image of electrical conductivity distribution below the passive continental margin in order to:

  • image the tectonic units in the investigated area
  • assess the former and current magmatic activity at the passive margin
  • investigate the influence of pre-existing structures on the breakup process

Time Frame

  • 2011-2013

Principal Investigators

 

  • PD Dr. Oliver Ritter (GFZ)
  • Dr. Ute Weckmann (GFZ)
  • Dr. Marion Jegen (GEOMAR)

Pesonnel

  • Dr. Gerhard Kapinos (GFZ)

Cooperations

  • Dr. Gaby Schneider (Geological Survey of Namibia)
  • Mr. Karl-Heinz Hoffmann (Geological Survey of Namibia)
  • Mr. K. Katjiuongua (Geological Survey of Namibia)

Methods & Equipment:

  • Magnetotellurics
  • S.P.A.M. MkIV Instruments
  • Induction coils  MFX5, MFX6 (Metronix)
  • Ag/AgCl-Elektrodes (GFZ)

Publications/Results

  • n/a

Acknowledgements

  • DFG (RI1127/9-1) for funding of the experiment and personell
  • GFZ for additional funding of the experiment
  • Geophysical Instrument Pool Potsdam (GIPP-MT) for providing the instruments

Additional Information

  • Field work: Oct. 2011 - Nov. 2011
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