Deep Seismic Structure (Mauritania and Central Morocco)

  • W. Weigel
  • Gerd Wissmann
  • P. Goldflam

Abstract

This paper presents two crustal sections through the Moroccan and Mauritanian continental margin in the vicinity of the Canary and Cape Verde Islands. The sections are based mainly on joint refraction surveys of the Institut fur Geophysik (Hamburg) and the Federal Institute for Geosciences and Natural Resources (BGR, Hannover) and additional information from published refraction work in the survey areas.

On both sections rift basins were crossed, in which evaporites had formed diapirs. A 7.1 – 7.3 km/s layer could be followed from the rise to the shelf in both areas, while Moho arrivals could only be observed over the continental rise of Mauritania. Here the typical oceanic layer 2 seems to be thin or missing in a more than 100 km wide zone of transitional crust, in which the 7.1 km/s layer probably forms the top of the crystalline basement. From this structural relationship a model is postulated, which interprets that prominent 7.1 km/s refraction horizon as the cooled and solidified top of the original elongated mantle plume that lead to the splitting up and contributed to the drifting of the continents. A thick layer with a velocity of 5.8 km/s overlying the postulated plume surface off Morocco could then either constitute gt; 100 km of thinned continental crust or massive carbonate sediments. From the refraction results clear indications for an oceanic crust exist only more than 100 km west of the present continental slope.

The lithological interpretation of the seismic velocities is complicated by the presence of high velocity (vp gt; 5 km/s) carbonate platform rocks under the continental slope and of volcanic rocks (intrusions on the shelf, sea-mounts and islands on the rise and slope).

Keywords

Convection Shale Drilling Cretaceous Jurassic 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1982

Authors and Affiliations

  • W. Weigel
    • 1
  • Gerd Wissmann
    • 2
  • P. Goldflam
    • 1
  1. 1.Institut für GeophysikUniversität HamburgHamburgGermany
  2. 2.Bundesanstalt für Geowissenschaften and RohstoffeHannover 51Germany

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