CRUSTAL STRUCTURE AND OCEAN-CONTINENT TRANSITION AT MARGINAL RIDGE - THE COTE-DIVOIRE GHANA MARGINAL RIDGE

Crustal structure of the Cote d'Ivoire-Ghana marginal ridge and its tr ansition with oceanic lithosphere are deduced from multichannel seismi c reflection, wide-angle seismic, and gravity data. The CIGMR is cut i nto rotated blocks and displays a crustal structure quite similar to t hat of the nearby northern Ivorian extensional basin. These results st rongly support that the CIGMR represents an uplifted fragment of conti nental crust. Transition with the oceanic crust appears sharp; contine ntal crustal thinning occurs over less than 5 km. We did not find evid ence for underplating and/or contamination as anticipated from such a sharp contact between continental and oceanic crust.