TECTONICS AND DEEP-STRUCTURE OF THE NORTH-WESTERN MEDITERRANEAN BASIN

Crustal data, derived from geophysical experiments in the Valencia Trough and the Provencal Basin, are compared and integrated in the framework of the north-western Mediterranean Basin. This basin is a Neogene extensional rift, located within a region of compression between the European and African plates. The northern margin of the Valencia Trough and the Provencal Basin can be compared with other Atlantic-type margins, whereas the southern margin is affected by calc-alkaline volcanism related to subduction. Thinned continental crust, covered by a thick volcanic layer in the deep Catalan margin, is widespread in the Valencia Trough and on both sides of the Provencal Basin, whereas oceanic-type crust is restricted to a narrow domain. The Provencal Basin may have been formed by a simple shear process behind a subduction zone. A geodynamic consequence of this simple shear model is overlap of the thin crust of the Provencal Basin by the thick crust of the Sardinia margin.