Gravity tectonics in the SE Basin (Provence, France) imaged from seismic reflection data

Abstract

AbstractUsing industrial seismic data available in the French Southeast Basin in Provence, we put into evidence thin skinned processes that have dominated tectonics in this basin since the Oligocene. These interpretations are then replaced within the regional structural framework of SW France with geological maps and field work. A thick Mesozoic and Cenozoic sedimentary cover is detached on a main décollement frequently localized within the Triassic evaporites. The underlying basement is undeformed. The Mid-Durance fault, the Luberon, Trévaresse, and the Ventoux-Lure thrust zones and the Diois-Baronnies fold and thrust belt are produced by thin-skinned tectonics, the associated structures having no roots within the pre-Triassic basement. This thin-skinned deformation is interpreted as resulting from a regional southward gravity mass flow, induced by the westward Alps extrusion, followed in recent times by radial collapse of the Alps. The incipient stage of this gravity sliding occurred during the Late Oligocene in the Diois-Baronnies (the former Mesozoic Vocontian basin), and then rapidly progressed to the south across the Ventoux-Lure thrust zone in Provence during the Miocene. Southward, this gravity sliding vanishes approaching the E-W trending structural high of the Eocene Pyrénéo-Provençal orogenic belt in southern Provence.