Sur l'existence, en Provence, d'une phase tectonique oligocene d'origine profonde

Abstract

Abstract The results of a study of structures in the Triassic units of southeastern France suggest the existence of an Oligocene tectonic phase independent of those in the late Cretaceous and late Eocene. In the areas studied (Barjols, Huveaune, Grapeau, Gareoult) the structures are essentially vertical with no evidence of lateral displacement. Deep seated movement in the basement complex produced uplift and faulting. As a result of this activity, the Stampian deposits contain conglomerates with elements produced by the fragmentation of the Permian and basement complexes. The age of the orogenic movements is post-Eocene. It is clear that deformation was complete before the Vindobonian (Miocene) as evidenced by the continental deposits of that age which overlie the Triassic structures. Also the Vindobonian deposits which overlie the Jurassic and Cretaceous in other areas are at the same level as those overlying the deformed Triassic strata. Because the faulting has affected part of the Stampian deposits it could be concluded that deformation was post-Stampian. However, in the Huveaune basin where the faults limiting the Triassic structure affect the Stampian deposits, the structures are directly overlain by the Stampian, proving that the orogenic and glyptogenic phenomena were contemporaneous, and establishing a Stampian age for the tectonic phase.