The influence of syndepositional basin floor deformation on the geometry of turbiditic sandstones: a reinterpretation of the Côte de L’Âne area (Sanguinière-Restefonds sub-Basin, Grès d’Annot, Late Eocene, France)

Abstract

Abstract The Côte de l’Âne section has been previously interpreted as shallow marine deposits (deltaic system with delta-front to bay head and back-barrier environments). The purpose of this article is (1) to suggest a reinterpretation of these facies of the Grès d’Annot in this area as deep marine deposits and (2) to discuss the effect of an evolving seafloor topography during sedimentation on the stacking pattern of turbiditic deposits. The facies analysis of the sedimentary succession is based on eight measured sedimentological logs and on the visual correlation of identified surfaces. Detailed sedimentological observations permitted the identification of a turbidite facies spectrum, schematized in nine facies associations. Outcrop-scale analysis highlights a downstream thickening of the sedimentary sequence resulting from a strong control by tectonic deformation. This deformation is mainly a flexure with a half-wavelength longer than 500m. Associated normal faults may be related to a gravity slide of unconsolidated sediments accommodated within the flexure. Finally, detailed correlations based on the genetic unit model in the Restefonds-Sanguinière system establish the effect of an evolving seafloor topography during sedimentation on the stacking pattern of turbiditic deposits.