Stratigraphie sismique de la marge éocène du Nord du bassin de Santos (Brésil) : relations plate-forme/ systèmes turbiditiques ; distorsion des séquences de dépôt

Abstract

Abstract Because of a high siliciclastic sediment supply rate, the Eocene Brazilian passive margin shows sedimentary geometries that differ from the classical models. Two orders of sequences or cycles have been identified: 1.5–9 and 12 My. During high rates of accommodation and low sediment supply, at a 12 My time-scale, ramp morphologies occur with well developed transgressive and highstand systems tract and shelf margin wedges, at 1.5–9 My intervals, whereas turbiditic deposits are rare to non-existent. During low rates of accommodation and high sediment supply, at a 12 My time-scale, a slope morphology is built with well-expressed aggradational transgressive and lowstand systems tracts at 1.5 My intervals. Within transgressive and highstand systems tracts, turbiditic sedimentation occurs because of the increasing slope during aggradation of shelfbreak deposits.