Segmentation of an obliquely rifted margin, Campos and Santos basins, southeastern Brazil

We make the case for Early Cretaceous transfer zones that segment the obliq uely rifted Atlantic margin of southeastern Brazil. Our interpretation is b ased on published literature, Bouguer-corrected gravity, regional reflectio n seismic profiles, and well data. In the Santos and Campos basins, Neocomi an rift architecture was strongly influenced by preexisting fabric and stru ctures of the Late Proterozoic (Brasiliano orogeny). The Atlantic margin in herited an east-northeast-west-southwest orientation so that rifting was ob lique to the margin. On a regional map of Bouguer-corrected gravity, a nearshore belt of positiv e anomalies correlates with an interpreted broad Moho uplift in the footwal l of Neocomian extensional faults. Farther offshore, a second belt of posit ive anomalies correlates with a presalt ridge of eroded volcanic or basemen t anticlines covered by thin Aptian evaporites, interpreted as a failed spr eading center. Intervening negative anomalies coincide with the main rift b asin. All three belts show apparent offsets along linear zones trending wes t-northwest-east-southeast, which we interpret as transfer zones. The verge nce of half rifts tends to change across transfer zones, compartmentalizing the rifted margin into subbasins. Our results have implications for the risks associated with distribution, m aturation, and migration of hydrocarbons within the prolific Early Cretaceo us lacustrine petroleum system of the Campos and Santos basins.