Flexure as a Tectonic Control on the Large Scale Geomorphic Characteristics of the Eastern Brazil Coastal Zone

Abstract

Based on the integration of sedimentological, geomorphic and topography data with flexural modeling of the subsidence of marginal basins we suggest that regional geomorphic features along the eastern Brazil coastal zone are related to the flexural deformation of the lithosphere due to the sedimentary loads placed on the continental margin. The extensional stresses resulting from this flexural deformation can exert its influence continentwards to a distance of 100 km from the shoreline. These stresses have a magnitude great enough to cause reactivation of ancient faults generated during the separation of South America and Africa, as well as generation of new ones, thus inducing a neotectonic control in the configuration and evolution of the shoreline and the coastal zone. This mechanism although modeled for just two profiles should be valid for the entire continental margin, with variations due to differences in distribution of sedimentary loads along that margin.