The Influence of Mantle Convection on the Escarpment Evolution at Divergent Continental Margins

Based on analytical, numerical or purely conceptual models, in the last decades different mechanisms were proposed to explain the existence of large escarpment along divergent continental margins persisting for more than 100 million years, invoking both syn- and post-rift geodynamic processes. One difficult aspect to explain about escarpment evolution along divergent margins is the expressive variability of denudation rate through the post-rift phase. Here I propose that the interaction of edge-driven convection in the asthenosphere with the base of the lithosphere can induce a variable thermal perturbation in the continental lithosphere that create intermittent vertical displacement of the surface with magnitude of hundreds of meters. I show that these topographic perturbations are sufficient to produce an expressive variability in the rate of erosion of the landscape, similar to the denudation pattern observed in mature continental margins, like in the Atlantic Margin of southern Africa. The present results are based on numerical simulations that combine thermochemical convection in the mantle, flexure of the lithosphere and surface processes of erosion and sedimentation.