Anomalous topography in the western Atlantic caused by edge-driven convection

Abstract

The western Atlantic region contains a long-wavelength intraplate topography anomaly that is defined by the NE-SW trending Bermuda Rise and two adjacent topography lows. Using numerical experiments, we test the hypothesis that the anomalous topography may be the surface response to edge-driven convection. A primary edge-driven convection cell and secondary flow circulation develops at a modeled continent-ocean plate margin and induces subsidence at the continent-ocean margin, an off-shore peak/plateau of high topography on the ocean plate, and distal ocean plate subsidence. Unlike hot spots, the edge-driven convection cell and associated topography migrate with moving surface plates. The flow cell and wavelength of topography is broadened with continent-ward motion of the lithosphere relative to the mantle, whereas a migration in the ocean-ward direction suppresses the formation of the edge-driven convection cell and surface topography. The wavelength of observed anomalous topography in the western Atlantic and estimates of plate motions relative to a fixed hot spot reference frame are consistent with the former. Copyright 2004 by the American Geophysical Union.