Continental Margin of Western South America

Abstract

The continental margin of the west coast of South America marks the seismically active, tectonic boundary between the converging Nasca and South American plates. The Peru-Chile Trench is the dominant morphologic element of the margin and persists as a structural feature from the coast of western Colombia to Tierra del Fuego, at the southern tip of South America. Variations in the trench morphology, sediment distribution, volcanism and orogenesis in the Andes, and the seismicity are interpeted to be the likely consequence of variations in the rate and direction of plate convergence and the effectiveness of geologic boundary conditions within the continental lithosphere. Some outstanding problems are cited also.