Convergent margins have been shown to be of two types. Accretionary margins reflect the addition of sedimentary material to an overriding crustal plate during underthrusting of oceanic crust. Erosional margins reflect tectonic stripping of crustal material and its transport to depth by the underthrusting ocean crust. Understanding the reasons for these two types of margins is critical in determining global sedimentary mass balances, element cycling between the crust and mantle, and may shed light on the features and processes which create earthquakes along convergent margins. The present award will support examination of the Chile margin, a region of intense erosion produced by the underthrusting of an active spreading center. Specifically, multi-channel seismic reflection data will be processed from an undisturbed section of the margin and compared to detailed analysis of data from a highly eroded section. Comparison of these data sets will provide a unique picture of temporal changes in margin structure and erosion.
