9804680 DeCelles It is generally acknowledged that the arc-continental interactions along the western coast of South America has involved major crustal shortening that has both thickened the crust and raised the elevation of the land surface over the thickened crust and formed basins in the foreland position. However, there are at least two periods of crustal thickening in Bolivia, and only the younger one has received documentation. The older (late Cretaceous to mid tertiary) episode of thrusting and foreland basin evolution remains virtually undocumented, yet is required to assess total shortening and to understand the origin of the present topography and syn orogenic deposits. This project will study these sediments in order to test two hypotheses for their origin. The results are expected to test between these hypotheses and also allow for a rigorous comparison between the Andes and other retroarc fold-thrust belts, such as the North American Cordillera.
