A COMPARISON OF MODERN FOLD-THRUST BELTS AND PLATEAUS TO ANCIENT SYSTEMS

Modern orogenic systems such as the Himalaya, Andes and Zagros have active fold-thrust belts that border high elevation “hinterland” plateaus. If fold-thrust belts and plateaus are mechanically linked, a comparison between the modern systems may provide needed insight as to how they are linked. This comparison includes the amount of shortening in the fold-thrust belt, size of the plateau, geophysical data, and type of convergent system. Two systems that illustrate possible differences in the anatomy of plateaus and fold-thrust belts are the central Andean plateau and Turkey/Iranian plateau. In the central Andes, thick crust and high magnitudes of shortening imply a strong link between development of the fold-thrust belt and plateau (similar to Himalayan-Tibetan orogen). In the Middle East, the Turkey/Iranian plateau is underlain by a much thinner crust than isostatically compensated elevation would suggests, as well as low magnitudes of shortening in the fold-thrust belt. This evaluation of the similarities and differences may provide understanding for ancient orogenic systems such as the Sevier fold-thrust belt in the western U.S. Cordillera and its associated “nevadaplano” and to the anatomy of the Appalachian orogen.