9706630 Burchfiel The Indian-Asian collision zone is the type locality of a continent-continent collision, and studies of this zone reveal the tectonic processes of such collisions that are not obtainable in more ancient collision systems. Of particular concern is the controversy between the hypotheses of extrusion and rotation, in this case of blocks of Asian crust . Is the shortening of the Asian crust accomplished by extrusion of wedge-shaped blocks of crust, or by rotation-aided movement of these blocks. This study will address this issue by both structural and paleomagnetic approaches. The field structural and associated kinematic studies will allow testing of the extrusion models, and the paleomagnetic studies will allow testing of the rotational studies. Together both hypotheses can be tested for this critical region of southwest China, and will provide a strong context for the interpretation of more ancient mountain belts where structural overprinting have made these questions much more difficult to address.
