Teleseismic imaging of subducting lithosphere and Moho offsets beneath western Tibet
Résumé
Teleseismic images suggest that the Tarim plate plunges V45 ‡S, down to V300 km depth, beneath NW Tibet. The 410 km discontinuity shallows by V10 km under the plateau, implying V100 ‡C cooler upper mantle. The deepest Moho on record (V90 km) lies under W Qiangtang. It rises abruptly by V20 and V10 km beneath the Altyn Tagh Fault and Bangong Suture, respectively. V p /V s ratios are normal, except in the Yecheng flexural basin and deep under the south Karakax volcanics (V1.92). W Kunlun's Neogene tectonics are simply accounted for by oblique subduction of lithospheric mantle beneath an upward-extruding thrust wedge of the Tarim crust. ß 2004 Published by Elsevier B.V.