Abstract: A Deep Seismic Reflection Profile Across Tibet: Project INDEPTH

Larry D. Brown, K. D. Nelson, Zhao Wenjin, J. T. Kuo

Project INDEPTH (International Deep Profiling of Tibet and the Himalaya) is a collaboration to collect a 2000 km seismic reflection profile across the Himalaya and Tibetan Plateau, a geologically unique region formed by the collision of India with southeast Asia. A 100 km test survey was carried out in the Tethyan Himalaya in the summer of 1992 by a team of Chinese and U.S. scientists, jointly funded by the Chinese Ministry of Geology and Mineral Resources, the Chinese National Natural Sciences Foundation and the U.S. National Science Foundation. The core of the seismic experiment was a CDP reflection profile using explosive sources. Key reflections include those from the main Himalayan thrust detachment, dipping from about 10 to 12 sec (28-42 km), and those at about 23 sec, interpret d to be from the Moho at 75 km depth. The latter constitute the deepest Moho reflections yet mapped by reflection profiling. In addition to these deeper targets, the survey was designed to encompass shallow structures such as the Southern Tibetan Detachment, a north-dipping normal fault contemporaneous with overthrusting. The survey is also the first seismic profile in one of the north-south Quaternary grabens that transect the southern Tibet Plateau. The next phase of Project INDEPTH targets the Indus-Tsangpo suture to test the extent of underthrusting by the Indian continent. Future legs will transect Neogene basins of the central Plateau and the bounding Qaidam and Tarim Basins north of the Tibet-Qinghai Plateau.

AAPG Search and Discovery Article #90986©1994 AAPG Annual Convention, Denver, Colorado, June 12-15, 1994