Seismic imaging of the downwelling Indian lithosphere beneath central Tibet.
A tomographic image of the upper mantle beneath central Tibet from INDEPTH data has revealed a subvertical high-velocity zone from approximately 100- to approximately 400-kilometers depth, located approximately south of the Bangong-Nujiang Suture. We interpret this zone to be downwelling Indian mantle lithosphere. This additional lithosphere would account for the total amount of shortening in the Himalayas and Tibet. A consequence of this downwelling would be a deficit of asthenosphere, which should be balanced by an upwelling counterflow, and thus could explain the presence of warm mantle beneath north-central Tibet.
Tilmann
Frederik
F
Department of Physics, New Mexico State University, Las Cruces, NM 88003, USA. tilmann@esc.cam.ac.uk
Ni
James
J