Seismic images of the architecture of the colliding plates in Tibet are still controversial. Especially the northern limit of the mantle part of the lithosphere of the subducting Indian plate is not well known. The use of increasingly sophisticated seismic technologies yields new images that have significant implications for our understanding of the evolution and ongoing dynamics of the collision of the Indian and Asian plates. We herein present direct observations of the plate structure beneath the Tibetan plateau, by inspection of converted seismic waves. By assembling sections of P-S and S-P converted waves we have mapped the Indian and Asian plates along a number of profiles that traverse the plateau. We have furthermore identified a Tibetan plate that forms a distinct Lithospheric block, and is sandwiched between the Asian and Indian plates. In the westernmost part of Tibet, the Asian plate is underthrusting beneath the Indian plate, while in central and eastern Tibet the Indian plate is underthrusting beneath the Tibetan plate. There are indications of Asian plate subduction in northern Tibet that are connected with a thickening of the Tibetan Plate. The seismic velocities in the Tibetan plate are slower than in the Indian and Asian plates, suggesting a significant temperature difference and hence different rheological behavior in the post-Collision deformation of the Tibetan plate.

---

Yuan, X.; Kind, R.; Zhao, J.; Liu, H.; Kumar, R. (2010): The Architecture of Colliding Tectonic Plates in Tibet. 70. Jahrestagung der Deutschen Geophysikalischen Gesellschaft (DGG) (Bochum 2010).