Tomographic imaging of the underthrusting Indian slab and mantle upwelling beneath central Tibet

To better understand the pattern of convergence between the Indian and Eurasian plates, we determine a high-resolution P-wave tomography of the crust and upper mantle under central Tibet using a large number of high-quality data collected by the ANTILOPE and Hi-CLIMB projects. A significant low-velocity zone is detected above the northward underthrusting Indian slab under the Indus-Tsangpo suture, which may reflect the fault zones and cracks in the Asian crust and lithosphere as well as melts and/or fluids associated with the dehydration of the underthrusting Indian slab. The variations in the diving depth and extending distance of the Indian plate, under the ANTILOPE and Hi-CLIMB seismic profiles, may be caused by the differences in the viscosity contrast between the Indian slab and the surrounding mantle as well as the strong structural heterogeneities in the upper mantle under the study region. High-velocity zones are revealed in the mid- to lower crust under southern Tibet, which may reflect the complex pattern of material flows. Different velocity anomalies exist beneath the rifts in southern Tibet, suggesting that the those rifts are formed in different ways. Interpretive cartoons illustrating the dynamic evolution under central Tibet. The dashed lines show the uncertain results in our tomographic image or inferred from other results.