High‐Resolution 3‐D Shear Wave Velocity Model of the Tibetan Plateau: Implications for Crustal Deformation and Porphyry Cu Deposit Formation

The high topography of the Tibetan Plateau was generated by the Cenozoic India‐Eurasia collision. A high‐resolution shear wave velocity model can provide improved understanding of the Tibetan structure and crustal deformation with complicated tectonic evolution. Based on continuous seismic observations at approximately 400 stations, we collected over 10,000 Rayleigh wave phase velocity dispersion curves extracted from ambient noise cross‐correlation functions. A direct surface wave inversion method was applied to obtain an S wave velocity model of the Tibetan crust. A heterogeneous structure including several prominent low‐velocity zones (LVZs) and relatively narrow low‐velocity bands connecting the LVZs is revealed. Our model shows significant crustal low‐velocity structures with lateral variations along the Himalayan front. In the eastern segment of the Lhasa terrane, the LVZ is spatially correlated with Miocene porphyry Cu deposits, which are probably related to strong tearing of the Indian lithosphere, while preexisting weak zones contribute to the LVZs in the western segment. Meanwhile, the LVZ along the Bangong‐Nujiang suture could be considered as a channel for eastward extrusion of ductile material, that is, crustal flow on geological timescales. This “flow” in the middle‐lower crust probably contributed to the formation of the V‐shaped conjugate strike‐slip fault system in central Tibet. The development of conjugate strike‐slip faults, however, ceased near 90°E, since the eastward “flow” was blocked by an intracrustal high‐velocity block in Amdo. This preexisting rigid zone (containing the Amdo microcontinent) hence influences the pattern of material transport inside the Tibetan crust and the deformation of the plateau. Key Points Three‐dimensional architecture of crustal low‐velocity zones of the Tibetan Plateau is obtained by dense array ambient noise tomography Low‐velocity zones along southern Tibet and the Miocene porphyry Cu deposit formation are related to Indian lithosphere tearing Eastward crustal flow blocked by a rigid block in Amdo contributed to the formation of conjugate strike‐slip faults in central Tibet