Oblique Rifting in the Southern Tibetan Plateau Revealed From 3‐D High‐Resolution Seismic Travel‐Time Tomography Around the India–Eurasia Continental Collision Zone

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AbstractThe India–Eurasia continental collision zone (IECCZ) is an ideal setting for studying plate collision processes, plateau uplift mechanisms, and orogenic activities. Several models have attempted to explain the north–south (N‒S) collision and east–west (E‒W) extension based on geological and geophysical observations. Among them, the subduction of the subducted Indian lower crust (SILC) and the deep geometric shape of the southern Tibetan rifts are still controversial. To address these issues, we selected P‐ and S‐wave arrival times from 35,193 earthquakes recorded by 575 permanent and temporary stations and applied an improved double‐difference tomography method to obtain high‐resolution 3‐D P‐ and S‐wave velocity structures of the crust and uppermost mantle and relocated earthquake event locations around the IECCZ. The N‒S velocity profiles display a northward‐subducting high‐velocity layer stretching from the 20–40 km depth range in the Himalayan belt to the 50–60 km depth range beneath the northern Lhasa terrane (NL), suggesting that the eclogitized SILC extended beyond the Indus–Yarlung suture, reaching the NL. Additionally, the E‒W velocity profile at the SILC front reveals a discrete high‐velocity layer at depths of 40–60 km beneath the Longgar, Tingri–Nyima, Xianza‐Dinggye, and Yadong–Gulu rifts, implying that the SILC experienced tearing. Based on a comprehensive analysis of the seismicity, large‐earthquake source mechanisms near the Moho, and tomographic images of the study area, we proposed a new dynamic model of the India–Eurasia collision and N–S‐trending rifts. The significant characteristic of this model is that the rifts cut through the crust obliquely, not vertically.