Lithospheric structure beneath Tibet based on gravity data from World Gravity Map 2012

An appreciation of the geodynamics of the Cenozoic great collision between the India and Eurasia plates necessitates an understanding of the lithospheric structure beneath Tibet. Here, we utilise the World Gravity Map 2012 (WGM2012) gravity data to derive the lithospheric density variations and gravity anomaly beneath Tibet, employing the multi-scale inversion and regularised downward continuation methods. The findings indicate that the E-W striking structures persist to a depth of 90 km. The deep lithospheric mantle displays block-like density anomalies that exhibit a distinct N-S trend with increasing depth. The results clearly indicate a decoupling between the lithospheric crust and mantle. It is possible that changes may occur along the Indian plate’s subduction front, which subducts to the south of 32°N along the western portion of the subduction zone, as indicated by the apparent density of the lithospheric mantle. In contrast, in the central and eastern regions, the Indian lithosphere appears to subduct primarily north of the Indus-Tsangbo suture zone (30°N), where it may undergo tearing and delamination beneath the Lhasa block. This phenomenon promotes the convection of soft materials and the upwelling of mantle material, which causes the Tibetan lithosphere to thin and stretch in an E-W direction. At a depth of 150 km beneath central Tibet, alternating lower-density belts trending north–south may be connected at greater depth. These structures likely reflect lithospheric deformation, which plays a crucial role in shaping the geodynamics of the region.