A study of Mesozoic-Cenozoic tectonic evolution of the Tarim Basin with S-wave receiver functions

During the early Cenozoic, the collision and convergence between India and Eurasia resulted in the uplift of the Tibetan Plateau and continuous northward compression, forming the Circum-Tibetan Plateau Basin and Orogen System (CTPBOS). The Tarim Basin, located between the Tibetan Plateau and the Tianshan Mountains, plays a crucial role for studying the convergence-driving strain propagation mechanism intra-Asian continent during the growth processes of the Tibetan Plateau. Owing to the lack of accurate geophysical information on the deep structure of the Tarim crust, the mechanism of Cenozoic deformation in the Tarim Basin has been under debate. In this paper, the teleseismic data acquired by the broadband seismic profile across the Tarim Basin from south to north and the S-wave receiver function method were used to obtain the depth of the Moho and the discontinuities in the lithosphere beneath the Tarim Basin. The SRF result shows that the Moho geometry has an abrupt relief under the Bachu Uplift, and Moho offset under the fault zone between the Kalashayi Fault and the Tumuxiuke Fault. The regional dip of the Moho under the Bachu area can be explained by the root of the Bachu basement-involved uplift cutting across the whole crust and locally penetrating into the mantle lithosphere. The Bachu Uplift, located in the central Tarim terrane, has a relatively weak lithosphere. In the process of forming the Tarim large igneous province during the early Permian, the crust beneath the Bachu area was weakened and thinned by the thermo-mechanical erosion from upwelling mantle plume. As the collision and convergence of India and Eurasia since the early Cenozoic, the convergence-driving strain was propagated into the Tarim Basin. The pre-existing weak Bachu Uplift was reactivated. The Tarim Basin absorbs Cenozoic compressional deformation through the crustal shortening and Moho offset of the Bachu Uplift. The S-receiver function study shows that the Moho geometry has an abrupt flexure and offset beneath the Bachu Uplift of the Tarim Basin. It is can be supposed that the Tarim Basin absorbs Cenozoic compressional deformation by the crustal shortening. The Cenozoic deformation was cutting through the entire crust and locally penetrating into the mantle lithosphere. image