Variations of the effective elastic thickness over China and surroundings and their relation to the lithosphere dynamics

The effective elastic thickness (Te) characterizes response of the lithosphere to a long-term tectonic loading. As a proxy of the lithospheric strength, Te can be used to address mechanical behavior and deformation of the blocks with complex geological structure. Here we use the multitaper coherence method to determine spatial variations of Te in China and surroundings based on the topography and Bouguer gravity anomaly data. The results show that the Te values are high (>70 km) over the cratons, e.g. India craton, the Siberian Craton, North China Block and also variations of these values are significant over these blocks. Low Te corresponds to the young orogens, e.g. Himalayas, Altun Shan–Qilian Shan–Longmenshan, Qinling–Dabie, and Daxingʹanling–Taihang Mountains etc. Combined with other data, the lateral variations of Te within the North China and South China Blocks and the Tibetan Plateau indicate that the lithospheric strength in China Mainland depends on both lithospheric structure and mantle dynamics. We guess that during the Mesozoic–Cenozoic period, the strength of the lithosphere might have been significantly altered by the thermodynamic processes associated with the India–Eurasia collision in the southwest and the subduction of the Pacific plate in the east. The Te variations also play a major role in the lithospheric evolution and deformation since the Mesozoic.