中国大陆大型盆地的岩石圈结构及构造意义

The study of lithosphere structure within the basin is helpful to understand the formation and evolution of the basin and the relationship with regional tectonics.Surface-wave tomography is an important tool for investigating the S-wave velocity structure and dynamics of the Earth's interior. In this study a new lithospheric S-wave velocity model up to 300 km depth in East Asia is obtained by combining our newly measured Rayleigh wave phase and group velocities using the earthquake-based two-station analysis with previous published dispersion measurements. We focuse on the deep velocity structures and the lithospheric thicknesses beneath six sedimentary basins (Tarim Basin, Qaidam Basin, Sichuan Basin, Ordos Basin, Bohai Basin and Songliao Basin) in Mainland China. The results show that the lithospheric thicknesses of the basins in eastern China vary significantly from the basins in central and western China. Tarim Basin, Sichuan Basin and Ordos have the thickest lithosphere (up to about 200 km), while Bohai Basin and Songliao Basin have the thinnest lithosphere. Qaidam Basin has the intermediate lithospheric thickness. The lithospheric thicknesses in each basin show significant lateral variations, suggesting the differences of the interior deformation in basins. The basin-mountain junction belts have the strongest deformation due to regional compression and material intrusion. The regional compression due to the subduction of Indian plate to the Eurasian plate may have played an important role in the formation and evolution process for the basins surrounding the Tibetan Plateau. Ordos Basin shows thick lithosphere in the western part and sharp lithosphere thinning in the eastern part, which may imply that the lithosphere thinning of the North China Craton only occurs in the eastern part.