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基于由瑞利面波层析成像所得的青藏高原及其邻区的群速度纯频散,以线性的深度反演获取的S波速度分布为非线性反演的初始模型,用快速模拟退火方法进行速度和层厚度的联合反演.根据非线性反演结果求得研究区地壳、岩石圈和软流层的厚度分布.结果表明,青藏高原内部具有巨厚的地壳,厚度为60～80km,其岩石圈相对邻区较薄,厚度在130～160km之间,且在内部呈现出以90°E～92°E北北东向为界的东、西分块图像.高原的软流层厚度较周边地区要厚(150～230km),其内部羌塘块体西部的软流层最厚.在区域上的分布特点为,印度的地壳厚度较薄即32～38km,岩石圈厚度可达190km,软流层厚度相当薄仅60km左右;四川盆地和塔里木盆地的地壳厚度均小于50km,其岩石圈厚度要比高原内部厚,而软流层厚度则相对于高原内部要薄.文中还讨论了羌塘块体西部的典型壳-幔过渡带特征和其形成机制.
Based on the pure group velocity dispersion of the Qinghai-Tibet plateau and its adjacent areas obtained from Rayleigh surface-wave tomography, the S-wave velocity distribution obtained from the linear depth inversion is used as the initial model for the nonlinear inversion. The fast simulated annealing method The joint inversion of velocities and layer thicknesses was carried out.The thickness distribution of the crust, lithosphere and asthenosphere in the study area was obtained based on the nonlinear inversion results.The results show that the crust in the interior of the Qinghai-Tibet Plateau has a thickness of 60-80 km, Its lithosphere is relatively thin and has a thickness of 130-160km, and presents the eastern and western sub-regions of the image with the north-east direction of 90 ° E-92 ° E as its boundary. The thickness of the asthenosphere in the plateau The thickness of the asthenosphere in the western part of the Qiangtang block is thicker than that in the surrounding area (150 ~ 230km), and its distribution in the area is that the thickness of the crust in India is 32 ~ 38km and the lithosphere thickness can reach 190km soft flow relatively thin thickness of only about 60km;. Sichuan and Tarim crust thickness is less than 50km, which lithosphere thickness than the thickness of the internal plateau, the soft flow of the layer thickness is thin relative to the inner plateau also discussed in the Characteristics of Typical Crust - Mantle Transitional Zone in Western Qiangtang Block Into the mechanism.