青藏高原东南缘地质构造基本形态与地震各向异性基本特征

青藏高原东南缘受印度板块NE向推挤和高原物质SE向挤出及四川盆地、 华南块体阻挡的共同作用, 成为高原物质SE向逃逸的关键通道。 本文综述了青藏高原东南缘由不同震相和不同方法得到的不同深度的地震各向异性结果, 结合区域内断裂分布、 地表运动、 构造应力以及深部结构等方面, 全面分析了青藏高原东南缘上地壳至中下地壳及上地幔的介质各向异性与变形耦合特征。 青藏高原东南缘壳幔地震各向异性的差异反映了区域内复杂的深部构造和壳幔变形。 由于青藏高原形成机制、 壳幔耦合状态和软弱层分布形态等科学问题尚处于学术探讨之中, 有效结合不同数据和综合多种方法, 有益于获得更加准确、 精细的地壳—上地幔地震各向异性图像, 对深部物质运动与动力模式进行更有效的约束。

Basic Characteristics of Tectonics and Seismic Anisotropy in the Southeastern Margin of the Qinghai-Tibet Plateau

The southeastern (SE) margin of the Qinghai-Tibet Plateau is jointly affected by the northeastward pushing of the Indian plate, the southeastward extrusion of the plateau material, and the blocking of the Sichuan Basin and South China Block, which has become a key channel of the southeastward escaping material of the Qinghai-Tibet Plateau. In this paper, we summarizes the results of seismic anisotropy of different depths obtained by different seismic phases and different methods in the SE margin of the Qinghai-Tibet Plateau. Combining the distribution of faults, surface movement, tectonic stress and deep structure in the region, we comprehensively analyzed the medium anisotropy and deformation coupling characteristics from the upper crust to the middle-to-lower crust and upper mantle. The difference in seismic anisotropy of the crust and the upper mantle in the SE margin of the Qinghai-Tibet Plateau reflects the complex deep structure as well as crust and upper mantle deformation in this region. As scientific issues such as the formation mechanism of the Qinghai-Tibet Plateau, the coupling state of crust and mantle and the distribution of weak layers are still under academic discussion, it is beneficial to obtain more accurate and detailed seismic anisotropy images of crust and upper mantle by effectively combining different data and synthesizing various methods, thereby providing more effective constraints on the research of deep material movement and dynamic model.