青藏高原东南缘构造应力场重构

采用有限元方法，针对青藏高原东南缘建立更细致、更精确的三维有限元弹性模型。选取9种不同的应力边界条件，分别进行优化分析后处理，将对应台站形变模拟值与GPS实测值进行误差分析，最终选取最佳方案作为古构造应力场。结果表明，青藏高原东南缘4 Ma BP的古应力场主要起源于中国大陆周围板块的相互作用，特别是印度板块NNE向强烈碰撞作用，成为中国大陆尤其是西南部青藏高原地区构造应力场最主要的动力来源，控制各个块体相互作用的方式和运动格局。青藏高原东南缘古应力场主要包括几个力源：西北部青藏高原侧向挤压造成的WE向应力约105 MPa；西南部直接来自于印度板块的NE-WS向应力约70 MPa；南部NS向作用力33 MPa；东南部扬子块体侧向NW-SE阻挡力56 MPa；北东部受扬子块体强烈EW向阻挡力90 MPa。这些力源共同作用于青藏高原东南缘，形成现今复杂应力场。

Tectonic Stress Field Reconstruction in Southeastern Tibetan Plateau

Using finite element method on the southeast margin of the Tibetan plateau, this paper establishes a more detailed and accurate three dimensional finite element model of elastic, selects the stress of the nine different boundary conditions, applies optimization analysis for each project in post-processing, analyzes the corresponding station deformation GPS simulated values and measured error, and finally chooses the best solution as palaeotectonic stress field. Results show that around four million years ago the ancient stress field of the southeast margin of Tibetan plateau mainly originated from intense collision of the Indian plate NNE with the Chinese mainland plate. The mainland of China, especially the Tibetan plateau in southwest region, is the main power source of the tectonic stress field, and controls how the various blocks interact and their motion patterns. The paleostress field on the southeastern edge of the Tibet plateau mainly includes the following sources: The NE-WS directional stress in the southwest is about 70 MPa directly from the Indian plate. Southern NS force 33 MPa; lateral NW-SE blocking force of southeast Yangtze block is 56 MPa. At the same time, the strong EW blocking force of the Yangtze block in the eastern north is 90 MPa, and these forces act together on the southeastern edge of the Tibetan plateau, forming a complex stress field.