Research actuality of crustal stress field in the Sichuan—Yunnan region
The Sichuan—Yunnan region,located in the eastern margin of the Tibetan Plateau,is not only the foreland of the collision between the Indian and the Eurasian plates,but also an important site for the study of crustal deformation and the eastward escape of plateau materials.The regional crust is cut into multiple secondary blocks by crisscross active faults and block boundaries.Severe tectonic movements have caused strong lateral inhomogeneity in the stress field.This paper provides a systematic summary of recent research progress on the stress field in the Sichuan—Yunnan region.By analyzing the results of surface deformation field,in-suit stress measurement,and focal mechanism solution,the paper presents an in-depth analysis of the stress field direction and heterogeneity characteristics of different scales.The surface deformation field in the Sichuan—Yunnan region along the Xianshuihe—Xiaojiang fault as the boundary of the western region,to the intersection area of Red River fault and Lijiang—Xiaojinhe fault,are obvious clockwise rotation deformation.Under the eastward compression of the Tibetan Plateau,the stress field in the region is bounded by the Longmenshan fault—Lijiang—Xiaojinhe fault,with the north side dominated by NE-SW,E-W compression and NW-SE,N-S tension.The principal compressive stress on the south side is fan-shaped along the fault,basically consistent with the surface deformation field,while the principal tensile stress is arc-shaped along the fault,basically consistent with the contour shape of the terrain.At the same time,the crust-mantle deformation in the Sichuan—Yunnan region may be coupled in the north and decoupled in the south.In this paper,it is found that the tectonic stress field under the large fault zone,such as Longmenshan fault,Red River fault and Lijiang—Xiaojinhe fault shows a segmented variation,which is related to the deformation of deep media revealed by seismic anisotropy.
万方数据
维普
