ACTIVE DEFORMATION STYLE IN SOUTH-EASTERN AND NORTH MARGINS OF TIBETAN PLATEAU

In south\|eastern margin of Tibetan plateau, the Western Yunnan area of China, the NNW\|striking faults are dominant active structures. Their dextral strike\|slips cause conjugate slips along NE\|striking faults, and these left shears induce blocks’ clockwise rotations along vertical axes. For example, Simao Block in the south part of Western Yunnan is bounded by Red River Fault (east), Lancang—Gengma Fault (west), Nandinghe Fault (north), and Dian Bien Phu Fault (south); and the right shears of Red River Fault and Lancang—Gengma Fault induced conjugate left shear along Nandinghe Fault and Dian Bien Phu Fault, and laters’ sinistral slips caused clockwise rotation of the Block. This rotation has been proved by geodetic measurements (Jiang, et al., 1993) and palaeomagnetic measurement (Wu, et al., 1987). In Pu’er area, which is located in the central part of Simao Block, several small\|scale blocks are clockwise rotated by sinistral shears of NE\|striking faults (Wang Yang, 1996). Block rotation along vertical axis is main active deformation style in Western Yunnan.