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以GPS数据给出的川滇地区(96°~108°E,21°~35°N)速度场为约束,依据研究区已知断裂分布情况建立连接断层元模型,用最小二乘方法反演了该地区主要活动断层的现今错动速率.结果显示,印藏碰撞引起的北北东向推挤和高原隆升引起的重力势能作用造成青藏高原物质东向挤出.遇到来自稳定华南块体的阻挡后,高原东南部物质相对稳定欧亚板块转向南东方向继而向南运动,使得川滇地区围绕喜马拉雅东构造结作顺时针转动,造成川滇地块东侧断裂作左旋走滑活动,而其西侧断裂以右旋走滑活动为主.其中甘孜-玉树、鲜水河、安宁河、则木河、大凉山、小江断裂及其向南西方向延伸的部分和打洛-景洪、湄沾断裂构成青藏高原东南部东向挤出的东北边界和东边界,左旋速率分别为0.3~14.7,8.9~17.1,(5.1±2.5),(2.8±2.3),(7.1±2.1),(9.4±1.2),(10.1±2.0),(7.3±2.6)和(4.9±3.0)mm/a.青藏高原东南部东向挤出的西南边界似乎不是由单一断裂带构成,而是在较宽范围内形成的一条右旋剪切带.位于红河断裂北东侧的南华-楚雄-建水断裂和西南侧的无量山断裂带、龙陵-澜沧断裂活动性较强,分别具有(4.2±1.3),(4.3±1.1)和(8.5±1.7)mm/a的右旋走滑活动.但金沙江断裂目前基本不活动,红河断裂的活动性不强.龙门山一带没有发现明显的地壳活动,而其西北方向的活动带(龙日坝断裂)约有(5.1±1.2)mm/a的右旋走滑分量.川滇菱形块体内部的一些断裂表现出较强的活动性,其中理塘断裂左旋走滑速率为(4.4±1.3)mm/a,拉张速率(2.7±1.1)mm/a;玉农希断裂及其周边地区右旋剪切形变速率为(2.7±2.3)mm/a,地壳缩短速率(6.7±2.3)mm/a.丽江-小金河断裂中段活动性强于北段和南段,达到左旋走滑(5.4±1.2)mm/a,拉张(0.5±1.0)mm/a.与此同时,讨论了不同断裂锁定深度对结果的影响,并得到鲜水河断裂的锁定深度为15km,70%置信区间为11~19km.上述反演结果表明,研究区存在多条错动速率非常有限的活动断裂,将地壳分割成多个相互运动的地块,青藏高原的东向挤出通过这些断裂的活动被吸收和调整,而不是少数大型走滑断裂的快速走滑造成向东南方向的“逃逸”.
The velocity field of Sichuan-Yunnan region (96 ° ~108 ° E, 21 ° -35 ° N) given by GPS data is a constraint. Based on the known fracture distribution in the study area, a connected fault element model is established, and the least-square method The current dislocation rate of the main active faults in the area shows that the eastward extrusion of the plateau material caused by the north-north eastward thrust caused by the Indian-Tibet collision and the plateau uplift caused the eastward extrusion of the Qinghai-Tibet plateau, After the block of the body, the material in the southeastern plateau is relatively stable. The Eurasian plate turns to the south and then moves to the south, turning the Sichuan-Yunnan region clockwise around the East Himalayan structural knot, causing the left-lateral strike-slip fault on the eastern side of the Sichuan-Yunnan block , While the fault on the west side is dominated by dextral strike-slip events, of which the Ganzi-Yushu, Xianshuihe, Anninghe, Zemuhe, Daliangshan, Xiaojiang faults and their extension to the southwest are similar to that of the Daluo-Jinghong , And the Maixian fault formed the northeast boundary and the east boundary eastward of the Qinghai-Tibet Plateau. The left-lateral velocities were 0.3 ~ 14.7, 8.9 ~ 17.1, (5.1 ± 2.5), (2.8 ± 2.3), (7.1 ± 2.1) (9.4 ± 1.2), (10.1 ± 2.0), (7.3 ± 2.6) and (4.9 ± 3.0) mm / a respectively. The southeastern Tibetan Plateau The southwest boundary of the eastward extrusion does not seem to consist of a single fault but a wide range of dextral shear zones. The South China-Chuxiong-Jianshui fault northwest of the Red River fault and the southwestern The Wuliangshan fault zone and Longling-Lancang fault are highly active and have right-lateral strike-slip events of (4.2 ± 1.3), (4.3 ± 1.1) and (8.5 ± 1.7) mm / a, The activities of the Honghe fault are not active, and no obvious crustal activity is found in the Longmenshan area, while the activity belt in the northwest direction (Longjiaba fault) has a dextral strike-slip (5.1 ± 1.2) mm / a Some of the faults in Sichuan-Yunnan rhombic blocks show strong activity, of which the left-lateral slip rate is (4.4 ± 1.3) mm / a and the tension rate is 2.7 ± 1.1 mm / a The dextral shear deformation rate was (2.7 ± 2.3) mm / a and the crustal shortening rate was (6.7 ± 2.3) mm / a in the Nixi fault and its surrounding area. The Lijiang-Xiaojinhe fault had stronger mobility in the middle section than the north section and the southern section (5.4 ± 1.2) mm / a and 0.5 (0.5 ± 1.0) mm / a for left-lateral strike-slip, respectively. Meanwhile, the effect of different depths of fracture locking on the results was discussed and the depth of lock of the Xianshuihe fault Degree of 15km and 70% confidence interval of 11 ~ 19km.The above inversion results show that there are many active faults with very limited rate of dislocation in the study area, and the crust is divided into a lot of moving blocks, the east of the Qinghai-Tibet Plateau Extruded through these fractured activities are absorbed and adjusted, rather than a few large-scale strike-slip fracture rapid slippage caused by “escape” to the southeast.