Late Cenozoic to recent transtensional deformation across the Southern part of the Gaoligong shear zone between the Indian plate and SE margin of the Tibetan plateau and its tectonic origin
Late Cenozoic to recent transtensional deformation across the Southern part of the Gaoligong shear zone between the Indian plate and SE margin of the Tibetan plateau and its tectonic origin
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DOI：
10.1016/j.tecto.2008.04.007
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发表时间：
2008-11
期刊：
影响因子：
2.9
通讯作者：
G. Wang;Gang Wang;Jinlin Wan;E. Wang;D. Zheng;Feng Li
中科院分区：
文献类型：
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作者：
G. Wang;Gang Wang;Jinlin Wan;E. Wang;D. Zheng;Feng Li
在青藏高原东南部，高黎贡山剪切带构成了腾冲地块与保山地块的分界线，是东喜马拉雅构造系中主要的新生代走滑断裂系统之一。山脉最高海拔3623米，宽20公里，长400公里。剪切带的核心由一条狭窄的糜棱岩带组成，具有右旋走滑组构，形成于渐新世和中新世印度相对于欧亚大陆向北运动期间。在南边，山脉的海拔降低，终点是蜿蜒的断层。后者是青藏高原东南部一系列北东-南西向活动的左旋走滑断裂之一。高黎贡山高程变化的原因和时间尚不清楚，但根据我们最近的构造和裂变径迹年代学工作，高程的下降是晚新生代以来高黎贡山南段东西向伸展以及沿其东西边界活动的正断层的结果。向南，东部边界断裂系统与一系列游移走滑断裂展布合并，而西部边界断裂系统与移动断裂弯曲成平行。这种几何关系表明，高黎贡山剪切带东西边界的正断层是由北东向北西向伸展的北东-南西向左旋运动转化为东北向的东西向伸展形成的。由此产生的正断层作用导致了剪切带南部地形的下降。瑞丽斜向滑移断裂(左行逆冲滑动)下盘糜棱岩的11个样品的裂变径迹数据获得了8.4~0.9 Ma的年龄，与界头和芒邦盆地内的火山活动同龄。晚新生代至近代，印度板块相对于青藏高原东南缘沿右侧萨甘断裂向北运动期间，沿旺旺断裂和瑞丽断裂的左行走滑运动，适应了高黎贡山剪切带及其邻近构造单元的差异顺时针旋转。
Within the southeastern part of the Tibetan plateau the Gaoligong Shan shear zone forms the boundary between the Tengchong and Baoshan blocks and is one of the main Cenozoic strike–slip fault systems of the eastern Himalayan syntaxis. The mountain ranges rise to a maximum elevation of 3623 m, with a width of 20 km and a length of 400 km. The core of the shear zone consists of a narrow belt of mylonitic rocks with right-lateral strike–slip fabrics formed during the northward movement of India relative to Eurasia in Oligocene and Miocene time. To the south the mountains decreases in elevation and end against the Wanding fault. The latter is one of a series of NE–SW striking, active left-lateral strike–slip faults within the southeastern part of the Tibetan plateau. The cause and timing for the change in elevation of the Gaoligong Shan is unknown, but based on our recent structural and fission-track geochronological work, the decrease in elevation is the result of east-west extension across the southern part of the Gaoligong shear zone inferred from the late Cenozoic and active normal faults along its eastern and western boundaries. Southward the eastern boundary fault system merges with a series of splays of the Wanding strike–slip fault, while the western boundary fault system is bent into parallelism with the Wanding fault. This geometric relationship suggests that the normal faulting along the eastern and western boundary of the Gaoligong shear zone was caused by transfer of the NE–SW left-lateral movement along the Wanding fault into E–W extension on faults to the northeast. The resultant normal faulting caused the lowering of the topography in the southern part of the shear zone. Fission track data from 11 samples from the mylonitic rocks in the footwall of the Ruili oblique slip fault, (left-lateral thrust slip) yielded ages between 8.4 and 0.9 Ma, coeval with volcanism within the Jietou and Mangbang basins. The left-lateral strike–slip movement along the Wanding and Ruili faults is interpreted to have accommodated differential clockwise rotation of the Gaoligong shear zone and its adjacent tectonic units during late Cenozoic to Recent time, during the northward movement of the Indian plate with respect to the southeastern margin of the Tibetan plateau along the right-lateral Sagaing fault.