青藏高原东部构造块体的运动学及形变特征分析

Analysis on Kinematics and Deformation Characteristic of Tectonic Blocks in Eastern Tibet Plateau

通过分析青藏高原东部的活动断裂资料和GPS速度场数据,试图阐述活动地块的几何学、运动学和形变特征。初步认为:(1)第四纪特别是晚更新世以来的活动地块边界带与早期的构造单元边界密切相关,但也具有明显的新生性;(2)根据两种资料推导出的各个活动地块的运动学特征基本上是吻合的,其中鲜水河-玉树-玛尼断裂带是一条重要的分界线,其南、北部活动地块的运动方式差异明显;(3)除了活动地块的边界带强烈活动外,各个地块内部也显示出很强的变形;(4)晚更新世以来,青藏高原地壳的运动学和形变特征表现为在印度板块挤压力作用下,活动地块在向NE方向的运动过程中遇到稳定地块阻挡,调节方式是地壳增厚以及南、北部地块分别向SE-SSE和NWW-W方向的构造软弱部位水平侧向迁移。

Based on the analyses of active faults and Global Position System （GPS） data of the eastern Tibet plateau, the paper attempts to discuss the geometry, kinematics and deformation of the active blocks in eastern Tibet plateau. The preliminary conclusions are： （1） The boundaries of the ＂active＂ blocks which have actived in Quaternary, especially in Late Pleistocene are associated with the primary boundaries of the tectonic units （those are five suture zones and a deep, lithospheric fault zone between the terraines） , a few were newly formed since late Quaternary Period; （2） The kinematics characteristic of all active blocks induced from the active faults data are as same as one from GPS data, as the boundary, Xianshuihe - Yushu - Mani fault belt is very important for the movement way of the active blocks at the southern the fault belt is different from the ones at the northern side ; （3） Not only does the intensive deformation exist within the boundary zone between two active blocks, but also the deformation has taken place in the active blocks interior since Quaternary Period; （4） Since Late Pleistocene, the kinematics and deformation characteristic of the Tibet plateau crust should be that： when the active blocks moved to NE under the Indian plate compression, the steady blocks （i.e. Xiyu block region, Huabei block region, Nanhua block region） at the front held up the movement of the blocks, meanwhile the adjustment way of the active blocks was thickening crust and the blocks horizontal transfer to the tectonic weaker places, that is, the active blocks at the south of Xianshuihe - Yushu - Mani fault belt rotated clockwise to SE -SSE as an entirety around the Eastern Himalayan Syntaxis, while the blocks in the northern side of the fault belt displaced sinisterly to NWW -W.