论文部分内容阅读
GPS测量结果表明青藏高原水平位移场在其东部绕喜马拉雅东构造结呈顺时针转动,其地球动力学成因难以在二维模型中模拟.由于青藏高原地壳巨厚、下地壳温度高,岩石层流变性质可能会呈现脆性的上地壳、柔性的下地壳和黏滞系数较大的岩石圈上地幔,在岩石圈下又存在黏滞系数较低的软流层的复杂分层流变结构.在上述研究成果的基础上,利用三维球坐标系下的Maxwell体有限元模型模拟了青藏高原在印度板块推挤下的变形.模拟结果显示,柔软下地壳的存在使整个青藏高原在印度板块的推挤下表现为整体抬升,高原南缘和喜马拉雅东构造结抬升迅速,而由于周边地块下地壳相对较硬而封闭、仅高原东南部存在高温柔软的通道,青藏高原软的下地壳的存在还使得高原整体隆起达到一定高度后,下地壳和软流层的物质向东、东南流动,并拖曳上地壳作类似运动,形成绕喜马拉雅东构造结的顺时针转动.
The results of GPS measurements show that the horizontal displacement field of the Qinghai-Tibet Plateau turns clockwise around the eastern Himalayan structural junction and the geodynamics of the Tibetan Plateau is hard to be simulated in the two-dimensional model. Because of the thick crust in the Qinghai-Tibet Plateau, the high crustal temperature, The metamorphism may present brittle upper crust, flexible lower crust and lithospheric upper mantle with high viscosity coefficient. In the lithosphere, there are complex stratified rheological structures with lower viscous coefficient. Based on the above research results, the deformation of the Qinghai-Tibet Plateau under the push of the Indian plate is simulated by using the Maxwell finite element model in the three-dimensional spherical coordinate system. The simulation results show that the soft crust has pushed the entire Tibetan Plateau in the Indian plate The crust is uplifted as a whole, and the eastern junction of the plateau and the Himalayas is rapidly uplifted. Due to the relatively hard and enclosed crust below the surrounding plots, high-temperature soft channels exist in the southeastern plateau. The soft lower crust of the Qinghai-Tibet Plateau After the whole uplift of the plateau reaches a certain height, the materials in the lower crust and the asthenosphere flow eastwards and southeastwards and drag the upper crust for similar movements to form Eastern Himalayan clockwise junction.