青藏高原东南缘旋转变形的三维动力学模拟分析

发布时间：2018-03-27 13:43

本文选题：青藏高原东南缘　切入点：数值模拟　出处：《中国地质科学院》2017年硕士论文

【摘要】：在印度板块向欧亚板块北向俯冲过程中,在鄂尔多斯块体和华南块体的的阻挡作用下,青藏高原内部的物质受到挤压。同时,在青藏高原东南缘内一系列断裂带的综合作用下,青藏高原东南缘的物质开始向南"逃逸",呈现出青藏高原东南缘顺时针旋转变形的运动学特征。论文针对青藏高原东南缘旋转变形的运动特征和块体内部张性活动构造发育并旋转这一现象,以青藏高原东南缘内一些列活动断裂及其所围限的块体模型为基础,综合考虑了 GPS速度场、震源机制解及地应力测量的构造应力场、块体单元内部及其周缘活动构造空间分布特征、岩石圈圈层结构及其物质特征等现实情况,运用数值模拟的方法分别构建了青藏高原东南缘二维弹性、粘弹性和三维粘弹性有限元模型。通过与该地区的GPS速度场、震源机制解、实测应力场等数据的对比,深入探讨了青藏高原东南缘的构造应力场分布特征及该区域旋转变形的动力学机制。数值模拟的位移场与相对于华南块体的实测GPS速度场表现出的物质运动特征基本一致。从整体运动趋势来看,青藏高原东南缘内物质运动表现为由北部的北东-北北东向运动,到中部区域顺时针旋转为南东-南南东向,再到南部则旋转为南西向运动。青藏高原东南缘最大主应力表现为围绕喜马拉雅东构造结呈扇形展布的特征,最大主压应力场从北部的北北东和北东向向南部逐渐顺时针旋转为近南北向。以南北地震带南段为界,在华南板块最大主应力呈南东向分布。对比震源机制解、水压致裂实验等地应力实测数据,本文数值模拟的构造应力场分布特征与实测构造应力场特征基本一致。青藏高原东南缘的动力学机制是印度板块向欧亚板块的俯冲作用,缅甸板块对巽他板块的拉张作用,菲律宾板块向东运动产生的拉张作用,鄂尔多斯块体和华南块体的阻挡作用以及上地幔和下地壳的拖拽作用共同形成的。在这几种动力来源的共同作用下,藏东地区,川滇菱形块体的西北部以及阿坝块体内部处于挤压环境,鲜水河-小江断裂带、龙门山断裂带和昆仑山断裂带呈现出走滑运动特征;滇中地区及滇西南地区表现为拉张环境,红河断裂带南段的走滑拉张特征,实皆断裂带呈现出近南北向的走滑特征。
[Abstract]:During the northward subduction of the Indian plate to the Eurasian plate, under the blocking action of the Ordos block and the South China block, the material inside the Qinghai-Xizang Plateau was squeezed. At the same time, under the combined action of a series of fault zones in the southeastern margin of the Tibetan Plateau, The material in the southeastern margin of the Qinghai-Xizang Plateau began to escape southward, showing the kinematic characteristics of clockwise rotational deformation in the southeastern margin of the Qinghai-Xizang Plateau. The paper aims at the kinematic characteristics of the rotational deformation in the southeastern margin of the Qinghai-Tibet Plateau and the tensional activity inside the block. The dynamic structure develops and rotates. Based on some active faults in the southeast margin of the Qinghai-Xizang Plateau and their block models, the tectonic stress field of GPS velocity field, focal mechanism solution and geostress measurement are considered synthetically. The two-dimensional elasticity of the southeast margin of the Qinghai-Xizang Plateau has been constructed by using the numerical simulation method in the practical situations such as the spatial distribution characteristics of the active structures inside the block unit and its periphery, the structure of the lithosphere and its material characteristics, etc. The finite element models of viscoelasticity and three-dimensional viscoelasticity are compared with the data of GPS velocity field, focal mechanism solution and measured stress field in this area. The distribution characteristics of tectonic stress field and the dynamic mechanism of rotational deformation in the southeast margin of Qinghai-Xizang Plateau are discussed in depth. The displacement field simulated by numerical simulation and the material motion characteristics of GPS velocity field compared with the measured GPS velocity field of South China block are presented. Basically consistent. Judging from the overall movement trend, The material movement in the southeastern margin of the Qinghai-Xizang Plateau shows a movement from the north to the north, and to the central region, which rotates clockwise from the south to the south to the south to the east. To the south, the maximum principal stress of the southeastern margin of the Qinghai-Xizang Plateau is characterized by the fan-shaped distribution around the eastern Himalayan tectonic junction. The maximum principal compressive stress field rotates clockwise from the north to the north from the north to the north to the south to the north to the south. Taking the southern segment of the north-south seismic belt as the boundary, the maximum principal stress in the South China plate is distributed in the south-east direction. The distribution characteristics of tectonic stress field simulated in this paper are basically consistent with the observed tectonic stress field characteristics. The dynamic mechanism of the southeast margin of the Qinghai-Xizang Plateau is the subduction of the Indian plate to the Eurasian plate. The extension of the Myanmar plate to the Sunda plate and the eastward movement of the Philippine plate, The blocking effect of the Ordos block and the South China block, and the drag-down of the upper mantle and the lower crust are formed together. The northwestern Sichuan-Yunnan rhombic block and Aba block are in a compressional environment. The Xianshuihe-Xiaojiang fault zone, the Longmenshan fault zone and the Kunlun mountain fault zone show the characteristics of runaway movement, and the central and southwestern Yunnan areas show extensional environment. The strike-slip extensional characteristics of the southern section of the Honghe fault zone are all strike-slip features in the near S-N direction.
【学位授予单位】：中国地质科学院
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：P315.2

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