【摘要】 青藏高原东缘地区活动断裂极其发育,强震繁发,特别是2008年5月12日的汶川MS8.0级地震的发生,使得众多地球科学家认识到有必要更为全面地了解和认识该地区的地应力场背景和地球动力学环境.本论文结合活动构造的性质和分布特征,在考虑重力因素的条件下,利用三维粘弹性有限元模拟分析青藏高原东缘现今地应力场的分布特征和控制因素.模拟结果表明,印度板块与欧亚板块的持续碰撞和稳定华南块体的阻挡控制着青藏高原东缘总体的动力学环境,主要活动断裂和次一级活动断裂的展布对地应力场分布特征具有不同程度的影响,在不同的构造位置具有不同的地应力场特征,同时决定了相应活动断裂的性质.巴颜喀拉块体的水平最大主应力方向总体上为东西向;印度板块向北运动过程中对缅甸块体产生的剪切拉伸的作用和南海伸展性的边界使得水平最大主应力方向在川滇地块发生了偏转,同时造成了围绕喜马拉雅东构造结的旋转变形.青藏高原东缘在近地表区域由于受到地形地貌的影响,地应力随深度发生了不同程度的变化,在地形梯度较大和块体边界地壳结构发生较大变化的区域,如龙门山断裂带附近,地壳浅部的地应力随深度发生较为明显的变化,而地势比较平缓和地壳岩石物性比较稳定的地区,由浅到深的地应力变化较小.更多还原

【Abstract】 In the Eastern Qingzang plateau there exist many active faults and the strong earthquakes occur frequently.The MS 8.0 earthquake of Wenchuan on the May 12,2008 is very destructive and unexpected.So it is indispensable to understand the background of crustal stress and the geodynamic environment considering as many influence factors as possible.This paper focuses on the characters of the present crustal stress of Eastern Qingzang plateau and analysis the influence factors using 3D viscoelastic FE numerical modeling.The 3D FE model includes the distribution and property of active faults and self-gravity.The simulation results show that the plate tectonics is dynamic source of the crustal stress of the Eastern Qingzang plateau,the main and secondary active faults dominate the distribution of crustal stress.The crustal stress property is dissimilar in different tectonic position and dominates the active fault property.The directions of horizontal maximum principal stress in Bayankala block are almost E-W which is restricted by the continuous collision between India plate and Euroasia plate and the blocking of Huanan block.The directions of horizontal maximum principal stress in Chuandian block are deflective under the shear dragging induced by the India plate and extensive South China Sea boundary,and the block rotates around Eastern Himalaya syntaxes.The shallow crustal stress of Eastern Qingzang plateau varied with depth in different degree at different position.The crustal stress varied obviously with depth in the large gradient topography and the block boundary zone with large different crust structure and physical properties such as Longmenshan faults,and the crustal stress is varied less obvious in gentle topography and inner block.更多还原