【作者】 肖兰喜；

【导师】 朱元清；

【作者基本信息】 中国地震局地球物理研究所 ， 固体地球物理学， 2003， 博士

【摘要】 近半个世纪以来，国内外许多地球科学家为了解释青藏高原的形成和演化及动力学过程，进行了大量的野外考察与观测，开展了地质学、地球物理学、地震学研究以及数值模拟和实验研究，特别是空间测地技术(GPS)的应用，观测到了中国大陆地壳现今运动的空间分布，这些观测结果为进一步研究青藏高原地区对中国大陆其它块体的相互作用提供了重要的约束条件。 本文在前人研究的基础上，根据青藏高原和中国大陆岩石层结构的已有研究结果，在地壳运动速度场和最大水平主压应力方向观测结果的约束下，对板块相互作用对中国大陆岩石层地球动力学过程的影响进行了研究，主要讨论板块互相作用下中国大陆岩石层板内构造运动的动力学机制。 研究内容：(1)建立了中国大陆岩石层粘弹性物理模型；(2)．在GPS观测结果和震源机制解研究结果的约束下，讨论了中国大陆岩石层运动的动力学机制；(3)．建立了青藏高原地壳非均匀运动在中国大陆岩石层内产生扰动速度场和应力场的模型并进行了数值模拟，讨论了青藏高原地区地壳内弹性应变能释放和积累对华北地区各岩石层的影响；(4)．探索性的研究了扰动场与强震活动的关系；(5)．研究了华北地区深部断裂的非均匀活动与地壳形变异常的关系。 研究思路方法：在中国大陆岩石层数值模型中，采用三维Maxwell粘弹体。模型参数以中国大陆岩石层结构特征为基础，并考虑了岩石流变参数的可变范围。为了便于研究和讨论，本文设计了两种具有典型意义的模型，并将计算结果与已有研究结果进行对比，注重研究以下问题：(1)．中国大陆岩石层流变特性与板块边界作用强度的关系；(2)．不同流变强度模型中最大水平主压应力随深度分布情况的相对变化；(3)．分析在不同边界条件下，中国大陆板内的相互作用和与青藏高原的关系。 为了探讨扰动场的特点，对青藏高原地区地壳百年尺度内非均匀运动在中国大陆产生扰动作用进行了研究，从岩石层之间相互影响和相互作用的角度，探讨青藏高原地区地壳运动的非均匀性对其深部岩石层传递板块相互作用力的扰动和对中国大陆其它块体的影响；同时，探讨该扰动场与中国西部地区强震活动与华北地区强震活动相关性之间的关系。 主要成果及创新性：本文的主要意义在于，基于中国大陆模型，探讨了岩石流变强度与板块运动的关系，分别分析了板块相互作用和青藏高原形成后高原本身的重力作用对中国大陆岩石层的影响过程，给出了青藏高原地区地壳短时期内非均匀运动在中国大陆产生扰动场的结果，探讨了华北地区深部岩石层的动力来源，首次从深部断裂加速蠕滑的角度探讨邢台地震前地壳形变的物理机制。本文的主要结果是： (1)在现有观测资料的约束下，印度板块、太平洋板块和菲律宾板块对中国大陆板块的作用强度之比是4：1．25：1；板块边界的碰撞作用在模型坚硬层内形成较高的最大水平主压应力，青藏高原重力势等垂直向作用在青藏高原地壳内的软弱层形成较高的最大水平主压应力，这种垂直向作用力，在青藏高原南部地区向北推挤的过程中遇到了强烈的阻挡，使得高原周围其它地区增加对中国大陆其它块体的推挤作用。 (2)深、浅部岩石层不同的水平最大主压应力和速度场表明，两个模型中水平最大主压应力沿深度的不同分布是边界作用强度变化的主要原因，但各个板块的作用强度之比保持不中国地震局地球物理研究所博士论文变。 (3)青藏高原地区地壳非均匀活动在中国大陆岩石层引起扰动场的研究结果表明，在保持板块边界作用强度不变的情况下，青藏高原地区岩石层上部地壳运动的增强，增加了其岩石层下部的向前推挤，同时也增加了对其它块体的推挤作用，以上地慢盖层内最大水平主压应力的扰动值为例，华北地区比青藏高原南部地区小一个量级。从扰动场大小的空间分布来看，青藏高原地区的每一轮强震活动并不都能在华北地区引起一轮强震活动。该结果可以描述华北地区与青藏高原地区强震活动时序的内在规律，从岩石层相互作用的角度，可以得到华北地区强地震活动滞后青藏高原强地震活动约80年。 (4)本文给出的扰动作用可以同时影响华北地区整个岩石层。邢台地震前深部断裂存在非均匀活动的研究结果表明，深部断裂沿水平方向加速蠕滑时，可以在地壳内形成水平最大剪应力扰动值高速集中区，水平最大剪应力扰动值增加的速度是深部断裂不加速蠕滑时的几百倍;模型表面垂直位移与邢台地震前地表面垂直位移变化趋势一致，根据其上升和下降的年速率推断邢台地震前深部断裂沿水平方向加速蠕滑量为1米左右。深部断裂的加速蠕滑导致了岩石层下层内的能量向中上部地壳内快速转移，加速了强震在该区的孕育过程。邢台地震前存在深部断裂沿水平方向加速活动的结论，符合邢台地震前地壳形变异常的观测结果，合理地给出了邢台强震后期可能的地球动力过程。更多还原

【Abstract】 In the past fifty years, for the purpose of understanding the form and evolvement of Tibetan Plateau and their geodynamic process, many geoscientists in China and overseas have making a lot of field investigations and observations, doing many geognosy, geophysics, seismology researches, and developing some numerical computations and laboratorial researches. All of the results, especially the GPS observation data, make it possible for us to probe the geodynamic driving mechanism of continental lithosphere in China by the India-Eurasia collision.Under the restricts of the observation results of the horizon principal stress direction and the GPS data, and on the base of former researches about the lithosphere structures of Tibetan Plateau and other part of the mainland of China, we mainly study the geodynamic process and the geodynamic driving mechanism of continental lithosphere in China by plates collision.The main contents are: 1) establishing the physical model of continent lithosphere for numerical computation, 2) under the restricts of the observation result of the horizon principal stress direction and the GPS data, probing into the long term geodynamic driving mechanism of continental lithosphere in China, 3) establishing new model for computing the disturbing stress field in China, which is caused by the uneven activity of crust movement in Tibetan Plateau, 4)by using the spatial distribution of disturbing stress field to explain the strong earthquake activity relation between in Tibetan Plateau and in North China area,5) taking Xingtai strong earthquake in 1966 as example to understand the relation between the speedup activity of deep-seated fault in upper mantle and the vertical deformation on the earth’s surface .In the computation model, the medium of lithosphere is treated as Maxwell medium. The physical parameters of the model accorded with the lithosphere structures, and the viscosity coefficient has an alterable range. Two different models are adopted in the paper. Model I is that the material of the upper mantle in lithosphere has lower viscosity coefficient, Model II is that the material of the upper mantle in lithosphere has higher viscosity coefficient. By comparing the different results calculated from different model and different boundary condition, we explore the connection between the intensity of plate driving force and the viscosity coefficient of model, and the characteristic of long term geodynamic driving mechanism of continental lithosphere in different layers, and the different behavior of the India-Eurasia collision and the additional forces in vertical direction which included geopotential of Tibetan Plateau landform, buoyancy of heat convection in upper mantle.The strong earthquake activity in China not only relates with the background stress field but also with the disturbing stress field. A new model for calculating this disturb is present, and the disturbing stress, caused by the speedup or quietude of crustal movement in Tibetan Plateau are given. On the base of these results calculated from the model, the geodynamics process of the strong earthquake brewing correlation between in Tibetan Plateau and in North China is discussed.The main purpose of this paper is to probe into the driving mechanism to China continent by continental collision and by geopotential of Tibetan Plateau landform from the viewpoint of geodynamics process, to present a new model to calculate the disturbing stress, and to explain the possible mechanism of crustal deformation before Large Earthquake in Xingtai in 1966. The main conclusions are as follows.1) When the horizon principal stress direction, and the velocity of crust movement calculated from the two three-dimensional Maxwell viscoelastic models are generally good agreement withresults from seismology study and geodetic in china continent and its vicinity, the intensity ratio of driving force to China continental lithosphere from India plate, pacific plate and Philippine plate is 4:1.25:1. The behaviors of the India-Eurasia coll更多还原