| Under the double influences of India-Eurasian plate collision and the eastward movement of the Qinghai Tibet Plateau, the peculiar geomorphic feature and tectonic movement have been come into existence in eastern Tibet margin. The occurrence of Wenchuan Ms8.0Earthquake makes this area the hot spot of geo science study both at home and abroad.The following paper researches the crustal deformation and dynamical mechanics in eastern Tibet margin with the Longmen Shan fault and the seismic region of Wenchuan as the researching priority. Firstly, after summarizing the former researches and combining the GPS and leveling data, the paper meticulously analyzes crustal deformation in eastern Tibet margin. It further explores the different patterns of various secondary blocks in absorbing the interior deformation through the comparison of horizontal and vertical rates. Secondly, the paper describes in details the characteristics of deep crustal structure in eastern Tibet margin, and demonstrates the relationships of upper crustal deformation and deep crustal structure after combining seismic tomography image materials. Finally, the paper, with the deep dynamical mechanics in Longmen Shan area as researching priority, inverts the sliding rate and analyzes the deep structure in Longmen Shan fault zone through geodetic survey. Meanwhile, the paper, combining co-seismic deformation and aftershocks distribution in Wenchuan, explores in depth the deep structure pattern of Longmen Shan fault and the causes leading to Wenchuan Earthquake through such perspectives as geodetic survey, geology, gravity and crustal deep exploration, and puts forward the reasonable dynamical mechanics model. The innovation points are as follows:1. Synthesizing multi-period GPS and leveling data, the paper further refines the description of3D crustal deformation characteristics in eastern Tibet margin. On the basis of least square collocation model, the paper meticulously analyzes the general movement and the interior strain rate field of the secondary blocks. Through comparing the profiles of horizontal and vertical rates, the paper discusses in depth the different patterns of various secondary blocks in absorbing interior deformation in eastern Tibet margin.2. With the seismic tomography image technology, the paper, after analyzing the crustal structure characteristics at the depth of70km in eastern Tibet margin, finds out that the crustal uplifting area and the distribution of crustal low-speed body are better corresponded, which testifies the point of view that the crustal deformation in this area is influenced by crustal low-velocity body movement.3. On the basis of negative dislocation theory, the paper, after inverting and analyzing the3D sliding rate and the deep structure characteristics in Longmen Shan fault with the method of PSO algorithm, puts forward the stage theory to the sliding rate of Longmen Shan fault. Meanwhile, on the basis of the previous researches, the paper analyzes quantitatively its deep structure characteristics, and accurately describes such fault parameter as its deep dip angle and interlock depth.4. On the basis of the above researches and combining the coseismic deformation and aftershocks distribution of Wenchuan earthquake, the paper puts forward the deep dynamical mechanics of Longmen Shan region, which believes that the reverse-dip slip movement in the southern part of Longmen Shan fault is mainly caused by the blockage of Sichuan Basin and the uplifting of deep crustal low-velocity body accumulation, and the causes leading to Wenchuan earthquake is also under the influence of this deep substance movement.5. To the peculiar topographic feature and uplifting rate of Gongga Mountain area, the paper primarily discusses its tectonic movement mechanics through such factors as plate extrusion, deep crustal structure and the erosion of the crustal river, which offers new researching train of thought for further analyzing the deep dynamical mechanics in this area. |
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