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收集了喜马拉雅东构造结地震台阵17个宽频带流动地震台站,以及东构造结周边地区布设的32个宽频带流动台站和中国地震台网10个宽频带固定台站的远震波形资料,并对这共计59个台站所记录的XKS(SKS,SKKS和PKS)波形资料作偏振分析,采用最小切向能量的网格搜索法和叠加分析方法求得每一个台站的XKS波的快波偏振方向和快、慢波的时间延迟,并结合其他研究在该区域取得的各向异性参数结果,获得了喜马拉雅东构造结及周边地区上地幔各向异性图像.从得到的结果来看,喜马拉雅东构造结的上地幔快波方向基本为NE-SW方向,其周边地区的快波方向自西向东呈现出NE-SW方向到E-W方向,然后到NW-SE方向,最后为N-S方向的逐步变化,其周边地区的快波方向表现出围绕东构造结顺时针旋转的变化特征.通过该区域快波方向与地表构造走向和运动速度场变化特征的对比分析,喜马拉雅东构造结及周边地区的快波方向与该区域地表构造走向和由GPS得到地表运动速度场运动趋势相一致,说明该区域地表变形特征与深部上地幔变形特征是一致的,其岩石圈变形是一种垂直连贯变形模式.喜马拉雅东构造结的快波方向为NE方向,与印度板块向青藏高原下NE方向的俯冲一致,说明稳定坚硬的印度块体向NE方向俯冲到青藏高原下方是引起该区域岩石圈变形的主要原因.围绕喜马拉雅东构造结的周边地区的快波方向呈现出顺时针旋转的环形变化特征,我们推测稳定坚硬的印度板块对青藏高原NE方向的俯冲作用,又由于缅甸块体下俯冲板片的东向俯冲和西向后撤对缅甸弧后的岩石圈产生了被动的西向拖曳力作用,使得绕喜马拉雅东构造结周边地区岩石圈产生了顺时针旋转的环形变形,进而形成了快波方向绕喜马拉雅东构造结顺时针旋转的各向异性特征.
Teleseismic waveform data collected from 17 broadband mobile seismic stations in the East Himalayan structural knot array and 32 broadband mobile stations deployed in the surrounding area of the East structural knot and 10 broadband fixed stations in China’s seismic network , And analyzed the XKS (SKS, SKKS and PKS) waveform data recorded by a total of 59 stations for polarization analysis. The grid search method and superposition analysis method with minimum tangential energy were used to obtain the XKS wave of each station Fast wave polarization direction and fast and slow wave time delay, combined with other studies in the region obtained anisotropic parameters results obtained in the eastern Himalayan structural knot and the upper mantle anisotropy images from the results obtained The fast-wave direction of the upper mantle in the east Himalayan tectonic knot is basically NE-SW direction. The fast-wave direction in the periphery of the Himalayan tectonic knot shows NE-SW direction to EW direction from west to east, and then to NW-SE direction and finally to NS direction , The fast-wave direction in the surrounding area shows a clockwise rotation around the east tectonic knot.According to the comparative analysis of the characteristics of fast-wave direction and surface tectonic strike and movement velocity in the region, The direction of the fast wave in the Yadong tectonic knot and the surrounding area is consistent with the trend of the surface structure and the movement velocity of the surface velocity field obtained by GPS, which shows that the surface deformation features of this area are consistent with the deformation characteristics of the upper mantle. The lithosphere deformation Is a vertically coherent deformation pattern.The fast-wave direction of the eastern Himalayan tectonic knot is the NE direction, which is consistent with the subduction of the Indian plate to the NE direction under the Qinghai-Tibet Plateau, indicating that the stable and hard Indian subduction subducted to the NE direction below the Qinghai- The main reason for lithospheric deformation in this region is that the fast-wave direction around the eastern Himalayan tectonic knot exhibits a clockwise rotation with a ring-shaped variation. We speculate that the subduction of the stable and hard Indian plate on the NE direction of the Tibetan Plateau, The eastward subduction and westward retraction of the subducting slab subducted slabs exert a passive westward drag on the lithosphere behind the Burma arc so that the lithosphere around the East Himalayan structural knot produces a clockwise rotation of the ring deformation, The anisotropic characteristics of the fast wave direction clockwise around the Himalayan structural knot are formed.