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对国家数字地震台网和云南、四川、甘肃、青海区域数字地震台网,以及布设在川、滇、藏地区的宽频带流动地震台网共116个台站所记录的远震SKS波形资料作偏振分析,采用叠加分析方法求得每一个台站的SKS快波偏振方向和快慢波的时间延迟,获得青藏高原东部及其邻近地区的上地幔各向异性图像.将该地区全球定位系统(GPS)的观测结果与上地幔各向异性分布相结合作地壳-地幔耦合变形的分析,研究表明青藏高原内部和高原外部的云南地区具有不同的壳幔变形特征,在高原的东缘地区(大致位于川滇西部的26°~27°N之间)存在一个壳幔变形的横向过渡带.过渡带以南地区的快波偏振方向从滇西南的S60°~70°E逐渐转变到滇东南的近东西向,以北的滇西北部和川西南部,快波偏振方向为近似的南北向.高原内部表现为强壳幔耦合型,高原外部则属于壳幔解耦型.这一横向过渡带与地表的断裂走向不一致,但在地壳和上地幔,其地球物理场(如:地壳厚度,布格重力异常和构造应力方向等)都具有横向过渡的特征.该横向过渡带邻近东喜马拉雅构造结,在板块边界动力学上有着重要的意义.
The teleseismic SKS waveform recorded by the National Digital Seismic Network and the digital seismic networks in Yunnan, Sichuan, Gansu, Qinghai and the broadband mobile seismograph networks in Sichuan, Yunnan and Tibet were recorded Polarization analysis, using the superposition analysis method to obtain the fast polarization and fast-slow wave delay of SKS at each station, and obtain the upper mantle anisotropy image in the eastern part of the Qinghai-Tibet Plateau and its adjacent areas.Global positioning system (GPS ) And the upper mantle anisotropy distribution for crustal-mantle coupling deformation analysis, the study shows that the interior of the Tibetan Plateau and Yunnan Plateau have different crust-mantle deformation characteristics, in the eastern edge of the plateau (generally located in There is a lateral transitional crust-mantle deformation zone between 26 ° -27 ° N in the western Sichuan-Yunnan region.The polarization direction of the fast wave to the south of the transitional zone gradually shifts from S60 ° -70 ° E in southwestern Yunnan to near-southeast Yunnan In the east-west direction, northwestern Yunnan and southwestern Sichuan, the fast-wave polarization direction is approximately north-south direction.The interior of plateau is characterized by strong crust-mantle coupling type and the outer plateau belongs to crust-mantle decoupling type. However, in the crust and the upper mantle, the geophysical fields (such as crustal thickness, Bouguer gravity anomalies and tectonic stress directions, etc.) have the characteristics of lateral transition. The lateral transitional zone is adjacent to the East Himalayan structure Knot, in the plate boundary dynamics has important significance.