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利用蒙古中南部地区布设的69套宽频带数字地震仪2011年8月—2013年7月记录的远震事件,使用时间域反褶积方法提取接收函数,并挑选高质量Pms震相,通过改进的剪切波分裂方法对研究区地壳各向异性参数进行了研究,最终获取了1473对各向异性参数.经过统计分析,有48个台站可以归纳出两个方向的各向异性,11台站得到单个方向的各向异性,而剩余10个台站各向异性方向比较发散.结果显示,各向异性在蒙古中南部地壳中呈不均匀分布,有54个台站得到了NE-SW向各向异性,快波偏振方向平均值为N58°E±16°,与最大水平主应力σHmax方向和区域内主要断层走向一致,说明这部分地壳各向异性的主要成因存在于上地壳,可能与流体填充的微裂隙有关.而NW-SE向各向异性在53个台站被观测到,各向异性方向变化范围平均N132°E±16°,与研究区大部分SKS分裂快波方向具有较好的一致性,说明下地壳成岩矿物晶体定向排列是各向异性的主要成因.研究区地壳各向异性的分层特征总体上支持岩石圈受到NE-SW向挤压的动力学模型.
Based on the teleseismic events recorded by 69 sets of broadband digital seismographs in central and southern Mongolia from August 2011 to July 2013, the time domain deconvolution method was used to extract the receiver function and select the high quality Pms phase. Shear-wave splitting method was used to study the anisotropic parameters of the crust in the study area, finally obtaining 1473 pairs of anisotropic parameters.According to statistical analysis, 48 stations can be summarized in two directions of anisotropy, 11 sets The results show that anisotropy is unevenly distributed in the crust of central-southern Mongolia, and 54 stations get the NE-SW direction The average anisotropy and fast wave polarization directions are N58 ° E ± 16 °, consistent with the direction of the maximum horizontal principal stress σHmax and the main faults in the region, indicating that the main genesis of this part of the crustal anisotropy exists in the upper crust and may be related to Fluid-filled microcracks, while the NW-SE anisotropy was observed at 53 stations with an anisotropy range of N132 ° E ± 16 ° on average, which is in contrast to most of the SKS splitting fast directions in the study area Good consistency, explanation Crust diagenetic mineral crystal alignment is the main cause of anisotropy. Characteristic crust layered anisotropy studies generally support area lithosphere dynamics model NE-SW subjected to extrusion.