中文摘要：

青藏高原东北缘记录了印度—欧亚大陆板块碰撞和汇聚的远场效应,且仍正处于侧向生长阶段.而地壳各向异性则反映了高原地壳的形变特征.为此,本文主要利用甘肃数字地震台网（2001年1月—2010年10月）波形记录资料,采用SAM方法进行剪切波分裂研究,得到青藏高原东北缘地壳各向异性的平均剪切波分裂参数及剩余地震各向异性参数,两个参数分别反映了区域构造和应力场特征及局部构造和局部断裂特征.研究结果表明：快剪切波2个优势偏振方向分别为NE47.72°±21.83°和121.65°±22.07°,慢剪切波平均时间延迟为2.63±1.31ms·km-1.快剪切波平均偏振方向反映了该区域的水平主压应力方向,快剪切波偏振方向的第二优势取向揭示了NWW的局部构造意义,表明应力环境受本区NWW深大断裂带的影响.各个台站的剩余快剪切波偏振方向的优势取向与断裂走向一致,表明活动断裂控制着剩余快剪切波偏振方向.剩余慢剪切波时间延迟变化反映了断裂引起地震各向异性程度,形变具有区域特征.

英文摘要：

The northeastern margin of Tibetan plateau is surrounded by the Alashan block to the north,the Tarim basin to the northwest,the Ordos block to the east,and Songpan-Garzêterrane to the south.As the northern terminus of contiguous deformation,it records far field effects ofcollision and convergence occurring between the Indian and Eurasian,it is still in the stages of uplift and deformation,so it is an ideal region for studying the far field effects of collision and convergence between the India and Eurasian plate.Seismic anisotropy is one of the main specialities of the Earth,which can be interpreted with the Lattice Preferred Orientation（LPO）of minerals and shape Preferred Orientation of cracks or melts caused by tectonic stress.In this study,we use the seismic data recorded by the Gansu and Ningxia Province Seismic Network from Jan.2001 to Oct.2010.And seismic anisotropy is obtained by using the SAM technique.The average time delay and polarization are caused by the regional structure and stress field,whereas the residual values of the splitting parameters are considered to be related to local structures such as local faults.The residual polarization of fast shear-waves suggests the strike direction of local fault.The residual delay of slow shear-waves suggests the contribution extent induced by local fault.During our data process,we take the posterior choice on earthquakes with small epicenters that is a makeshift for the regions lacking earthquakes,but is useful to increase the credibility of the analysis for fast-wave polarization.The results show that the crustal seismic anisotropy in the northeastern margin of Tibetan vary in different tectonic blocks.There are the two average polarization of fast shear-waves,which are individually at NE47.72°±21.83°and 121.65°±22.07°,and the average time delay of slow shear-waves is 2.63±1.03ms·km-1.The first dominant polarization of fast shear-waves is almost consistent with the regional principal compressive stress due to collision between Indian and Asian p