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利用六盘山地区宽频带流动地震台阵的远震体波记录,采用接收函数方法研究台阵下方的地壳上地幔结构,并采用接收函数振幅加权叠加方法对这一地区平均地壳厚度和泊松比进行估算.研究结果显示,青藏高原东北缘和鄂尔多斯的接触过渡带接收函数震相复杂,地壳变形强烈,青藏高原东北缘地壳平均厚度约为51.5km,六盘山下方地壳厚度在53.5km,鄂尔多斯西南缘地壳平均厚度约为50km,整个莫霍面呈下凹状.泊松比计算结果显示,六盘山东侧和西侧地壳泊松比值在正常范围内(0.25～0.26),六盘山下方的地壳泊松比值偏高(0.27～0.29),推测与地壳中存在部分熔融.泊松比值的横向变化,指示测线范围地壳物质组成和力学性质存在横向差异,反映在欧亚板块与印度板块碰撞作用影响下青藏高原下地壳物质存在向北东方向的流动.
Using the teleseismic body-wave records of the broadband mobile seismic array in the Liupanshan area, the receiver function method is used to study the structure of the crust and upper mantle below the array. The average crustal thickness and Poisson’s ratio of this area are calculated by the receiver function amplitude weighted superposition method The results show that the contact facies of the contact transition belt between the northeastern margin of the Qinghai-Tibet Plateau and Ordos is complex and the deformation of the crust is strong. The average crustal thickness of the northeastern margin of the Qinghai-Tibet Plateau is about 51.5km, that of the lower crust of Liupan Mountains is 53.5km, and the southwestern margin of Ordos The average crustal thickness is about 50km, and the entire Moho is concave. The Poisson’s ratio calculation shows that the crustal Poisson’s ratio in the east and west of Liupan Mountains is within the normal range (0.25 ~ 0.26), and the crust Poisson (0.27-0.29), suggesting partial melting in the crust. Lateral variations of Poisson’s ratios indicate that there are lateral differences in crustal composition and mechanical properties of the survey line, which are reflected by the collision between the Eurasian plate and the Indian plate The lower crustal material in the Tibetan Plateau flows to the northeast.