山东地区地壳及上地幔结构研究

利用布设在山东省境内的宽频带流动地震观测台阵和国家地震局固定地震观测台站记录的地震数据, 应用接收函数和SKS波分裂方法, 研究山东地区的地壳与上地幔结构, 得到该区域的地壳厚度、地壳平均P波与S波的波速比以及SKS波分裂延迟的分布情况。结果表明, 山东地区地壳厚度范围为28~39 km; 胶南隆起的北段和南段以及鲁西隆起北侧济阳凹陷的地壳厚度小于32 km, 鲁西隆起下方的地壳比较厚。研究区 P波与S波的波速比主要分布在1.67~1.94之间, 鲁西隆起西南部和胶南隆起北段该比值小于1.75, 可能是由中上地壳增厚以及下地壳减薄和拆沉造成。鲁西隆起南北P波与S波的波速比差异反映地壳活动的差异。地幔物质的各向异性显示, 山东地区西部的地壳减薄和拆沉可能仍在进行。

Study on Crust and Upper Mantle Structure in Shandong Area

This paper records seismic data, using the broadband seismic station and the state seismic station in Shandong Province. Receiver function and shear-waves splitting are applied to study the earth’s crust and upper mantle structure beneath Shandong and its adjacent area. This study analyzed the crust thickness distribution of the region, distribution of crustal average P and S wave velocity ratio, and the regional distribution of shear wave splitting delay. It can be seen that the range of crust thickness in Shandong region is 28?39 km. The crustal thickness of the northern and southern sections of the Jiaonan uplift is less than 32 km. The crustal thickness of Jiyang depression on the north side of west Shandong uplift is also within 32 km. The lithosphere below the western Shandong uplift is relatively thicker. The velocity ratios of P and S in the study area are mainly distributed in the range of 1.67?1.94. In the southwest part of the Luxi uplift and the northern part of the Jiaonan uplift, the wave velocity ratio of P and S is less than 1.75, which may be caused by the thickening of the middle and upper crust, and the thinning and subsidence of the lower crust. The difference between velocity ratio of P and S in the north and south of the west uplift reflects the difference of crustal activity. The anisotropy of mantle material indicates that crust thinning and subsidence in the west of Shandong region may still be ongoing.