ACTA Scientiarum Naturalium Universitatis Pekinensis
Study on Crust and Upper Mantle Structure in Shandong Area
QU Ping1, LÜ Jie1, GUO Zhen2, YU Yong2, CHEN Yongshun2,†
1. School of Earth and Space Sciences, Peking University, Beijing 100871; 2. Department of Ocean Science and Engineering, Southern University of Science and Technology, Shenzhen 518055; † Corresponding author, E-mail: johnyc@sustech.edu.cn
Abstract 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. Key words receiver function; crust thickness; wave velocity ratio of P and S; shear-waves splitting; Tanlu fault zone
山东地区位于中国大陆东部, 被北北东走向的郯庐断裂带分为东、西两部分, 东部主要由胶北隆起、胶莱盆地和胶南隆起构成[1], 西部的主要构造单元为鲁西隆起和济阳凹陷[2]。鲁西隆起位于华北
克拉通东部, 在地貌上与华北克拉通西部有明显的差异。由于热侵蚀和拆沉作用, 华北克拉通东部岩
[3‒7]石圈遭到破坏, 出现明显的减薄现象 。鲁西隆起中, 新生代构造格局为北北西向的盆‒山格局[8]。
北京大学学报(自然科学版) ,
Fig. 1
第 56 卷 第 4 期2020 年 7 月
曲平等 山东地区地壳及上地幔结构研究analysis result of the stations in Shandong area
第 56 卷 第 4 期2020 年 7 月
曲平等 山东地区地壳及上地幔结构研究
第 56 卷 第 4 期2020 年 7 月
曲平等 山东地区地壳及上地幔结构研究
化。这一异常结构在 SM057 台站东西两侧不存在。SM057台站位于南北贯穿山东地区的郯庐断裂带, 对于该处观测到的地壳异常结构, 后续工作中需要收集其南北两侧更密集的台站观测资料, 进行更深入的探索。
Savage M K. Seismic anisotropy and mantle deformation: what have we learned from shear wave splitting?. Reviews of Geophysics, 1999, 37(1): 65‒106 Yu Y, Chen Y J. Seismic anisotropy beneath the southern Ordos block and the Qinling-dabie orogen, China: Eastward Tibetan asthenospheric flow around the southern Ordos. Earth and Planetary Science Letters, 2016, 455: 1‒6 Zhu L, Kanamori H. Moho depth variation in southern California from teleseismic receiver functions. Journal of Geophysical Research: Solid Earth, 2000, 105 (B2): 2969‒2980 Laske G, Masters G, Reif C. CRUST 2.0: a new global crustal model at 2×2 degrees [EB/OL]. (2001) [2016‒09‒01]. http://mahi.ucsd.edu/gabi/rem.dir/crust/ crust2.html Dellinger J A, Gray S H, Murphy G E, et al. Efficient 2.5-D true-amplitude migration. Geophysics, 2000, 65 (3): 943‒950 Zhang S, Karato S. Lattice preferred orientation of olivine aggregates deformed in simple shear. Nature, 1995, 375: 774‒777 Earle P S, Shearer P M. Characterization of global seismograms using an automatic-picking algorithm. Bulletin of the Seismological Society of America, 1994, 84(2): 366‒376 [20] Chen L, Tao W, Zhao L, et al. Distinct lateral variation [14] [15] [16] [17] [18] [19]第 56 卷 第 4 期2020 年 7 月