Crustal S-velocity structure and radial anisotropy beneath the southern part of central and western North China Craton and the adjacent Qilian Orogenic Belt from ambient noise tomography

查看全文 作　　者：LING [1,2]Yuan;CHEN [1,2,3]Ling;WEI [4]ZiGen;JIANG [5]MingMing;WANG [1,2]Xu

机构地区：[1]State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China;[2]College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049;[3]CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China;[4]State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy and Geophysics, Chinese Academy of Sciences, Wuhan 430077, China;[5]Key Laboratory of the Earth and Planetary Physics, Chinese Academy of Sciences, Beijing 100029, China

出　　处：《Science China Earth Sciences》索引2017年第60卷第10期,共17页

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41225016,91414301&41688103);the Strategic Priority Research Program(B)of the Chinese Academy of Sciences(Grant No.XDB03010802) 摘　　要：The crustal S-velocity structure and radial anisotropy along a dense linear portable seismic array with 64 broadband seismic stations were investigated from ambient noise tomography with about one-year-long ambient noise recordings. The array transverses the southern part of the central North China Craton(CNCC) and western NCC(WNCC) from east to west and reaches the adjacent Qilian Orogenic Belt(QOB). The phase velocity structures of Rayleigh waves at 5–35 s and Love waves at 5–30 s were measured. The crustal S-velocity structures(Vsv and Vsh) were constructed from the dispersion data(Rayleigh and Love waves,respectively) from point-wise linear inversion with prior information of the Moho depth and average crustal Vp/Vs ratio. The radial anisotropy along the profile was calculated based on the discrepancies between Vsv and Vsh as 2×(Vsh.Vsv)/(Vsh+Vsv). The results show distinct structural variations in the three major tectonic units. The crustal architecture in the southern CNCC is complicated and featured with wide-distributed low-velocity zones(LVZs), which may be a reflection of crustal modification resulting from Mesozoic-Cenozoic tectonics and magmatic activities. The pronounced positive radial anisotropy in the lower-lowermost crust beneath the Shanxi-Shaanxi Rift and the neighboring areas could be attributed to the underplating of mantle mafic-ultramafic materials during the Mesozoic-Cenozoic tectonic activation. In southern Ordos, the overall weak lateral velocity variations, relative high velocity and large-scale positive radial anisotropy in mid-lower crust probably suggest that the current crustal structure has preserved its Precambrian tectonic characteristics. The low-velocity westward-dipping sedimentary strata in the Ordos Block could be attributed to the Phanerozoic whole-basin tilting and the uneven erosion since late Cretaceous. Integrated with previous studies, the systematic comparison of crustal architecture was made between the southern and northern part of CNCC-WNCC. The similarities and differences may have a relation with the tectonic events and deformation histories experienced before and after the Paleoproterozoic amalgamation of the NCC. The nearly flat mid-crustal LVZ beneath the southern QOB weakens gradually as it extends to the east, which is a feature probably associated with crustal vertical superpositionand ductile shear deformation under the intensive compressional regime due to the northeastward growth and expansion of the Tibetan Plateau. 关键词：地壳速度结构各向异性环境噪声层析成像克拉通径向中国西部

相关文献

参考文献（88）
引证文献（8）
耦合文献（936）

参考文献(88)

引证文献(8)

耦合文献(936)

互联网出版许可证新出网证(渝)字10号全国400电话 - 免长途话费

Crustal S-velocity structure and radial anisotropy beneath the southern part of central and western North China Craton and the adjacent Qilian Orogenic Belt from ambient noise tomography

参考文献(88)

引证文献(8)

耦合文献(936)

用户提示