A seismic receiver function study for the crustal and upper mantle structures of the Lower Yangtze and adjacent areas and its geological implications
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    Abstract:

    We present here high- resolution seismic sections of crustal and uppermost mantle structures along two dense linear arrays across the Lower Yangtze region in a SE- NW orientation. Our seismic receiver function images reveal deep structural characteristics of the major blocks and deep structural responses of the late Mesozoic magmatic rocks and associated ore deposits. ①The crustal structures appear to be dominated by the newly initiated or reactivated geological features since the Mesozoic. ②Abundant low- velocity phases (indicating low- velocity materials) were observed in the mid- lower crust of the Dabie block. These low- velocity materials may act as the ductile shear zone in the deep crust, which is likely related to the dynamic processes responsible for the exhumation of the Dabie ultrahigh pressure metamorphic rocks.③We observed folded and imbricated seismic converters in the mid- lower crust of the Huaiyu Shan area in the eastern segment of the Jiangnan orogenic belt, which are analogous with previous seismic observation in the Xuefeng Shan area in the western segment and are interpreted as reflecting a buried Proterozoic Jiangnan orogen. ④The Moho and LAB discontinuities imaged exhibit local bulge deformation directly beneath the Dexing ore deposits and the Cretaceous South Anhui granite cluster, which probably indicate local mantle lithosphere destruction by asthenospheric upwelling in some weak zones of the lithosphere in the Lower Yangtze region during the Mesozoic. Our seismic observations reveal several significant subsurface features in the Lower Yangtze and adjacent areas that indicate distinct geological events during different evolving eras of the eastern South China continent. This provides critical geophysical constraints for understanding the formation and early evolution of the South China plate, as well as the deep mechanism of the intensive late Mesozoic magmatism and associated metallogenesis in eastern South China.

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YE Zhuo, LI Qiusheng, ZHANG Hongshuang, WANG Xiaoran, HAN Rubing, WU Qingyu.2020. A seismic receiver function study for the crustal and upper mantle structures of the Lower Yangtze and adjacent areas and its geological implications[J]. Acta Geologica Sinica,94(3):707-715

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History
  • Received:May 20,2019
  • Revised:August 28,2019
  • Adopted:November 12,2019
  • Online: December 19,2019
  • Published: