Lithospheric Electrical Characteristics in South China and Its Geodynamic Implication
详细信息   
摘要


     The lithosphere-asthenosphere boundary hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">LABhansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> is one of the main boundary of the earthhansi-font-family: calibri; mso-hansi-theme-font: minor-latin">s interior. Magnetotelluric hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">MThansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> sounding is the most effective method for investigation of the electrical structure of the crust and upper mantle of the earth. LAB is feasibly detectable by using long-period MT data. The high-quality MT data had been acquired on grid of 4°×4° in South China under SinoProbe-01-03 project. We inverted the average apparent resistivity calculated from the off-diagonal elements by using one-dimension Occamhansi-font-family: calibri; mso-hansi-theme-font: minor-latin">s method. We interpret the recovered 1D geoelectric structure by classifying the lithosphere of the South China as five different typeshansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">1hansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> the craton type, the representive data are from Shaoyang hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Hunan Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin">and Shibing hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Guizhou Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> sites; hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">2hansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> the tectonic boundary type, the representive data are from Dazhou and Pengzhou hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Sichuan Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> as well as Jingmen hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Hubei Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> sites; hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">3hansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> the moderate reformed lithosphere type, the representive data are from Huzhou hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Zhejiang Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> and Yunfu hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Guangdong Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> sites; hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">4hansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> the strong reformed lithosphere type, the representive data are from Ganzhou hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Jiangxi Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> and Jieyang hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Guangdong Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> as well as Xiapu hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Fujian Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> sites; hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">5hansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> the orogenic belt type, the representive data is from Yingshan hansi-font-family: calibri; mso-hansi-theme-font: minor-latin">Hubei Provincehansi-font-family: calibri; mso-hansi-theme-font: minor-latin"> site. The lithospheric thicknesses of the South China vary from 60 km to 145 km except Shaoyang, Shibing and Jieyang sites. Our results show that the lithosphere of the South China is thinner in the south and north regions, and thicker in the middle region; while the lithosphere of the South China is unevenly reformed in the east region. The results in present study are different from that of the previously published literatures, in most of which indicated that the significant characteristic of the lithospheric thickness of the South China is thinning from west to east. Our results support that the lithosphere of the South China is mechanically strong and hence stable. The tectonic extension occurred since the Late Mesozoic may limitedly reform the lithosphere of the South China, and the most possible reforming mechanism is by hot asthenospheric materials diapiring and underplating.

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