Neoproterozoic Crustal Composition and Orogenic Process of the Zhanggongshan Area, Anhui—Jiangxi Provinces
Zhanggongshan area of Anhui-Jiangxi border, located in the northern margin of the Jiangnan orogen (South Yangtze River), contains very thick low greenschist-facies metamorphic flysch rocks dominated by argillo calcareous fine-grained clastic rocks with minor volcanic materials. The geological feature and petrochemical analysis show that they resulted from low-speed spreading of small oceanic basins in continental margin and characterized with initial features of oceanic crust basic rock, indicating that they belong to part of the westward extension of the Fuchuan ophiolite in southern Anhui Province. Combined with sedimentary characteristic, magmatic and tectonic occurrences in the area, this study proposed that the Neoproterozoic Anhui-Jiangxi border underwent a series of tectonic development processes from the splitting of the southeastern margin of ancient Yangzi plate, limited subduction of small oceanic basins in continental margin, arc-continent collision orogeny and finally to post-orogenic rifting sedimentation of continental crust.