THE PROTEROZOIC TECTONIC FRAMEWORK AND EVOLUTION OF THE NORTH QINLING OROGEN, CENTRAL CHINA
DONG Yun peng, ZHANG Guo wei, ZHAO Xia and YAO An ping (Institute of Orogenic Geology, Department of Geology, Northwest University, Xi'an 710069, China)
The Qinling orogen is a gigantic composite collision orogenic belt undergoing multistage complicated plate rifting and convergence. The geologic framework is built up through interaction of three blocks, which are North China, South Qinling and South China blocks, and separated by the Shangdan and Mianlue suture zones, respectively. Geology, geochemistry and isotopic chronology of the ophiolite, magmatism and metamorphism show that there exist the Meso Neoproterozoic ophiolite, arc magmatism and back arc basin in south margin of the North Qinling massif. They are combined with the related magmatism, regional metamorphism and chronology of the tectonic events suggest that the had been evolved into an active continental margin with plate rifting, oceanic crust subduction and ophiolite emplacement along the southern margin of the North Qinling massif during the Mesoproterozoic to Neoproterozoic.