TECTONIC CONDITIONS NECESSARY FOR RUTILE MINERALIZATION IN THE EASTERN SEGMENT OF QINLING MOUNTAINS
Li Boyun Qian Ziqiang Zhou Jianmin Xu Shaokang Yang liuping (MCI Geological Institute for Chemical Minerals)
Four different tectonic conditions necessary for the formation of major rutile deposits along the eastern segment of the Qinling mountains have been narrowed out mainly through investigating the geology and geochemistry of the ore bearing beds and analyzing the tectonic events related to source beds. Evolution of the crust in the study area has entered a stage of the intensive division form continental to oceanic crust since the middle Proterozoic time when mantle derived source beds got shaped in the kuanping oceanic basin north of the Qinling mountains and on the Tongbai dabie old land. In contrast, sedimentation related source beds were traceable to some basins caused by tensional events along the northern margin of the Yangtze massif. By the late Palaeozoic period, the crust of the study area proceeded with evolution from oceanic to continental crust, accompanying marginal rifting to lead crust-derived source beds.