Tectonic Setting and Prospects of Porphyry Copper Deposits in Zhongdian Island Arc Belt

Abstract

Located in the south of Yidun island arc of theSanjiang tectonic-magmatic-metallogenic belt, southwestern China, the Zhongdian island arc belt includes two ophiolite-melange belts, i.e., EW-striking Louji ophiolite-melangebelt and Shudu ophiolite-melange belt. The former serves as the boundary between the Zhongdian island arc belt and the Yangtze platform whereas the latter dividesthe Zhongdian island arc belt into the western part and the eastern part. The western part is earlier (250～203 Ma) than the eastern part (218～203 Ma). An analysis of the duration (250～203 Ma) shows that the activity time of the Shudu Ocean,corresponding to Shudu ophiolite-melange belt, should be ca. 250 Ma, close to theactivity time of Garze-Litang suture. The Shudu ophiolite-melange belt and theGarze-Litang ophiolite-melange belt therefore belong to the Emeishan great igneous province. The lithology is characterized by tholeiite in both ophiolite-melange belts. Within the Zhongdian island arc zone, both the eastern porphyry belt and the western porphyry belt are of great potential in search for porphyry copper deposits. The Pulang Porphyry copper deposit is superlarge in size in potential of resources. The Zhongdian porphyry copper deposit is likely to become an important base area in copper-polymetallic resources of China. The exploration work is very promising.