Petrogenetic–metallogenetic setting and temporal–spatial framework of the Yueshan district, Anhui Province, east-central China

Abstract

The Yueshan district is located in the Anqing–Guichi ore deposit area of the Middle–Lower Yangtze Metallogenic Belt. Two groups of intrusive rocks and three main types of ore mineralization occur in this district: diorite plutons (e.g. Yueshan, Zongpu, Wuheng, and Yangshan) and granite plutons (Hongzhen and Dalongshan), Cu–Au–(Fe) skarn deposits (e.g. Anqing, Tiepuling), Cu–Mo–Au–(Pb–Zn) hydrothermal vein-type deposits (Tongniujing), and hydrothermal uranium mineralization (Dalongshan). Detailed geological and geochemical work suggests that the Cu–Au–(Fe) skarn deposits and the Cu–Mo–Au–(Pb–Zn) hydrothermal vein-type deposits have a close spatial and genetic relationship with the dioritic plutons, whereas the hydrothermal uranium mineralization is associated with A-type granite plutons. Based on the highly precise dating of metal deposits and related plutons in the Yueshan district, such as the molybdenite Re–Os, Os–Os dating, ³⁹Ar–⁴⁰Ar dating of potassium-bearing minerals and quartz, several Rb–Sr isochrons, SHRIMP zircon U–Pb dating + single-grain zircon U–Pb dating, and the SHRIMP zircon U–Pb dating of Hongzhen granite pluton, we suggest that the extensive magmatism and mineralization in the Yueshan district took place in two episodes: (1) the first episode involved the mineralization of both skarn and vein-type hydrothermal deposits, c.a. 136–139 Ma, related to diorite plutons emplaced at 138.7 ± 0.5 Ma; (2) the second episode attended the hydrothermal uranium mineralization at 106.4 ± 2.9 Ma, related to granite intrusive activity at 126.8 ± 1.0 Ma. These two times of Yueshan petrogenetic–metallogenetic development appear to be consistent with a tectonic environment transition from compression to extension.

Keywords:

• granitoid magmatism
• mineralization
• hydrothermal deposits
• Yueshan district
• Middle–Lower Yangtze Metallogenic Belt

Acknowledgements

This research was financially supported by funds from the National Natural Science Foundation of China (Grant Nos. 40830426, 40803015, 40672062), the China National Key Basic Science Research Project (Grant No. 2007CB411405), the Programme for New Century Excellent Talents in University, the Scientific Research Project of CODES, the Centre of Excellence in Ore Deposits, University of Tasmania (Grant Nos. CODES2009 P2.N3, CODES2006N2.3), and the Anhui Provincial Science Foundation for Distinguished Young Scholars (08040106907, 04045063). We would like to thank Huaying Liang and Hengxiang Yu for their lab works in the Australian National University.