Zircon U-Pb and molybdenite Re-Os dating for the Beiya gold-polymetallic deposit in the western Yunnan Province and its geological significance
滇西北衙金多金属矿床锆石U-Pb和辉钼矿Re-Os年龄及其地质意义

The Beiya gold-polymetallic deposit lies in the middle of the Cenozoic Jinshajiang-Ailaoshan alkali-rich intrusion belt in the western Yunnan Province. It is a representative ore deposit in studying Himalaya epoch mineralization and shows bright future for further prospecting. The first highly precise dating of the rock-forming and mineralization in Beiya gold-polymetallic deposit is provided in this paper. The U-Pb LA-ICP-MS dating of the zircon from Hongnitang quartz syenite porphyry yields an age of 36.48±0.26Ma. Re-Os dating of molybdenite separated from the skarn ore bodies gives a model age of 36.87±0.76Ma. These ages suggest that the mineralization in the Beiya gold-polymetallic deposit is genetically associated to the quartz syenite porphyry. The Re contents of molybdenite indicate that the ore-forming materials are derived from mantle and crust. Based on the same ages of the rock-forming and mineralization in Beiya gold-polymetallic deposit and other deposits in jingshajiang-Ailaoshan metallogenic belt, it is proposed that these deposits all occurred under the background of India-Eurasia collision when the tectonic regime changing make the thickened lower crust and upper mantle melt partially.