U-Pb and Re-Os geochronology of the Tongcun Molybdenum deposit and Zhilingtou gold-silver deposit in Zhejiang Province, Southeast China, and its geological implications

Mesozoic ore deposits in Zhejiang Province, Southeast China, are divided into the northwestern and southeastern Zhejiang metallogenic belts along the Jiangshan-Shaoxing Fault. The metal ore deposits found in these belts are epithermal Au-Ag deposits, hydrothermal-vein Ag-Pb-Zn deposits, porphyry-skarn Mo (Fe) deposits, and vein-type Mo deposits. There is a close spatial-temporal relationship between the Mesozoic ore deposits and Mesozoic volcanic-intrusive complexes. Zircon U-Pb dating of the ore-related intrusive rocks and molybdenite Re-Os dating from two typical deposits (Tongcun Mo deposit and Zhilingtou Au-Ag deposit) in the two metallogenic belts show the early and late Yanshanian ages for mineralization. SIMS U-Pb data of zircons from the Tongcun Mo deposit and Zhilingtou Au-Ag deposit indicate that the host granitoids crystallized at 169.7 ± 9.7 Ma (2σ) and 113.6 ± 1 Ma (2σ), respectively. Re-Os analysis of six molybdenite samples from the Tongcun Mo deposit yields an isochron age of 163.9 ± 1.9 Ma (2σ). Re-Os analyses of five molybdenite samples from the porphyry Mo orebodies of the Zhilingtou Au-Ag deposit yield an isochron age of 110.1 ± 1.8 Ma (2σ). Our results suggest that the metal mineralization in the Zhejiang Province, southeast China formed during at least two stages, i.e., Middle Jurassic and Early Cretaceous, coeval with the granitic magmatism.