The metallogenic epoch and geological implications of the tungsten-tin polymetallic deposits in southern Jiangxi Province, China: Constraints from cassiterite U-Pb and molybdenite Re-Os isotopic dating

The Nanling Range is one of the rare large granite provinces in China, and many of the exposed Mesozoic granites are closely related to tungsten-tin polymetallic mineralization in time, space and genesis. Southern Jiangxi Province, characterized by densely distributed tungsten deposits and multiple associated resources (Sn, Mo, Bi, Cu, Ag, Sb, Hg, and rare earth elements), is an important part of the Nanling region. Keshuling, Baxiannao and Bikeng in southern Jiangxi are exocontact-zone quartz vein subtype tungsten deposits, while Jinzhuping is a endocontact-zone quartz vein subtype tungsten-tin deposit. In this study, we present four cassiterite U-Pb ages and five molybdenite Re-Os ages from samples of the above four deposits to define the metallogenic era. The cassiterite U-Pb ages for Keshuling, Baxiannao and Bikeng are 157.5 +/- 4.1 Ma, 158.8 +/- 2.9 Ma and 159.0 +/- 2.0 Ma within the 2 sigma error, while the cassiterite U-Pb and molybdenite Re-Os ages of the endocontact-zone quartz vein subtype ores in Jinzhuping are 156.6 +/- 3.8 Ma and 157.9 +/- 4.2 Ma, respectively. Comparison of these ages of ore minerals with the genetically related granitic rocks shows that there was no resolvable time difference between the granite emplacement and hydrothermal mineralisation, both of which were products of early tectono-magmatic activity in the Yanshanian period in Nanling. The ore-forming ages of the different types of ore bodies generally become younger from the granitic bodies outward. We present a genetic model in which ore forming fluids migrated outward from the granitic source and formed ore bodies in tungsten-tin deposits of southern Jiangxi Province.