Re-Os dating of molybdenite from the Shilu Cu(Mo) deposit in western Guangdong Province and its geological implications

Abstract：Located in Yangchun basin of western Guangdong Province, the Shilu deposit has developed oxidized Cu and skarn Cu-Mo ore bodies. The skarn ore body genetically is associated with the Shilu granodiorite. Direct Re-Os dating of molybdenite collected from the skarn ore bodies in the Shilu deposit was carried out to better understand the age of mineralization. The results show that the five molybdenite samples from quartz-vein-type ore have 187Re-187Os model ages ranging from (104±1.5) Ma to (104.6±1.5)Ma, with an average of (104.34±0.66)Ma and an isochron age of (104.1±1.3)Ma, consistent with the age of the related granodiorite (107±0.72Ma), which implies that the mineralization took place in the early Cretaceous. Based on previous studies, it is suggested that the Shilu skarn Cu-Mo deposit was formed later than 50Ma when the Jurassic Cu-Fe deposits in Yanchun basin were generated, thus belonging to the large-scale Cretaceous mineralization in South China. It was formed in a lithosphere extension tectonic setting, which was different from the setting of the Jurassic Cu-Fe deposits in this area.