In situ zircon and cassiterite U-Pb ages constraints on concealed granite and W mineralization in the Kuimeishan deposit, Nanling Region, South China

Abstract

The Nanling tungsten‑tin province in South China hosts numerous world-class quartz vein type tungsten deposits. The quartz-wolframite veins are generally spatially associated with granitic intrusions; however, their genetic relationship has been controversial. The Kuimeishan deposit (53,000 t WO3 total resource) is one of the historically most important quartz vein type tungsten deposits in the Nanling region, and is underlain by a concealed granitic intrusion. Here we use a comprehensive geochronological approach, based on zircon and cassiterite U-Pb isotopic analysis, to assess the age relationship between granite and tungsten mineralization. Zircon from the concealed granite and cassiterite in hydrothermal quartz veins yielded U-Pb ages of 159.5 ± 0.6 Ma and 158.4 ± 1.9 Ma, respectively, confirming that magma emplacement and the formation of mineralized veins occurred synchronously. We conclude that the concealed granitic intrusion likely has an intimate genetic connection with the Kuimeishan vein type tungsten mineralization. The trace element composition of zircon shows distinct positive Ce anomalies which record a low-oxygen fugacity environment, which also indicates the ore potential of the granite. Zircon εHf(t) values from the granite vary mostly from −11.9 to −8.9 with Hf model ages (TDM2) ranging from 1.77 to 1.95 Ga. The granite likely represents reworked ancient continental crust without significant contributions of the mantle, typical of W mineralized granite. The concealed mineralized granite intrusion indicates potential for tungsten exploration at depth.