Re–Os molybdenite age of the Cu–Mo skarn ore deposit at Suoerkuduke in East Junggar, NW China and its geological significance

The Suoerkuduke Cu–Mo ore is a medium-sized skarn deposit in the East Junggar orogen of the southern Altaids, Xinjiang, Northwest China. We measured Re–Os isotopes of a molybdenite veinlet from the main ore body, of which eight yielded model ages ranging from 303 ± 5 to 317 ± 5 Ma with a well-constrained 187Re–187Os isochron age of 305 ± 7 Ma, a MSWD of 4.9 and a weighted average model age of 310 ± 4 Ma with a MSWD of 4.2. The 187Re–187Os isochron age is consistent with the weighted mean model age, within error, and indicates that the time of Cu–Mo mineralization was at c. 310 Ma in the late Carboniferous. This new age is close to the youngest porphyry-related Cu–Mo metallogenic epoch (c. 311 Ma) in the East Junggar region, and is not, as previously suggested, in the Permian. Considering the implications of this new age, we propose that the Suoerkuduke deposit was part of a large-scale porphyry–skarn system, which formed by the interaction between far-traveled hydrothermal fluids and the calcium-rich volcanic wall rocks.