Accessory mineral chemistry as a monitor of petrogenetic and metallogenetic processes: A comparative study of zircon and apatite from Wushan Cu- and Zhuxiling W(Mo)-mineralization-related granitoids

摘要

In this study, we explore the chemistry of accessory apatite and zircon as tools to monitor the petrogenetic and metallogenetic processes involved in the formation of the Wushan Cu- and Zhuxiling W (Mo)-mineralization related granodiorite porphyry. The Wushan granitoids are metaluminous with A/CNK of 0.88-1.01, and the Zhuxiling intrusions are weakly peraluminous with higher A/CNK values (1.02-1.12). The Wushan granitoids have epsilon(Nd)(t) values of -4.6 to -4.7, which, combined with the relatively elevated Mg-# values (57-62) and adakitic features (high Sr/Y ratios of 51-60), indicate that they were derived from melting of a thickened lower crust of the Yangtze block with addition of small amounts of mantle components. Compared to the Wushan granitoids, the Zhuxiling granitoids have relatively high (Sr-87/Sr-86)(i) (0.7094-0.70951) and low epsilon(Nd)(t) values (-5.9 to -6.3) and zircon epsilon(Hf)(t) values (-3.8 to -9.0), suggesting their derivation dominantly from partial melting of the Neoproterozoic crust.