Geology, fluid inclusion, and stable isotope constraints on the mineralization of the Nuocang skarn Pb-Zn polymetallic deposit, western Gangdese, Tibet

The Nuoang Pb-Zn polymetallic deposit is located in the Linzizong volcanic area of western Gangdese, Tibet, China. Three types of fluid inclusions including type L, type V, and type S have been discussed in the Nuocang deposit. The ore-forming fluids evolved from moderate to high temperature and moderate to high salinity in the pre ore stage through low to moderate temperature and low salinity in the syn-ore stage, and to low temperature and low salinity in the post-ore stage. The delta(34)Scur values of -0.6 to 2.7 parts per thousand, and Pb-206/Pb-204 Pb-207/Pb-204, Pb-208/Pb-204 values of 18.629 to 18.738, 15.646 to 15.793, and 38.907 to 39.340, respectively, indicate the ore-forming materials are dominantly derived from an upper crustal source mixing with minor amounts of mantle-derived components from the subducted slab of Neo- Tethys. The calculated EDH2O and 5180H(2)O values of the gangue minerals in different ore stages range from-180 to-106 parts per thousand and from -8.6 to 3.0 parts per thousand, respectively, suggesting the original fluids was magmatic hydrothermal. Significant addition of meteoric water to the magmatic-hydrothermal system considered to be responsible for metal deposition. Locally, boiling has also been considered as another mechanism for ore precipitation in the Nuocang hydrothermal system.