The metallogenic mechanism of the Shabulengshan Cu-Zn deposit: Constrain from fluid inclusions, O-H and in situ S isotopes

The Shabulengshan deposit, located in the southern Great Xing'an Range, Inner Mongolia, is a newly discovered medium-sized copper-zinc deposit. Ore bodies are hosted in the Late Permian Dashizha Formation and the Early Jurassic Manketouebo Formation volcanic rocks and slate. Based on the mineral assemblage and interaction of the hydrothermal veins, the ore-forming stages can be divided into: molybdenite-quartz veins (stage- I), Cu-Zn polymetallic sulfide-quartz veins (stage- II) and quartz-calcite veins (stage- III). Three types of the fluid inclusions can be identified in the deposit: H2O-NaCl fluid inclusions (Type- I a, I b), gas-rich fluid inclusions (Type- II a, II b) and daughter mineral-bearing fluid inclusions (Type-). The homogenization temperature and the salinity of fluid inclusions of stage I, stage II and stage III are 313 similar to 412 degrees C and 3.2% similar to 48.5% NaCleqv, 310 similar to 367 degrees C and 1.0% similar to 7.8% NaCleqv, 178 similar to 283 degrees C and 2.7% similar to 5.0% NaCleqv, respectively. The calculated pressure is 15 similar to 32MPa with the estimated depth of 3.2 similar to 4.4km. The fluid inclusions and Raman spectrum analysis shows that the inclusions of main mineralization stage (Stage II) widely obtain CH4 +/- CO2 components. It indicates that the main ore-forming stage of Shabulangshan Cu-Zn deposit belongs CH4 +/- CO2 bearing hydrothermal system with medium to high temperatures and medium to low salinities. The delta D values of different stages vary from 136 parts per thousand to -146 parts per thousand, with the calculated delta O-18 values between -4.38 parts per thousand and 5.42 parts per thousand, indicating the ore-forming initially coming from magmatic water and mixed with a meteoric water. In situ delta S-34 values of sulfides value ranges from - 0.8 parts per thousand to - 9.0 parts per thousand, suggesting the metallogenic materials of Shabulengshan deposit have the deep magmatic source characteristics. The ore -forming fluid are characterized by low delta D values and CH4 components, indicating that organic materials from the strata addition may added in the ore-forming fluids. Therefore, the metallogenic process of Shabulengshan deposit can be summarized as follows: the ore -forming fluid boiling took place when it migrated to faults from deep-source magma, and then the ore -forming fluids interacted with strata. Synchronously, this process causes CH4 and CO2 escaping and drove the metal converging and participation.