Abstract:

The Suoerkuduke Cu-Mo deposit located in the northern margin of Junggar Terrane, is hosted by skarn and andesite of Middle Devonian volcanic rocks of Beitashan Formation. The orebodies are stratoid, lenticular and vein types. Helium and argon isotopic compositions of fluid inclusions in pyrite from epidote skarn, andesite and ore were analyzed by using an inert gas isotopic mass spectrometer. The analysis results indicated that the ⁴He content ranges from 0.882 1×10^-8 cm³ STP/g to 13.341 0×10^-8 cm³ STP/g, the ³He/⁴He ranged from 0.88 Ra to 1.76 Ra, the He content from mantle varied from 13.27% to 26.93%, all of these characteristics showed that the He in ore-forming fluids derived mainly from crust. The ⁴⁰Ar content varied from 4.237 6×10^-8 cm³ STP/g to 13.970×10^-8 cm³ STP/g, the ⁴⁰Ar/³⁶Ar was 301.07 to 331.55，and the radiogenic ⁴⁰Ar* varied from 1.71% to 10.87%，indicated Ar in the ore-forming fluid was mainly from atmospheric water. The composition of He and Ar in three kinds of pyrite was similar. Combining deposit fluid inclusion and isotopic characteristics, we suggested that helium and argon isotopes of fluid inclusions in pyrite were mixture of crust fluid, mantle fluid and atmospheric water. The formation of deposit closely related with skarn and andesite, which imply that the ore genesis was skarn type Cu-Mo deposit.