Helium and Argon Isotopic Compositions of Fluid Inclusions in Pyrite from Saridala Gold Deposit in Xinjiang

Saridala gold deposit is located within Bing Daban ductile shear zone in the northern margin of Middle Tianshan. After analyzing the subsequent processes that may affect He-Ar original isotopic compositions of ore-forming fluid, the helium and argon isotopic compositions of fluid inclusions in pyrite were analyzed to trace fluid origin by using an inert gas isotopic mass spectrometer.Research results indicate that R/Ra ratios range from 0.34~1.59Ra, which primarily consist of crust-radioactive He with some mantle-derived He; Samples share coincident argon isotopic compositions with ⁴⁰Ar/³⁶Ar and ³⁶Ar/³⁸Ar ratios ranging from 305 to 359 with an average of 336, and from 5.34 to 5.44 with an average of 5.40, respectively, which yield Ar isotopic compositions of general atmospheric saturated water with some capture of radioactive ⁴⁰Ar. He and Ar isotopic compositions indicate that ore-forming fluid of the Saridala gold deposit is derived fromcrust, which origin from deep circulation of atmospheric water, and the mantle-derived He means nothing to do with direct mantle process but drops a hint that may existed certain geologic bodies related to the interaction between mantle and crust.