The source of ore-forming fluids in the Bolong copper mine area,Tibet

The Bolong porphyry copper deposit was founded the largest copper deposits in central Tibet Plateau in recent years by No.5 Geological Party,Tibet Bureau of Geology and Mineral Exploration and Development.In order to identify Source of Ore-Forming Fluids in the Bolong copper mine and samples of fluid inclusions in pyrite and quartz form Copper Mine Area were Sampled to test their noble gas isotope or gas composition.Testing has shown that ³He/⁴He were 3.03 and 8.51,and ⁴⁰ Ar/³⁶Ar were 214.94 and 284.23,it showed that ore-forming fluid may be come from the crust-mantle mixed source.Gaseous composition of fluid inclusion mainly composed of H₂O,followed by CO₂,in addition to a small amount of N₂,CH₄,C₂H₆,H₂S and Ar,Portion of the sample composition also contains O₂,it showed that ore-forming fluids mixed with high oxygen fugacity component.Combined with H-O isotopes of quartz inclusions that source was based with magma source and mixed with atmospheric composition,thus we considered that ore-forming fluids of the Bolong copper mine should be mixed with source of mantle and Crustal,Early mineralization dominated deep source fluid,and it mixed some atmospheric precipitation with the evolution of the fluid advanced.With high oxygen fugacity characteristics Nujiang oceanic crust subducted slab carried large amounts minerals melted and explained the overlying mantle wedge,and occured crust-mantle mixed,formed the initial of magma,Contaminated lower crust component during ascending,and affected by deep-cycle precipitation and emplaced into the upper crust to form the Bolong copper deposit finally.