The Daduhe gold field at the eastern margin of the Tibetan Plateau: He, Ar, S, O, and H isotopic data and their metallogenic implications

The Daduhe gold field comprises several shear-zone-controlled Tertiary lode gold deposits distributed at the eastern margin of the Tibetan Plateau. The deposits are hosted in a Precambrian granite-greenstone terrane within the Yangtze Craton. The gold mineralization occurs mainly as auriferous quartz veins with minor sulphide minerals. Fluid inclusions in pyrite have He-3/He-4 ratios of 0.16 to 0.86 R-a, whereas their Ar-40/Ar-36 ratios range from 298 to 3288, indicating a mixing of fluids of mantle and crust origins. The delta S-34 values of pyrite are of 0.7-4.2 parts per thousand (n= 12), suggesting a mantle source or leaching from the mafic country rocks. delta O-18 values calculated from hydrothermal quartz are between - 1.5 parts per thousand and +6.0 parts per thousand and delta D values of the fluids in the fluid inclusions in quartz are - 39 parts per thousand and - 108 parts per thousand. These ranges demonstrate a mixing of magmatic/metamorphic and meteoric fluids. The noble gas isotopic data, along with the stable isotopic data suggest that the ore-forming fluids have a dominantly crustal source with a significant mantle component. (c) 2006 Elsevier B.V. All rights reserved.