Mantle-Derived Fluids Involved in Large-Scale Gold Mineralization, Jiaodong District, China: Constraints Provided by the He-Ar and H-O Isotopic Systems

摘要

The Jiaodong super-large gold metallogenic region is located on the eastern margin of the North China craton and the western margin of the Circum-Pacific tectonic belt. Ore-forming chronology indicates that these deposits formed at 120 + - 10 Ma. Helium and argon isotope compositions of fluid inclusions in pyrite range in ~3He/~4He ratios from 0.38 to 2.36 R/Ra (R: ~3He/~4He ratios of samples; Ra: ~3He/~4He ratios of Beijing air, 1.4 X 10~(-6)) and in ~(40)Ar/~(36)Ar ratios from 310 to 1148. delta~(18)O and 5D values of fluid inclusions in quartz are -2.16 to +6.28 per thousand and -65 to -98 per thousand, respectively. A consistent relationship between H-0 and He-Ar isotopic systems show that mantle-source fluids were involved in large-scale metallogeny in the Jiaodong region. The fluids were produced accompanying delamination, lithosphere thinning, and crust-mantle interaction that occurred in the eastern North China craton during the Early Cretaceous (140-120 Ma).