Helium Isotope Geochemistry of Ore-forming Fluids from Furong Tin Orefield in Hunan Province, China

Abstract. The Furong tin orefield, located in southern Hunan, China, is a newly-discovered super-large tin orefield. In contrast to most other tin deposits associated with S-type granites, the Furong tin deposit is closely associated with the Qitianling A-type granite. The ³He/⁴He ratios of fluid inclusions in pyrite and arsenopyrite from this orefield range from 0.13 to 2.95 Ra. The influence of various post-mineralization processes on the helium isotopic composition of ore-forming fluid inclusions are estimated negligible. Thus, the analytical values of helium isotopic composition basically represent the original values of ore-forming fluids at the time they were trapped.
The ³He/⁴He ratios of ore-forming fluids from the Furong orefield indicate the existence of mantle-source components. It supports the idea that both the Furong tin orefield and Qitianling granite formed under the geodynamic background of mantle upwelling and crustal extension.