Origin of ore-forming fluids of the Zn-Pb-(Cu) deposits in the Jinbao mine district  of eastern Guizhou Province, China:  Evidence from chemical compositions of fluid inclusions and their lithium isotopes

Abstract

In this study, fluid inclusion leachates, extracted from gangue quartz that is associated with ore minerals, are used to measure elemental components and Li isotopic compositions to investigate the sources of the ore-forming fluids of Zn-Pb-(Cu) deposits in the Jinbao mine district, the origins of which are still in controversy. Major components of the fluid inclusions are chloride-(Na,Ca). Interestingly, the elemental correlation (Na/Ba vs. Cl/Ba and Ca/Ba vs. Cl/Ba) shows that four deposits we investigated in the Jinbao mine district share common components in sources. The Li and its isotopic signatures (Li: 92.2 to 587.4 ng/L and the majority of δ⁷Li values: <+10‰) indicate that the ore-forming fluids in the Jinbao mine district may be originated from concealed granite magma. The δ⁷Li values of >+12‰, obviously higher than reported Li-rich peraluminous magma, are interpreted to be derived from the isotopic fractionation during fluid exsolution and the mixture between magmatic fluids and other fluids with higher δ⁷Li values. This study proves that Li isotopes could be a useful tool to track the sources of ore-forming fluids in Zn-Pb deposits.