Different proportion of mantle-derived noble gases in the Cu–Fe and Fe skarn deposits: He–Ar isotopic constraint in the Edong district, Eastern China

Cu and Fe skarns are two economically important types of skarn deposit worldwide, but the critical factors controlling the difference in metal associations remain enigmatic. The Edong ore district, China, presents an excellent opportunity to study the differences between Cu–Fe and Fe skarn deposits. We have measured He–Ar isotopes trapped in fluid released by crushing pyrite and chalcopyrite from four well known Cu–Fe and Fe deposits in the...