Iron Isotope Fractionation during Skarn Cu-Fe Mineralization

Fe isotopes have been applied to the petrogenesis of ore deposits. However, behavior iron in mineralization porphyry-skarn deposits is still poorly understood. In this study, we report mineral separations (magnetite, pyrite, chalcopyrite and pyrrhotite) from two different skarn deposits, i.e., Tonglvshan Cu-Fe deposit developed an oxidized hydrothermal system Anqing Cu a reduced system. both calculated equilibrium fluids are lighter than those intrusions responsible for porphyry mineralization, corroborating “light-Fe fluid” hypothesis. Interestingly, oxidized-Tonglvshan has reduced-Anqing deposit, which best understood as result prior precipitation magnetite (heavy Fe) fluid systems pyrrhotite (light The δ56Fe pyrite shows inverse correlation with Tonglvshan. isotope fractionation between offset line at 350 °C lies FeS-chalcopyrite pyrite-chalcopyrite °C. These observations consistent FeS pathway towards formation. That is, during formation depends on path initial FeS-fluid pyrite-fluid due increasing extent isotopic exchange fluids. This finding, together data other allows us propose that effect Porphyry-skarn dominant mechanism controls characteristics.