Cu isotopes in minerals of the Mikheevskoe gold-copper-porphyry deposit (Southern Urals)

Research subject. Minerals of Cu from the Mikheevskoe gold-copper-porphyry deposit in the Southern Urals. Aim. To obtain preliminary data on the isotopic composition of Сu in minerals of various ore types from the largest porphyry deposit of the Urals followed by their interpretation. Methods. The 65Cu/63Cu isotope ratio values were determined using a multicollector inductively coupled plasma mass spectrometer Neptune Plus at the Research Center “Geoanalytik” (IGG of Ural Branch of the Russian Academy of Sciences). In total, 12 samples of three main technological ore types from this deposit were analyzed. Results. The δ65Cu values in the minerals of sulfide, friable, and oxidized ores ranged from –0.36 to +0.25‰ (chalcopyrite, fahlore), from –0.64 to +0.68‰ (bornite, chalcocite, pyrite), and from –2.14 to +0.30‰ (malachite, azurite), respectively. Conclusions: The absence of wide variations in δ65Cu values indicates the formation of the deposit under the conditions of a limited number of stages of hydrothermal ore formation, associated with the evolution of a single hydrothermal system. The obtained data agree well with the values of δ65Cu in porphyry-type deposits from different regions of the world. The conducted study contributes to the current knowledge on behavior of Cu-isotopes in minerals from ore deposits.