Exploration potential of Cu isotope fractionation in porphyry copper deposits

We examined the copper isotope ratio of primary high temperature Cu-sulfides, secondary low temperature Cu-sulfides (and Cu-oxides) as well as Fe-oxides in the leach cap, which represent the weathered remains of a spectrum of Cu mineralization, from nine porphyry copper deposits. Copper isotope ratios are reported as δ65Cu‰=((65Cu/63Cusample/65Cu/63CuNIST 976 standard)−1) ⁎ 103. Errors for all the analyses are ±0.14‰ (determined by multiple analyses of the samples) and mass bias was corrected through standard-sample-standard bracketing. The overall isotopic variability measured in these samples range from −16.96‰ to 9.98‰.