Effect of S on the aqueous and gaseous transport of Cu in porphyry and epithermal systems: Constraints from in situ XAS measurements up to 600 °C and 300 bars

• DOI: 10.1016/j.chemgeo.2017.06.039
• Publication Date: 2017-07-04T03:45:24Z
• Authors: M. Louvel; A. Bordage; B. Tripoli; D. Testemale; J.-L. Hazemann; J. Mavrogenes
• Keywords: X-ray absorption spectroscopy

Abstract The effect of S on the solubility of Cu in high-temperature fluids at conditions relative to porphyry and epithermal ore deposit formation has been investigated conducting in situ X-ray absorption (XAS) and Raman spectroscopy from 325 to 600 °C at 300 bars. The experimental results identify the Cl or S-complexes responsible for Cu transport in high-temperature fluids and provide information on transport in porphyry/epithermal systems and the effect of fluid composition on the transfer of Cu from the porphyry to the epithermal environment. In S-free HCl solutions, Cu solubility is about 10 times higher in high-density (ρ > 0.6 g·cm− 3) versus low-density (ρ Overall, these results suggest that the presence of S of mixed oxidation state (sulfide S2 −, sulfite S4 + and sulfate S6 +) limits transport of Cu in porphyry and epithermal systems and may even trigger Cu precipitation. Furthermore, these experiments provide evidence that the presence of the S3− ion does not increase Cu solubility in fluids. Thus, if present in such environments, S3− ion could fractionate Cu from Au in porphyry-epithermal environments.