Solubility of gold in the reduced carbonic fluid

The first experimental data on the gold solubility in the fluid with composition CO-CO2 and C-O-S with small water content at the pressure 200 MPa and temperature 950°С are reported. Solubility in the fluid C-O-S is about 27 ppm. Estimation of the solubility of gold in fluid CO-CO2 with 10–15 mol.% CO is less accurate: its value is at least 2–3 ppm, but it probably can reach 200–300 ppm. The high solubility of gold found in this work, and previously Pt (Simakin et al., 2016), in the reduced carbon dioxide can explain the formation of these noble metal ore occurrence in the Gluli intrusion (Polar Siberia) by their fluid extraction and re-deposition at temperatures below the solidus. The reducing of a substantially oxidized carbon dioxide fluid, established by mineralogical sensors, was probably caused by subsolidus oxidation of olivine.