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Gold speciation and transport in geological fluids: insights from experiments and physical-chemical modelling

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Pokrovski Gleb, Akinief Nikolay, Borisova Anastassia, Zotov Alexandre, Kouzmanov Kalin,
Project Chemistry and P-T of fluids trapped in co-genetic opaque ore and transparent gangue minerals: What are the real ore-precipitating fluids?
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Original article (peer-reviewed)

Journal Geological Society of London Special Publication “Gold-transporting fluids in the Earth’s crust”
Title of proceedings Geological Society of London Special Publication “Gold-transporting fluids in the Earth’s crust”


This contribution overviews available experimental, thermodynamic, and molecular data on Au aqueous speciation, solubility, and partitioning in major types of geological fluids in the Earth’s crust, from low-temperature aqueous solution to supercritical hydrothermal-magmatic fluids, vapors, and silicate melts. Critical revisions of these data allow generation of a set of thermodynamic properties of the AuOH, AuCl2-, AuHS, and Au(HS)2- complexes dominant in aqueous hydrothermal solutions; however, other complexes involving different sulfur forms, chloride, and alkali metals may operate in high-temperature sulfur-rich fluids, vapors, and melts. The large affinity of Au for reduced sulfur is responsible for Au enrichment in S-rich vapors and sulfide melts, which are important gold sources for hydrothermal deposits. Thermodynamic, speciation, and partitioning data, and their comparison with Au and S contents in natural fluid inclusions from magmatic-hydrothermal gold deposits provide new constraints on the major physical-chemical parameters (temperature, pressure, salinity, acidity, redox) and ubiquitous fluid components (sulfur, carbon dioxide, arsenic) affecting Au concentration, transport, precipitation, and fractionation from other metals in in crust. The availability and speciation of sulfur and their changes with the fluid and melt evolution are the key factors controlling gold behavior in most geological situations.