Hydrothermal transport of Cu and Fe: internally-consistent thermodynamic model and application to formation of world-class iron-oxide-copper-gold (IOCG) ore deposits
Final Report Abstract
This project addressed the chemical processes leading to formation of high-grade Cu-Au mineralization in iron oxide copper gold (IOCG) ore deposits. Building on previous research on the Prominent Hill deposit in southern Australia, work in this project comprised assessing the thermodynamic data for Cu, Fe and S from compilation and critical review of experimental literature data, constraining the chemical composition of the end-member fluid types involved into fluid mixing processes from fluid inclusion and mineral chemistry data and performing geochemical modeling of fluid mixing and fluid-rock interaction processes. Critical review and recalculation of experimental data of aqueous species of Cu, Fe and S resulted in a refined thermodynamic model for these elements, which will subsequently become integrated into the internally consistent data set for fluid-mineral equilibria developed earlier. Fluid and mineral chemistry data from a range of mineralization styles including sub-economic magmatic-hydrothermal Cu mineralization and barren mineralization in the Mount Woods IOCG system have further constrained the compositon of the end-members involved into fluid mixing processes. Geochemical modeling of fluid mixing between the oxidized volcanic lake water derived fluid and the reduced magmatic-hydrothermal fluid has resulted in important insight into the chemical processes that cause formation of high-grade Cu mineralization. Key observations are that fluid mixing can cause massive Cu-Fe sulfide mineralization and also the development of depositscale sulfide zoning as observed at the world-class IOCG deposits Prominent Hill and Olympic Dam.
Publications
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Fluorite as indicator mineral in iron oxide-copper-gold systems: explaining the IOCG deposit diversity. Chemical Geology, 548, 119674.
Schlegel, Tobias U.; Wagner, Thomas & Fusswinkel, Tobias
