Redox Equilibria

The basic aspects of redox geochemistry are reviewed to provide a useful compendium the connection between aqueous-hydrothermal and igneous realms Earth. description system is intimately coupled knowledge acid-base properties solvent in which exchanges take place. For magmas, then silicate melts, approaches reporting state were so far cantered around sole concept oxygen fugacity, f O 2 . Mastering experimental observational petrology was key constrain processes behind very large range relative fugacity observed on Although current descriptions melts magma thermodynamic mainly based oxides or mineral-like molecular components, disregarding actual melt reactivity poses many limits our understanding true chemical involving oxygen, iron other redox-sensitive elements. Because unlike aqueous solutions, lack full description, compositional dependencies solved by means empirical treatments their combinations. However, these can bias interpretation recorded analyzed samples used identify several (e.g., batch fractional crystallization, elemental recycling, degassing, deep fluid infiltration) characterize evolution its geodynamic environment. This short aims at stimulating quest for comprehensive unifying picture from we could extrinsic way similar solutions molten salts.