Magma Redox

The redox state (oxygen fugacity) of a magma governs its mass balance and activity of oxygen, which bears on the sequestration of sidero/chalcophile elements into ores, the degassing of magmas and the geochemical cycles of atmophile elements (C, H, S, N). We use redox sensitive elements as redox indicators in magmas based on the prediction that these elements should have a fO2-dependent mineral/melt partition coefficient. The partition coefficients are experimentally calibrated in high P and T experiments, and used to examine the redox state of mantle-derived magmas or their complementary residues, or the igneous processes by which magmas 'breathe'.

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