Diffusion-driven Fractionation of Iron Isotopes in Oxidized and Reduced Silicate

Isotopic fractionation of the major elements of molten basalt by chemical and thermal diffusion

Samples produced in piston cylinder experiments were used to document the thermal isotopic fractionation of all the major elements of basalt except for aluminum and the fractionation of iron isotopes by chemical diffusion between a natural basalt and rhyolite. The thermal isotopic fractionations are summarized in terms of a parameter Xi defined as the fractionation in per mil per 100 C per atom...

Diffusion-driven magnesium and iron isotope fractionation in Hawaiian olivine

Iron oxides stimulate sulfate-driven anaerobic methane oxidation in seeps.

Seep sediments are dominated by intensive microbial sulfate reduction coupled to the anaerobic oxidation of methane (AOM). Through geochemical measurements of incubation experiments with methane seep sediments collected from Hydrate Ridge, we provide insight into the role of iron oxides in sulfate-driven AOM. Seep sediments incubated with (13)C-labeled methane showed co-occurring sulfate reduct...

Stable isotope fractionation by thermal diffusion through partially molten wet and dry silicate rocks

Water plays a fundamental role in affecting geochemical transport and physical properties of magmas. Here we show the previously undocumented behavior of water within partially molten silicate resting in a temperature gradient, producing O, Li and H isotope redistribution by thermal diffusion leading to enrichment of light isotopes at the hot end of the gradient. After weeks to months, fully mo...

Iron isotopic fractionation between silicate mantle and metallic core at high pressure

The +0.1‰ elevated 56Fe/54Fe ratio of terrestrial basalts relative to chondrites was proposed to be a fingerprint of core-mantle segregation. However, the extent of iron isotopic fractionation between molten metal and silicate under high pressure-temperature conditions is poorly known. Here we show that iron forms chemical bonds of similar strengths in basaltic glasses and iron-rich alloys, eve...