Carbon–fluid equilibria and the oxidation state of the upper mantle

IT has been proposed that the oxidation state of the Earth's upper mantle is buffered by C–O fluids in equilibrium with elemental carbon1,2. A large body of data on the oxygen fugacities (fo2) recorded by mantle rocks and their derivative melts now allows us to test this proposal. By comparing the measured fo2 values with those calculated for carbon–CO2–CO… CONTINUE READING