Oxygen thermobarometry of abyssal spinel peridotites: the redox state and C-O-H volatile composition of the Earth's sub-oceanic upper mantle

Abstract

We have applied the spinel peridotite oxygen barometer to abyssal spinel peridotites from the mid-Atlantic, central Indian, southwest Indian and American-Antarctic ocean ridge systems. The results indicate that the oxygen fugacity (fO2) of the suboceanic mantle is on average 0.9 ± 0.7 (n = 33; ± 1sd) log units below the Fayalite-Magnetite-Quartz (FMQ) fO2 buffer. Suboceanic mantle is more reduced than the subcontinental mantle. -from Authors