Garnet peridotites reveal spatial and temporal changes in the oxidation potential of subduction.

ABSTRACT: Changes in the oxygen fugacity (fO₂) of the Earth's mantle have been proposed to control the spatial and temporal distribution of arc-related ore deposits, and possibly reflect the evolution of the atmosphere over billions of years. Thermodynamic calculations and natural evidence indicate that fluids released from subducting slabs can oxidise the mantle, but whether their oxidation potential varied in space and time remains controversial. Here, we use garnet peridotites from western Norway to show that there is a linear decrease in maximum fO₂ with increasing depth in the mantle wedge. We ascribe this relation to changes in the speciation of sulfur released in slab fluids, with sulfate, controlling maximum oxidation, preferentially released at shallow depths. Even tho

SUBMITTER: Rielli A 

PROVIDER: S-EPMC6219559 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature