The oxidation of mantle wedge in Earth’s middle age

The redox state of Earth’s mantle exerts a fundamental influence on volcanic degassing and the composition of the atmosphere, yet its long-term evolution remains uncertain. Here we use a machine-learning classifier to identify primitive arc basalts and reconstruct mantle wedge’s oxygen fugacity over time. Our results show that the redox state of mantle wedge raised in Earth’s middle-age. This Mesoproterozoic oxidation was asynchronous with surface oxygenation, suggesting that deep Earth processes, such as the enhanced fluxes of serpentinite-derived fluids, drove the oxidation of mantle wedge. The establishment of an oxidized mantle wedge may have reduced volcanic oxygen sinks and facilitated atmospheric oxygen accumulation in Mesoproterozoic, with implications for the rise of early eukaryotic life.