%0 Article %J Science Advances %D 2022 %T Destabilization of deep oxidized mantle drove the Great Oxidation Event %A O’Neill, Craig %A Aulbach, Sonja %N 7 %P eabg1626 %U https://www.science.org/doi/abs/10.1126/sciadv.abg1626 %V 8 %1 10.1126/sciadv.abg1626 %K ASPECT %X The rise of Earth’s atmospheric O2 levels at ~2.4 Ga was driven by a shift between increasing sources and declining sinks of oxygen. Here, we compile recent evidence that the mantle shows a significant increase in oxidation state leading to the Great Oxidation Event (GOE), linked to sluggish upward mixing of a deep primordial oxidized layer. We simulate this scenario by implementing a new rheological model for this oxidized, bridgmanite-enriched viscous material and demonstrate slow mantle mixing in simulations of early Earth’s mantle. The eventual homogenization of this layer may take ~2 Ga, in line with the timing of the observed mantle redox shift, and would result in the increase in upper mantle oxidation of >1 log(fO2) unit. Such a shift would alter the redox state of volcanic degassing products to more oxidized species, removing a major sink of atmospheric O2 and allowing oxygen levels to rise at ~2.4 Ga. Delayed mixing of primordial mantle drove the Great Oxidation Event.