Destabilization of deep oxidized mantle drove the Great Oxidation Event.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 35179960.
- Also identified by DOI 10.1126/sciadv.abg1626 and PMC identifier 8856610.
- Licence recorded as CC BY-NC.
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Abstract
The rise of Earth's atmospheric O<sub>2</sub> 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(<i>f</i>O<sub>2</sub>) unit. Such a shift would alter the redox state of volcanic degassing products to more oxidized species, removing a major sink of atmospheric O<sub>2</sub> and allowing oxygen levels to rise at ~2.4 Ga.