Decreasing extents of Archean serpentinization contributed to the rise of an oxidized atmosphere.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34930924.
- Also identified by DOI 10.1038/s41467-021-27589-7 and PMC identifier 8688491.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
At present, molecular hydrogen (H<sub>2</sub>) produced through Fe(II) oxidation during serpentinization of ultramafic rocks represents a small fraction of the global sink for O<sub>2</sub> due to limited exposures of ultramafic rocks. In contrast, ultramafic rocks such as komatiites were much more common in the Early Earth and H<sub>2</sub> production via serpentinization was a likely factor in maintaining an O<sub>2</sub>-free atmosphere throughout most of the Archean. Using thermodynamic simulations, this work quantifies the global O<sub>2</sub> consumption attributed to serpentinization during the past 3.5 billion years. Results show that H<sub>2</sub> generation is strongly dependent on rock compositions where serpentinization of more magnesian lithologies generated substantially higher amounts of H<sub>2</sub>. Consumption of >2 Tmole O<sub>2</sub> yr<sup>-1</sup> via low-temperature serpentinization of Archean continents and seafloor is possible. This O<sub>2</sub> sink diminished greatly towards the end of the Archean as ultramafic rocks became less common and helped set the stage for the Great Oxidation Event.