Mantle data imply a decline of oxidizable volcanic gases could have triggered the Great Oxidation

• Published in: Nature communications Vol. 11; no. 1; p. 2774
• Main Authors: Kadoya, Shintaro, Catling, David C., Nicklas, Robert W., Puchtel, Igor S., Anbar, Ariel D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 02.06.2020; Nature Publishing Group; Nature Portfolio
• Subjects: 704/106/413; 704/2151/209; 704/2151/213/4114; 704/47/4112; Accumulation; Astrobiology; Atmosphere; Carbon; Carbon cycle; Cyanobacteria; Evolution; Extrasolar planets; Gases; Humanities and Social Sciences; Hypotheses; Mantle; multidisciplinary; Oxidation; Oxygenation; Photosynthesis; Science; Science (multidisciplinary); Volcanic gases
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-020-16493-1

Aerobic lifeforms, including humans, thrive because of abundant atmospheric O 2 , but for much of Earth history O 2 levels were low. Even after evidence for oxygenic photosynthesis appeared, the atmosphere remained anoxic for hundreds of millions of years until the ~2.4 Ga Great Oxidation Event. The delay of atmospheric oxygenation and its timing remain poorly understood. Two recent studies reveal that the mantle gradually oxidized from the Archean onwards, leading to speculation that such oxidation enabled atmospheric oxygenation. But whether this mechanism works has not been quantitatively examined. Here, we show that these data imply that reducing Archean volcanic gases could have prevented atmospheric O 2 from accumulating until ~2.5 Ga with ≥95% probability. For two decades, mantle oxidation has been dismissed as a key driver of the evolution of O 2 and aerobic life. Our findings warrant a reconsideration for Earth and Earth-like exoplanets. The early Earth’s atmosphere had very low oxygen levels for hundreds of millions of years, until the 2.4 Ga Great Oxidation Event, which remains poorly understood. Here, the authors show that reducing Archean volcanic gases could have prevented atmospheric O 2 from accumulating, and therefore mantle oxidation was likely very important in setting the evolution of O 2 and aerobic life.