Skip to Main content Skip to Navigation
Journal articles

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Abstract : The Proterozoic Era records two periods of abundant positive carbon isotope excursions (CIEs), conventionally interpreted as resulting from increased organic carbon burial and leading to Earth’s surface oxygenation. As strong spatial variations in the amplitude and duration of these excursions are uncovered, this interpretation is challenged. Here, by studying the carbon cycle in the Dziani Dzaha Lake, we propose that they could be due to regionally variable methane emissions to the atmosphere. This lake presents carbon isotope signatures deviated by ~ + 12‰ compared to the modern ocean and shares a unique combination of analogies with putative Proterozoic lakes, interior seas or restricted epireic seas. A simple box model of its Carbon cycle demonstrates that its current isotopic signatures are due to high primary productivity, efficiently mineralized by methanogenesis, and to subsequent methane emissions to the atmosphere. By analogy, these results might allow the reinterpretation of some positive CIEs as at least partly due to regionally large methane emissions. This supports the view that methane may have been a major greenhouse gas during the Proterozoic Era, keeping the Earth from major glaciations, especially during periods of positive CIEs, when increased organic carbon burial would have drowned down atmospheric CO2.
Document type :
Journal articles
Complete list of metadata

Cited literature [83 references]  Display  Hide  Download
Contributor : Cécile Bernard Connect in order to contact the contributor
Submitted on : Monday, October 26, 2020 - 10:56:06 AM
Last modification on : Friday, August 5, 2022 - 12:01:14 PM
Long-term archiving on: : Wednesday, January 27, 2021 - 6:31:44 PM


Cadeau_et_al_2020_C cycle Dzia...
Publisher files allowed on an open archive




Pierre Cadeau, Didier Jézéquel, Christophe Leboulanger, 
 Éric Fouilland, Emilie Le Floc’h, et al.. Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere. Scientific Reports, Nature Publishing Group, 2020, 10 (1), ⟨10.1038/s41598-020-75100-x⟩. ⟨mnhn-02978019⟩



Record views


Files downloads