FN Archimer Export Format PT J TI Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere BT AF Cadeau, Pierre Jézéquel, Didier Leboulanger, Christophe Fouilland, Eric Le Floc’h, Emilie Chaduteau, Carine Milesi, Vincent Guélard, Julia Sarazin, Gérard Katz, Amandine d’Amore, Sophie Bernard, Cecile Ader, Magali AS 1:1;2:1;3:2;4:4;5:4;6:1;7:1;8:1;9:1;10:1;11:1;12:3;13:1; FF 1:;2:;3:;4:;5:;6:;7:;8:;9:;10:;11:;12:;13:; C1 Université de Paris, Institut de physique du globe de Paris, CNRS, 75005, Paris, France MARBEC Sète, France, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France UMR 7245 MCAM, Muséum National D’Histoire Naturelle - CNRS, Paris, France MARBEC Sète, France, Univ Montpellier, CNRS, Ifremer, IRD, Sète, France C2 IPGP, FRANCE IRD, FRANCE MNHN, FRANCE CNRS, FRANCE UM MARBEC IN WOS Cotutelle UMR DOAJ copubli-france IF 4.379 TC 21 UR https://archimer.ifremer.fr/doc/00656/76784/77944.pdf https://archimer.ifremer.fr/doc/00656/76784/77945.pdf LA English DT Article CR MAYOBS1 BO Marion Dufresne AB 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. PY 2020 PD OCT SO Scientific Reports SN 2045-2322 PU Springer Science and Business Media LLC VL 10 IS 1 UT 000586493900001 DI 10.1038/s41598-020-75100-x ID 76784 ER EF