A large epeiric methanogenic Bambuí sea in the core of Gondwana supercontinent?

Caetano-Filho, Sérgio; Sansjofre, Pierre; Ader, Magali; Paula‐Santos, Gustavo M.; Guacaneme, Cristian; Babinski, Marly; Bedoya-Rueda, Carolina; Kuchenbecker, Matheus; Reis, Humberto Luís Siqueira; Trindade, R. I.

doi:10.1016/j.gsf.2020.04.005

Cited by 28 publications

(48 citation statements)

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“…The paleogeography may thus one of the key factors in the establishment of restricted environment, e.g. interior seas or restricted epireic seas, could thus have a significant influence on the occurrence of CIEs, as suggested for example in the case of the Neoproterozoic positive δ 13 C excursions of the Bambui Group, Brazil 65 .…”

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confidence: 99%

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Cadeau

Jézéquel

Leboulanger

et al. 2020

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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.

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confidence: 99%

Carbon isotope evidence for large methane emissions to the Proterozoic atmosphere

Cadeau

Jézéquel

Leboulanger

et al. 2020

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“…The Bambuí Group carbon isotope evolution evolves dramatically, represented by a unique and extreme positive δ 13 C carb and δ 13 C org excursions reaching values as high as +16 and −14‰, respectively, occurring at the sequence boundary between the two lowermost 2 nd -order sequences of the unit (Fig. 6.4; the Middle Bambuí Isotope Excursion - MIBE;Caetano-Filho et al, 2020). This carbon isotope excursion is commonly associated with enhanced restriction of the basin, however, with the main controls still discussed Caetano-Filho et al, 2020).…”

Section: Resultsmentioning

confidence: 99%

“…(iii) At the end of the highstand systems tract in Well 1 section and through the overlying sequence in all section, a coupled δ 13 C positive excursion is observed and reaches extremely heavy isotope compositions (up to +14‰ for δ 13 C carb and to −14‰ for δ 13 C org ; Fig. 6.4;Caetano-Filho et al, 2020). This positive δ 13 C excursion was named as the Middle Bambuí Isotope Excursion and represents extreme paleoenvironmental disturbances in the basin carbon cycle, probably driven by enhanced restriction due to late Neoproterozoic orogen build-ups surrounding the basin Caetano-Filho et al, 2020).…”

Section: Bambuí Group São Francisco Basinmentioning

confidence: 90%

“…6.4;Caetano-Filho et al, 2020). This positive δ 13 C excursion was named as the Middle Bambuí Isotope Excursion and represents extreme paleoenvironmental disturbances in the basin carbon cycle, probably driven by enhanced restriction due to late Neoproterozoic orogen build-ups surrounding the basin Caetano-Filho et al, 2020).…”

Section: Bambuí Group São Francisco Basinmentioning

confidence: 98%

“…This lithological control over isotope shifts within HST interval of the Well 1 led to the dismissing of isotope compositions from the EHST in terms of primary signals. High amounts of siliciclastic represent more favorable conditions to post-depositional alteration of both δ 13 C carb and δ 13 C org (Caetano-Filho et al, 2020).…”

Section: Bambuí Group São Francisco Basinmentioning

confidence: 99%

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