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| Mand, Kaarel; Lalonde, Stefan; Robbins, Leslie J.; Thoby, Marie; Paiste, Kart; Kreitsmann, Timmu; Paiste, Paarn; Reinhard, Christopher T.; Romashkin, Alexandr E.; Planavsky, Noah J.; Kirsimae, Kalle; Lepland, Aivo; Konhauser, Kurt O.. |
| The oceans probably remained well-oxygenated for millions of years after the Palaeoproterozoic Lomagundi-Jatuli Event, according to high concentrations and isotope signatures of redox-sensitive metals in the 2-billion-year-old Zaonega Formation, Russia. The approximately 2,220-2,060 million years old Lomagundi-Jatuli Event was the longest positive carbon isotope excursion in Earth history and is traditionally interpreted to reflect an increased organic carbon burial and a transient rise in atmospheric O-2. However, it is widely held that O-2 levels collapsed for more than a billion years after this. Here we show that black shales postdating the Lomagundi-Jatuli Event from the approximately 2,000 million years old Zaonega Formation contain the highest... |
| Tipo: Text |
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| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00663/77461/82873.pdf |
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| Mänd, Kaarel; Lalonde, Stefan; Paiste, Kärt; Thoby, Marie; Lumiste, Kaarel; Robbins, Leslie J.; Kreitsmann, Timmu; Romashkin, Alexander E.; Kirsimäe, Kalle; Lepland, Aivo; Konhauser, Kurt O.. |
| The Zaonega Formation in northwest Russia (~2.0 billion years old) is amongst the most complete successions that record the middle of the Palaeoproterozoic era. As such, geochemical data from the formation have played a central role in framing the debate over redox dynamics in the aftermath of the Great Oxidation Event (GOE). However, uncertainty over local redox conditions and the degree of hydrographic restriction in the formation has led to contradictory interpretations regarding global oxygen (O2) fugacity. Here, we provide new iron (Fe) isotope data together with major and trace element concentrations to constrain the local physiochemical conditions. The Zaonega Formation sediments show authigenic Fe accumulation (Fe/Al ≫ 1 wt.%/wt.%) and δ56Fe... |
| Tipo: Text |
Palavras-chave: Isotope geochemistry; Redox stratification; Benthic Fe shuttle; Dissimilatory iron reduction. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00688/79959/82885.pdf |
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