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dc.contributor.authorBakakas, Karen
dc.contributor.authorMoussavou, Mathieu
dc.contributor.authorPrave, Anthony R.
dc.contributor.authorLepland, Aivo
dc.contributor.authorMbina, Michel
dc.contributor.authorKirsimäe, Kalle
dc.date.accessioned2021-07-20T23:35:38Z
dc.date.available2021-07-20T23:35:38Z
dc.date.issued2020-07-21
dc.identifier.citationBakakas , K , Moussavou , M , Prave , A R , Lepland , A , Mbina , M & Kirsimäe , K 2020 , ' The Palaeoproterozoic Francevillian succession of Gabon and the Lomagundi-Jatuli event ' , Geology , vol. Early View . https://doi.org/10.1130/G47651.1en
dc.identifier.issn0091-7613
dc.identifier.otherPURE: 268762412
dc.identifier.otherPURE UUID: da6ca5d9-58b3-4fe8-bbcb-5f20e678c16b
dc.identifier.otherORCID: /0000-0002-4614-3774/work/78204836
dc.identifier.otherWOS: 000583944400014
dc.identifier.urihttp://hdl.handle.net/10023/23610
dc.descriptionThe study was supported from Estonian Research Agency grant PRG447 to KK, AL and KB.en
dc.description.abstractThe Paleoproterozoic Francevillian succession of Gabon has figured prominently in concepts about Earth’s early oxygenation and genesis of a large positive excursion in carbon-isotope values, the Lomagundi-Jatuli event (LJE). Here we present a detailed study of a 139-m-long core of Francevillian rocks marked by carbonate δ13C (δ13Ccarb) values of 5‰–9‰ that decline upsection to near 0‰, a trend inferred by many workers as a fingerprint of the LJE and its termination. However, we show that the shift in δ13Ccarb values coincides with a facies change: shallow-marine facies are marked by the strongly positive values, whereas deeper-marine facies (below storm wave base) are at ~0‰. The most circumspect interpretation of such facies dependence of δ13Ccarb is that shallow-marine settings record the isotope effects of local physical and biochemical processes driving the ambient dissolved inorganic carbon (DIC) pool to heavier values, and the lighter values (~0‰) in deeper-water facies track the DIC of the open-marine realm where δ13C was largely unaffected by fractionations occurring in shallow-water settings. Further, a transgressing redoxcline created conditions for precipitation of Mn-bearing minerals and chemotrophic microbial biota, including methane cycling communities evident by organic δ13C (δ13Corg) values of –4‰ and Δδcarb-org values as high as 46‰. Thus, the Francevillian C-isotope profile reflects basin-specific conditions and is not a priori an indicator of global C-cycle disturbances nor of the termination of the LJE.
dc.format.extent6
dc.language.isoeng
dc.relation.ispartofGeologyen
dc.rightsCopyright © 2020 Geological Society of America. This work has been made available online in accordance with publisher policies or with permission. Permission for further reuse of this content should be sought from the publisher or the rights holder. This is the author created accepted manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at https://doi.org/10.1130/G47651.1en
dc.subjectQE Geologyen
dc.subjectI-PWen
dc.subject.lccQEen
dc.titleThe Palaeoproterozoic Francevillian succession of Gabon and the Lomagundi-Jatuli eventen
dc.typeJournal articleen
dc.description.versionPostprinten
dc.contributor.institutionUniversity of St Andrews.School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews.Marine Alliance for Science & Technology Scotlanden
dc.contributor.institutionUniversity of St Andrews.Scottish Oceans Instituteen
dc.contributor.institutionUniversity of St Andrews.St Andrews Sustainability Instituteen
dc.contributor.institutionUniversity of St Andrews.St Andrews Isotope Geochemistryen
dc.identifier.doihttps://doi.org/10.1130/G47651.1
dc.description.statusPeer revieweden
dc.date.embargoedUntil2021-07-21


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