Academic Journal
Post-depositional REE mobility in a Paleoarchean banded iron formation revealed by La-Ce geochronology: A cautionary tale for signals of ancient oxygenation
| العنوان: | Post-depositional REE mobility in a Paleoarchean banded iron formation revealed by La-Ce geochronology: A cautionary tale for signals of ancient oxygenation |
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| المؤلفون: | Bonnand, Pierre, Lalonde, S.V., Boyet, Maud, Heubeck, C., Homann, Martin, Nonnotte, P., Foster, Ian, Konhauser, K.O., Köhler, I. |
| المساهمون: | Laboratoire Magmas et Volcans (LMV), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Observatoire de Physique du Globe de Clermont-Ferrand (OPGC), Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Clermont Auvergne 2017-2020 (UCA 2017-2020 )-Centre National de la Recherche Scientifique (CNRS), Laboratoire Géosciences Océan (LGO), Université de Bretagne Sud (UBS)-Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)-Université de Brest (UBO)-Centre National de la Recherche Scientifique (CNRS), Friedrich-Schiller-Universität = Friedrich Schiller University Jena Jena, Germany, University College of London London (UCL), University of Alberta, GeoZentrum Nordbayern, Friedrich-Alexander Universität Erlangen-Nürnberg = University of Erlangen-Nuremberg (FAU), Deutsche Forschungsgemeinschaft (DFG)German Research Foundation (DFG) KO5111/1-1, DFGGerman Research Foundation (DFG) He2418/13-1, LabexMER ANR-10-LABX-19, EU Prestige COFUND-GA2013-609102, European Union's Horizon 2020 research and innovation programme 716515, 682778, NSERCNatural Sciences and Engineering Research Council of Canada RGPIN-165831, ANR-10-LABX-0019,LabexMER,LabexMER Marine Excellence Research: a changing ocean(2010), ANR-17-EURE-0015,ISBlue,Interdisciplinary Graduate School for the Blue planet(2017) |
| المصدر: | ISSN: 0012-821X ; Earth and Planetary Science Letters ; https://uca.hal.science/hal-03101213 ; Earth and Planetary Science Letters, 2020, 547, pp.116452. ⟨10.1016/j.epsl.2020.116452⟩. |
| بيانات النشر: | HAL CCSD Elsevier |
| سنة النشر: | 2020 |
| مصطلحات موضوعية: | trace element signatures, Ce anomalies, La-Ce geochronology, rare earth element mobility, [SDU]Sciences of the Universe [physics], [SDV.MP]Life Sciences [q-bio]/Microbiology and Parasitology |
| الوصف: | International audience ; Precambrian banded iron formations (BIF) are chemical sedimentary deposits whose trace element signatures have been widely used to interrogate the chemical composition and redox state of ancient seawater. Here we investigated trace element signatures in BIF of the 3.22 Ga Moodies Group, Barberton Greenstone Belt (South Africa), which are interbedded with near-shore siliciclastic sedimentary rocks and represent one of the oldest known shallow-water occurrences of BIF. Unusual rare earth element (REE) signatures, notably with pronounced negative Ce anomalies in shale-normalized spectra, have been previously reported for chemical sediments of the Moodies Group, which we confirm here through an expanded dataset for Moodies BIF spanning three different localities. We find negative Ce anomalies as low as 0.2 Ce/Ce* that are associated with unusual enrichment of LREE relative to HREE in the sample set. While total REE abundances and certain REE features appear strongly related to the concentration of detrital indicators (e.g., Zr), and are likely primary, other features, notably LREE enrichment, cannot be explained as a primary feature of the sediment. This is better explained by later addition of REE from a LREE-enriched but Ce-depleted fluid that generated the significant negative Ce anomalies observed in surface samples of Moodies Group BIF. This REE addition event influenced both Sm-Nd and La-Ce isotope systematics, the latter yielding an isochron of 60 +/- 32 Ma, thus constraining the timing of emplacement of the negative Ce anomalies to the past 100 Ma, possibly upon surface exposure of the Barberton Greenstone Belt to wetter conditions during the Cenozoic. Our findings constitute a cautionary tale in that even the most immobile elemental redox proxies may be more sensitive to post-depositional modification than previously thought, and demonstrate the clear advantage offered by paleoredox proxies coupled to radiometric geochronometers to enable the direct dating of ancient signals of ... |
| نوع الوثيقة: | article in journal/newspaper |
| اللغة: | English |
| DOI: | 10.1016/j.epsl.2020.116452 |
| الاتاحة: | https://uca.hal.science/hal-03101213 https://uca.hal.science/hal-03101213v1/document https://uca.hal.science/hal-03101213v1/file/Bonnand%20et%20al%20_%20BIF-2020_revised_HAL.pdf https://doi.org/10.1016/j.epsl.2020.116452 |
| Rights: | http://creativecommons.org/licenses/by-nc-nd/ ; info:eu-repo/semantics/OpenAccess |
| رقم الانضمام: | edsbas.C79B1440 |
| قاعدة البيانات: | BASE |
| DOI: | 10.1016/j.epsl.2020.116452 |
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