Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation
Abstract Low-oxygen settings and transition zones between strictly anoxic and oxic conditions may have characterised large expanses of Precambrian continental margins, where oxygen-breathing, complex life emerged and diversified. Accurate reconstructions of oxygen levels in such conditions are there...
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| Format: | Article |
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Nature Portfolio
2025-02-01
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| Series: | Communications Earth & Environment |
| Online Access: | https://doi.org/10.1038/s43247-025-02088-5 |
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| author | Romain Guilbaud Morten B. Andersen Helen M. Freeman Jeffrey Paulo H. Perez David Uhlig Liane G. Benning |
| author_facet | Romain Guilbaud Morten B. Andersen Helen M. Freeman Jeffrey Paulo H. Perez David Uhlig Liane G. Benning |
| author_sort | Romain Guilbaud |
| collection | DOAJ |
| description | Abstract Low-oxygen settings and transition zones between strictly anoxic and oxic conditions may have characterised large expanses of Precambrian continental margins, where oxygen-breathing, complex life emerged and diversified. Accurate reconstructions of oxygen levels in such conditions are therefore required, but current geochemical proxies fail in identifying transitional redox conditions. Uranium isotopes are an emerging palaeoredox proxy, as large isotope fractionations are recorded during the reduction of uranium into anoxic sediments. Their potential application to transitional conditions is, however, unclear, because the redox regulating mineralogy of such environments and the associated isotope fractionations are poorly constrained. Here, we explore the mineralogical transformations occurring during the partial oxidation of mackinawite. We show that green rust, a key mineral of Precambrian oceans, forms as a by-product of mackinawite oxidation, along with uraninite and polysulphide. We also demonstrate that this mechanism records a large abiotic uranium isotope fractionation during its reaction with aqueous iron sulphide. |
| format | Article |
| id | doaj-art-8f54284ff01a4c4aad470920a3c3dadb |
| institution | Kabale University |
| issn | 2662-4435 |
| language | English |
| publishDate | 2025-02-01 |
| publisher | Nature Portfolio |
| record_format | Article |
| series | Communications Earth & Environment |
| spelling | doaj-art-8f54284ff01a4c4aad470920a3c3dadb2025-02-09T12:55:56ZengNature PortfolioCommunications Earth & Environment2662-44352025-02-01611910.1038/s43247-025-02088-5Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionationRomain Guilbaud0Morten B. Andersen1Helen M. Freeman2Jeffrey Paulo H. Perez3David Uhlig4Liane G. Benning5Centre National de la Recherche Scientifique (CNRS), Géosciences Environnement Toulouse (UMR 5563)School of Earth and Environmental Sciences, Cardiff UniversityPriestley Centre for Climate Futures, University of LeedsGFZ Helmholtz Centre for Geosciences, TelegrafenbergInstitut für Geologische Wissenschaften, Freie Universität BerlinGFZ Helmholtz Centre for Geosciences, TelegrafenbergAbstract Low-oxygen settings and transition zones between strictly anoxic and oxic conditions may have characterised large expanses of Precambrian continental margins, where oxygen-breathing, complex life emerged and diversified. Accurate reconstructions of oxygen levels in such conditions are therefore required, but current geochemical proxies fail in identifying transitional redox conditions. Uranium isotopes are an emerging palaeoredox proxy, as large isotope fractionations are recorded during the reduction of uranium into anoxic sediments. Their potential application to transitional conditions is, however, unclear, because the redox regulating mineralogy of such environments and the associated isotope fractionations are poorly constrained. Here, we explore the mineralogical transformations occurring during the partial oxidation of mackinawite. We show that green rust, a key mineral of Precambrian oceans, forms as a by-product of mackinawite oxidation, along with uraninite and polysulphide. We also demonstrate that this mechanism records a large abiotic uranium isotope fractionation during its reaction with aqueous iron sulphide.https://doi.org/10.1038/s43247-025-02088-5 |
| spellingShingle | Romain Guilbaud Morten B. Andersen Helen M. Freeman Jeffrey Paulo H. Perez David Uhlig Liane G. Benning Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation Communications Earth & Environment |
| title | Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation |
| title_full | Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation |
| title_fullStr | Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation |
| title_full_unstemmed | Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation |
| title_short | Mackinawite partial oxidation to green rust produces a large, abiotic uranium isotope fractionation |
| title_sort | mackinawite partial oxidation to green rust produces a large abiotic uranium isotope fractionation |
| url | https://doi.org/10.1038/s43247-025-02088-5 |
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