Integrated Approach to Investigate Magnetite Cycle in Marine Methanic Sediments
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Le résumé fourni par la source
Magnetite (Fe3O4), a ubiquitous sedimentary iron mineral, is crucial for paleomagnetic records preservation. However, reactive ferric iron minerals, including magnetite, can undergo reduction in aquatic sediments above and within the sulfidic zone and at the Sulfate-Methane Transition Zone (SMTZ), resulting in the production of dissolved ferrous iron. Partial reoxidation of the reduced iron at the oxic-anoxic interface can lead to authigenic magnetite precipitation. Yet, magnetite persistence and behavior in deeper methanic sediments have remained poorly understood. Here we explore magnetite dynamics in different sub- methanic zones (deeper, middle and upper) of Mediterranean continental shelf sediments, including the potential for its authigenic precipitation. Sequential extractions revealed increasing magnetite concentrations accompanied by low-temperature magnetization (Verwey transition). First-order reversal curve (FORC) analyses supported nanoscale authigenic magnetite presence. The results highlight a net increase in single-domain magnetite in the middle methanic zone with declines in the upper and deeper zones. Microbial analyses pointed to iron reduction throughout the methanic zone, alongside potential precipitation of magnetite and a decline in methanogenesis functional genes. Sediment incubations with spiked 57Fe-ferrihydrite showed gross precipitation of isotopically enriched 57Fe-magnetite in the upper methanic zone. Our combined findings distinguish between gross and net magnetite precipitation, suggesting authigenic magnetite formation within the methanic zone, with reshaping and smoothing of the original magnetic signal. They also emphasize the limitations of relying on a single-method approach to unravel such complex processes. We propose that the methanic zone plays a critical role in the early diagenesis of magnetic minerals, driven by dynamic cycles of magnetite dissolution and authigenic precipitation.
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Le contrôle bibliographique ouvert
DOI retrouvé dans Crossref DOI retrouvé ; titre concordant.
- Titre Crossref
- Integrated Approach to Investigate Magnetite Cycle in Marine Methanic Sediments
- Date Crossref
- 31/03/2025
- Éditeur
- openRxiv
- Type
- posted-content
Ce recoupement confirme des métadonnées liées au DOI. Il ne confirme ni la méthode ni les conclusions de l’étude, et il ne compte pas comme une seconde source scientifique indépendante.
Où se fait cette recherche
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Ben-Gurion University of the Negev Department of Earth and Environmental Sciences pays non établi dans la noticeUniversité ou école supérieure
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University of Lausanne Institute of Earth Surface Dynamics pays non établi dans la noticeUniversité ou école supérieure
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Hebrew University of Jerusalem The Institute of Earth Sciences pays non établi dans la noticeUniversité ou école supérieure
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Israel Oceanographic and Limnological Research pays non établi dans la noticeStructure de recherche
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Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung pays non établi dans la noticeStructure de recherche
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Geological Survey of Israel pays non établi dans la noticeOrganisme public
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Alfred-Wegener-Institute pays non établi dans la noticeStructure de recherche
Department of Earth and Environmental Sciences — Ben-Gurion University of the Negev, Institute of Earth Surface Dynamics — University of Lausanne et The Institute of Earth Sciences — Hebrew University of Jerusalem, avec 4 autres affiliations.
Une affiliation ne permet pas de déduire la nationalité d’un auteur.