Iron Isotopes Reveal Fe Export Driven by Change of Tropical Weathering Regime
Abstract Unraveling paleoenvironmental signals recorded in laterites is crucial for quantifying weathering‐driven elemental fluxes at the Earth's surface. New stable iron isotope data (δ 56 Fe), combined with (U‐Th)/He ages in Fe‐oxides from a ferruginous duricrust from French Guiana, reveal the response of Fe hosted in laterite to past changes in weathering intensity. The δ 56 Fe values increase with decreasing age, with a pronounced shift at around 6 Ma reflecting a change from a ferruginous laterization to a bauxitization regime. This shift indicates a transition from a weathering regime characterized by Fe redistribution within the laterite to one featuring significant Fe loss and redox processes. Isotope mass‐balance modeling reveals that intensified weathering during the bauxitization phase led to the loss of 35%–70% of Fe from the duricrust. Our work highlights the importance of lateritic profiles as environmental archives.
Authors
- Adrien Duvivier
- Abel Guihou (ORCID: https://orcid.org/0000-0001-7347-378X)
- Cécile Quantin (ORCID: https://orcid.org/0000-0002-4786-7205)
- Cécile Gautheron (ORCID: https://orcid.org/0000-0001-7068-9868)
- Thierry Allard (ORCID: https://orcid.org/0000-0002-9422-7980)
- Damien Guinoiseau (ORCID: https://orcid.org/0000-0002-8966-0878)
- Pierre Deschamps (ORCID: https://orcid.org/0000-0003-1687-3765)
- Julien Bouchez (ORCID: https://orcid.org/0000-0003-4832-1615)
- Sophie Cornu (ORCID: https://orcid.org/0000-0002-2433-5898)
- Silvana Bressan Riffel (ORCID: https://orcid.org/0000-0002-2606-5270)
- Beatrix Heller (ORCID: https://orcid.org/0000-0002-9388-3978)
- Zuzana Fekiacova-Castanet
Institutions
- Centre National de la Recherche Scientifique (FR)
- Universidade Federal do Rio Grande do Sul (BR)
- Institut de physique du globe de Paris (FR)
- Université Paris Cité (FR)
- Aix-Marseille Université (FR)
- Université Paris-Saclay (FR)
- Sorbonne Université (FR)
- Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (FR)
- Centre de Recherche et d’Enseignement de Géosciences de l’Environnement (FR)
- Institut des Sciences de la Terre (FR)
- Geosciences Paris-Saclay (FR)
- Université Gustave Eiffel (FR)
- Institut de Recherche pour le Développement (FR)
- Structure et Instabilité des Génomes (FR)
- Université Savoie Mont Blanc (FR)
- Université Grenoble Alpes (FR)
Publication Details
- Journal
- Geophysical Research Letters
- Published
- 2026-08-14
- DOI
- https://doi.org/10.1029/2026gl122534
- Primary Topic
- Geochemistry and Elemental Analysis
- Type
- article
- Field-Weighted Citation Impact
- 0.00
Funders
- Agence Nationale de la Recherche