94554 20210902121750.0 doi 10.1016/j.epsl.2020.116400 sideral 118617 ART-2020-118617 eng Blattmann, Thomas M. Ferromagnetic resonance of magnetite biominerals traces redox changes 2020 Access copy available to the general public Unrestricted Redox variations govern a multitude of key geochemical and microbiological processes within lacustrine and marine systems, yet the interpretation of these geological archives can be limited because redox-sensitive microorganisms leave behind sparse fossil evidence. Here, we assess a biologically controlled magnetic proxy through investigation of a well-constrained sedimentary record covering a perturbation of redox-conditions driven by a complete trophic cycle in Lake Constance. Ferromagnetic resonance spectroscopy of sediments reveals strong uniaxial anisotropy, indicative of single-domain magnetite particles in intact or fragmentary chain arrangements, which are an unambiguous trait of magnetotactic bacteria (MTB) and their magnetofossil remains. We show that biogenic magnetite formed intra-cellularly in MTB faithfully records changing redox-conditions at or close to the sediment water-interface. Biogenic magnetite within sedimentary records points to the proliferation of MTB parallel to a decline in water column dissolved oxygen and the formation of sulfidic surface sediments in Lake Constance associated with an episode of eutrophication (1955–1991). We conclude that magnetofossils may serve as a sensitive geological proxy to reconstruct dynamic redox-changes along the sediment-water interface and bottom waters. info:eu-repo/grantAgreement/ES/DGA/E35-17R info:eu-repo/grantAgreement/ES/MINECO/CTQ2015-64486-R info:eu-repo/semantics/openAccess by-nc-nd http://creativecommons.org/licenses/by-nc-nd/3.0/es/ 5.255 2020 GEOCHEMISTRY & GEOPHYSICS 7 / 87 = 0.08 2020 Q1 T1 2.829 2020 Earth and Planetary Sciences (miscellaneous) 2020 Q1 Space and Planetary Science 2020 Q1 Geophysics 2020 Q1 Geochemistry and Petrology 2020 Q1 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Lesniak, Barbara García-Rubio, Inés Universidad de Zaragoza (orcid)0000-0002-1827-1250 Charilaou, Michalis Wessels, Martin Eglinton, Timothy I. Gehring, Andreas U. 2003 395 Universidad de Zaragoza Dpto. Física Materia Condensa. Área Física Materia Condensada 545 (2020), 116400 1-7 Earth planet. sci. lett. Earth and Planetary Science Letters 0012-821X 1359951 http://zaguan.unizar.es/record/94554/files/texto_completo.pdf Versión publicada 49297 http://zaguan.unizar.es/record/94554/files/texto_completo.jpg?subformat=icon icon Versión publicada oai:zaguan.unizar.es:94554 articulos driver 2021-09-02-09:48:13 ARTICLE