ORIGINAL RESEARCH article
Front. Mar. Sci.
Sec. Marine Biogeochemistry
This article is part of the Research TopicDeep-sea Material and Energy Cycles: Insights from Sediments, Fe-Mn Nodules, and Authigenic Carbonates, and Their Carbon Sequestration, Hydrocarbon Accumulation, and Ore-forming SignificancesView all 9 articles
Integrated Geochemical and Biomarker signature of fast-growing Fe-Mn Nodules from the Gulf of Finland, Baltic Sea
Provisionally accepted
- 1Shirshov Institute of Oceanology of Russian Academy of Sciences, Moscow, Russia
- 2Vernadsky Institute of Geochemistry and Analytical Chemistry of Russian Academу of Sciences, Moscow, Russia
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Ferromanganese (Fe-Mn) nodules are widespread on the Baltic Sea seafloor. They rapidly grow and show diverse morphologies. Ferromanganese (Fe-Mn) nodules, characterized by rapid growth and diverse morphologies, are widespread on the Baltic Sea seafloor. This study provides a comprehensive analysis of the bulk elemental composition, internal structures, and organic matter (OM) characteristics based on n-alkane distributions in Fe-Mn nodules and their underlying sediments from the Gulf of Finland. The investigated nodules are of diagenetic origin and include both Fe-rich and Mn-rich types. The have spheroidal and discoidal morphologies with pronounced concentric layering. The results indicate that the nodules accumulate both terrestrial and bacterially derived OM which undergoes active diagenetic transformation. Regularized Canonical Correlation Analysis (rCCA) applied to this integrated dataset revealed a strong multivariate relationship between organic matter and elemental composition. The analysis of Internal microstructures revealed microglobular, twisted fibrous, and colloform textures, alongside biomorphic features. These textures reflect coupled abiotic and biological mineralization processes. The absence of correlation between nodule morphology, geochemical type, and underlying sediment properties demonstrates that highly localized microenvironments control nodule formation. This study refines the genetic model of shallow-water fast-growing Fe-Mn nodules, highlighting the crucial role of organic matter-driven diagenesis under dynamic redox conditions in ore formation.
Keywords: diagenesis1, Geochemistry2, n-alkanes3, rCCA4, Redox conditions
Received: 03 Oct 2025; Accepted: 29 Oct 2025.
Copyright: © 2025 Shulga, Perfilov and Ryazantsev. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Natalia Shulga, nash.ocean@gmail.com
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