Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis

Abstract Sedimentary pyrite iron and sulphur isotope compositions (δ56FePYR, δ34SPYR, Δ33SPYR) are commonly used to reconstruct global ocean properties and the evolving oxidation state of Earth’s surface, motivating exploration of impacts of diagenesis on pyrite-based proxies. Along with auxiliary p...

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Main Authors: Virgil Pasquier, Johanna Marin-Carbonne, Thomas Giunta, Livio Ruffine, Itay Halevy
Format: Article
Language:English
Published: Nature Portfolio 2025-03-01
Series:Communications Earth & Environment
Online Access:https://doi.org/10.1038/s43247-025-02213-4
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author Virgil Pasquier
Johanna Marin-Carbonne
Thomas Giunta
Livio Ruffine
Itay Halevy
author_facet Virgil Pasquier
Johanna Marin-Carbonne
Thomas Giunta
Livio Ruffine
Itay Halevy
author_sort Virgil Pasquier
collection DOAJ
description Abstract Sedimentary pyrite iron and sulphur isotope compositions (δ56FePYR, δ34SPYR, Δ33SPYR) are commonly used to reconstruct global ocean properties and the evolving oxidation state of Earth’s surface, motivating exploration of impacts of diagenesis on pyrite-based proxies. Along with auxiliary petrographic and porewater data, we present coupled microscale δ56FePYR-δ34SPYR-Δ33SPYR in accumulating sediments on the oxic margin of the Black Sea. The coevolution of microscale δ56FePYR-δ34SPYR-Δ33SPYR distributions provides insight into porewater S species production, consumption, and buildup on pyritization pathways. “Early” pyrite is characterized by low δ56FePYR and δ34SPYR values consistent with microbially-mediated iron and sulphate reduction and iron (oxyhydr)oxide sulphidization at low sulphide-to-iron ratios. In contrast, “sulphidic zone” pyrite displays distinct late-stage morphologies and higher δ56FePYR and δ34SPYR, which reflect sulphide accumulation at the sulphate-methane transition zone and direct sulphidization of residual iron phases. We propose that coupled δ56FePYR-δ34SPYR-Δ33SPYR distributions constrain pyritization pathways and microbial and physico-chemical aspects of the depositional environment.
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spelling doaj-art-fd2a7b532cfd4aca928092bb9084c0362025-08-20T03:04:53ZengNature PortfolioCommunications Earth & Environment2662-44352025-03-016111510.1038/s43247-025-02213-4Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesisVirgil Pasquier0Johanna Marin-Carbonne1Thomas Giunta2Livio Ruffine3Itay Halevy4Institute of Earth Sciences, University of LausanneInstitute of Earth Sciences, University of LausanneIfremer, University of Brest, CNRS, UMR 6538 Geo-OceanIfremer, University of Brest, CNRS, UMR 6538 Geo-OceanEarth and Planetary Sciences, Weizmann Institute of ScienceAbstract Sedimentary pyrite iron and sulphur isotope compositions (δ56FePYR, δ34SPYR, Δ33SPYR) are commonly used to reconstruct global ocean properties and the evolving oxidation state of Earth’s surface, motivating exploration of impacts of diagenesis on pyrite-based proxies. Along with auxiliary petrographic and porewater data, we present coupled microscale δ56FePYR-δ34SPYR-Δ33SPYR in accumulating sediments on the oxic margin of the Black Sea. The coevolution of microscale δ56FePYR-δ34SPYR-Δ33SPYR distributions provides insight into porewater S species production, consumption, and buildup on pyritization pathways. “Early” pyrite is characterized by low δ56FePYR and δ34SPYR values consistent with microbially-mediated iron and sulphate reduction and iron (oxyhydr)oxide sulphidization at low sulphide-to-iron ratios. In contrast, “sulphidic zone” pyrite displays distinct late-stage morphologies and higher δ56FePYR and δ34SPYR, which reflect sulphide accumulation at the sulphate-methane transition zone and direct sulphidization of residual iron phases. We propose that coupled δ56FePYR-δ34SPYR-Δ33SPYR distributions constrain pyritization pathways and microbial and physico-chemical aspects of the depositional environment.https://doi.org/10.1038/s43247-025-02213-4
spellingShingle Virgil Pasquier
Johanna Marin-Carbonne
Thomas Giunta
Livio Ruffine
Itay Halevy
Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
Communications Earth & Environment
title Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
title_full Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
title_fullStr Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
title_full_unstemmed Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
title_short Microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
title_sort microscale iron and sulphur isotopic compositions reveal pyritization pathways during early diagenesis
url https://doi.org/10.1038/s43247-025-02213-4
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AT thomasgiunta microscaleironandsulphurisotopiccompositionsrevealpyritizationpathwaysduringearlydiagenesis
AT livioruffine microscaleironandsulphurisotopiccompositionsrevealpyritizationpathwaysduringearlydiagenesis
AT itayhalevy microscaleironandsulphurisotopiccompositionsrevealpyritizationpathwaysduringearlydiagenesis