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Isotopically “heavy” pyrite in marine sediments due to high sedimentation rates and non-steady-state deposition

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  • Jiarui Liu, University of California at Los Angeles
  • ,
  • Gilad Antler, Ben-Gurion University of the Negev, The Interuniversity Institute for Marine Science Eilat
  • ,
  • André Pellerin, Ben-Gurion University of the Negev
  • ,
  • Gareth Izon, Massachusetts Institute of Technology
  • ,
  • Ingrid Dohrmann, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research
  • ,
  • Alyssa J. Findlay
  • ,
  • Hans Røy
  • Shuhei Ono, Massachusetts Institute of Technology
  • ,
  • Alexandra V. Turchyn, University of Cambridge
  • ,
  • Sabine Kasten, Alfred Wegener Institute - Helmholtz Centre for Polar and Marine Research, University of Bremen
  • ,
  • Bo Barker Jørgensen

Sedimentary pyrite formation links the global biogeochemical cycles of carbon, sulfur, and iron, which, in turn, modulate the redox state of the planet’s surficial environment over geological time scales. Accordingly, the sulfur isotopic composition (δ34S) of pyrite has been widely employed as a geochemical tool to probe the evolution of ocean chemistry. Characteristics of the depositional environment and post-depositional processes, however, can modify the δ34S signal that is captured in sedimentary pyrite and ultimately preserved in the geological record. Exploring sulfur and iron diagenesis within the Bornholm Basin, Baltic Sea, we find that higher sedimentation rates limit the near-surface sulfidization of reactive iron, facilitating its burial and hence the subsurface availability of reactive iron for continued and progressively more 34S-enriched sediment-hosted pyrite formation (δ34S ≈ −5‰). Using a diagenetic model, we show that the amount of pyrite formed at the sediment-water interface has increased over the past few centuries in response to expansion of water-column hypoxia, which also impacts the sulfur isotopic signature of pyrite at depth. This contribution highlights the critical role of reactive iron in pyrite formation and questions to what degree pyrite δ34S values truly reflect past global ocean chemistry and biogeochemical processes. This work strengthens our ability to extract local paleoenvironmental information from pyrite δ34S signatures.

OriginalsprogEngelsk
TidsskriftGeology
Vol/bind49
Nummer7
Sider (fra-til)816-821
ISSN0091-7613
DOI
StatusUdgivet - jul. 2021

Bibliografisk note

Funding Information:
We acknowledge the skipper and crew of R/V Aurora, and colleagues at the Center for Geomicrobiology (Aarhus, Denmark) for assistance during sampling. We recognize contributions and technical assistance from Susann Henkel, Ingrid Stimac, Karina Bom-holt Oest, Jeanette Pedersen, and Felix Beulig. This work was supported by the Danish National Research Foundation (DNRF grant 104), the Danish Council for Independent Research (DFF-7014-00196), the European Research Council (ERC Advanced Grant 294200), the Helmholtz Association (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Bremerhaven), and the Alfred P. Sloan Foundation via the Deep Carbon Observatory. Antler acknowledges financial support from the Israel Science Foundation (2361/19). Pellerin is supported by the Zuckerman STEM Leadership Program. Izon recognizes a MISTI award (“Decrypting Early Earth’s Oxygenation”) in addition to continued support from R. Summons under the auspices of the Simons Collaboration on the Origin of Life. Findlay acknowledges a Marie-Curie European Fellowship (SedSulphOx, MSCA 746872). Turchyn acknowledges financial support from the National Environmental Research Council (NERC–NE/T006838/1). Liu gratefully recognizes continued support and discussions from Tina Treude and Jiasheng Wang. We thank Peter McGold-rick and two anonymous reviewers for their helpful and constructive reviews of this paper.

Funding Information:
We acknowledge the skipper and crew of R/V Aurora, and colleagues at the Center for Geomicrobiology (Aarhus, Denmark) for assistance during sampling. We recognize contributions and technical assistance from Susann Henkel, Ingrid Stimac, Karina Bomholt Oest, Jeanette Pedersen, and Felix Beulig. This work was supported by the Danish National Research Foundation (DNRF grant 104), the Danish Council for Independent Research (DFF-7014-00196), the European Research Council (ERC Advanced Grant 294200), the Helmholtz Association (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research in Bremerhaven), and the Alfred P. Sloan Foundation via the Deep Carbon Observatory. Antler acknowledges financial support from the Israel Science Foundation (2361/19). Pellerin is supported by the Zuckerman STEM Leadership Program. Izon recognizes a MISTI award (?Decrypting Early Earth?s Oxygenation?) in addition to continued support from R. Summons under the auspices of the Simons Collaboration on the Origin of Life. Findlay acknowledges a Marie-Curie European Fellowship (SedSulphOx, MSCA 746872). Turchyn acknowledges financial support from the National Environmental Research Council (NERC?NE/T006838/1). Liu gratefully recognizes continued support and discussions from Tina Treude and Jiasheng Wang. We thank Peter McGoldrick and two anonymous reviewers for their helpful and constructive reviews of this paper.

Publisher Copyright:
© 2021 Geological Society of America. For permission to copy, contact editing@geosociety.org.

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