Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formation

Jiarui Liu; André Pellerin; Jiasheng Wang; David Rickard; Gilad Antler; Jie Zhao; Zhou Wang; Bo Barker Jørgensen; Shuhei Ono

doi:10.1016/j.gca.2021.09.026

Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formation

Jiarui Liu, André Pellerin, Jiasheng Wang^*, David Rickard, Gilad Antler, Jie Zhao, Zhou Wang, Bo Barker Jørgensen, Shuhei Ono

^*Corresponding author for this work

Department of Biology - Microbiology

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

39 Citations (Scopus)

11 Downloads (Pure)

Abstract

The marine sulfate inventory represents the largest standing pool of electron acceptors, which, via microbial sulfate reduction, is responsible for roughly half of the organic matter mineralization globally in marine sediments. In addition to the oxidation of buried organic matter, sulfate reduction can be coupled to the oxidation of methane migrating upward. Multiple sulfur isotope ratios were measured for porewater sulfate, sulfide, elemental sulfur and pyrite from core samples collected from continental shelf (19–96 m water depth) in the Baltic Sea and slope (1098 m water depth) in the Andaman Sea, in order to test if their isotope systematics can be used to trace the two different sulfate reduction processes. For shallow shelf sediments (<43 cm below seafloor), both δ³⁴S and Δ³³S values of porewater sulfate increased with increasing depth as a result of organoclastic sulfate reduction (OSR). However, the Δ³³S values of both porewater sulfate and sulfide decreased as the δ³⁴S values increased downcore at 43–73 cm depth where sulfate reduction was coupled to anaerobic oxidation of methane (AOM). Pyrite in shelf sediments yielded positive Δ³³S values, reflecting Δ³³S of porewater sulfide produced by OSR. In contrast, pyrite in slope sediments yielded negative Δ³³S values as low as −0.15‰, as a result of mixing of sulfides derived from OSR and AOM. This is consistent with the slowly migrating sulfate–methane transition (SMT) in slope sediments inferred from sulfur and iron speciation, carbon isotope ratios of carbonates, and magnetic susceptibility data. A stable SMT, focusing AOM at roughly the same depth over the past few millennia, further provides favorable conditions for prolonged pyrite formation with the development of cubic crystals, while the sulfur isotope difference between bulk pyrite and macroscopic pyrite reflects the significance of OSR throughout the sediment column. We conclude that minor sulfur isotopes provide a unique proxy that can be applied to differentiate OSR and AOM and the origin of pyrite in diverse sediments and sedimentary rocks. This contribution highlights strong local diagenetic controls on pyrite formation and its multiple sulfur isotopic composition in various marine settings.

Original language	English
Journal	Geochimica et Cosmochimica Acta
Volume	316
Pages (from-to)	309-330
Number of pages	22
ISSN	0016-7037
DOIs	https://doi.org/10.1016/j.gca.2021.09.026
Publication status	Published - Jan 2022

Keywords

Anaerobic oxidation of methane
Morphology of euhedral pyrite crystals
Ocean margin sediments
Organoclastic sulfate reduction
Quadruple sulfur isotopes
Sulfate–methane transition

Access to Document

10.1016/j.gca.2021.09.026

Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formationAccepted manuscript, 2.35 MB

Cite this

@article{950249ec76dd4222b242d1d634636f19,

title = "Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formation",

abstract = "The marine sulfate inventory represents the largest standing pool of electron acceptors, which, via microbial sulfate reduction, is responsible for roughly half of the organic matter mineralization globally in marine sediments. In addition to the oxidation of buried organic matter, sulfate reduction can be coupled to the oxidation of methane migrating upward. Multiple sulfur isotope ratios were measured for porewater sulfate, sulfide, elemental sulfur and pyrite from core samples collected from continental shelf (19–96 m water depth) in the Baltic Sea and slope (1098 m water depth) in the Andaman Sea, in order to test if their isotope systematics can be used to trace the two different sulfate reduction processes. For shallow shelf sediments (<43 cm below seafloor), both δ34S and Δ33S values of porewater sulfate increased with increasing depth as a result of organoclastic sulfate reduction (OSR). However, the Δ33S values of both porewater sulfate and sulfide decreased as the δ34S values increased downcore at 43–73 cm depth where sulfate reduction was coupled to anaerobic oxidation of methane (AOM). Pyrite in shelf sediments yielded positive Δ33S values, reflecting Δ33S of porewater sulfide produced by OSR. In contrast, pyrite in slope sediments yielded negative Δ33S values as low as −0.15‰, as a result of mixing of sulfides derived from OSR and AOM. This is consistent with the slowly migrating sulfate–methane transition (SMT) in slope sediments inferred from sulfur and iron speciation, carbon isotope ratios of carbonates, and magnetic susceptibility data. A stable SMT, focusing AOM at roughly the same depth over the past few millennia, further provides favorable conditions for prolonged pyrite formation with the development of cubic crystals, while the sulfur isotope difference between bulk pyrite and macroscopic pyrite reflects the significance of OSR throughout the sediment column. We conclude that minor sulfur isotopes provide a unique proxy that can be applied to differentiate OSR and AOM and the origin of pyrite in diverse sediments and sedimentary rocks. This contribution highlights strong local diagenetic controls on pyrite formation and its multiple sulfur isotopic composition in various marine settings.",

keywords = "Anaerobic oxidation of methane, Morphology of euhedral pyrite crystals, Ocean margin sediments, Organoclastic sulfate reduction, Quadruple sulfur isotopes, Sulfate–methane transition",

author = "Jiarui Liu and Andr{\'e} Pellerin and Jiasheng Wang and David Rickard and Gilad Antler and Jie Zhao and Zhou Wang and J{\o}rgensen, {Bo Barker} and Shuhei Ono",

note = "Publisher Copyright: {\textcopyright} 2021 Elsevier Ltd",

year = "2022",

month = jan,

doi = "10.1016/j.gca.2021.09.026",

language = "English",

volume = "316",

pages = "309--330",

journal = "Geochimica et Cosmochimica Acta",

issn = "0016-7037",

publisher = "Pergamon Press",

}

Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formation. / Liu, Jiarui; Pellerin, André; Wang, Jiasheng et al.
In: Geochimica et Cosmochimica Acta, Vol. 316, 01.2022, p. 309-330.

Research output: Contribution to journal/Conference contribution in journal/Contribution to newspaper › Journal article › Research › peer-review

TY - JOUR

T1 - Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formation

AU - Liu, Jiarui

AU - Pellerin, André

AU - Wang, Jiasheng

AU - Rickard, David

AU - Antler, Gilad

AU - Zhao, Jie

AU - Wang, Zhou

AU - Jørgensen, Bo Barker

AU - Ono, Shuhei

PY - 2022/1

Y1 - 2022/1

N2 - The marine sulfate inventory represents the largest standing pool of electron acceptors, which, via microbial sulfate reduction, is responsible for roughly half of the organic matter mineralization globally in marine sediments. In addition to the oxidation of buried organic matter, sulfate reduction can be coupled to the oxidation of methane migrating upward. Multiple sulfur isotope ratios were measured for porewater sulfate, sulfide, elemental sulfur and pyrite from core samples collected from continental shelf (19–96 m water depth) in the Baltic Sea and slope (1098 m water depth) in the Andaman Sea, in order to test if their isotope systematics can be used to trace the two different sulfate reduction processes. For shallow shelf sediments (<43 cm below seafloor), both δ34S and Δ33S values of porewater sulfate increased with increasing depth as a result of organoclastic sulfate reduction (OSR). However, the Δ33S values of both porewater sulfate and sulfide decreased as the δ34S values increased downcore at 43–73 cm depth where sulfate reduction was coupled to anaerobic oxidation of methane (AOM). Pyrite in shelf sediments yielded positive Δ33S values, reflecting Δ33S of porewater sulfide produced by OSR. In contrast, pyrite in slope sediments yielded negative Δ33S values as low as −0.15‰, as a result of mixing of sulfides derived from OSR and AOM. This is consistent with the slowly migrating sulfate–methane transition (SMT) in slope sediments inferred from sulfur and iron speciation, carbon isotope ratios of carbonates, and magnetic susceptibility data. A stable SMT, focusing AOM at roughly the same depth over the past few millennia, further provides favorable conditions for prolonged pyrite formation with the development of cubic crystals, while the sulfur isotope difference between bulk pyrite and macroscopic pyrite reflects the significance of OSR throughout the sediment column. We conclude that minor sulfur isotopes provide a unique proxy that can be applied to differentiate OSR and AOM and the origin of pyrite in diverse sediments and sedimentary rocks. This contribution highlights strong local diagenetic controls on pyrite formation and its multiple sulfur isotopic composition in various marine settings.

AB - The marine sulfate inventory represents the largest standing pool of electron acceptors, which, via microbial sulfate reduction, is responsible for roughly half of the organic matter mineralization globally in marine sediments. In addition to the oxidation of buried organic matter, sulfate reduction can be coupled to the oxidation of methane migrating upward. Multiple sulfur isotope ratios were measured for porewater sulfate, sulfide, elemental sulfur and pyrite from core samples collected from continental shelf (19–96 m water depth) in the Baltic Sea and slope (1098 m water depth) in the Andaman Sea, in order to test if their isotope systematics can be used to trace the two different sulfate reduction processes. For shallow shelf sediments (<43 cm below seafloor), both δ34S and Δ33S values of porewater sulfate increased with increasing depth as a result of organoclastic sulfate reduction (OSR). However, the Δ33S values of both porewater sulfate and sulfide decreased as the δ34S values increased downcore at 43–73 cm depth where sulfate reduction was coupled to anaerobic oxidation of methane (AOM). Pyrite in shelf sediments yielded positive Δ33S values, reflecting Δ33S of porewater sulfide produced by OSR. In contrast, pyrite in slope sediments yielded negative Δ33S values as low as −0.15‰, as a result of mixing of sulfides derived from OSR and AOM. This is consistent with the slowly migrating sulfate–methane transition (SMT) in slope sediments inferred from sulfur and iron speciation, carbon isotope ratios of carbonates, and magnetic susceptibility data. A stable SMT, focusing AOM at roughly the same depth over the past few millennia, further provides favorable conditions for prolonged pyrite formation with the development of cubic crystals, while the sulfur isotope difference between bulk pyrite and macroscopic pyrite reflects the significance of OSR throughout the sediment column. We conclude that minor sulfur isotopes provide a unique proxy that can be applied to differentiate OSR and AOM and the origin of pyrite in diverse sediments and sedimentary rocks. This contribution highlights strong local diagenetic controls on pyrite formation and its multiple sulfur isotopic composition in various marine settings.

KW - Anaerobic oxidation of methane

KW - Morphology of euhedral pyrite crystals

KW - Ocean margin sediments

KW - Organoclastic sulfate reduction

KW - Quadruple sulfur isotopes

KW - Sulfate–methane transition

UR - http://www.scopus.com/inward/record.url?scp=85118323219&partnerID=8YFLogxK

U2 - 10.1016/j.gca.2021.09.026

DO - 10.1016/j.gca.2021.09.026

M3 - Journal article

AN - SCOPUS:85118323219

SN - 0016-7037

VL - 316

SP - 309

EP - 330

JO - Geochimica et Cosmochimica Acta

JF - Geochimica et Cosmochimica Acta

ER -

Multiple sulfur isotopes discriminate organoclastic and methane-based sulfate reduction by sub-seafloor pyrite formation

Abstract

Keywords

Access to Document

Other files and links

Fingerprint

Cite this