Paired organic matter and pyrite δ34S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2

Raven, Morgan Reed; Fike, David A.; Bradley, Alexander S.; Gomes, Maya L.; Owens, Jeremy D.; Webb, Samuel A.

doi:10.1016/j.epsl.2019.01.048

Title: Paired organic matter and pyrite δ³⁴S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2

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Abstract

The sulfur (S) isotope composition of pyrite in the sedimentary record has played an important part in our understanding of the evolution of biogeochemical cycles throughout Earth history. However, the kinetics of pyritization are complex and depend strongly on the reactivity and mineralogy of available iron. As a second major sink for sulfide in anoxic sediments, organic matter (OM) provides essential context for reconstructing the distribution and isotopic composition of environmental sulfide. To first order, roughly parallel pyrite and OM δ³⁴S profiles reflect changes in sulfide, while independent patterns require alternative explanations, including changes in iron availability or OM characteristics. We apply this framework to Ocean Anoxic Event 2 (OAE-2, ~94 Mya), a period of enhanced burial of reduced C and S (in OM and pyrite) that has been associated with an expansion of reducing marine conditions. We present paired S-isotope records for pyrite and OM along with profiles of OM S:C ratio and S redox speciation from four well-characterized lithologic sections with a range of depositional environments (Pont d'Issole, Cismon, Tarfaya Basin, and Demerara Rise) to reconstruct both local redox structure and global mechanisms impacting the C, S and Fe cycles around OAE-2.

Authors:

^[1]; Fike, David A. ^[2];

^[2]; Gomes, Maya L. ^[3];

^[4]; Webb, Samuel A. ^[5]

Univ. of California, Santa Barbara, CA (United States); Washington Univ., St. Louis, MO (United States)
Washington Univ., St. Louis, MO (United States)
Johns Hopkins Univ., Baltimore, MD (United States)
Florida State Univ., Tallahassee, FL (United States)
Stanford Univ., Menlo Park, CA (United States)

Publication Date:: Wed Feb 13 00:00:00 EST 2019

Research Org.:: SLAC National Accelerator Lab., Menlo Park, CA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 1529254

Alternate Identifier(s):: OSTI ID: 1635869

Grant/Contract Number:: 80NSSC18K1532; AC02-76SF00515

Resource Type:: Accepted Manuscript

Journal Name:: Earth and Planetary Science Letters

Additional Journal Information:: Journal Volume: 512; Journal Issue: C; Journal ID: ISSN 0012-821X

Publisher:: Elsevier

Country of Publication:: United States

Language:: English

Subject:: 54 ENVIRONMENTAL SCIENCES; sulfur isotopes; X-ray absorption spectroscopy; ocean anoxic events; marine carbon burial pyrite; organic matter sulfurization

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                    Raven, Morgan Reed, Fike, David A., Bradley, Alexander S., Gomes, Maya L., Owens, Jeremy D., and Webb, Samuel A. Paired organic matter and pyrite δ34S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2.  United States: N. p., 2019. 
Web.  doi:10.1016/j.epsl.2019.01.048.

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                    Raven, Morgan Reed, Fike, David A., Bradley, Alexander S., Gomes, Maya L., Owens, Jeremy D., & Webb, Samuel A. Paired organic matter and pyrite δ34S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2.  United States.  https://doi.org/10.1016/j.epsl.2019.01.048

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                    Raven, Morgan Reed, Fike, David A., Bradley, Alexander S., Gomes, Maya L., Owens, Jeremy D., and Webb, Samuel A. Wed .  
"Paired organic matter and pyrite δ34S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2".  United States.  https://doi.org/10.1016/j.epsl.2019.01.048.  https://www.osti.gov/servlets/purl/1529254.

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@article{osti_1529254,

  title        = {Paired organic matter and pyrite δ34S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2},

  author       = {Raven, Morgan Reed and Fike, David A. and Bradley, Alexander S. and Gomes, Maya L. and Owens, Jeremy D. and Webb, Samuel A.},

  abstractNote = {The sulfur (S) isotope composition of pyrite in the sedimentary record has played an important part in our understanding of the evolution of biogeochemical cycles throughout Earth history. However, the kinetics of pyritization are complex and depend strongly on the reactivity and mineralogy of available iron. As a second major sink for sulfide in anoxic sediments, organic matter (OM) provides essential context for reconstructing the distribution and isotopic composition of environmental sulfide. To first order, roughly parallel pyrite and OM δ34S profiles reflect changes in sulfide, while independent patterns require alternative explanations, including changes in iron availability or OM characteristics. We apply this framework to Ocean Anoxic Event 2 (OAE-2, ~94 Mya), a period of enhanced burial of reduced C and S (in OM and pyrite) that has been associated with an expansion of reducing marine conditions. We present paired S-isotope records for pyrite and OM along with profiles of OM S:C ratio and S redox speciation from four well-characterized lithologic sections with a range of depositional environments (Pont d'Issole, Cismon, Tarfaya Basin, and Demerara Rise) to reconstruct both local redox structure and global mechanisms impacting the C, S and Fe cycles around OAE-2.},

  doi          = {10.1016/j.epsl.2019.01.048},

  journal      = {Earth and Planetary Science Letters},

  number       = C,

  volume       = 512,

  place        = {United States},

  year         = {Wed Feb 13 00:00:00 EST 2019},

  month        = {Wed Feb 13 00:00:00 EST 2019}

}

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Title: Paired organic matter and pyrite δ34S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2

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Citation Formats

Title: Paired organic matter and pyrite δ³⁴S records reveal mechanisms of carbon, sulfur, and iron cycle disruption during Ocean Anoxic Event 2