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Alyssa Jean Lehsau Findlay

Sulfide oxidation affects the preservation of sulfur isotope signals

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DOI

  • Alyssa J. Findlay
  • Valeria Boyko, Ben Gurion Univ Negev, Ben Gurion University, Dept Geol & Environm Sci
  • ,
  • Andre Pellerin
  • Khoren Ayetisyan, Ben Gurion Univ Negev, Ben Gurion University, Dept Geol & Environm Sci
  • ,
  • Qingjun Guo, Chinese Acad Sci, Chinese Academy of Sciences, Institute of Geographic Sciences & Natural Resources Research, CAS, Inst Geog Sci & Nat Resources Res, State Key Lab Resources & Environm Informat Syst
  • ,
  • Xi Yang, Chinese Acad Sci, Chinese Academy of Sciences, Institute of Geographic Sciences & Natural Resources Research, CAS, Inst Geog Sci & Nat Resources Res, State Key Lab Resources & Environm Informat Syst
  • ,
  • Alexey Kamyshny, Ben Gurion Univ Negev, Ben Gurion University, Dept Geol & Environm Sci

The accumulation of oxygen in Earth's atmosphere and oceans in the late Archean had profound implications for the planet's biogeochemical evolution. Oxygen impacts sulfur cycling through the oxidation of sulfide minerals and the production of sulfate for microbial sulfate reduction (MSR). The isotopic signature of sulfur species preserved in the geologic record is affected by the prevailing biological and chemical processes and can therefore be used to constrain past oxygen and sulfate concentrations. Here, in a study of a late Archean analogue, we find that the sulfur isotopic signature in the water column of a seasonally stratified lake in southern China is influenced by MSR, whereas model results indicate that the isotopic signature of the underlying sediments can be best explained by concurrent sulfate reduction and sulfide oxidation. These data demonstrate that small apparent sulfur isotope fractionations (delta S-34(sulfate-AVS) = 4.2 parts per thousand-1.5 parts per thousand; AVS-acid volatile sulfides) can be caused by dynamic sulfur cycling at millimolar sulfate concentrations. This is in contrast to current interpretations of the isotopic record and indicates that small fractionations do not necessarily indicate very low sulfate or oxygen.

Original languageEnglish
JournalGeology
Volume47
Issue8
Pages (from-to)739-743
Number of pages5
ISSN0091-7613
DOIs
Publication statusPublished - Aug 2019

    Research areas

  • BACTERIAL DISPROPORTIONATION, LOW-SULFATE, FRACTIONATION, LAKE, SYSTEMS

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