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Variability in sulfur isotope records of Phanerozoic seawater sulfate
  • Theodore Michael Present,
  • Jess Adkins,
  • Woodward Fischer
Theodore Michael Present
California Institute of Technology, California Institute of Technology

Corresponding Author:[email protected]

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Jess Adkins
California Institute of Technology, California Institute of Technology
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Woodward Fischer
California Institute of Technology, California Institute of Technology
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Abstract

The δ34S of seawater sulfate reflects processes operating at the nexus of sulfur, carbon, and oxygen cycles. However, knowledge of past seawater sulfate δ34S values must be derived from proxy materials that are impacted differently by depositional and post-depositional processes. We produced new timeseries estimates for the δ34S value of seawater sulfate by combining 6710 published data from three sedimentary archives—marine barite, evaporites, and carbonate-associated sulfate—with updated age constraints on the deposits. Robust features in multiple records capture temporal trends in the δ34S value of seawater and its interplay with other Phanerozoic geochemical and stratigraphic trends. However, high-frequency discordances indicate that each record is differentially prone to depositional biases and diagenetic overprints. The amount of noise, quantified from the variograms of each record, increases with age for all δ34S proxies, indicating that post-depositional processes obscure detailed knowledge of seawater sulfate’s δ34S value deeper in time.
28 Sep 2020Published in Geophysical Research Letters volume 47 issue 18. 10.1029/2020GL088766