Triple oxygen and multiple sulfur isotope constraints on the evolution of the post-Marinoan sulfur cycle

Peter W. Crockford, Benjamin R. Cowie, David T. Johnston, Paul F. Hoffman, Ichiko Sugiyama, Andre Pellerin, Thi Hao Bui, Justin Hayles, Galen P. Halverson, Francis A. Macdonald, Boswell A. Wing

Research output: Contribution to journalArticlepeer-review

42 Scopus citations


Triple oxygen isotopes within post-Marinoan barites have played an integral role in our understanding of Cryogenian glaciations. Reports of anomalous δO17 values within cap carbonate hosted barites however have remained restricted to South China and Mauritania. Here we extend the δO17 anomaly to northwest Canada with our new measurements of barites from the Ravensthroat cap dolostone with a minimum δO17 value of -0.75‰. For the first time we pair triple oxygen with multiple sulfur isotopic data as a tool to identify the key processes that controlled the post-Marinoan sulfur cycle. We argue using a dynamic 1-box model that the observed isotopic trends both in northwest Canada and South China can be explained through the interplay between sulfide weathering, microbial sulfur cycling and pyrite burial. An important outcome of this study is a new constraint placed on the size of the post-Marinoan sulfate reservoir (≈0.1% modern), with a maximum concentration of less than 10% modern. Through conservative estimates of sulfate fluxes from sulfide weathering and under a small initial sulfate reservoir, we suggest that observed isotopic trends are the product of a dynamic sulfur cycle that saw both the addition and removal of the δO17 anomaly over four to five turnovers of the post-Marinoan marine sulfate reservoir.

Original languageEnglish
Pages (from-to)74-83
Number of pages10
JournalEarth and Planetary Science Letters
StatePublished - 1 Feb 2016
Externally publishedYes


  • Barite
  • Cap dolostone
  • Neoproterozoic
  • Snowball earth
  • Sulfur cycle
  • Triple oxygen

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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