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dc.contributor.authorLeavitt, William Davie
dc.contributor.authorHalevy, Itay
dc.contributor.authorBradley, Alexander S.
dc.contributor.authorJohnston, David T
dc.date.accessioned2015-03-04T19:59:27Z
dc.date.issued2013
dc.identifier.citationLeavitt, W. D., I. Halevy, A. S. Bradley, and D. T. Johnston. 2013. “Influence of Sulfate Reduction Rates on the Phanerozoic Sulfur Isotope Record.” Proceedings of the National Academy of Sciences 110 (28) (June 3): 11244–11249. doi:10.1073/pnas.1218874110.en_US
dc.identifier.issn1091-6490en_US
dc.identifier.urihttp://nrs.harvard.edu/urn-3:HUL.InstRepos:14081356
dc.description.abstractPhanerozoic levels of atmospheric oxygen relate to the burial histories of organic carbon and pyrite sulfur. The sulfur cycle remains poorly constrained, however, leading to concomitant uncertainties in O2 budgets. Here we present experiments linking the magnitude of fractionations of the multiple sulfur isotopes to the rate of microbial sulfate reduction. The data demonstrate that such fractionations are controlled by the availability of electron donor (organic matter), rather than by the concentration of electron acceptor (sulfate), an environmental constraint that varies among sedimentary burial environments. By coupling these results with a sediment biogeochemical model of pyrite burial, we find a strong relationship between observed sulfur isotope fractionations over the last 200 Ma and the areal extent of shallow seafloor environments. We interpret this as a global dependency of the rate of microbial sulfate reduction on the availability of organic-rich sea-floor settings. However, fractionation during the early/mid-Paleozoic fails to correlate with shelf area. We suggest that this decoupling reflects a shallower paleoredox boundary, primarily confined to the water column in the early Phanerozoic. The transition between these two states begins during the Carboniferous and concludes approximately around the Triassic–Jurassic boundary, indicating a prolonged response to a Carboniferous rise in O2. Together, these results lay the foundation for decoupling changes in sulfate reduction rates from the global average record of pyrite burial, highlighting how the local nature of sedimentary processes affects global records. This distinction greatly refines our understanding of the S cycle and its relationship to the history of atmospheric oxygen.en_US
dc.description.sponsorshipEarth and Planetary Sciencesen_US
dc.language.isoen_USen_US
dc.publisherProceedings of the National Academy of Sciencesen_US
dc.relation.isversionofdoi:10.1073/pnas.1218874110en_US
dash.licenseLAA
dc.subjectPhanerozoic oxygenen_US
dc.subjectsulfate-reducing bacteriaen_US
dc.titleInfluence of sulfate reduction rates on the Phanerozoic sulfur isotope recorden_US
dc.typeJournal Articleen_US
dc.description.versionVersion of Recorden_US
dc.relation.journalProceedings of the National Academy of Sciencesen_US
dash.depositing.authorJohnston, David T
dash.waiver2013-03-09
dc.date.available2015-03-04T19:59:27Z
dc.identifier.doi10.1073/pnas.1218874110*
dash.contributor.affiliatedLeavitt, William
dash.contributor.affiliatedJohnston, David


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