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Riverine evidence for isotopic mass balance in the Earth’s early sulfur cycle

Torres, Mark A. and Paris, Guillaume and Adkins, Jess F. and Fischer, Woodward W. (2018) Riverine evidence for isotopic mass balance in the Earth’s early sulfur cycle. Nature Geoscience, 11 (9). pp. 661-664. ISSN 1752-0894. https://resolver.caltech.edu/CaltechAUTHORS:20180611-140642568

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Abstract

During a time of negligible atmospheric pO_2, Earth’s early sulfur cycle generated a spectacular geological signal seen as the anomalous fractionation of multiple sulfur isotopic ratios. The disappearance of this signal from the geologic record has been hypothesized to constrain the timing of atmospheric oxygenation, although interpretive challenges exist. Asymmetry in existing S isotopic data, for example, suggests that the Archaean crust was not mass balanced, with the implication that the loss of S isotope anomalies from the geologic record might lag the rise of atmospheric O_2. Here, we present new S isotopic analyses of modern surface and groundwaters that drain Archaean terrains in order to independently evaluate Archaean S cycle mass balance. Natural waters contain sulfur derived from the underlying bedrock and thus can be used to ascertain its S isotopic composition at scales larger than typical geological samples allow. Analyses of 52 water samples from Canada and South Africa suggest that the Archaean crust was mass balanced with an average multiple S isotopic composition equivalent to the bulk Earth. Overall, our work supports the hypothesis that the disappearance of multiple S isotope anomalies from the sedimentary record provides a robust proxy for the timing of the first rise in atmospheric O_2.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1038/s41561-018-0184-7DOIArticle
https://rdcu.be/5O0bPublisherFree ReadCube access
ORCID:
AuthorORCID
Torres, Mark A.0000-0002-9599-2748
Paris, Guillaume0000-0001-8368-1224
Adkins, Jess F.0000-0002-3174-5190
Fischer, Woodward W.0000-0002-8836-3054
Additional Information:© 2018 Springer Nature Limited. Received: 5 February 2018; Accepted: 19 June 2018; Published online 23 July 2018. M.A.T. acknowledges support from the Caltech Texaco Postdoctoral fellowship and the California Alliance for Graduate Education and the Professoriate (AGEP). This work was supported from funds supplied by the David and Lucile Packard Foundation, a Caltech GPS Division Discovery Award (W.W.F), and a grant from the National Science Foundation (EAR-1349858) to W.W.F and J.F.A. This project benefited from the use of instrumentation made available by the Caltech Environmental Analysis Center. All authors acknowledge helpful comments provided by B. Wing on an earlier draft of this manuscript. Author Contributions: G.P. and M.A.T conducted the laboratory analyses. All authors contributed to the sample collection, data analysis and manuscript preparation. Data availability: All original data generated as part of this study are available in Supplementary Tables 2 and 3 and online from the PANGEA repository (https://doi.pangaea.de/10.1594/PANGAEA.890986). The Canadian precipitation chemistry analyses are available online at ec.gc.ca/natchem. Compiled analyses of the sulfur isotopic composition of Archaean sulfides are available in the original publications (see citations in Supplementary Table 1). Code availability: The code used to generate perform the data analysis can be accessed at github.com/torres-lab. The authors have no competing interests.
Funders:
Funding AgencyGrant Number
Caltech Texaco Postdoctoral FellowshipUNSPECIFIED
California Alliance for Graduate Education and the ProfessoriateUNSPECIFIED
David and Lucile Packard FoundationUNSPECIFIED
Caltech Division of Geological and Planetary SciencesUNSPECIFIED
NSFEAR-1349858
Issue or Number:9
Record Number:CaltechAUTHORS:20180611-140642568
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20180611-140642568
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:86968
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:23 Jul 2018 16:45
Last Modified:09 Mar 2020 13:19

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