A Caltech Library Service

SQUID–SIMS is a useful approach to uncover primary signals in the Archean sulfur cycle

Fischer, Woodward W. and Fike, David A. and Johnson, Jane E. and Raub, Timothy D. and Guan, Yunbin and Kirschvink, Joseph L. and Eiler, John M. (2014) SQUID–SIMS is a useful approach to uncover primary signals in the Archean sulfur cycle. Proceedings of the National Academy of Sciences of the United States of America, 111 (15). pp. 5468-5473. ISSN 0027-8424. PMCID PMC3992679.

PDF - Published Version
See Usage Policy.

PDF - Supplemental Material
See Usage Policy.

[img] Plain Text (Dataset) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


Many aspects of Earth’s early sulfur cycle, from the origin of mass-anomalous fractionations to the degree of biological participation, remain poorly understood—in part due to complications from postdepositional diagenetic and metamorphic processes. Using a combination of scanning high-resolution magnetic superconducting quantum interference device (SQUID) microscopy and secondary ion mass spectrometry (SIMS) of sulfur isotopes (^(32)S, ^(33)S, and ^(34)S), we examined drill core samples from slope and basinal environments adjacent to a major Late Archean (∼2.6–2.5 Ga) marine carbonate platform from South Africa. Coupled with petrography, these techniques can untangle the complex history of mineralization in samples containing diverse sulfur-bearing phases. We focused on pyrite nodules, precipitated in shallow sediments. These textures record systematic spatial differences in both mass-dependent and mass-anomalous sulfur-isotopic composition over length scales of even a few hundred microns. Petrography and magnetic imaging demonstrate that mass-anomalous fractionations were acquired before burial and compaction, but also show evidence of postdepositional alteration 500 million y after deposition. Using magnetic imaging to screen for primary phases, we observed large spatial gradients in Δ^(33)S (>4‰) in nodules, pointing to substantial environmental heterogeneity and dynamic mixing of sulfur pools on geologically rapid timescales. In other nodules, large systematic radial δ^(34)S gradients (>20‰) were observed, from low values near their centers increasing to high values near their rims. These fractionations support hypotheses that microbial sulfate reduction was an important metabolism in organic-rich Archean environments—even in an Archean ocean basin dominated by iron chemistry.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle Information CentralArticle
Fischer, Woodward W.0000-0002-8836-3054
Fike, David A.0000-0003-2848-0328
Raub, Timothy D.0000-0002-7471-0246
Guan, Yunbin0000-0002-7636-3735
Kirschvink, Joseph L.0000-0001-9486-6689
Additional Information:© 2014 National Academy of Sciences. Freely available online through the PNAS open access option. Edited by Mark H. Thiemens, University of California, San Diego, La Jolla, CA, and approved March 10, 2014 (received for review December 4, 2013). This paper benefited greatly from the thoughtful comments of two anonymous reviewers. The Agouron Institute and National Aeronautic and Space Administration Exobiology Award NNX09AM91G supported this work. Author contributions: W.W.F., D.A.F., T.D.R., J.L.K., and J.M.E. designed research; W.W.F., D.A.F., J.E.J., and T.D.R. performed research; W.W.F., D.A.F., J.E.J., T.D.R., Y.G., J.L.K., and J.M.E. contributed new reagents/analytic tools; W.W.F., D.A.F., J.E.J., T.D.R., Y.G., and J.M.E. analyzed data; and W.W.F., D.A.F., and J.E.J. wrote the paper. The authors declare no conflict of interest. This article is a PNAS Direct Submission. This article contains supporting information online at
Funding AgencyGrant Number
Agouron InstituteUNSPECIFIED
Subject Keywords:mass independent fractionation; MIF; metamorphism; metasomatism
Issue or Number:15
PubMed Central ID:PMC3992679
Record Number:CaltechAUTHORS:20140408-101812632
Persistent URL:
Official Citation:Woodward W. Fischer, David A. Fike, Jena E. Johnson, Timothy D. Raub, Yunbin Guan, Joseph L. Kirschvink, and John M. Eiler SQUID–SIMS is a useful approach to uncover primary signals in the Archean sulfur cycle PNAS 2014 111 (15) 5468-5473; published ahead of print April 1, 2014, doi:10.1073/pnas.1322577111
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:44753
Deposited By: Ruth Sustaita
Deposited On:08 Apr 2014 17:52
Last Modified:09 Mar 2020 13:19

Repository Staff Only: item control page