Related Experiment Video
Updated: Jun 12, 2026

Preparation of Authigenic Pyrite from Methane-bearing Sediments for In Situ Sulfur Isotope Analysis Using SIMS
Published on: August 31, 2017
Explaining the structure of the Archean mass-independent sulfur isotope record
Itay Halevy1, David T Johnston, Daniel P Schrag
1Department of Earth and Planetary Sciences, Harvard University, Cambridge, MA 02138, USA. itay.halevy@gmail.com
Abstract:
Sulfur isotopes in ancient sediments provide a record of past environmental conditions. The long-time-scale variability and apparent asymmetry in the magnitude of minor sulfur isotope fractionation in Archean sediments remain unexplained. Using an integrated biogeochemical model of the Archean sulfur cycle, we find that the preservation of mass-independent sulfur is influenced by a variety of extra-atmospheric mechanisms, including biological activity and continental crust formation. Preservation of atmospherically produced mass-independent sulfur implies limited metabolic sulfur cycling before approximately 2500 million years ago; the asymmetry in the record indicates that bacterial sulfate reduction was geochemically unimportant at this time. Our results suggest that the large-scale structure of the record reflects variability in the oxidation state of volcanic sulfur volatiles.
Related Concept Videos
Microbes and the Sulfur Cycle
Sulfur Assimilation
Diversity of Archaea III
Diversity of Archaea IV
Diversity of Archaea II
Mass Spectrometry: Isotope Effect

