- journal_title：Geology
- Contributor：Kenneth H. Williford ; Julien Foriel ; Peter D. Ward ; Eric J. Steig
- Publisher：Geological Society of America
- Date：2009-
- Format：text/html
- Language：en
- Identifier：10.1130/G30054A.1
- journal_abbrev：Geology
- issn：0091-7613
- volume：37
- issue：9
- firstpage：835
- section：Articles
Stable sulfur isotopes from the reduced sulfur fraction of Late Triassic–Early Jurassic marine sediments at Kennecott Point in British Columbia, Canada, show evidence for a major perturbation in sulfur cycling coincident with a major carbon cycle perturbation in the wake of a mass extinction event at the Triassic-Jurassic boundary. The δ34S of reduced sulfur shifts from values consistent with open system bacterial sulfate reduction (−30‰) to values higher than any previously reported for Early Jurassic sulfates (20‰) and consistent with complete utilization of sulfate and Rayleigh fractionation in a closed system. We suggest that this isotopic shift was initiated by declining seawater sulfate concentration due to evaporite deposition in nascent Atlantic rift zones and enhanced by a local mechanism, such as a decoupling of the zone of sulfate reduction from the sulfate supply due to a catastrophic increase in the flux of land-derived sediments reaching the sea in the wake of massive terrestrial plant die-off during the Triassic–Jurassic mass extinction.