Deconvolving microbial and environmental controls on marine sedimentary pyrite sulfur isotope ratios

• 成果类型: Article
• 署名作者: Bryant, R. N.; Houghton, J. L.; Jones, C.; Pasquier, V.; Halevy, I.; Fike, D. A.
• 署名单位: Washington University (WUSTL); Purdue University System; Purdue University; Weizmann Institute of Science
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-13879
• DOI: 10.1126/science.adg6103
• 发表日期: 2023-11-24
• 页码: 912-915
• 关键词: sulfate reduction rates; fractionation; carbon; extinction; abundance; oxygen; MODEL

摘要

Reconstructions of past environmental conditions and biological activity are often based on bulk stable isotope proxies, which are inherently open to multiple interpretations. This is particularly true of the sulfur isotopic composition of sedimentary pyrite (delta S-34(pyr)), which is used to reconstruct ocean-atmosphere oxidation state and track the evolution of several microbial metabolic pathways. We present a microanalytical approach to deconvolving the multiple signals that influence delta S-34(pyr), yielding both the unambiguous determination of microbial isotopic fractionation (epsilon(mic)) and new information about depositional conditions. We applied this approach to recent glacial-interglacial sediments, which feature over 70% variations in bulk delta S-34(pyr) across these environmental transitions. Despite profound environmental change, epsilon(mic) remained essentially invariant throughout this interval and the observed range in delta S-34(pyr) was instead driven by climate-induced variations in sedimentation.