Sedimentary parameters control the sulfur isotope composition of marine pyrite

• 成果类型: Article
• 署名作者: Halevy, I.; Fike, D. A.; Pasquier, V.; Bryant, R. N.; Wenk, C. B.; Turchyn, A. V.; Johnston, D. T.; Claypool, G. E.
• 署名单位: Weizmann Institute of Science; Washington University (WUSTL); Purdue University System; Purdue University; University of Cambridge; Harvard University
• 刊物名称: SCIENCE
• ISSN/ISSBN: 0036-13097
• DOI: 10.1126/science.adh1215
• 发表日期: 2023-11-24
• 页码: 946-951
• 关键词: sulfate reduction rates; organic-carbon content; elemental sulfur; bacterial disproportionation; polysulfide anions; seawater chemistry; aqueous-solutions; secular variation; cariaco basin; degrees-c

摘要

Reconstructions of coupled carbon, oxygen, and sulfur cycles rely heavily on sedimentary pyrite sulfur isotope compositions (delta S-34(pyr)). With a model of sediment diagenesis, paired with global datasets of sedimentary parameters, we show that the wide range of delta S-34(pyr) (similar to 100 per mil) in modern marine sediments arises from geographic patterns in the relative rates of diffusion, burial, and microbial reduction of sulfate. By contrast, the microbial sulfur isotope fractionation remains large and relatively uniform. Over Earth history, the effect of increasing seawater sulfate and oxygen concentrations on sulfate and sulfide transport and reaction may explain the corresponding increase observed in the delta S-34 offset between sulfate and pyrite. More subtle variations may be related to changes in depositional environments associated with sea level fluctuations and supercontinent cycles.