Multiple-Isotope Insights into the Earth's Early Sulfur Cycle

对地球早期硫循环的多同位素见解

• 批准号: 0003419
• 负责人: James Farquhar
• 金额: $ 20.97万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-05-01 至 2004-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0003419&HistoricalAwards=false
• 关键词: Multiple; Isotope; Insights; into; Earth

FarquharEAR-0003419Preliminary sulfur multiple-isotope data point to a fundamental change in the processes controlling the sulfur cycle during the Paleoproterozoic (2.0 to 2.5 Ga). These data suggest that before this time, the sulfur cycle was strongly influenced by atmospheric sulfur chemistry. After this time, the sulfur cycle was more strongly influenced by oxidative weathering and microbial sulfate reduction, and is inferred to be similar to the modern, pre-anthropogenic sulfur cycle. To extend these preliminary conclusions and to understand the role of oxidative weathering and microbial reduction on the Precambrian sulfur cycle, a three part strategy is needed: (1) Additional documentation of the sulfur multiple-isotope geochemistry in sedimentary, metasedimentary and igneous rocks will provide a record of the role of atmospheric sulfur chemistry in the sulfur cycle over time; (2) A deeper examination of the Paleoproterozoic transition period that is evidenced by D33S shifts in our preliminary data, will add new insights into the changes that occurred at 2.0-2.5 Ga and explore possible links to the intensity of oxidatitve weathering and the atmospheric oxidation state; (3) further investigation of the Archean sulfur cycle will constrain the roles of atmospheric reactions, oxidative weathering, and microbial activity in the Earth's earliest sulfur cycle.

FarquharEAR-0003419初步的硫多同位素数据表明，古元古代（2.0 至 2.5 Ga）期间控制硫循环的过程发生了根本性变化。 这些数据表明，在此之前，硫循环受到大气硫化学的强烈影响。 此后，硫循环受到氧化风化和微生物硫酸盐还原的更强烈影响，并推断与现代人类活动前的硫循环相似。为了扩展这些初步结论并了解氧化风化和微生物还原对前寒武纪硫循环的作用，需要采取三部分策略：（1）沉积岩、变沉积岩和火成岩中硫多同位素地球化学的额外记录将提供大气硫化学在硫循环中随时间变化的作用的记录； (2) 对初步数据中 D33S 变化所证明的古元古代过渡期进行更深入的研究，将为 2.0-2.5 Ga 发生的变化提供新的见解，并探索氧化风化强度和大气氧化态之间的可能联系； (3)对太古宙硫循环的进一步研究将制约地球最早硫循环中大气反应、氧化风化和微生物活动的作用。