Sulfur Chemistry and Sulfate Reducing Bacteria of Archean Oceans

对已发表的太古宙沉积物大块岩石样品的硫同位素数据进行分析，得出了太古宙大气-海洋-生物圈系统的新模型：早在38 - 32亿年前，海洋就富含硫酸盐，硫酸盐浓度约为现在的1/3，比现代海洋温度高30- 40摄氏度，并且在世界范围内支持非常高的硫酸盐还原细菌活性；太古宙早期的大气中已经含有相当数量的游离氧。本研究的目的是通过考察澳大利亚Warrawoona群沉积物的硫-碳-铁化学和硫、碳、氧同位素组成的微观尺度变化，验证上述模型和其他太古宙大气-海洋-生物圈模型；格陵兰岛的伊苏亚群；和南非无花果树集团合作，使用配备激光消融系统的最先进的稳定同位素比质谱仪。

Analyses of the published sulfur isotopic data on bulk rock samples of Archean sediments have led to a new model for the Archean atmosphere-ocean-biosphere system: the oceans, as far back as about 3.8-3.2 billion years ago, were already sulfate rich with a sulfate concentration of about 1/3 of the present level, were 30- 40 oC warmer than modern oceans, and supported a very high activity of sulfate reducing bacteria world wide; the early Archean atmosphere already contained appreciable amounts of free oxygen. The objective of the proposed research is to test the above and other models for the Archean atmosphere-ocean-biosphere by examining the sulfur-carbon-iron chemistry and the microscopic- scale variation in the sulfur, carbon and oxygen isotopic compositions of sediments from the Warrawoona Group, Australia; the Isua Group, Greenland; and the Fig Tree Group, South Africa, using a state-of-the-art stable isotope ratio mass spectrometer equipped with a laser ablation system.