Peering into the Cradle of Life: multiple sulphur isotopes reveal insights into environmental conditions and early sulphur metabolism some 3.5 Ga ago

地球和生命科学中最有趣的问题之一是生命在何时何地出现在我们的星球上。距今3500 Ma的保存完好的沉积物中含有清晰的生命痕迹：由碳质物质组成的微观结构，被解释为微化石、叠层石、地球化学和同位素证据，这些证据记录了地球上早期丰富的微生物生态系统的存在。不幸的是，由于已经稀疏的岩石记录在沉积后发生了严重的变化，任何更古老的生命记录都丢失了。在同位素证据中，多种硫同位素已成为主要的生物特征，无论是在现代世界，还是在古代岩石中，包括最古老的保存完好的演替之一，即来自南非巴伯顿绿岩带的沉积岩。此外，与质量无关的硫同位素分馏似乎是地球大气成分的主要记录者，最突出的是自由氧的存在。因此，将使用多种硫同位素和互补的地球化学分析来窥探生命的摇篮。

One of the most intriguing questions in Earth and Life Sciences is where and when life emerged on our planet. Well preserved sediments with an age of 3500 Ma contain clear traces of life: microscopic structures composed of carbonaceous material and interpreted as microfossils, stromatolites, and geochemical and isotopic evidence that document the early presence of a rich microbial ecosystem on Earth. Any older record of life is unfortunately lost due to severe postdepositional alteration of an already sparse rock record. Among the isotopic evidence, multiple sulphur isotopes have become a prime biosignature, both in the modern world but more so in ancient rocks, including one of the oldest well preserved succession, i.e. sedimentary rocks from the Barberton Greenstone Belt, South Africa. In addition, mass-independent sulphur isotope fractionation appears to be a prime recorder of Earth’s atmospheric composition, most prominently in respect to the presence of free oxygen. Consequently, multiple sulphur isotopes and complementary geochemical analyses will be used in order to peer into the cradle of life.