Resolving sedimentary sulphur cycling during the Shunga Event (early Paleoproterozoic) with sulphur isotopes

早古元古代的关键事件之一是约2000马老顺嘎事件中大量有机物的沉积。在俄罗斯西北部的Fennoscandian地盾上的Onega盆地，原生沉积有机质、迁移的焦沥青和石化的水下溢油构成了一个厚的沉积序列。岩石学和地球化学证据清楚地表明，有机质通过多种好氧和厌氧途径被微生物再矿化。硫同位素证据表明，微生物硫循环，最突出的是细菌硫酸盐还原似乎是最重要的，但它发生在高度可变的条件下。由此产生的沉积硫化物显示出广泛的结构谱，强调了成岩领域的时空变异性。对顺嘎事件的定性和定量认识需要对其沉积和成岩历史进行严格的评估，以揭示其对太古宙-元古代过渡时期海洋-大气系统演化的重要性。

One of the key events during early Paleoproterozoic time is the deposition of unprecedented amounts of organic matter during the ca. 2000 Ma old Shunga Event. Autochthonous sedimentary organic matter, migrated pyrobitumen und petrified subaquatic oil spills characterize a thick sedimentary succession in the Onega Basin on the Fennoscandian Shield, NW Russia. Petrographic and geochemical evidence clearly indicates that the organic matter is being remineralized microbially via a diverse suite of aerobic and anaerobic pathways. Sulphur isotopic evidence suggests that microbial sulphur cycling, and most prominently bacterial sulphate reduction appears to be of prime importance but that it occurred under highly variable conditions. Resulting sedimentary sulphides display a wide textural spectrum, underlining temporal and spatial variability in the diagenetic realm. A qualitative and quantitative understanding of the Shunga event requires a firm assessment of its depositional and diagenetic history in order to unravel its importance for the evolution of the ocean-atmosphere system during the Archean-Proterozoic transition.