Abstract The recent expansion of studies at hydrothermal submarine vents from investigation of abiotic methane formation to include abiotic production of organics such acetate and formate, and rising interest in processes of abiotic organic synthesis on the ocean-world moons of Saturn and Jupiter, have raised interest in potential Earth analogs for investigation of prebiotic/abiotic processes to an unprecedented level. The deep continental subsurface provides an attractive target to identify analog environments where the influence of abiotic carbon cycling may be investigated, particularly in hydrogeological isolated fracture fluids where the products of chemical water-rock reactions have been less overprinted by the biogeochemical signatures of the planet’s surficial water and carbon cycles. Here we report, for the first time, a comprehensive set of concentration measurements and isotopic signatures for acetate and formate, as well as the dissolved inorganic and organic carbon pools, for saline fracture waters naturally flowing 2.4 km below surface in 2.7 billion year-old rocks on the Canadian Shield. These geologically ancient fluids at the Kidd Creek Observatory were the focus of previous investigations of fracture fluid geochemistry, microbiology and noble gas-derived residence times. Here we show the fracture waters of Kidd Creek contain high concentrations of both acetate and formate with concentrations from 1200 to 1900 µmol/L, and 480 to 1000 µmol/L, respectively. Acetate and formate alone account for more than 50% to 90% of the total DOC – providing a very simple “organic soup”. The unusually elevated concentrations and profoundly 13C-enriched nature of the acetate and formate suggest an important role for abiotic organic synthesis in the deep carbon cycle at this hydrogeologically isolated site. A variety of potential abiotic production reactions are discussed, including a radiolytically driven H, S and C deep cycle that could provide a mechanism for sustaining deep subsurface habitability. Scientific discoveries are beginning to reveal that organic-producing reactions that would have prevailed on Earth before the rise of life, and that may persist today on planets and moons such as Enceladus, Europa and Titan, can be accessed in some specialized geologic settings on Earth that provide valuable natural analog environments for the investigation of abiotic organic chemistry outside the laboratory.

中文翻译：

---

进入非生物碳循环的窗口——加拿大地盾 27 亿年前母岩裂缝水中的乙酸盐和甲酸盐

摘要 最近对热液海底喷口的研究从非生物甲烷形成的研究扩展到包括有机物如醋酸盐和甲酸盐的非生物生产，以及对土星和木星海洋世界卫星上非生物有机合成过程的兴趣日益浓厚，引起了人们的兴趣。将潜在的地球类似物用于研究益生元/非生物过程达到前所未有的水平。深层大陆地下提供了一个有吸引力的目标来确定可以研究非生物碳循环影响的模拟环境，特别是在水文地质孤立的压裂液中，化学水-岩石反应的产物很少被地球表面的生物地球化学特征覆盖。水循环和碳循环。在这里，我们第一次报告，一套全面的醋酸盐和甲酸盐浓度测量和同位素特征，以及溶解的无机和有机碳库，用于在加拿大地盾上 27 亿年历史的岩石中自然流过地表以下 2.4 公里的咸水裂缝水。Kidd Creek 天文台的这些地质上古老的流体是先前对压裂流体地球化学、微生物学和惰性气体衍生停留时间进行调查的重点。在这里，我们展示了 Kidd Creek 的裂缝水含有高浓度的乙酸盐和甲酸盐，浓度分别为 1200 至 1900 µmol/L 和 480 至 1000 µmol/L。仅醋酸盐和甲酸盐就占 DOC 总量的 50% 至 90% 以上——提供了一种非常简单的“有机汤”。乙酸盐和甲酸盐异常升高的浓度和富含 13C 的性质表明非生物有机合成在这个水文地质隔离地点的深层碳循环中发挥着重要作用。讨论了各种潜在的非生物生产反应，包括辐射驱动的 H、S 和 C 深循环，它可以提供维持深层地下宜居性的机制。科学发现开始揭示，在地球上的某些特殊地质环境中，可以访问在生命出现之前在地球上盛行的有机生产反应，并且今天可能在土卫二、欧罗巴和泰坦等行星和卫星上持续存在为实验室外的非生物有机化学研究提供了宝贵的天然模拟环境。