Testing the geological fate of abiogenic carbonaceous matter

有机质(OM)作为前寒武纪岩石中潜在的生物特征，一直是众多研究的焦点。然而，OM本身不能作为生命的证据，因为存在大量的非生物来源，如陨石输送和非生物有机合成。后者可能是由热液能量、撞击、闪电或紫外线辐射推动的，在早期地球上进行的程度可能比今天大得多。在拟议的项目中，将进行P，T实验来研究由费托合成(FTT)产生的非生物OM的热演化。其目的是为区分前寒武纪岩石和其他地质样品中的生物和非生物有机质提供线索。以蒙脱土为催化剂，莫雷型反应容器为催化剂，在水热条件下进行FTT合成。所产生的非生物OM在冷封压力容器(CSPV，金袋)中，在静石压力(1.5kbar)下人工成熟10个不同的时间间隔(10min-1年)。并以始新世未成熟油页岩制备的I型干酪根为参照物。采用GC-MS、GC-C-IRMS、催化加氢裂解(HHYY)和拉曼光谱对FTT衍生的有机质及其成熟产物(沥青和干酪根)进行了分析。然后将在不同P、T条件下成熟的非生物OM的特性与太古代真实世界的材料进行比较。我们预计，这些结果将为我们提供可靠的线索，了解保存在携带土著OM的最古老陆地岩石的不同相中的单个干酪根的生物成因。

Organic matter (OM) has been in the focus of numerous investigations as a potential biosignature in Precambrian rocks. However OM can not per se been taken as evidence of life, because there existed numerous abiogenic sources, such as delivery from meteorites and abiogenic organic synthesis. The latter, possibly fueled by hydrothermal energy, impacts, lightning, or UV-radiation, may have proceeded to a much greater extent on the early Earth than today. In the proposed project, a P,T-experiment will be performed to investigate the thermal evolution of abiotic OM generated by Fischer-Tropsch type (FTT) synthesis. The goal is to provide clues to the distinction of biogenic and abiotic OM in Precambrian rocks and other geological samples. FTT synthesis will be performed under hydrothermal conditions using Morey-type reaction vessels and montmorillonite clay as a catalyst. The resulting abiotic OM are artificially maturated in cold-seal pressure vessels (CSPV, gold bags) at lithostatic pressure (1,5kbar) for 10 different time intervals (10min-1yr). Type I kerogen prepared from an immature Eocene oil shale is run in parallel as a reference. The FTT-derived OM and its maturation products (bitumen and kerogen) are analysed using GC-MS, GC-C-IRMS, catalytic hydropyrolysis (HyPy), and Raman-spectroscopy. The properties of abiotic OM maturated under different P,T-conditions will then be compared to Archaean real-world materials. We expect that the results will provide us with a robust clues to the biogenicity of individual kerogens preserved in different facies of the oldest terrestrial rocks carrying indigenous OM.