Chemolithotrophic life in ultramafic rocks: carbon substrates and pathways enabled by water-rock reactions using field and experimental hydrothermal investigations

在地球最古老的岩石、陨石和其他行星的大气中检测到了甲烷和其他碳氢化合物。在地球上，这些碳氢化合物通常被认为是生物活动的产物，因此可以表明今天或数十亿年前生命的存在。因此，碳氢化合物的研究对于研究早期地球生命的起源和进化，以及在极端环境和其他行星上寻找生命具有重要意义。然而，碳氢化合物也可以通过非生物（非成因）反应产生，但合成这些碳氢化合物的条件尚不清楚。为了区分生物烃和非生物烃，必须确定产生非生物烃的地质条件和反应抑制剂。随后，必须确定非生物碳氢化合物的独特地球化学指标。在自然环境中，识别非生物碳氢化合物更加困难。地下水与其流经的岩石之间的反应，例如蛇纹石化（超镁铁岩的水合），为非生物碳氢化合物的生产以及化能自养生命创造了适宜的条件。生物反应可以修改或套印非生物特征。因此，必须研究有利于非生物碳氢化合物生产和化能自养生命的位置的碳循环，以确定这些改变，确定可以在蛇纹石化过程中产生的极端pH条件下生存的生命，并确定这些系统中的生命对蛇纹石化产物的依赖性。对超镁铁质岩石中的早期生命和水-岩石反应的研究将通过增进对地球生命进化和非生物碳氢化合物生产的了解而使加拿大受益。

Methane and other hydrocarbons have been detected in Earth's oldest rocks, meteorites, and the atmospheres of other planets. On Earth, these hydrocarbons are often thought to be products of biological activities, and thus can indicate the presence of life today or billions of years ago. Therefore the investigation of hydrocarbons has implications for the study of the origin and evolution of life on early Earth, and the search for life in extreme environments and on other planets. Hydrocarbons, however, can also be produced by non-biological (abiogenic) reactions, yet the conditions under which these hydrocarbons are synthesized are not well understood. To differentiate between the biogenic and abiogenic hydrocarbons, the geologic conditions for creating abiogenic hydrocarbons and reaction inhibitors must be determined. Subsequently, unique geochemical indicators must be identified for abiogenic hydrocarbons. In natural settings, there is added difficulty identifying abiogenic hydrocarbons. Reactions between groundwater and the rock it flows through, such as serpentinization (the hydration of ultramafic rock), produce conditions amendable for abiogenic hydrocarbon production as well as chemolithotrophic life. Biological reactions can modify or overprint abiogenic signatures. Therefore, studying carbon cycling in locations favourable for abiogenic hydrocarbon production and chemolithotrophic life must be examined to determine these modifications, to identify life that can survive in extreme pH conditions that are created during serpentinization, and to determine the dependence of life in these systems on products of serpentinization. The research into early life and water-rock reactions in ultramafic rocks will benefit Canadians through the advancement of knowledge of life's evolution on Earth and the production of abiogenic hydrocarbons.