Hydrogen and methane from precambrian shield rocks and microbiological sinks for gases produced by water-rock interactions: energy for the deep biosphere

地球深层地下微生物环境的能源基础的科学调查是地质学家，行星科学家，微生物学家和天体生物学家之间跨学科合作的最前沿，也是我在地球和环境同位素地球化学研究计划的主要重点。我们对加拿大、南非和芬兰稳定的前寒武纪古生物的深层生物圈研究表明，基于化学合成而不是光合作用的微生物生命并不局限于地球上发生重大岩浆或热液活动的那些地区。在高度断裂的地质静止盾地形中，在数万至数百万年的时间尺度上，低温的产物（<约。200 oC）水岩作用（WRI）可以积累并作为深层微生物群落的基质。特别是，我们正在研究的前寒武纪地盾遗址含有mM水平的溶解H2 -水平，使这些沃茨成为地球上最富含H2的环境。我们的研究还涉及开发诊断环境参数，以区分WRI生产的非生物成因碳氢化合物，微生物过程产生的碳氢化合物气体，或沉积盆地天然气矿床。这些发现扩展了我们对地球地下环境可居住性的概念，并可能大大增加对地下生物圈相对重要性的估计。出现了两条调查路线，它们将构成此Discovery应用程序的两个总体目标的基础。目标一：重新评估框架解释微生物甲烷同位素签名在寒冷的环境中在北方和目标二：调查的意义H2和CH 4从前寒武纪盾岩石在全球范围内通过耦合研究的活性气体和稀有气体溶解在断裂地下水。

Scientific investigations of the energy basis for deep subsurface microbial environments on earth are at the forefront of interdisciplinary collaboration between geologists, planetary scientists, microbiologists and astrobiologists and a major focus of my research program in Isotope Geochemistry of the Earth and Environment. Our deep biosphere research on the stable Precambrian cratons of Canada, South Africa and Finland has demonstrated that microbial life based on chemosynthesis rather than photosynthesis is not limited to those parts of the earth where significant magmatic or hydrothermal activity occurs. In the highly fractured geologically quiescent Shield terrains, over timescales of tens of thousands to millions of years, the products of low temperature (< approx. 200oC) water-rock interaction (WRI) can accumulate and serve as substrate for deep microbial communities. In particular, the Precambrian Shield sites we are studying contain mM levels of dissolved H2 - levels that place these waters among the most H2-rich environments on the planet. Our research also addresses developing diagnostic environmental parameters to distinguish between abiogenic hydrocarbons produced by WRI, from hydrocarbon gases produced by microbial processes, or found in sedimentary basin natural gas deposits. These discoveries have expanded our conception of the habitability of the earth's subsurface environment and may significantly increase estimates of the relative importance of the subsurface biosphere. Two lines of inquiry have arisen that will form the basis for the two Overall Objectives for this Discovery application. Objective I: Reevaluating frameworks for interpreting microbial CH4 isotopic signatures in cold environments in the North and Objective II: Investigating the significance of H2 and CH4 from Precambrian Shield rocks on a global scale through a coupled study of active gases and noble gases dissolved in fracture groundwaters.