1 Department of Earth and Space Sciences, University of Washington , Seattle, Washington.
2 Space Science Institute , Boulder, Colorado.
Astrobiology. 2017 Nov;17(11):1138-1160. doi: 10.1089/ast.2016.1606. Epub 2017 Sep 14.
Low-temperature serpentinization is a critical process with respect to Earth's habitability and the Solar System. Exothermic serpentinization reactions commonly produce hydrogen as a direct by-product and typically produce short-chained organic compounds indirectly. Here, we present the spectral and mineralogical variability in rocks from the serpentine-driven Lost City Hydrothermal Field on Earth and the olivine-rich region of Nili Fossae on Mars. Near- and thermal-infrared spectral measurements were made from a suite of Lost City rocks at wavelengths similar to those for instruments collecting measurements of the martian surface. Results from Lost City show a spectrally distinguishable suite of Mg-rich serpentine, Ca carbonates, talc, and amphibole minerals. Aggregated detections of low-grade metamorphic minerals in rocks from Nili Fossae were mapped and yielded a previously undetected serpentine exposure in the region. Direct comparison of the two spectral suites indicates similar mineralogy at both Lost City and in the Noachian (4-3.7 Ga) bedrock of Nili Fossae, Mars. Based on mapping of these spectral phases, the implied mineralogical suite appears to be extensive across the region. These results suggest that serpentinization was once an active process, indicating that water and energy sources were available, as well as a means for prebiotic chemistry during a time period when life was first emerging on Earth. Although the mineralogical assemblages identified on Mars are unlikely to be directly analogous to rocks that underlie the Lost City Hydrothermal Field, related geochemical processes (and associated sources of biologically accessible energy) were once present in the subsurface, making Nili Fossae a compelling candidate for a once-habitable environment on Mars. Key Words: Mars-Habitability-Serpentinization-Analogue. Astrobiology 17, 1138-1160.
低温蛇纹石化对于地球的宜居性和太阳系来说是一个关键过程。放热蛇纹石化反应通常会直接产生氢气，并间接地产生短链有机化合物。在这里，我们展示了地球上蛇纹石化驱动的失落城热液场和火星含水富橄榄石的尼利福萨地区岩石的光谱和矿物变化。对失落城的一系列岩石进行了近红外和热红外光谱测量，波长与收集火星表面测量的仪器相似。失落城的结果显示了一系列光谱上可区分的富镁蛇纹石、钙碳酸盐、滑石和角闪石矿物。对尼利福萨地区岩石中低级变质矿物的综合检测进行了绘图，并在该地区发现了以前未检测到的蛇纹石露头。对两个光谱系列的直接比较表明，失落城和火星尼利福萨地区的诺亚纪（4-37 亿年前）基岩都具有相似的矿物学。基于这些光谱相的绘图，暗示该矿物组合在整个地区广泛存在。这些结果表明，蛇纹石化曾经是一个活跃的过程，表明在地球生命最初出现的时期，水和能源是可用的，并且为前生物化学提供了一种手段。尽管在火星上识别出的矿物组合不太可能与失落城热液场下的岩石直接类似，但相关的地球化学过程（以及相关的可生物利用能源）曾经存在于地下，使尼利福萨成为火星上曾经宜居环境的有力候选者。关键词：火星-宜居性-蛇纹石化-模拟。天体生物学 17，1138-1160。
