Opaque phase petrology and geochemical modeling as a guide to abiotic organic synthesis in the Mid-Atlantic Ridge 15°N area

橄榄岩托管的热液系统的最有趣的方面之一是强烈的还原性的喷口流体，由于在超镁铁质寄主岩石的亚铁水解产生氢。在这些系统中溶解的氢的水平是如此之高，还原的溶解碳物种比溶解的无机碳更稳定。虽然它是不确定的程度有机合成发生在热液系统中，它有潜在的重要影响的碳流和碳和能源的微生物生态系统中的现代和古代热液系统。在这里，我建议确定矿物学库存的氧化物/硫化物/自然金属相的蛇纹岩从大西洋中脊15ºN地区的磁性和电子探针技术。这些相不仅指示蛇纹石化过程中的温度和氧化还原条件，它们也是有机合成反应的重要表面催化剂。样品包括来自Logatchev热液区和大洋钻探计划（ODP）第209航次的蛇纹岩。用电子探针和透射电镜分析了硫化物、氧化物、金属合金以及蛇纹水镁石相的组成和共生关系。相岩石学和地球化学建模将用于估计温度，流体通量，pH值和氧化还原条件在蛇纹石化。这些约束条件被用于一个同伴项目，以计算水-超镁铁岩相互作用的主要条件下的有机合成反应的化学亲和力。

One of the most intriguing aspects of peridotite-hosted hydrothermal systems is the strongly reduced nature of the vent fluids, due to the production of hydrogen by hydrolysis on ferrous iron in the ultramafic host rock. The levels of dissolved hydrogen in these systems are so high that reduced dissolved carbon species are more stable that dissolved inorganic carbon. While it is uncertain to what extent organic synthesis takes place in hydrothermal systems, it has potentially important ramifications for carbon flow and carbon and energy sources for microbial ecosystems within modern and ancient hydrothermal systems. Here, I propose to determine the mineralogical inventory of oxide/sulfide/native metals phases in serpentinites from the Mid-Atlantic Ridge 15ºN area by magnetic and electron microprobe techniques. These phases are not only indicative of temperature and redox conditions during serpentinization, they are also important surface catalysts for organic synthesis reactions. Samples include serpentinites from the Logatchev hydrothermal field and from Ocean Drilling Program (ODP) Leg 209. Electron microprobe and transmission electron microscope analyses are employed to characterize the composition and intergrowth of sulfides, oxides, metal alloys as well as serpentine-brucite phases. Phase petrology and geochemical modelling will be employed to estimate temperature, fluid flux, pH, and redox conditions during serpentinization. These constraints are used in a companion project to calculate the chemical affinities of organic synthesis reactions under the prevailing conditions of water-ultramafic rock interaction.