Alteration of basaltic glass from the North Pond area, Mid-Atlantic Ridge 22°46'N, 46°05'W, Expedition 336

请拨资金用于玄武岩蚀变和微生物参与的矿物学和地球化学研究，使用钻芯样品和培养载玻片。在IODP 336探险期间，在中大西洋海脊西侧的北池塘地区发现了岩石样品。北池是全球最丰富、最寒冷、通风最好的山脊侧翼的代表。这些系统在确定海洋化学方面发挥了关键作用，然而，控制化学交换速率和大小的水文地质-地球化学-微生物耦合却知之甚少。探险336号安装了海底观测站，这些观测站将允许对地层流体进行采样，促进培养实验，并在未来几年深入了解地下室以下的微生物活动。这里提出的钻芯材料的补充分析包括地球化学和X射线显微层析研究以及电子和拉曼显微镜研究。美国的合作科学家将使用相同材料的裂片进行X射线吸收光谱和分子微生物学研究。该项目的主要目标是详细和全面地描述年轻洋壳中的玄武岩玻璃蚀变。其中一个重点是确定据信与微生物活动有关的蚀变特征，并收集其生物起源的进一步证据。对蚀变物质及其原生前体相进行的地球化学调查将提供有关海水循环期间化学变化的方向和大小以及与玄武岩结壳相关的蚀变的信息。矿物沉淀物的微量元素和稳定同位素组成作为流体成分和流体-岩石相互作用条件的记录器。这些结果将与对井筒内流体成分和温度的直接观测进行比较。将拟议研究中的观测和数据与我们的合作者和我们在北池未来几年的观测研究期间共同努力获得的观测和数据相结合，将使我们能够从根本上对海脊侧翼过程及其在海洋领域岩石圈、水圈和生物圈之间的交换预算中的作用获得新的见解。

Funds are requested for mineralogical and geochemical studies of basalt alteration and the involvement of microorganisms, using drill core samples and incubation slides. Rock samples were recovered during IODP Expedition 336 from the North Pond area on the western flank of the Mid-Atlantic Ridge. North Pond is representative of the globally most abundant, cold and wellventilated ridge flanks. These systems play a pivotal role in setting the chemistry of the oceans, yet, the hydrogeological-geochemical-microbiological couplings controling the rates and magnitudes of chemical exchange are very poorly understood. Expedition 336 installed seafloor observatories that will allow sampling formation fluids, facilitate incubation experiments, and provide insights into subbasement microbiological activities in the forthcoming years. The supplemental analyses of drill core material proposed here include geochemical and x-ray microtomography studies as well as electron- and raman-microcopy investigations. Collaborating scientists in the US will conduct x-ray absorption spectroscopy and molecular microbiological studies using splits of the same materials. The project's primary goal is a detailed and comprehensive description of basalt glass alteration in young ocean crust. One focus is on identifying alteration features believed to be related to microbial activity and collect further evidence for their biogenicity. Geochemical investigations of altered materials and their primary precursor phases will provide information on the direction and magnitude of chemical changes during seawater circulation and the associated alteration of basaltic crust. Trace element and stable isotopic compositions of mineral precipitates are used as a recorder of fluid composition and conditions of fluid-rock interaction. These results will be compared with direct observations on fluid composition and temperature in the borehole. Merging observations and data from the proposed study with those to be obtained by our cooperators and our joint efforts during the next years of observatory studies at North Pond will allow us to obtain fundamentally novel insights into ridge flank processes and their role in exchange budgets between lithosphere, hydrophere, and biosphere in the oceanic realm.