Hydrothermal Sediment Alteration at Oceanic Spreading Centers: A Comparison of Thermogenic Organic Reactions in Laboratory and Natural Systems

Guaymas Basin （Gulf of California）、Escanaba槽（Gorda Ridge）和Middle Valley （Juan de Fuca Ridge北部）等海洋扩张中心上覆的沉积物有机质热液蚀变产生了重要的有机衍生蚀变产物。我们将在实验室进行200-400℃、300 bar的水热实验，以更好地约束调节有机化合物生成和稳定性的因素，以及有机-无机相互作用的程度和性质。含有天然沉积物和海水型流体或不同成分的实验将允许详细定量表征有机蚀变产物作为时间、温度、沉积物和流体成分的函数，并确定这些物种在天然热液系统中的来源和汇。沉积物蚀变实验将用于根据热蚀变有机质的相对丰度和分布校准古地温计，以供脊顶热液系统使用。研究结果将应用于自然环境，评价热液沉积蚀变过程中的地球化学条件，约束沉积物覆盖扩张中心的时温史。

Hydrothermal alteration of organic matter in sediments overlying oceanic spreading centers such as the Guaymas Basin (Gulf of California), Escanaba Trough (Gorda Ridge), and Middle Valley (northern Juan de Fuca ridge) results in the generation of significant organically derived alteration products. Hydothermal experiments will be conducted in the laboratory at 200-400oC and 300 bars to constrain better factors that regulate the generation and stability of organic compounds and the extent and nature of organic-inorganic interactions. Experiments containing natural sediments and seawater type fluids or varying composition will allow detailed quantitative characterization of organic alteration products as a function of time, temperature, and sediment and fluid composition, and identity sources and sinks for these species in natural hydrothermal systems. The sediment alteration experiments will be used to calibrate paleogeothermometers based on the relative abundance and distribution of thermally altered organic species for use in ridge crest hydrothermal systems. The results of this study will be applied to natural environments to evaluate geochemical conditions during hydrothermal sediment alteration and to constrain the time-temperature history of sediment-covered spreading centers.