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

在瓜伊马斯盆地(加利福尼亚州海湾)、埃斯卡纳巴海槽(戈尔达岭)和中谷(胡安德富卡海脊北部)等大洋扩张中心之上的沉积物中，有机质的热液蚀变导致产生重要的有机蚀变产物。水热实验将在200-400摄氏度和300巴的条件下在实验室进行，以限制更好地控制有机化合物的生成和稳定性以及有机-无机相互作用的程度和性质的因素。包含天然沉积物和海水类型流体或不同成分的实验将允许对有机蚀变产物随时间、温度、沉积物和流体组成的函数进行详细的定量表征，以及这些物种在天然热液系统中的身份源和汇。沉积物改造实验将用于校准古地温计，其依据是用于山脊热液系统的热蚀变有机物种的相对丰度和分布。这项研究的结果将应用于自然环境，以评价热液沉积物蚀变过程中的地球化学条件，并约束沉积物覆盖的扩张中心的时间-温度历史。

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.