Molybdenum Isotope Geochemistry in Marine Sediments

摘要0219651来自俄勒冈州州立大学的PI计划检验以下假设：在自生吸收过程中，Mo同位素被分馏，相对于重同位素，较轻的同位素被优先吸收，留下相对于海水同位素重的残留（溶解）Mo池。 为了证明这一假设，PI将分析来自秘鲁/智利边缘和加州边缘的现有近地表（顶部20 cm）孔隙水和沉积物样品中的98 Mo和95 Mo，以评估Mo的早期成岩行为。 此外，还计划到加利福尼亚州的圣巴巴拉盆地进行一次巡航，以收集和分析沉积物暴露于不断变化的氧化还原条件的区域的更深沉积物和孔隙水样品。 这些样品的结果将确定在什么条件下钼同位素分馏以及这种分馏是否保存在沉积记录中。 这一信息将有助于确定这种同位素是否可以用作识别沉积物中还原条件的替代物。

ABSTRACTOCE-0219651A PI from Oregon State University plans to test the hypothesis that during authigenic uptake Mo isotopes are fractionated with the lighter isotopes being preferentially taken up relative to the heavy isotopes leaving behind a residual (dissolved) Mo pool that is isotopically heavy relative to seawater. To prove the hypothesis, the PI will analyze existing near surface (top 20 cm) porewater and sediment samples from the Peru/Chile margin and the California margin for 98Mo and 95Mo to assess the early diagenetic behavior of Mo. In addition, a cruise is planned to the Santa Barbara Basin, CA, to collect and analyze deeper sediment and porewater samples from a region where sediments are exposed to continuously changing redox conditions. Results from these samples will determine under what conditions molybdenum isotopes fractionate and whether this fractionation is preserved in the sedimentary record. This information will help determine whether this isotope can be used as a proxy for identifying reducing conditions in sediments.