Molybdenum Isotope Geochemistry in Marine Sediments

来自俄勒冈州立大学的PI计划验证一个假设，即在自生吸收过程中，Mo同位素被分离，相对于重同位素，轻同位素被优先吸收，留下一个相对于海水同位素重的残余（溶解）Mo池。为了证明这一假设，PI将分析现有的近地表（顶部20厘米）孔隙水和沉积物样本，这些样本来自秘鲁/智利边缘和加利福尼亚边缘的98Mo和95Mo，以评估Mo的早期成岩行为。此外，计划乘船前往加利福尼亚州圣巴巴拉盆地，收集和分析沉积物暴露于不断变化的氧化还原条件下的更深的沉积物和孔隙水样本。这些样品的结果将决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。这些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代理。

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.