Barium in sediments and pore waters of several ODP Leg 170 and Leg 205 sites

Barium concentrations were measured on 17 pore fluid and 13 sediment samples from Sites 1253 and 1254 drilled offshore Costa Rica during Ocean Drilling Program (ODP) Leg 205. An additional 83 pore fluid and 29 sediment samples were analyzed for Ba concentrations from Sites 1039 and 1040 drilled during ODP Leg 170 offshore Costa Rica. Sites 1039/1253 and 1040/1254 are part of a transect across the Middle America Trench offshore Nicoya Peninsula. The entire incoming sediment section is being underthrust beneath the margin, providing an ideal setting to examine Ba cycling in the shallow levels of the subduction zone. Results from these analyses indicate that a significant amount of Ba is liberated from the mineral barite (BaSO4) in the uppermost hemipelagic sediments arcward of the trench. The shallow distillation of Ba may impact the amount of sedimentary Ba reaching the deeper subduction zone.

本数据集针对大洋钻探计划（Ocean Drilling Program，以下简称ODP）第205航次在哥斯达黎加近海钻取的1253、1254站位样品，完成了钡（Barium）浓度的测定工作，共涉及17份孔隙流体样品与13份沉积物样品。此外，本次研究还对ODP第170航次在哥斯达黎加近海钻取的1039、1040站位的样品进行了钡浓度分析，涵盖83份孔隙流体样品与29份沉积物样品。1039/1253与1040/1254站位共同组成了横跨尼科亚半岛近海中美洲海沟的断面剖面。所有随俯冲板片输入的沉积物层序均在大陆边缘下方发生俯冲掩覆，为研究俯冲带浅部圈层的钡循环提供了绝佳的实验载体。本次分析结果显示，海沟向弧一侧的最上层半远洋沉积物中，大量钡从重晶石（BaSO₄）矿物中释放。浅层钡分馏作用可能会影响抵达俯冲带深部的沉积物钡赋存总量。