F and Cl in Peridotite Minerals: Analytical Development and Applications to Fluid Cycling in the Earth's Mantle

海洋板块形成于称为海脊的海底岩浆中心。在数百万年的时间里，构造板块被推离山脊，并通过一个称为俯冲的过程沉入地球深处。从诞生于海脊到在俯冲海沟中再循环，海洋板块吸收了大量的海水，在俯冲过程中被带入地球内部。深部流体的存在极大地改变了岩石的物理和化学性质，并触发了俯冲洋板块上方弧火山的熔融和形成（例如，安第斯山脉火山链）。解开地球内部流体的路径对于了解弧火山如何以及在何处形成至关重要;然而，俯冲带中流体的元素循环仍然知之甚少。 该项目将利用伍兹霍尔海洋研究所最先进的微分析设施，在俯冲带深处曾经平衡的岩石中开发新的流体通道、氟和氯示踪剂。为了实现这项研究的目标，该团队将进一步改进分析方法，以分析非常低浓度的流体示踪剂。最终目标是推进当前的分析技术，并利用岩石矿物中氟和氯的分布来跟踪俯冲带环境中的全球流体循环。

Oceanic plates are built in submarine magmatic centers called ridges. Over millions of years, tectonic plates are pushed away from ridges and sink back into the deep Earth via a process called subduction. From birth at a ridge to recycling in a subduction trench, oceanic plates incorporate considerable amounts of seawater, carried into the interior of the Earth during subduction. The presence of fluids at depth dramatically modifies the physical and chemical properties of rocks and trigger melting and formation of arc volcanoes above subducting oceanic plates (e.g., Andes volcanic chain). Unraveling the pathways of fluids inside the Earth is critical to understand how and where arc volcanoes form; yet, elemental cycling of fluids in subduction zones remain poorly understood. This project will take advantage of state-of-the-art micro-analytical facilities at the Woods Hole Oceanographic Institution to develop novel tracers of fluid pathways, fluorine and chlorine, in rocks that were once equilibrated at depth in a subduction zone. In order to accomplish the goals of this study, the team will be furthering the analytical methods to analyze fluid tracers at very low concentrations. The ultimate goal is to advance current analytical techniques and use the distribution of fluorine and chlorine in rock minerals to track global fluid cycling in subduction zone settings.