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

大洋板块建立在海底岩浆中心，称为海脊。在数百万年的时间里，构造板块被推离海脊，并通过一种称为俯冲的过程沉入地球深处。从在海脊出生到在俯冲海沟中循环，海洋板块吸收了相当数量的海水，在俯冲过程中被带到地球内部。深部流体的存在极大地改变了岩石的物理和化学性质，引发了俯冲板块(例如安第斯火山链)上方弧形火山的熔融和形成。揭开地球内部流体的路径对于了解弧形火山如何形成以及在哪里形成至关重要；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量分析设施，开发曾经在俯冲带深处平衡的岩石中流体路径的新型示踪剂氟和氯。为了实现这项研究的目标，该团队将进一步发展分析方法，以分析极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追踪俯冲带背景下的全球流体循环。

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.