NSFGEO-NERC: Sulfur Cycling at Subduction Zones

俯冲带是一个关键的阀门调解全球S处理和弧火山作用的气候效应，弧岩浆的经济潜力，和固体地球水库的氧化状态。然而，在整个俯冲系统的输入，处理和再循环的S仍然是不准确的知道。这一国际项目的目标是俯冲带硫循环中的主要未知因素。该项目的US-NSF重点（PI普朗克，LDEO）将填补一个关键的知识空白，在俯冲带地幔的S输入。它将涉及对汤加、马里亚纳群岛、阿留申群岛、阿拉斯加和中美洲海沟的沉积剖面进行广泛分析，选择这些剖面代表硫沉积和成岩作用以及极端同位素变化的端元海洋环境。大洋钻探计划的岩心将通过X射线荧光岩心扫描进行分析，这是一种量化沉积物中硫的主要宿主-非均匀浸染的黄铁矿和重晶石的战略方法。岩芯扫描结果将指导巴勒莫大学与Aiuppa教授和维齐尼教授合作进行的散装硫和硫同位素分析的离散采样。在巴勒莫收集的试点数据表明，耦合元素分析仪-质谱技术的质量和明确的硫化物与硫酸盐为主的制度，可能会出现在一个单一的沉积部分。其结果将是第一次全面估计（不确定性）的通量和同位素组成的S进入端员trenches和改进的全球estimations.The英国-NERC的一部分，这个项目（PI马瑟，牛津大学）将采取一种新的方法来了解火山弧S输出。它将首次测量未脱气的橄榄石型弧熔体包裹体中的硫同位素组成。在爱丁堡NERC离子微探针实验室收集的试验数据证明了该技术的可行性，并在Fuego火山的熔体包裹体中产生了正δ（34）S。计划中的工作将包括来自与沉积物目标相同的俯冲系统的经过充分研究的熔融包裹体套件（见上文）。这将确保该项目的美国和英国部分之间的密切合作，并允许首次直接追踪从沉积物输入到电弧输出的硫同位素。

Subduction zones are a key valve mediating global S processing and the climatic effects of arc volcanism, the economic potential of arc magmas, and the oxidation state of solid Earth reservoirs. Yet, the inputs, processing and recycling of S throughout the subduction system are still inaccurately known. This international project targets major unknowns in the sulfur cycle at subduction zones. The US-NSF focus of this project (PI Plank, LDEO) will fill a key knowledge gap in terms of S inputs to the mantle at subduction zones. It will involve extensive analysis of sedimentary sections at the Tonga, Marianas, Aleutians, Alaska and Central America trenches, chosen to represent end-member oceanic environments for sulfur deposition and diagenesis and extreme isotopic variations. Ocean Drilling Programs cores will be analyzed by XRF core scanning, a strategic approach to quantify heterogeneously disseminated pyrite and barite, major hosts of sulfur in sediment. Core scanning results will guide discrete sampling for bulk sulfur and sulfur isotope analyses at the University of Palermo, in collaboration with Prof. Aiuppa and Vizzini. Pilot data collected in Palermo demonstrate the quality of the coupled Elemental Analyzer-Mass Spectrometry technique and the clear sulfide- vs. sulfate-dominated regimes that may occur in a single sedimentary section. The outcome will be the first comprehensive estimates (with uncertainties) for the fluxes and isotopic compositions of S into end-member trenches and improved global estimates.The UK-NERC part of this project (PI Mather, Oxford) will take a novel approach to understanding volcanic arc S outputs. It will measure for the first time the sulfur isotopic composition in undegassed olivine-hosted arc melt inclusions. Pilot data collected at NERC Ion Microprobe Facility at Edinburgh demonstrate the viability of the technique, and yield positive delta(34)S in melt inclusions from Fuego volcano. Planned work will include well-studied melt inclusions suites from the same subducting systems as the sediment targets (above). This will ensure close collaboration between the US and UK parts of this project, and allow for the first-time direct tracing of sulfur isotopes from sediment input to arc output.