Collaborative Research: Element Recycling from UHP Metasediments: Evidence and Consequences

这是一项对已被俯冲到75公里处的超高压(UHP)变质沉积物的研究，目的是量化火山弧脱水和/或熔体提取过程中元素的循环过程。这项研究的目的是了解物质进出俯冲带和火山弧的流量。反过来，这是理解全球地球化学的基础，也是边缘倡议的中心目标。对超高压变质岩样品的研究将为常量、痕量元素和同位素交换温度计收集新的数据。选定的变质岩中的微量元素将与正常细粒沉积岩中的微量元素进行比较，以确定与熔体提取或脱水有关的系统变化。这一结果将限制俯冲变质沉积物中关键元素的预算，并通过流体和熔体运移将这些元素提取到弧下岩浆成因带中。更广泛的影响包括培训两名研究生，在论文和演讲中介绍结果，将SedDB全球沉积岩数据库中的数据存档，以及通过网络和国际和平组织的非正式讲座进行广泛和持续的外联工作。

This is a study of ultrahigh-pressure (UHP) metasediments that have been subducted to 75 km, to quantify element recycling processes during dehydration and/or melt extraction at volcanic arcs. The aim of the research is to understand the fluxes of material into and out of subduction zones and volcanic arcs. In turn, this is fundamental to understanding global geochemistry, and is a central goal of the MARGINS Initiative. This research on UHP metasedimentary samples will collect new data for major- and trace-element and isotope exchange thermometers. Trace elements in selected metasediments will be compared to those in normal fine-grained sedimentary rocks to identify systematic changes associated with melt extraction or dehydration. The results should provide constraints on the budget of key elements in subducting metasediments, and the extraction of these elements via fluid and melt transport into the zone of magma genesis beneath arcs. Broader impacts include training of two graduate students, presentation of results in papers and talks, archiving of data in the SedDB global sedimentary rock data base, and extensive, ongoing outreach efforts via web and informal lectures by the PI's.