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

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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.