"This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5)."
Collaborative Research: Synthesis and Integration of Magmagenetic Controls for Subduction Factory focus sites
Intellectual Merit: The MARGINS program ends in 2009, and the organization, synthesis, and integration of the most important results is a high priority for each of the four experiments. This proposal outlines a 3-year collaborative effort (between 5 US and 2 Japanese scientists) to do this for key aspects of the Subduction Factory experiment. In co-operation with the LDEO database group, geochemical and isotopic data for fresh, young igneous rocks from the Izu-Bonin-Mariana and Central America Subduction Factory focus sites will be compiled and filtered to generate a Subduction Factory Geochemical Reference Library of high-quality data for each arc system. Forward models to explain the most important differences between the chemical and isotopic compositions of lavas erupted from the volcanic front and rear-arc volcanoes at the two focus sites will be generated and tested against compositions in this Library. Models will be site-specific, using all available geophysical observations to generate thermal structure and melt distribution models appropriate for each focus site. Best estimates for the compositions of subducted sediments and oceanic crust at each focus site will be used as input to thermodynamic models simulating equilibrium metamorphic reactions, dehydration, and melting of subducted sediments and oceanic crust (slab) within the subduction zone. Interaction of these slab fluids and melts with overlying mantle peridotite to yield primitive basalt will be modeled using the "Arc Basalt Simulator" (ABS), an Excel macro that explicitly separates key forcing functions and is designed to be flexible and accessible. Several improvements to ABS will also be accomplished during this project.
Broader Impacts: This project is in response to calls for synthesis and integration efforts by the 2004 MARGINS Review Committee. Dissemination of results and training Earth scientists to use ABS will be accomplished at two free workshops at national scientific meetings. A lesson plan that uses ABS and the Subduction Factory Geochemical Library to explore the most important controls on subduction-zone magma genesis will be developed; this will be aimed at upper division Geoscience majors and beginning graduate students. Broader dissemination of the most important results to the general public will be accomplished via development of a Wikipedia entry for "Subduction Factory".
