The Role of the Slab and the Mantle in Volcanic Arc Petrogenesis: A B-Be-Li and Li Isotope Study of Off-Axis Arc Centers in Mexico and Central America

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RyanEAR-0229663This project will define the roles of the mantle wedge and subducting slab in generating volcanic arc lavas using B-Be-Li abundances and Li isotopes. The main scientific goal of the project is to better constrain the geochemical variability of sub-arc mantle regions, and the origins of that variation. Two different but comparable subduction systems will be studied: the Trans-Mexican Volcanic belt (TMVB) and the more vigorously subducting and B-enriched Guatemala segment of the Central American arc. These systems have low B/Be ratios and abundant off-axis volcanism, and offer the opportunity to assess the role of the mantle and constrain effects of crustal assimilation. The project will be conducted in two phases: 1) an undergraduate summer research experience, where students from the University of South Florida and other participating institutions measure B-Be-Li elemental abundances in lavas from these suites, and 2) MS/PhD student research on the Li isotope systematics of lavas from the TMVB, Guatemala, and key intraplate volcanic sites. This work plan will train a cadre of undergraduate and graduate students in the use of geochemistry as a tool in the study of volcanic arcs.