RUI: Collaborative Research: Linking Small-volume Silicic Magmas to a Yellowstone Super-eruption Using a Petrochronologic Approach

Yellowstone National Park and vicinity is home to three volcanic super-eruptions within the last two million years. Between super-eruptions, smaller effusions of compositionally similar lavas have erupted onto the surface, however the relationship between the timing of magma production for precursory and super-eruptions is unknown. This project seeks to test the contrasting hypotheses that Yellowstone super-eruptions are the culmination of gradual accumulation of magma that is periodically tapped by precursory eruptions, or alternatively, super-eruptions are the result of independent episodes of rapid magma production without connection to the smaller pre-cursor eruptions. This research bears on our understanding of how quickly large super-eruption volumes of magma may be generated and reside under active volcanic calderas, with implications for the assessment of eruption recurrence and volcanic hazards.

To assess the potential connections between super-eruptions and smaller lava effusions, the morphological, chemical, thermometric, isotopic, and age characteristics for small volume rhyolitic lavas that erupted between the 2.1 and 1.3 million year old super-eruptions will be used to establish the timescales and processes by which magmas are generated and evolve. These processes include partial melting of earlier-formed volcanic products and associated crystal recycling, magma crystallization and differentiation, as well as mixing and hybridization with mantle-derived basalts; the relative importance of each process is best explored through the crystal cargos of each eruption. Specifically, the minerals zircon and sanidine will be extracted from the lavas and analyzed by various state-of-the-art methods to assess the contribution of small volume magma batches to the super-eruption. Dating the intermittent eruptions will provide a framework for the recurrence interval of Yellowstone volcanism and bear upon the question of lifespans of eruptable magmas. This award will allow three undergraduate students from Westminster College (Utah) to participate in field and lab based research over three years, and promote knowledge and technology transfer between this undergraduate-only liberal arts college and the Isotope Geochronology Laboratory at Boise State University (Idaho). The collaborative model will allow students to interact with graduate students and laboratory technicians at Boise State University, and conduct hands-on research with instrumentation not available at Westminster College. Students will participate in data processing, interpretation, and presentation at local and national conferences; results from this study will be included in undergraduate courses at Westminster College, and displayed as interpretive materials on public lands near the eruption sites.