Collaborative Research: Synthesizing arc-scale geochemical, petrologic, and geophysical datasets to investigate causes of volcanic diversity in the Cascade Arc

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Subduction zones – locations where one of the Earth’s tectonic plates are pushed beneath another – are one of the most volcanically active environments on the planet. Decades of study on subduction zones have provided insight into the overarching processes that produce the magmas erupted, how the erupted magmas are produced at individual volcanoes, and a number of related questions. Despite this progress, a complex and largely unsolved problem is the cause of ubiquitous and dramatic variations in the amount and composition of magmas that erupt at volcanoes within the same subduction zone. Do these reflect processes acting deep within the Earth’s mantle, or in the overlying crust? Addressing this problem has important implications for understanding magma production and volcanic hazards, as worldwide almost a billion people live at risk from volcanoes. There is also a potential for scientific breakthrough by utilizing the existing large data sets acquired from recent NSF investments such as the MARGINS, GeoPRISMS, and EarthScope programs. However, addressing the question has proven challenging to date in part because of a lack of critical data for some locations, but largely because of the lack of suitable tools and approaches that allow us to quantitatively synthesize and compare the existing large data sets. Thus, this is a multidisciplinary study to conduct a quantitative comparison of existing large geophysical and compositional datasets at the spatial scales of the entire Cascades subduction zone, linked through sets of common intensive variables such as heat and density, to determine the primary drivers of intra-arc magmatic diversity. Building on a successful Proof of Concept project that demonstrates the promise of the approach (Till et al., 2019), the project will test hypotheses about the relative roles of mantle magmatic flux vs. crustal characteristics and crustal magma storage depths in producing variations in erupted compositions and fluxes, and in controlling the geophysical state of the crust along strike in the Quaternary Cascades arc. The project has the potential to transform our understanding of these important regions and will produce a number of important broader impacts including, catalyzing interdisciplinary collaborations between three PI’s at three institutions, producing expert datasets widely and easily available to the Earth Science community, supporting undergraduate experiential learning activities. Specifically, it will implement a new multi-year undergraduate research program CONVEcT program (Central Oregon Network for Volcano Education and Training) with research cohorts from Arizona State, Oregon State and Cornell Universities.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.