Collaborative Research: Volcanism on the Edge - Basaltic Volcanism from Source to Surface across the Colorado Plateau/Basin & Range Transition in SW Utah

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The American Southwest is home to nearly forty basaltic volcanic fields that collectively contain more than 2,000 Quaternary volcanoes, including many that have erupted relatively recently (past 50,000 years). Most of these volcanoes are considered to be “monogenetic” (i.e., they erupt only once), and they generally produce relatively small volume eruptions (1 km3). Nevertheless, it has recently become clear that such eruptions can pose significant hazards due to their wide variety of eruptive styles, including explosive behavior, and the fact that the location of any future eruption is unknown. In the southwest US, neither the cause of this volcanism nor the frequency of recent eruptions is well understood. This project will focus on volcanism in SW Utah, in the transition between the Colorado Plateau and the Basin and Range provinces, an area that is particularly enigmatic with regard to the causes of volcanism, and poorly constrained with regard to the nature and frequency of recent volcanic activity. By integrating detailed field observations and mapping, radiometric dating, physical volcanology, and geochemical analyses, this project will provide key constraints on the sources, processes, and timescales of magma ascent and storage leading to eruption, and the link to eruptive style and hazards. In addition to providing information about hazards to the public, this work includes mentoring and training of two PhD students and several undergraduate researchers in field, analytical and imaging techniques. PIs will also engage in a variety of outreach activities related to the project, including research-based educational activities for K-12 students and teachers, public talks, and a summer course for middle and high school students.The Southwest US contains at least 2229 Quaternary volcanoes, most of which are monogenetic. Significant questions surround the causes and sources of the volcanism, the ages and eruptive recurrence intervals, and the range of – and controls on – eruptive styles. Understanding the processes that govern monogenetic volcanism in the Southwest US, and the time scales over which these processes operate, is critical for hazard and risk assessment. In addition, the mafic nature of many of these monogenetic volcanic fields makes them ideal as probes of the mantle sources that they tap, and spatial-temporal-compositional variations can thus provide a unique record of the complex tectonic history in this area. We propose an integrated physical volcanology and petrology/geochemistry study of Quaternary volcanism in the SW Utah volcanic field, spanning the transition from the Basin and Range to the Colorado Plateau, to elucidate links between tectonics, magma sources, and eruptive styles and hazards. Primary objectives include: 1) establishing age ranges and systematic age progressions, if extant; 2) evaluating the range of eruptive styles and associated hazards; 3) determining potential relationships of eruptive activity to local tectonic features; 4) constraining the nature (lithospheric vs. asthenospheric), location (depth), and spatial heterogeneity of the mantle sources tapped in the eruptions; 5) assessing the relative importance of mantle versus crustal control on magma composition and eruptive style, and the influence of magmatic water content; and 6) constraining timescales and the importance of magma storage systems in ascent from source to surface. Our integrated approach will involve detailed field mapping, 40Ar/39Ar dating, textural analysis of eruptive products, and elemental and isotopic analyses at both the whole-rock and mineral scales.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.