EAPSI: Understanding Variations in Thermal Histories in Volcanic Centers Over Time and Space

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Large silicic volcanic centers are responsible for the most catastrophic volcanic eruptions on earth, including massive 'supervolcanic' eruptions. In order to potentially anticipate when a supervolcano is likely to erupt, it is important to understand the timescales over which magma is generated and stored prior to eruption. In particular, it is not clear for how long magmatic bodies reside in the subsurface in a mostly-solid state (i.e., as low-temperature crystal-rich mushes), relative to how long they spend in a mostly-liquid (i.e., high-temperature), eruptible state. This project will examine crystals from eruptive products from the Taupo Volcanic Zone (TVZ) in New Zealand, the most active volcanic zone in the world. The goals of this work are twofold: 1) to determine what proportion of a crystal's existence was spent at high temperatures within a magma reservoir; 2) to determine how magma evolves differently over both time and space within a volcanic center. This research will be conducted in collaboration with Dr. Fidel Costa Rodriguez, an expert on the use of diffusion profiles to determine magmatic temperatures, at Nanyang Technological University in Singapore.In order to determine what proportion of a crystal's existence was spent at high temperatures, it is necessary to constrain the absolute age of the crystal. Plagioclase crystal ages from a series of TVZ eruptions will be acquired by measuring U-series disequilibrium ages, and the difference between the crystallization age and the eruption age will yield the amount of time spent in the subsurface. Analyses of diffusion profiles (temperature-dependent trace element distributions) will be completed in order to determine what proportion of the crystal's subsurface existence was spent at high temperatures. Results will be compared between a series of eruptions to determine not only how volcanic centers evolve over time and space, but also what differences exist between the evolutions of eruptions of different magnitudes. This NSF EAPSI award is funded in collaboration with the National Research Foundation of Singapore.