Speaker: Laura Waters, New Mexico Tech, (hosted by Ethan Hyland)

Seminar Title: Why Doesn’t Continental Crust Evolve to its Fullest Potential?

Abstract: The paucity of high-silica rhyolite in volcanic arcs and its restricted occurrence as scattered aplite dikes throughout arc granitoid batholiths suggests there is a mechanism that prevents high-silica (near-eutectic) rhyolite melts from coalescing and erupting as discrete liquids at subduction zones. In contrast, large volumes (≥100 km^3) of high-silica rhyolite, including those that are relatively cold (700–750 °C) and hydrous, erupt in extensional tectonic settings. The emerging question is: What controls the eruption of high-silica rhyolite? In this talk, I use results of several experimental and petrologic studies on silica-rich magmas (rhyolites) from the Sierra Nevada Batholith and Long Valley to provide a crystallization (kinetic) perspective on what it takes to efficiently extract, move and erupt a eutectic melt and, thus, stratify continents.

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