The proportions, compositions, and interrelationships among crystalline phases and glasses in volcanic rocks cryptically record pre-eruptive intensive conditions, the timing of changes therein, and the devolatilization history coeval with eruptive ascent. These parameters are recognized as important monitoring tools at active volcanoes, as well as for interpreting geologic events at prehistoric and remote eruptions. Silicate magmas rich in H2O begin to solidify in response to two drivers: temperature decrease and decompression. Cooling has long been recognized as the dominant impetus for crystallization of basaltic (e.g., Hawaiian-type) magma during emplacement in the upper crust and in lava flows and pyroclastic eruptions. Decompression-driven crystallization is now appreciated as the dominant factor driving syn-eruptive crystallization of silica-rich (e.g., Mount St. Helens-type) magmas.

We design laboratory experiments aimed at quantifying the mechanism and kinetics of crystal nucleation in thermochemical environments that mimic natural eruptive conditions. Specific objectives include (a) constraining the nucleation rates of key phases with respect to effective undercooling, (b) correlating crystal textures with time-varying environmental conditions, (c) placing experimental results in a theoretical context, and (d) understanding intraphase phenomena such as heterogeneous nucleation and epitaxial growth of magmatic phases.