This project deals with the dynamics of magma ascent in volatile-rich volcanic systems such as Mount St. Helens. Petrological studies of natural samples are used to obtain temperature, oxygen fugacity and dissolved volatile data for the preeruption magmas. Projects planned for the next two years are: (1) A detailed study of the magma dynamics during 1980 cryptodome formation at Mount St. Helens, (2) An investigation of the changes in magma dynamics in the same system over the 1985-86 period, (3) Experiments on plagioclase growth rates in wet silicic magmas in collaboration with K. Cashman, and (4) Magma ascent rate studies of two volcanic systems of contrasting composition and magmatic properties, the Moat Rhyolites of Long Valley, Ca., and the Hawaiian basalts of Crater Flats Nevada.
