This ongoing project is designed to examine the behavior of water and carbon dioxide (the most abundant volatile components in terrestrial igneous rocks) in model and natural igneous systems. These components have significant effects on the behavior of silicate melts, and a knowledge of these effects is fundamental to understanding magma origin and evolution. The proposed work involves application of experimental petrology and analytical techniques to measure the bulk concentrations of H2O and CO2 and the concentrations of individual H- and C- bearing species in synthetic and natural glasses. The specific problems to be addressed include: mixed volatiles in silicate melts and glasses at elevated pressures; 13C/12C fractionation between vapor and silicate melts; measurement of the H2O and CO2 concentrations of natural volcanic glasses; measurement of H2O/CO2 ratios of individual bubbles in volcanic glasses; and experimental investigation of the effect of water on the degree of partial melting of mantle peridotite.
