I am numerically investigating the conservation of energy and mass for water oversaturation in a rising silicic magma body. I have constrained the calorimetric parameters of solution of water in rhyolite melt, and have developed a thermodynamically based solubility model for water in the melt (Yamashita, 1999). In combination, these investigations provides the ability to fully quantify the energetic effects of melt degassing (latent heat of solution of water in the melt and volume change) upon magma rise as a function of pressure and initial water content, thereby permitting a numerical simulation of a change in the P-V-T properties of the system. The results of the simulation suggest that below 100 Ma (the pressure range important to water oversaturation), the effect of heat of melt degassing is very minor (a temperature drop of only <10 K; Yamashita, 2000), and the adiabatic expansion of H2O vapor is a major factor controlling the P-V-T properties of the system. A full manuscript is in preparation.
Link to: Shigeru Yamashita's Research Interests