## Isentropic rise path of a water oversaturated magma body

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.

**(Above)**
Results of a numerical simulation of isentropic magma rise. An
integrated thermal history of a rhyolitic melt percel (+ exsolved
H2O vapor) is shown as a function of water content at initial
saturation pressure P0.

References:

- Yamashita, S., 1999. Experimental study
of the effect of temperature on water solubility in natural rhyolite
melt to 100 MPa.
*Journal of Petrology* 40, 1497-1507.
- Yamashita, S., 2000. Heat of solution of
water in rhyolite melt.
*EOS* 81, S433.

Link to: Shigeru Yamashita's Research
Interests