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Due to their volatile nature and low solubility in silicate melts at the surface of the Earth, the direct measurement of the volatile components H2O and CO2 in magmatic systems is dependent on the presence of glass inclusions trapped in a crystal host prior to eruption. These inclusions, along with the glassy rinds of submarine pillow lavas, represent one of the few windows researchers have into the pre-eruptive chemical characteristics of magmatic systems (e.g., Anderson et al. 2000; Roggensack 2001a; Metrich and Wallace 2008). This information is critically important, as it is volatile exsolution and expansion that provides much of the energy for explosive eruptions, plus it informs our broader understanding of geochemical fluxes in igneous environments (Wallace 2005), and helps us understand specific magmatic behavior such as pre-eruptive phase equilibria (Moore and Carmichael 1998). The dissolved volatile concentration in magmas also strongly influences their physical properties such as density and viscosity (Lange 1994; Ochs and Lange 1999), which in turn affect volcanological behavior such as eruption style (Sparks et al. 1994; Zhang et al. 2007).
In order to use melt inclusion volatile content measurements for petrologic interpretation, experimental volatile solubility data are critically necessary. Experimental solubility constraints allow the measured volatile contents in melt inclusions to be used to estimate intensive properties such as a minimum depth of entrapment of the inclusion (i.e., a calculated fluid saturation pressure), as well as to indicate the type of degassing process (i.e., open or closed system) that occurred during the emplacement and eruption of the magma (Fig. 1⇓). These estimates assume, of course, that the magma is saturated in a fluid containing H2O and/or CO2, and are not appropriate for a magma that is fluid-undersaturated. With the assumption of …