Program > Browse abstracts by speaker > Gauthier Inès

Experimentally determining controls on H2O and CO2 solubility in silica undersaturated melts
Inès Gauthier  1@  , Craig Lundstrom  1@  
1 : University of Illinois at Urbana-Champaign [Urbana]  (UIUC)

The presence of dissolved volatile species such as H2O and CO2 in silicate melts plays a major role in the chemical and physical behavior of magmas, thus impacting igneous and volcanic processes. To characterize the effects of these volatiles, it is essential to have reliable solubility models. Many experimental studies have characterized how solubilities of H2O and CO2 depend on pressure, temperature, and generally melt composition. A key compositional factor in H2O solubility is the ratio of alkalis to alumina in the magma. While the solubilities of H₂O and CO2 have been thoroughly studied for metaluminous melts, only a few studies have explored volatile solubilities in peralkaline systems. The presence of Na2CO3 appears to increase the solubility of H₂O in silica undersaturated melts (Lundstrom et al. 2022), indicating that both the alkali and CO2 content of silicate melts can have a major effect on H2O concentration. To address the gap in knowledge, I am running high pressure and temperature experiments for which the starting composition is a basanite with varying concentrations of H₂O, CO2, and sodium. Three cold seal vessel experiments were performed at 1 kbar and 910°C with fixed Na2O and CO2 contents of 4.9 and 0.4 wt% and variable water concentrations of 1, 6, and 12 wt% H2O. The experimental run products were then observed under a scanning electron microscope; no evidence (bubbles) of supersaturation of a volatile phase was found in any capsule, suggesting high water solubility in the melts. H₂O, CO2, of the glasses are yet to be measured. In the future, I will run piston-cylinder experiments at higher pressures and temperatures to avoid high degrees of crystallinity and to obtain accurate solubility values in the glasses. These experiments will enhance the understanding of the combined effects of peralkalinity and CO2 on water solubility in magmas.


Loading... Loading...