Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts

Journal of Geophysical Research B: Solid Earth
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Abstract

 We evaluate the melt‐vapor surface tension (σ) of natural, water‐saturated dacite melt at 200 MPa, 950–1055°C, and 4.8–5.7 wt % H2O. We experimentally determine the critical supersaturation pressure for bubble nucleation as a function of dissolved water and then solve for σ at those conditions using classical nucleation theory. The solutions obtained give dacite melt‐vapor surface tensions that vary inversely with dissolved water from 0.042 (±0.003) J m−2 at 5.7 wt % H2O to 0.060 (±0.007) J m−2 at 5.2 wt % H2O to 0.073 (±0.003) J m−2 at 4.8 wt % H2O. Combining our dacite results with data from published hydrous haplogranite and high‐silica rhyolite experiments reveals that melt‐vapor surface tension also varies inversely with the concentration of mafic melt components (e.g., CaO, FeOtotal, MgO). We develop a thermodynamic context for these observations in which melt‐vapor surface tension is represented by a balance of work terms controlled by melt structure. Overall, our results suggest that cooling, crystallization, and vapor exsolution cause systematic changes in σ that should be considered in dynamic modeling of magmatic processes.

Publication type Article
Publication Subtype Journal Article
Title Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts
Series title Journal of Geophysical Research B: Solid Earth
DOI 10.1029/2004JB003215
Volume 110
Issue 1
Year Published 2005
Language English
Publisher AGU
Contributing office(s) Volcano Hazards Program
Description 9 p.
First page 1
Last page 9
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