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

M. Mangan; T. Sisson

doi:10.1029/2004jb003215

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

M. Mangan·T. Sisson

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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 % H 2 O. 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 % H 2 O to 0.060 (±0.007) J m −2 at 5.2 wt % H 2 O to 0.073 (±0.003) J m −2 at 4.8 wt % H 2 O. 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, FeO total , 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.

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Journal of Geophysical Research B: Solid Earth Article

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BibTeX RIS

M. Mangan, T. Sisson. 2005-01-21. Evolution of melt-vapor surface tension in silicic volcanic systems: Experiments with hydrous melts. https://doi.org/10.1029/2004jb003215

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