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Publication - Professor Katharine Cashman

    The Influence of Phenocrysts on Degassing in Crystal-Bearing Magmas With Rhyolitic Groundmass Melts

    Citation

    deGraffenried, RL, Larsen, JF, Graham, NA & Cashman, KV, 2019, ‘The Influence of Phenocrysts on Degassing in Crystal-Bearing Magmas With Rhyolitic Groundmass Melts’. Geophysical Research Letters, vol 46., pp. 5127-5136

    Abstract

    The porosity at which a magma becomes permeable (i.e., the percolation threshold; ϕc) is important for magma degassing; it is also poorly constrained in crystal-bearing systems. To address this, we conduct high pressure-temperature decompression experiments on water-saturated rhyolitic melts with variable crystal contents. We find that crystal-bearing run products become permeable at ~55-vol.% vesicularity (crystal free), a value that is similar to that found in decompression-crystallization experiments using basaltic andesite compositions. Our results provide insight into controls on the eruption styles of hydrous, crystal-bearing magmas in general and controls on pulsatory Vulcanian behavior, in particular.

    Full details in the University publications repository