Magmatic Degassing: Experimental and Textural Constraints

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Gardner EAR- 0087853Volcanic eruptions are driven by the growth of gas bubbles. Many models suggest that magmas either erupt explosively or effuse as lava, depending on the magma's ability to degas efficiently, which is controlled by the melt transferring gas to bubbles. If bubbles and melt fail fall out of equilibrium, over-pressure develops and fragments the magma. Despite the central role that gas bubbles play in volcanism, experimental work has only recently begun to address their growth in silicate melts. This project addresses the dynamics of bubble growth in silicate melts through detailed analysis of the rates of bubble growth and equilibrium between bubbles and melt as a function of pressure drop. Controlled hydrothermal experiments will be used to impose variable decompression histories on gas-melt systems in order to examine how bubbles grow and at what rates of pressure decrease do bubbles-melt fail to remain in equilibrium. These data are crucial inboth understanding of eruption dynamics and developing better modeling of conduit flow in eruptions. Experiments will be performed in the Experimental Petrology Laboratory at the University of Alaska Fairbanks, and all products will be analyzed in the Advanced Instrumentation Laboratory at the University of Alaska Fairbanks.