From Bureau of Economic Geology, The
University of Texas at Austin (www.beg.utexas.edu).
For more information, please contact the author.
Bureau Seminar, May 14, 2010
Bubbling Waters (in volcanic eruptions): Experimental Constraints
Dr. James Gardner
Department of Geological Sciences
Volcanic eruptions are some of the most dramatic and deadly forces of nature. Such eruptions are driven by the release of gas, and especially water, that was dissolved in magma at depth. Indeed, both the intensity of explosive eruptions and whether magma erupts explosively or passively effuses as lava are dictated by the rate of gas release. Vesicles in pumice fragments are the cavities left by gas released by magma, but those vesicles are the culmination of bubble nucleation, growth, coalescence, and collapse, and thus present complex records that need to be deciphered. One way to decipher that record is to experimentally recreate gas-rich magma in the laboratory and subject it to known changes in temperature or pressure to trigger specific events of gas bubble formation. Such research has been a major area of focus in the Experimental Petrology Laboratory in the Department of Geological Sciences, and will be the focus of this talk. We will examine the kinetics of gas bubble nucleation, growth, and coalescence in molten silicate melts to investigate how magmas of different composition degas and ascend through the crust to erupt at the surface, and how that ascent may dictate the style and intensity of the resulting eruption.