EVALUATION OF SULFUR EMISSIONS FROM VOLCAN DE COLIMA USING MELT INCLUSION ANALYSIS AND GROUND-BASED SPECTROMETRY

The relationship between volatiles released during volcanic eruptions and those preserved in melt inclusions from the corresponding lavas has important implications for understanding shallow magmatic processes and for the prediction of eruptions. Some recent work has shown inconsistent relationships between the total mass of SO₂ emitted in an eruption, obtained using spectrometers and other remotely sensed data, and the sulfur content in melt inclusions. These inconsistencies have been attributed to the efficient exsolution and accumulation of SO₂ in a magma body prior to eruption. This process ultimately results in a disparity between melt inclusion and ground-based spectrometry estimates of total mass of sulfur emitted. SO₂ flux has been recorded by the Centro de Intercambio e Investigación en VulcanologÍa (CIIV) for Mexico’s most active volcano, Volcán de Colima, from 1998 to the present. These data have been recorded using the correlation spectrometer, or COSPEC, and a UV spectrometer device, FLYSPEC. An electron microprobe analysis of the sulfur content for melt inclusions in pyroxene and plagioclase phenocrysts was undertaken for rock samples from 1998-1999, 2004, and 2013-2014 andesitic flows and compared to the SO₂ flux library to identify any statistical relationships. Additionally, recent studies have suggested multiple sources for Volcán de Colima magmas. Melt inclusion analysis for the 1869, 1961-1962, and 1975-1976 flows are also being used to investigate the temporal evolution of SO₂ concentrations, magmatic source, and conduit plumbing of Volcán de Colima.