Reconstructing CO2 Concentrations in Basaltic Melt Inclusions from Mafic Cinder Cones Using Raman Analysis of Vapor Bubbles
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Melt inclusions record valuable information about pre-eruptive melt volatile concentrations. However, a vapor bubble commonly forms in inclusions after trapping, and this decreases the dissolved CO2 concentration in the trapped melt. To quantify CO2 loss to bubbles, Raman spectroscopic analysis was used to determine the densities of CO2 vapor in the bubbles. The samples analyzed in this study are from two Cascade cinder cones near Mt. Lassen and two Mexican cinder cones (Jorullo, Paricutin). Using analyses of dissolved CO2 and H2O in the glass in the inclusions, the measured CO2 vapor densities were used to reconstruct the original dissolved CO2 contents of the melt inclusions at the time of trapping. The Raman-restored CO2 values are similar to restored CO2 values calculated using a model of cooling and olivine crystallization in the trapped melts. This thesis includes unpublished co-authored material.