A textural and chemical study of lavas from Villarrica and Llaima Volcanoes, Chile: Evidence for magma recharge and mixing
Leach, Rebecca A.
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Villarrica (39°25' S, 71°57' W) and Llaima (38°42' S, 71°44' W) volcanoes are located in the Southern Volcanic Zone (SVZ) of Chile. They are both basaltic andesite volcanic open systems in which magma recharge and magma mixing are difficult to see because recharge magma and resident magma have similar compositions. In this study, recharge and mixing in these systems have been examined by conducting a detailed textural analysis with an additional analysis of the whole-rock chemistry. These analyses have been conducted on samples from eruptive events from Villarrica volcano (1945, 1971, 1984) compared with the products of the current (background) activity and on an eruptive event from Llaima volcano (1957). Crystal Size Distributions (CSDs) were created to observe textural changes in the samples. Plots comparing CSDs within a flow and between flows show subtle changes that suggest events of textural coarsening and magma mixing though these results are not well constrained. Results from the chemistry data and the textural study indicate that there may have been a recharge event that can be identified from this data.