Documenting Magma Evolution of the Fossa delle Felci (Salina Island, South Tyrrhenian Sea) by Integrating In Situ Plagioclase Data with Quantitative Modeling

Aaron Mayfield
July 2012

Abstract

Compositional diversity occurs via processes dominated by recharge, assimilation and fractional crystallization (RAFC), quantification of which can provide insights into eruption catalysts, and therefore assist in hazard mitigation. This study evaluates the relative roles of RAFC processes in Fossa delle Felci (Salina Island, Italy) magmas, which span the basalt to dacite range (52-65 wt% SiO2). Integration of petrographic, whole rock, and in situ plagioclase data with quantitative magma chamber models suggests differentiation dominated by fractional crystallization and magma recharge/mixing in reservoirs located at different crustal levels. At ~12 km depth, magma evolved through crystallization of a pyroxene dominated assemblage; plagioclase suppression at this depth is indicated by increasing plagioclase Sr concentrations with increasing whole rock SiO2. Magmas shoaled to shallow (~3 km) depths where plagioclase crystallized. Basalt intruded the more silicic chamber and was then erupted, followed by dacites through basaltic andesites.

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