Documenting the Origin of Compositional Diversity of Subduction Zone Magmatism, Alicudi, Aeolian Arc (Southern Tyrrhenian Sea, Italy) Using In Situ Plagioclase Data

Rachel Hunt
May 2012

Abstract

Processes that generate magma compositional diversity are important to document because composition affects degree of explosivity, which impacts hazard mitigation. Magnesium to silicon rich magmas are produced by processes such as magma recharge, assimilation, and fractional crystallization (RAFC) that occur in subvolcanic magma chamber(s). This study evaluates how magma chamber processes contribute to compositional diversity at Alicudi Volcano, Italy. Analytical and petrographic data from ten samples that span the subaerial history include whole rock major and trace elements and strontium/neodymium isotopes, and plagioclase textural types, major and trace elements, and strontium isotopes; numerical modeling was also conducted. Integration of these data suggests that recharge, assimilation, storage at different levels below the volcano, and homogenization occur in Alicudi’s magmatic system. Magma bodies shoaled and coalesced as the volcanic system matured. Understanding the physical and geochemical constraints of magma formation in plumbing systems enhances eruption prediction and hazard mitigation.

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