Volcanology Commons^™

Documenting The Origin Of Compositional Diversity Of Subduction Zone Magmatism, Alicudi, Aeolian Arc (Southern Tyrrhenian Sea, Italy) Using In Situ Plagioclase Data, Rachel Hunt

All Master's Theses

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 …

Documenting Magma Evolution Of The Fossa Delle Felci (Salina Island, South Tyrrhenian Sea) By Integrating In Situ Plagioclase Data With Quantitative Modeling, Aaron Mayfield

All Master's Theses

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 …

Petrogenetic Relationship Of The Postcaldera Eruptions Of Mount Mazama, Crater Lake, Oregon; Evolution Of A Sub-Volcanic Magma Chamber Following A Large Silicic Eruption, Michelle Leanna Tebbe

All Master's Theses

Mount Mazama is the volcanic edifice that cataclysmically erupted ~503 km of relatively homogeneous rhyodacite lava ~ 7,700 years ago, forming the caldera known as Crater Lake. Within a few hundred years, andesitic eruptions built three distinct volcanic edifices on the floor of Crater Lake; ~ 3000 years later, rhyodacite eruptions formed a dome (Bacon et al., 2002). How magmatic systems evolve following a shallow, relatively large silicic eruption is the focus of this study. In situ geochemical analysis coupled with high-resolution textural images of plagioclase crystals in the four postcaldera volcanic edifices were used to identify distinct crystal populations …

Documenting Magnatic Processes At Filicudi Island, Aeolian Arc, Italy: Integrating Quantitative Modeling And Plagioclase Textural And In Situ Compositional Data, Michelle Harris

All Master's Theses

Documenting the physiochemical processes that influence magma composition is critical for forecasting eruption styles and managing volcanic hazards. Compositional diversity of magmas develops through recharge, assimilation, and fractional crystallization (RAFC) within subvolcanic magma reservoirs. Integration of MELTS modeling, whole rock, plagioclase textural and in situ elemental and isotopic data from Filicudi Island, Italy allow documentation of the roles and relative chronology that RAFC played in the magmatic evolution and elucidates aspects of the magma plumbing system structure.

Results indicate a polybaric magma plumbing system with deeper (3.5-4 kilobars) and shallower (0.5-1.2 kilobars) storage regions. Within the deeper system, FC acted …