Date of Graduation

Fall 2022

Degree

Master of Natural and Applied Science in Geography, Geology, and Planning

Department

Geography, Geology, and Planning

Committee Chair

Gary Michelfelder

Abstract

Continental arc volcanoes are the single best portrayal of the evolution of recycled earth material stemming from subduction, one of the most important and foundational phenomena in global tectonics. Understanding the genesis of intermediate-composition magmas produced at arc volcanoes is a difficult process making them a focal point for investigation. Geochemical investigation of zircon and plagioclase mineral phases erupted from continental arcs can provide insight into magma process, generation, storage conditions, timescales and differentiation of sub-volcanic plumbing systems prior to eruption events. The Central Volcanic Zone is a prime example of continental arc volcanism through subduction, and is host to one of the largest magma reservoirs in the world, the Altiplano-Puna Magma Body (APMB). Specifically, Volcán Ollagüe, a continental arc volcano located on some of the thickest continental crust in the world (60-75km) and producing intermediate composition magmas is a prime candidate to investigate the magma source and storage conditions of intermediate-composition lavas and their interactions with the APMB. Using ⁴⁰Ar/³⁹Ar eruption ages, U-Pb zircon crystallization ages, and zircon trace element contents I assess the storage conditions, zircon crystal residence times, and magma accumulation of the erupted magmas at Ollagüe. Additionally, plagioclase textural and geochemical analysis are used to suggest a model of evolution of the sub-volcanic plumbing system, and magma storage conditions at Ollagüe. These data reveal rejuvenation conditions and the complexities of the plumbing system of Ollagüe. Ultimately these data confirm that compositional hybridization is being controlled through periodic high-to-low volume injections from an external source. With Ollagüe located on the edge of the APMB, it is very likely that the complexities and geochemical constraints of Ollagüe’s magma plumbing system are linked to the APMB

Keywords

Central Andean Volcanic Zone, Ollagüe, geochronology, geochemistry, composite volcanism, Altiplano-Puna Magma Body

Subject Categories

Geochemistry | Geology | Volcanology

Copyright

© Drew Allen Laviada-Garmon

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Open Access

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