Document Type

Thesis

Degree

Master of Science (MS)

Major/Program

Geosciences

First Advisor's Name

Rosemary Hickey-Vargas

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Grenville Draper

Second Advisor's Committee Title

Commitee member

Third Advisor's Name

Andrew Macfarlane

Third Advisor's Committee Title

Committee member

Keywords

Cordon Caulle, Volcano, historic eruptions, temperature, water content

Date of Defense

6-28-2019

Abstract

For better understanding of Plinian-hybrid eruptive events, I analyzed the variables that affect the pre-eruptive conditions of the latest three eruptive events of the Puyehue Cordon Caulle Volcanic Complex (PCCVC). The analysis was done by performing a petrological study of lava samples followed by Electron Probe Microanalysis (EPMA) on selected mineral phases. Mineral data were then used in established mathematical models to calculate pre-eruptive magma temperature and water content. The acquired data are compared to bulk measured water content, and the difference is utilized to estimate viscosities and evaluate the degassing regime. Results indicate that the historic eruptive events have similar bulk composition and pre-eruptive variables; the 2011 event has slightly lower temperature and higher water content. However, the differences do not suggest that the eruptive style varies in accordance with the variable changes but instead is controlled by external factors such as the regional tectonic regime. The influence of deep heat source is also possible.

Identifier

FIDC007806

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