Abstract

The degassing of bubbly silicic melts controls the explosivity of volcanic eruptions and the formation of obsidian. However, the deformation of bubbles leading up to degassing is not well understood. To examine deformation behavior of bubbles in silicic melts, high-temperature uniaxial deformation experiments were conducted on FOAMGLAS®, a closed-cell glass insulation foam manufactured by Owens Corning. Here, it is used as an analogue for initially impermeable bubbly melts. The microstructure of FOAMGLAS® is homogeneous and consists of regularly shaped bubbles filled with CO2, allowing for easy assessment of changes in foam microstructure with deformation. Additionally, the sample material visibly oxidizes at high temperatures (> 500°C) when in contact with air; oxidized areas in the sample interior indicate connected pathways along which degassing occurs. Uniaxial compression experiments at stresses of 0.13 MPa to 1 MPa and temperatures of 560°C to 570°C were conducted, all of which were above the glass transition at 525°C. Here the relationships among the imposed stresses and temperatures, sample strain, and the magnitudes of strain localization and deformation of bubbles is examine. At lower temperatures, deformation tends to localize in compaction bands, but bubbles in compaction bands only become connected, allowing gas escape, at higher stresses. An understanding of how deformation progresses in bubbly silicic melts with increasing strain at different stress and temperature conditions can allow for a better understanding of what conditions are likely to result in explosive eruptions as opposed to conditions that might favor the formation of obsidian.

Advisor

Judge, Shelley

Department

Geology

Disciplines

Geology | Volcanology

Keywords

FOAMGLAS, uniaxial compression, geology, geosciences, experimental, lab, bubbles, vesicles, obsidian, pumice

Publication Date

2023

Degree Granted

Bachelor of Arts

Document Type

Senior Independent Study Thesis

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© Copyright 2023 Lauren Kreeger