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Water solubility and bubble growth dynamics in rhyolitic silicate melts at atmospheric pressure Ryan, Amy
Abstract
This thesis is a high-temperature, low-pressure experimental study that quantifies the temperature-dependence of water (H₂O) solubility in a rhyolitic melt at atmospheric pressure, and assesses the sensitivity of the water exsolution and bubble growth processes to thermodynamic and kinetic parameters. In the investigation of H₂O solubility I defined the magnitude of retrograde solubility (-7.1x10-³ wt% H₂O per 100°C) and estimated the enthalpy and entropy of the H₂O exsolution reaction (ΔH⁰ = +17.8 kJ mol-¹, ΔS⁰ = 107 J K-¹ mol-¹). I also modelled the implications of retrograde solubility for the glass transition temperature (Tg) and outline the potential effect on cooling volcanic bodies at surface- and conduit-relevant pressures if cooling is slow enough to facilitate H2O resorption. In my investigation of bubble growth dynamics and the vesiculation process in my experimental products I recalibrated the estimates of H₂O exsolution enthalpy and entropy (ΔH⁰ = +18.5 kJ mol-¹, ΔS⁰ = 108 J K-¹ mol-¹). Additionally I identified the viscosity (η) dependence of average volumetric growth rate (dV/dt) (log dV/dt = -0.79 log η + 4.95) and have calculated the time to develop 60% porosity for melts of varying viscosities at conduit-relevant pressures that are up to 15% oversaturated with H₂O. By dismantling a complex system and individually investigating the behaviours of dissolved and exsolved H₂O I have developed models that can be used to study volcanic hazards past, present and future.
Item Metadata
Title |
Water solubility and bubble growth dynamics in rhyolitic silicate melts at atmospheric pressure
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Creator | |
Publisher |
University of British Columbia
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Date Issued |
2014
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Description |
This thesis is a high-temperature, low-pressure experimental study that quantifies the temperature-dependence of water (H₂O) solubility in a rhyolitic melt at atmospheric pressure, and assesses the sensitivity of the water exsolution and bubble growth processes to thermodynamic and kinetic parameters. In the investigation of H₂O solubility I defined the magnitude of retrograde solubility (-7.1x10-³ wt% H₂O per 100°C) and estimated the enthalpy and entropy of the H₂O exsolution reaction (ΔH⁰ = +17.8 kJ mol-¹, ΔS⁰ = 107 J K-¹ mol-¹). I also modelled the implications of retrograde solubility for the glass transition temperature (Tg) and outline the potential effect on cooling volcanic bodies at surface- and conduit-relevant pressures if cooling is slow enough to facilitate H2O resorption. In my investigation of bubble growth dynamics and the vesiculation process in my experimental products I recalibrated the estimates of H₂O exsolution enthalpy and entropy (ΔH⁰ = +18.5 kJ mol-¹, ΔS⁰ = 108 J K-¹ mol-¹). Additionally I identified the viscosity (η) dependence of average volumetric growth rate (dV/dt) (log dV/dt = -0.79 log η + 4.95) and have calculated the time to develop 60% porosity for melts of varying viscosities at conduit-relevant pressures that are up to 15% oversaturated with H₂O. By dismantling a complex system and individually investigating the behaviours of dissolved and exsolved H₂O I have developed models that can be used to study volcanic hazards past, present and future.
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Genre | |
Type | |
Language |
eng
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Date Available |
2014-11-19
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Provider |
Vancouver : University of British Columbia Library
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Rights |
Attribution-NonCommercial-NoDerivs 2.5 Canada
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DOI |
10.14288/1.0165561
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URI | |
Degree | |
Program | |
Affiliation | |
Degree Grantor |
University of British Columbia
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Graduation Date |
2015-02
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Campus | |
Scholarly Level |
Graduate
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Rights URI | |
Aggregated Source Repository |
DSpace
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Rights
Attribution-NonCommercial-NoDerivs 2.5 Canada