Vesiculation in rhyolite at low H2O contents: A thermodynamic model
We present experimental data on the thermodynamics and kinetics of bubble nucleation and growth in weakly H2O-oversaturated rhyolitic melts. The high-temperature (900-1100°C) experiments involve heating of rhyolitic obsidian from Hrafntinnuhryggur, Krafla, Iceland to above their glass transition tem...
Published in: | Geochemistry, Geophysics, Geosystems |
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Online Access: | http://hdl.handle.net/11375/21523 https://doi.org/10.1002/2015GC006024 |
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ftmcmaster:oai:macsphere.mcmaster.ca:11375/21523 2023-05-15T16:51:26+02:00 Vesiculation in rhyolite at low H2O contents: A thermodynamic model Ryan, Amy G. Russell, James K. Hess, Kai-Uwe Phillion, A.B. Dingwell, Donald B. Materials Science and Engineering 2015-12-21 http://hdl.handle.net/11375/21523 https://doi.org/10.1002/2015GC006024 en eng Wiley Ryan, Amy G., et al. "Vesiculation in rhyolite at low H2O contents: A thermodynamic model." Geochemistry, Geophysics, Geosystems 16.12 (2015): 4292-4310. doi:10.1002/2015GC006024 http://hdl.handle.net/11375/21523 2015 ftmcmaster https://doi.org/10.1002/2015GC006024 2022-03-22T21:14:21Z We present experimental data on the thermodynamics and kinetics of bubble nucleation and growth in weakly H2O-oversaturated rhyolitic melts. The high-temperature (900-1100°C) experiments involve heating of rhyolitic obsidian from Hrafntinnuhryggur, Krafla, Iceland to above their glass transition temperature (Tg ~ 690°C) at 0.1 MPa for times of 0.25-24 hours. During experiments, the rhyolite cores increase in volume as H2O vapour-filled bubbles nucleate and expand. The extent of vesiculation, as tracked by porosity, is mapped in temperature-time (T-t) space. At constant temperature and for a characteristic dwell time, the rhyolite cores achieve a maximum volume where the T-t conditions reach thermochemical equilibrium. For each T-t snapshot of vesiculation, we use 3D analysis of X-ray computed tomographic (XCT) images of the quenched cores to obtain the bubble number density (BND) and bubble size distribution (BSD). BNDs for the experimental cores are insensitive to T and t, indicating a single nucleation event. All BSDs converge to a common distribution, independent of T, melt viscosity (η), or initial degree of saturation, suggesting a common growth process. We use these data to calibrate an empirical model for predicting the rates and amounts of vesiculation in rhyolitic melts as a function of η and thermochemical affinity (A): two computable parameters that are dependent on T, pressure and H2O content. The model reproduces the experimental dataset and data from the literature to within experimental error, and has application to natural volcanic systems where bubble formation and growth are not diffusion limited (e.g., lavas, domes, ignimbrites, conduit infill). Canadian Foundation for Innovation Other/Unknown Material Iceland MacSphere (McMaster University) Krafla ENVELOPE(-16.747,-16.747,65.713,65.713) Hrafntinnuhryggur ENVELOPE(-16.713,-16.713,65.704,65.704) Geochemistry, Geophysics, Geosystems 16 12 4292 4310 |
institution |
Open Polar |
collection |
MacSphere (McMaster University) |
op_collection_id |
ftmcmaster |
language |
English |
description |
We present experimental data on the thermodynamics and kinetics of bubble nucleation and growth in weakly H2O-oversaturated rhyolitic melts. The high-temperature (900-1100°C) experiments involve heating of rhyolitic obsidian from Hrafntinnuhryggur, Krafla, Iceland to above their glass transition temperature (Tg ~ 690°C) at 0.1 MPa for times of 0.25-24 hours. During experiments, the rhyolite cores increase in volume as H2O vapour-filled bubbles nucleate and expand. The extent of vesiculation, as tracked by porosity, is mapped in temperature-time (T-t) space. At constant temperature and for a characteristic dwell time, the rhyolite cores achieve a maximum volume where the T-t conditions reach thermochemical equilibrium. For each T-t snapshot of vesiculation, we use 3D analysis of X-ray computed tomographic (XCT) images of the quenched cores to obtain the bubble number density (BND) and bubble size distribution (BSD). BNDs for the experimental cores are insensitive to T and t, indicating a single nucleation event. All BSDs converge to a common distribution, independent of T, melt viscosity (η), or initial degree of saturation, suggesting a common growth process. We use these data to calibrate an empirical model for predicting the rates and amounts of vesiculation in rhyolitic melts as a function of η and thermochemical affinity (A): two computable parameters that are dependent on T, pressure and H2O content. The model reproduces the experimental dataset and data from the literature to within experimental error, and has application to natural volcanic systems where bubble formation and growth are not diffusion limited (e.g., lavas, domes, ignimbrites, conduit infill). Canadian Foundation for Innovation |
author2 |
Materials Science and Engineering |
author |
Ryan, Amy G. Russell, James K. Hess, Kai-Uwe Phillion, A.B. Dingwell, Donald B. |
spellingShingle |
Ryan, Amy G. Russell, James K. Hess, Kai-Uwe Phillion, A.B. Dingwell, Donald B. Vesiculation in rhyolite at low H2O contents: A thermodynamic model |
author_facet |
Ryan, Amy G. Russell, James K. Hess, Kai-Uwe Phillion, A.B. Dingwell, Donald B. |
author_sort |
Ryan, Amy G. |
title |
Vesiculation in rhyolite at low H2O contents: A thermodynamic model |
title_short |
Vesiculation in rhyolite at low H2O contents: A thermodynamic model |
title_full |
Vesiculation in rhyolite at low H2O contents: A thermodynamic model |
title_fullStr |
Vesiculation in rhyolite at low H2O contents: A thermodynamic model |
title_full_unstemmed |
Vesiculation in rhyolite at low H2O contents: A thermodynamic model |
title_sort |
vesiculation in rhyolite at low h2o contents: a thermodynamic model |
publisher |
Wiley |
publishDate |
2015 |
url |
http://hdl.handle.net/11375/21523 https://doi.org/10.1002/2015GC006024 |
long_lat |
ENVELOPE(-16.747,-16.747,65.713,65.713) ENVELOPE(-16.713,-16.713,65.704,65.704) |
geographic |
Krafla Hrafntinnuhryggur |
geographic_facet |
Krafla Hrafntinnuhryggur |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
Ryan, Amy G., et al. "Vesiculation in rhyolite at low H2O contents: A thermodynamic model." Geochemistry, Geophysics, Geosystems 16.12 (2015): 4292-4310. doi:10.1002/2015GC006024 http://hdl.handle.net/11375/21523 |
op_doi |
https://doi.org/10.1002/2015GC006024 |
container_title |
Geochemistry, Geophysics, Geosystems |
container_volume |
16 |
container_issue |
12 |
container_start_page |
4292 |
op_container_end_page |
4310 |
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1766041550829125632 |