The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater.
The thermal histories of two subglacial rhyolite glasses from Torfajökull complex of south central Iceland have been determined from changes in the relaxation of enthalpy in the calorimetric glass transition interval. Heat capacity measurements of bulk glass samples from Rauðufossafjöll (sample numb...
Published in: | Journal of Geophysical Research: Solid Earth |
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2004
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Online Access: | https://eprints.lancs.ac.uk/id/eprint/21360/ https://doi.org/10.1029/2003JB002721 |
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ftulancaster:oai:eprints.lancs.ac.uk:21360 2023-08-27T04:10:12+02:00 The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. Wilding, Martin C. Smellie, John Morgan, Sally Lesher, C. E Wilson, Lionel 2004-08-11 https://eprints.lancs.ac.uk/id/eprint/21360/ https://doi.org/10.1029/2003JB002721 unknown Wilding, Martin C. and Smellie, John and Morgan, Sally and Lesher, C. E and Wilson, Lionel (2004) The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. Journal of Geophysical Research: Solid Earth, 109 (B8). B08201. Journal Article PeerReviewed 2004 ftulancaster https://doi.org/10.1029/2003JB002721 2023-08-03T22:18:01Z The thermal histories of two subglacial rhyolite glasses from Torfajökull complex of south central Iceland have been determined from changes in the relaxation of enthalpy in the calorimetric glass transition interval. Heat capacity measurements of bulk glass samples from Rauðufossafjöll (sample number JS.1.1) and Bláhnúkur (sample number JS.2.1) by differential scanning calorimetry show marked differences in the temperature of the onset of glass transition (Tg) on reheating. The average Tg is 750 K for JS.1.1, whereas it is 850 K for JS.2.1. These differences in the onset of Tg are related to quench rate through considerations of the activation energy and timescales for structural relaxation modeled, using the Kohlrausch-Williams-Watt function. Multiple glass samples from the two Torfajökull locations recover different average values and distributions of a fictive temperature, T f , which we interpret in terms of differences in the thermal histories of the glasses. In both glass samples the range of fictive temperatures and, by implication, apparent cooling rates, is lower than those estimated for a glass rapidly quenched by contact with cold (glacial melt) water and requires that the glass was annealed at temperatures in the glass transition interval associated with relaxation times of the order of 1000–10,000 s. The complex cooling histories of the Torfajökull samples show that the products of subglacial eruptions may be held at elevated temperatures for several hours and, as a result, may drive vigorous convection in the ice-bound vaults above erupting rhyolite deposits. Article in Journal/Newspaper Iceland Lancaster University: Lancaster Eprints Bláhnúkur ENVELOPE(-19.069,-19.069,63.977,63.977) Torfajökull ENVELOPE(-19.027,-19.027,63.898,63.898) Journal of Geophysical Research: Solid Earth 109 B8 |
institution |
Open Polar |
collection |
Lancaster University: Lancaster Eprints |
op_collection_id |
ftulancaster |
language |
unknown |
description |
The thermal histories of two subglacial rhyolite glasses from Torfajökull complex of south central Iceland have been determined from changes in the relaxation of enthalpy in the calorimetric glass transition interval. Heat capacity measurements of bulk glass samples from Rauðufossafjöll (sample number JS.1.1) and Bláhnúkur (sample number JS.2.1) by differential scanning calorimetry show marked differences in the temperature of the onset of glass transition (Tg) on reheating. The average Tg is 750 K for JS.1.1, whereas it is 850 K for JS.2.1. These differences in the onset of Tg are related to quench rate through considerations of the activation energy and timescales for structural relaxation modeled, using the Kohlrausch-Williams-Watt function. Multiple glass samples from the two Torfajökull locations recover different average values and distributions of a fictive temperature, T f , which we interpret in terms of differences in the thermal histories of the glasses. In both glass samples the range of fictive temperatures and, by implication, apparent cooling rates, is lower than those estimated for a glass rapidly quenched by contact with cold (glacial melt) water and requires that the glass was annealed at temperatures in the glass transition interval associated with relaxation times of the order of 1000–10,000 s. The complex cooling histories of the Torfajökull samples show that the products of subglacial eruptions may be held at elevated temperatures for several hours and, as a result, may drive vigorous convection in the ice-bound vaults above erupting rhyolite deposits. |
format |
Article in Journal/Newspaper |
author |
Wilding, Martin C. Smellie, John Morgan, Sally Lesher, C. E Wilson, Lionel |
spellingShingle |
Wilding, Martin C. Smellie, John Morgan, Sally Lesher, C. E Wilson, Lionel The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
author_facet |
Wilding, Martin C. Smellie, John Morgan, Sally Lesher, C. E Wilson, Lionel |
author_sort |
Wilding, Martin C. |
title |
The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
title_short |
The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
title_full |
The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
title_fullStr |
The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
title_full_unstemmed |
The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
title_sort |
cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. |
publishDate |
2004 |
url |
https://eprints.lancs.ac.uk/id/eprint/21360/ https://doi.org/10.1029/2003JB002721 |
long_lat |
ENVELOPE(-19.069,-19.069,63.977,63.977) ENVELOPE(-19.027,-19.027,63.898,63.898) |
geographic |
Bláhnúkur Torfajökull |
geographic_facet |
Bláhnúkur Torfajökull |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
Wilding, Martin C. and Smellie, John and Morgan, Sally and Lesher, C. E and Wilson, Lionel (2004) The cooling process recorded in sub-glacially erupted rhyolite glasses: rapid quenching, thermal buffering and the rate of formation of meltwater. Journal of Geophysical Research: Solid Earth, 109 (B8). B08201. |
op_doi |
https://doi.org/10.1029/2003JB002721 |
container_title |
Journal of Geophysical Research: Solid Earth |
container_volume |
109 |
container_issue |
B8 |
_version_ |
1775352070617956352 |