Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland
Several broadly circular structures up to 16 m in diameter, into which higher strata have sagged and locally collapsed, are present in a tephra outcrop on southwest Öræfajökull, southern Iceland. The tephra was sourced in a nearby basaltic tuff cone at Varða. The structures have not previously been...
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ftpubmed:oai:pubmedcentral.nih.gov:7175720 2023-05-15T16:38:18+02:00 Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland Smellie, J. L. Walker, A. J. McGarvie, D. W. Burgess, R. 2016-08-01 http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175720/ https://doi.org/10.1007/s00445-016-1048-x en eng Springer Berlin Heidelberg http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175720/ http://dx.doi.org/10.1007/s00445-016-1048-x © The Author(s) 2016 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. CC-BY Research Article Text 2016 ftpubmed https://doi.org/10.1007/s00445-016-1048-x 2020-05-03T00:33:26Z Several broadly circular structures up to 16 m in diameter, into which higher strata have sagged and locally collapsed, are present in a tephra outcrop on southwest Öræfajökull, southern Iceland. The tephra was sourced in a nearby basaltic tuff cone at Varða. The structures have not previously been described in tuff cones, and they probably formed by the melting out of large buried blocks of ice emplaced during a preceding jökulhlaup that may have been triggered by a subglacial eruption within the Öræfajökull ice cap. They are named ice-melt subsidence structures, and they are analogous to kettle holes that are commonly found in proglacial sandurs and some lahars sourced in ice-clad volcanoes. The internal structure is better exposed in the Varða examples because of an absence of fluvial infilling and reworking, and erosion of the outcrop to reveal the deeper geometry. The ice-melt subsidence structures at Varða are a proxy for buried ice. They are the only known evidence for a subglacial eruption and associated jökulhlaup that created the ice blocks. The recognition of such structures elsewhere will be useful in reconstructing more complete regional volcanic histories as well as for identifying ice-proximal settings during palaeoenvironmental investigations. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00445-016-1048-x) contains supplementary material, which is available to authorized users. Text Ice cap Iceland PubMed Central (PMC) Bulletin of Volcanology 78 8 |
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English |
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Research Article |
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Research Article Smellie, J. L. Walker, A. J. McGarvie, D. W. Burgess, R. Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland |
topic_facet |
Research Article |
description |
Several broadly circular structures up to 16 m in diameter, into which higher strata have sagged and locally collapsed, are present in a tephra outcrop on southwest Öræfajökull, southern Iceland. The tephra was sourced in a nearby basaltic tuff cone at Varða. The structures have not previously been described in tuff cones, and they probably formed by the melting out of large buried blocks of ice emplaced during a preceding jökulhlaup that may have been triggered by a subglacial eruption within the Öræfajökull ice cap. They are named ice-melt subsidence structures, and they are analogous to kettle holes that are commonly found in proglacial sandurs and some lahars sourced in ice-clad volcanoes. The internal structure is better exposed in the Varða examples because of an absence of fluvial infilling and reworking, and erosion of the outcrop to reveal the deeper geometry. The ice-melt subsidence structures at Varða are a proxy for buried ice. They are the only known evidence for a subglacial eruption and associated jökulhlaup that created the ice blocks. The recognition of such structures elsewhere will be useful in reconstructing more complete regional volcanic histories as well as for identifying ice-proximal settings during palaeoenvironmental investigations. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00445-016-1048-x) contains supplementary material, which is available to authorized users. |
format |
Text |
author |
Smellie, J. L. Walker, A. J. McGarvie, D. W. Burgess, R. |
author_facet |
Smellie, J. L. Walker, A. J. McGarvie, D. W. Burgess, R. |
author_sort |
Smellie, J. L. |
title |
Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland |
title_short |
Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland |
title_full |
Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland |
title_fullStr |
Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland |
title_full_unstemmed |
Complex circular subsidence structures in tephra deposited on large blocks of ice: Varða tuff cone, Öræfajökull, Iceland |
title_sort |
complex circular subsidence structures in tephra deposited on large blocks of ice: varða tuff cone, öræfajökull, iceland |
publisher |
Springer Berlin Heidelberg |
publishDate |
2016 |
url |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175720/ https://doi.org/10.1007/s00445-016-1048-x |
genre |
Ice cap Iceland |
genre_facet |
Ice cap Iceland |
op_relation |
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175720/ http://dx.doi.org/10.1007/s00445-016-1048-x |
op_rights |
© The Author(s) 2016 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.1007/s00445-016-1048-x |
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Bulletin of Volcanology |
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78 |
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8 |
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