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    Rights statement: This is the author’s version of a work that was accepted for publication in Journal of Volcanology and Geothermal Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Volcanology and Geothermal Research, 411, 2021 DOI: 10.1016/j.jvolgeores.2021.107175

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The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano

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The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano. / Hodgetts, A.G.E.; McGarvie, D.; Tuffen, H.; Simmons, I.C.

In: Journal of Volcanology and Geothermal Research, Vol. 411, 107175, 31.03.2021.

Research output: Contribution to Journal/MagazineJournal articlepeer-review

Harvard

Hodgetts, AGE, McGarvie, D, Tuffen, H & Simmons, IC 2021, 'The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano', Journal of Volcanology and Geothermal Research, vol. 411, 107175. https://doi.org/10.1016/j.jvolgeores.2021.107175

APA

Hodgetts, A. G. E., McGarvie, D., Tuffen, H., & Simmons, I. C. (2021). The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano. Journal of Volcanology and Geothermal Research, 411, [107175]. https://doi.org/10.1016/j.jvolgeores.2021.107175

Vancouver

Hodgetts AGE, McGarvie D, Tuffen H, Simmons IC. The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano. Journal of Volcanology and Geothermal Research. 2021 Mar 31;411. 107175. https://doi.org/10.1016/j.jvolgeores.2021.107175

Author

Hodgetts, A.G.E. ; McGarvie, D. ; Tuffen, H. ; Simmons, I.C. / The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano. In: Journal of Volcanology and Geothermal Research. 2021 ; Vol. 411.

Bibtex

@article{3874aa07d397436cb87c926b4afd54d4,
title = "The Th{\'o}r{\'o}lfsfell tuya, South Iceland – A new type of basaltic glaciovolcano",
abstract = "Basaltic tuyas are glaciovolcanoes that form when substantial focused eruptions take place beneath thick ice. None have been witnessed, so models reconstructing tuya formation are grounded in detailed fieldwork. A key feature of many basaltic tuyas is the presence of volcanic and volcaniclastic rocks that indicate the sustained presence of an encircling meltwater lake during the eruption. Here we provide the first description of {\TH}{\'o}r{\'o}lfsfell (Th{\'o}r{\'o}lfsfell), a basaltic tuya from Iceland, which is sufficiently distinct from previously described tuyas to be considered a new type of basaltic glaciovolcano. Th{\'o}r{\'o}lfsfell is an asymmetric tuya with an area of c.8 km2, base-to-top height of c.450 m, and volume of c.2.2 ± 0.4 km3 that has been emplaced onto the approximately 12o sloping lower southern flanks of Tindfjallaj{\"o}kull central volcano. Th{\'o}r{\'o}lfsfell shares only two major morphological characteristics with other basaltic tuyas: (1) a sub-horizontal top comprising subaerial lavas; (2) a clear vertical topographic expression, which reflects preferential upwards edifice growth due to lateral confinement by encircling ice and/or meltwater. There is no evidence for the presence of a large and long-lived syn-eruptive meltwater lake. The Th{\'o}r{\'o}lfsfell eruption is effusion-dominated, and there is a gradual reduction in cooling fractures in lavas with elevation. The eruption is divided into three Stages. Stage I forms a c.110 m thick drape onto an irregular but persistently c.12o dipping basement of older basaltic tuffs; Stage I consists of palaeoslope-parallel lava lobes with abundant cooling fractures, accompanied by abundant breccias. Stage II comprises a c.240 m thick stack of c.12o dipping stacked lava lobes with abundant cooling fractures, and occasional autobreccias. Stage III is c.110 m thick, and whilst early lavas have cooling fractures, the final Stage III lavas are sub-horizontal, subaerial pahoehoe lava flows. Our model for the formation of Th{\'o}r{\'o}lfsfell has two key features. The first is that the inclined basement has facilitated the downslope movement of meltwater away from the eruption site into an efficient gravity-assisted subglacial meltwater drainage system. The second is that there is a close connection between the vertical growth of the tuya and the ice above, with each successive lava in the growing stack being close to and/or in contact with the overlying ice. This repeated process provides the regular (but transient) meltwater supply necessary to produce a c.350 m stack of similarly-cooled lava carapaces. From a hazards perspective, a Th{\'o}r{\'o}lfsfell-style eruption is of little concern as rapid and steady meltwater drainage away from the eruption site would prevent the high-magnitude glacial outburst floods that require accumulated meltwater. The Th{\'o}r{\'o}lfsfell eruption provides a new perspective on effective meltwater dispersal away from tuya-building eruptions on dipping palaeoslopes, and on lava-ice interactions during subglacial eruptions. The products of other subglacial eruptions onto dipping basements, producing Th{\'o}r{\'o}lfsfell-type tuyas, await study. This first description of a new type of basaltic glaciovolcano may aid in the identification and interpretation of similar glaciovolcanoes on Earth and Mars that have yet to be discovered. ",
keywords = "Basaltic, Effusion-Dominated, Glaciovolcanism, Lava sheets, Palaeoslope, Stacked Lava Lobes, Tuya, Basalt, Buildings, Cooling, Fracture, Lakes, Volcanoes, Glacial outburst floods, Gravity-assisted, Ice interactions, Identification and Interpretation, Lateral confinement, Morphological characteristic, Subglacial meltwater, Volcaniclastics, Ice",
author = "A.G.E. Hodgetts and D. McGarvie and H. Tuffen and I.C. Simmons",
note = "This is the author{\textquoteright}s version of a work that was accepted for publication in Journal of Volcanology and Geothermal Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Volcanology and Geothermal Research, 411, 2021 DOI: 10.1016/j.jvolgeores.2021.107175",
year = "2021",
month = mar,
day = "31",
doi = "10.1016/j.jvolgeores.2021.107175",
language = "English",
volume = "411",
journal = "Journal of Volcanology and Geothermal Research",
issn = "0377-0273",
publisher = "Elsevier Science B.V.",

}

RIS

TY - JOUR

T1 - The Thórólfsfell tuya, South Iceland – A new type of basaltic glaciovolcano

AU - Hodgetts, A.G.E.

AU - McGarvie, D.

AU - Tuffen, H.

AU - Simmons, I.C.

N1 - This is the author’s version of a work that was accepted for publication in Journal of Volcanology and Geothermal Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Volcanology and Geothermal Research, 411, 2021 DOI: 10.1016/j.jvolgeores.2021.107175

PY - 2021/3/31

Y1 - 2021/3/31

N2 - Basaltic tuyas are glaciovolcanoes that form when substantial focused eruptions take place beneath thick ice. None have been witnessed, so models reconstructing tuya formation are grounded in detailed fieldwork. A key feature of many basaltic tuyas is the presence of volcanic and volcaniclastic rocks that indicate the sustained presence of an encircling meltwater lake during the eruption. Here we provide the first description of Þórólfsfell (Thórólfsfell), a basaltic tuya from Iceland, which is sufficiently distinct from previously described tuyas to be considered a new type of basaltic glaciovolcano. Thórólfsfell is an asymmetric tuya with an area of c.8 km2, base-to-top height of c.450 m, and volume of c.2.2 ± 0.4 km3 that has been emplaced onto the approximately 12o sloping lower southern flanks of Tindfjallajökull central volcano. Thórólfsfell shares only two major morphological characteristics with other basaltic tuyas: (1) a sub-horizontal top comprising subaerial lavas; (2) a clear vertical topographic expression, which reflects preferential upwards edifice growth due to lateral confinement by encircling ice and/or meltwater. There is no evidence for the presence of a large and long-lived syn-eruptive meltwater lake. The Thórólfsfell eruption is effusion-dominated, and there is a gradual reduction in cooling fractures in lavas with elevation. The eruption is divided into three Stages. Stage I forms a c.110 m thick drape onto an irregular but persistently c.12o dipping basement of older basaltic tuffs; Stage I consists of palaeoslope-parallel lava lobes with abundant cooling fractures, accompanied by abundant breccias. Stage II comprises a c.240 m thick stack of c.12o dipping stacked lava lobes with abundant cooling fractures, and occasional autobreccias. Stage III is c.110 m thick, and whilst early lavas have cooling fractures, the final Stage III lavas are sub-horizontal, subaerial pahoehoe lava flows. Our model for the formation of Thórólfsfell has two key features. The first is that the inclined basement has facilitated the downslope movement of meltwater away from the eruption site into an efficient gravity-assisted subglacial meltwater drainage system. The second is that there is a close connection between the vertical growth of the tuya and the ice above, with each successive lava in the growing stack being close to and/or in contact with the overlying ice. This repeated process provides the regular (but transient) meltwater supply necessary to produce a c.350 m stack of similarly-cooled lava carapaces. From a hazards perspective, a Thórólfsfell-style eruption is of little concern as rapid and steady meltwater drainage away from the eruption site would prevent the high-magnitude glacial outburst floods that require accumulated meltwater. The Thórólfsfell eruption provides a new perspective on effective meltwater dispersal away from tuya-building eruptions on dipping palaeoslopes, and on lava-ice interactions during subglacial eruptions. The products of other subglacial eruptions onto dipping basements, producing Thórólfsfell-type tuyas, await study. This first description of a new type of basaltic glaciovolcano may aid in the identification and interpretation of similar glaciovolcanoes on Earth and Mars that have yet to be discovered.

AB - Basaltic tuyas are glaciovolcanoes that form when substantial focused eruptions take place beneath thick ice. None have been witnessed, so models reconstructing tuya formation are grounded in detailed fieldwork. A key feature of many basaltic tuyas is the presence of volcanic and volcaniclastic rocks that indicate the sustained presence of an encircling meltwater lake during the eruption. Here we provide the first description of Þórólfsfell (Thórólfsfell), a basaltic tuya from Iceland, which is sufficiently distinct from previously described tuyas to be considered a new type of basaltic glaciovolcano. Thórólfsfell is an asymmetric tuya with an area of c.8 km2, base-to-top height of c.450 m, and volume of c.2.2 ± 0.4 km3 that has been emplaced onto the approximately 12o sloping lower southern flanks of Tindfjallajökull central volcano. Thórólfsfell shares only two major morphological characteristics with other basaltic tuyas: (1) a sub-horizontal top comprising subaerial lavas; (2) a clear vertical topographic expression, which reflects preferential upwards edifice growth due to lateral confinement by encircling ice and/or meltwater. There is no evidence for the presence of a large and long-lived syn-eruptive meltwater lake. The Thórólfsfell eruption is effusion-dominated, and there is a gradual reduction in cooling fractures in lavas with elevation. The eruption is divided into three Stages. Stage I forms a c.110 m thick drape onto an irregular but persistently c.12o dipping basement of older basaltic tuffs; Stage I consists of palaeoslope-parallel lava lobes with abundant cooling fractures, accompanied by abundant breccias. Stage II comprises a c.240 m thick stack of c.12o dipping stacked lava lobes with abundant cooling fractures, and occasional autobreccias. Stage III is c.110 m thick, and whilst early lavas have cooling fractures, the final Stage III lavas are sub-horizontal, subaerial pahoehoe lava flows. Our model for the formation of Thórólfsfell has two key features. The first is that the inclined basement has facilitated the downslope movement of meltwater away from the eruption site into an efficient gravity-assisted subglacial meltwater drainage system. The second is that there is a close connection between the vertical growth of the tuya and the ice above, with each successive lava in the growing stack being close to and/or in contact with the overlying ice. This repeated process provides the regular (but transient) meltwater supply necessary to produce a c.350 m stack of similarly-cooled lava carapaces. From a hazards perspective, a Thórólfsfell-style eruption is of little concern as rapid and steady meltwater drainage away from the eruption site would prevent the high-magnitude glacial outburst floods that require accumulated meltwater. The Thórólfsfell eruption provides a new perspective on effective meltwater dispersal away from tuya-building eruptions on dipping palaeoslopes, and on lava-ice interactions during subglacial eruptions. The products of other subglacial eruptions onto dipping basements, producing Thórólfsfell-type tuyas, await study. This first description of a new type of basaltic glaciovolcano may aid in the identification and interpretation of similar glaciovolcanoes on Earth and Mars that have yet to be discovered.

KW - Basaltic

KW - Effusion-Dominated

KW - Glaciovolcanism

KW - Lava sheets

KW - Palaeoslope

KW - Stacked Lava Lobes

KW - Tuya

KW - Basalt

KW - Buildings

KW - Cooling

KW - Fracture

KW - Lakes

KW - Volcanoes

KW - Glacial outburst floods

KW - Gravity-assisted

KW - Ice interactions

KW - Identification and Interpretation

KW - Lateral confinement

KW - Morphological characteristic

KW - Subglacial meltwater

KW - Volcaniclastics

KW - Ice

U2 - 10.1016/j.jvolgeores.2021.107175

DO - 10.1016/j.jvolgeores.2021.107175

M3 - Journal article

VL - 411

JO - Journal of Volcanology and Geothermal Research

JF - Journal of Volcanology and Geothermal Research

SN - 0377-0273

M1 - 107175

ER -