Silicic volcanism at Ljosufjoll, Iceland: Insights into evolution and eruptive history from Ar-Ar dating

Stephanie Flude, R. Burgess, D. W. McGarvie

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

Resumé

Ljosufjoll volcano is the largest outcrop of silicic volcanic material in the volcanic Snaefellsnes flank (non-rifting) zone of Iceland. The silicic eruptives range from trachytes to alkaline and peralkaline (comenditic) rhyolites and show evidence for eruption in both subaerial and subglacial environments. Thirteen silicic eruptive units have been identified and mapped by a combination of field observations and geochemical correlation. The trachytes probably formed by fractional crystallisation of a basaltic magma to form an alkali feldspar-rich trachytic mush, with continued fractionation of the interstitial melt producing low Ba and Sr rhyolite magma. Ar-Ar dating of feldspars and matrix (glass or holocrystalline groundmass) has been carried out on twelve of the units. Many units have a complex Ar-isotopic system, with many samples showing evidence for inherited Ar-40 in the form of feldspar xenocrysts. The deduced eruption ages span an age range from < 129ka to > 650ka. The eruptive history of Ljosufjoll probably extends further back than this but the products of previous eruptions have since been removed by erosion or buried. A syenite xenolith was dated at 1.1Ma, indicating that silicic, alkaline magmatism has been occurring at Ljosufjoll for over one million years. Eruptions of silicic material at Ljosufjoll appear to be more common during times of rapid climate change and fluctuating ice volume. (C) 2007 Elsevier B.V. All rights reserved.
OriginalsprogEngelsk
TidsskriftJournal of Volcanology and Geothermal Research
Vol/bind169
Udgave nummer3-4
Sider (fra-til)154
Antal sider175
ISSN0377-0273
DOI
StatusUdgivet - 2008
Udgivet eksterntJa

Citer dette

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title = "Silicic volcanism at Ljosufjoll, Iceland: Insights into evolution and eruptive history from Ar-Ar dating",
abstract = "Ljosufjoll volcano is the largest outcrop of silicic volcanic material in the volcanic Snaefellsnes flank (non-rifting) zone of Iceland. The silicic eruptives range from trachytes to alkaline and peralkaline (comenditic) rhyolites and show evidence for eruption in both subaerial and subglacial environments. Thirteen silicic eruptive units have been identified and mapped by a combination of field observations and geochemical correlation. The trachytes probably formed by fractional crystallisation of a basaltic magma to form an alkali feldspar-rich trachytic mush, with continued fractionation of the interstitial melt producing low Ba and Sr rhyolite magma. Ar-Ar dating of feldspars and matrix (glass or holocrystalline groundmass) has been carried out on twelve of the units. Many units have a complex Ar-isotopic system, with many samples showing evidence for inherited Ar-40 in the form of feldspar xenocrysts. The deduced eruption ages span an age range from < 129ka to > 650ka. The eruptive history of Ljosufjoll probably extends further back than this but the products of previous eruptions have since been removed by erosion or buried. A syenite xenolith was dated at 1.1Ma, indicating that silicic, alkaline magmatism has been occurring at Ljosufjoll for over one million years. Eruptions of silicic material at Ljosufjoll appear to be more common during times of rapid climate change and fluctuating ice volume. (C) 2007 Elsevier B.V. All rights reserved.",
author = "Stephanie Flude and R. Burgess and McGarvie, {D. W.}",
year = "2008",
doi = "10.1016/j.jvolgeores.2007.08.019",
language = "English",
volume = "169",
pages = "154",
journal = "Journal of Volcanology and Geothermal Research",
issn = "0377-0273",
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Silicic volcanism at Ljosufjoll, Iceland: Insights into evolution and eruptive history from Ar-Ar dating. / Flude, Stephanie; Burgess, R.; McGarvie, D. W.

I: Journal of Volcanology and Geothermal Research, Bind 169, Nr. 3-4, 2008, s. 154.

Publikation: Bidrag til tidsskriftTidsskriftartikelForskningpeer review

TY - JOUR

T1 - Silicic volcanism at Ljosufjoll, Iceland: Insights into evolution and eruptive history from Ar-Ar dating

AU - Flude, Stephanie

AU - Burgess, R.

AU - McGarvie, D. W.

PY - 2008

Y1 - 2008

N2 - Ljosufjoll volcano is the largest outcrop of silicic volcanic material in the volcanic Snaefellsnes flank (non-rifting) zone of Iceland. The silicic eruptives range from trachytes to alkaline and peralkaline (comenditic) rhyolites and show evidence for eruption in both subaerial and subglacial environments. Thirteen silicic eruptive units have been identified and mapped by a combination of field observations and geochemical correlation. The trachytes probably formed by fractional crystallisation of a basaltic magma to form an alkali feldspar-rich trachytic mush, with continued fractionation of the interstitial melt producing low Ba and Sr rhyolite magma. Ar-Ar dating of feldspars and matrix (glass or holocrystalline groundmass) has been carried out on twelve of the units. Many units have a complex Ar-isotopic system, with many samples showing evidence for inherited Ar-40 in the form of feldspar xenocrysts. The deduced eruption ages span an age range from < 129ka to > 650ka. The eruptive history of Ljosufjoll probably extends further back than this but the products of previous eruptions have since been removed by erosion or buried. A syenite xenolith was dated at 1.1Ma, indicating that silicic, alkaline magmatism has been occurring at Ljosufjoll for over one million years. Eruptions of silicic material at Ljosufjoll appear to be more common during times of rapid climate change and fluctuating ice volume. (C) 2007 Elsevier B.V. All rights reserved.

AB - Ljosufjoll volcano is the largest outcrop of silicic volcanic material in the volcanic Snaefellsnes flank (non-rifting) zone of Iceland. The silicic eruptives range from trachytes to alkaline and peralkaline (comenditic) rhyolites and show evidence for eruption in both subaerial and subglacial environments. Thirteen silicic eruptive units have been identified and mapped by a combination of field observations and geochemical correlation. The trachytes probably formed by fractional crystallisation of a basaltic magma to form an alkali feldspar-rich trachytic mush, with continued fractionation of the interstitial melt producing low Ba and Sr rhyolite magma. Ar-Ar dating of feldspars and matrix (glass or holocrystalline groundmass) has been carried out on twelve of the units. Many units have a complex Ar-isotopic system, with many samples showing evidence for inherited Ar-40 in the form of feldspar xenocrysts. The deduced eruption ages span an age range from < 129ka to > 650ka. The eruptive history of Ljosufjoll probably extends further back than this but the products of previous eruptions have since been removed by erosion or buried. A syenite xenolith was dated at 1.1Ma, indicating that silicic, alkaline magmatism has been occurring at Ljosufjoll for over one million years. Eruptions of silicic material at Ljosufjoll appear to be more common during times of rapid climate change and fluctuating ice volume. (C) 2007 Elsevier B.V. All rights reserved.

U2 - 10.1016/j.jvolgeores.2007.08.019

DO - 10.1016/j.jvolgeores.2007.08.019

M3 - Journal article

VL - 169

SP - 154

JO - Journal of Volcanology and Geothermal Research

JF - Journal of Volcanology and Geothermal Research

SN - 0377-0273

IS - 3-4

ER -