Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland
Field observations of extinct and exposed magma reservoirs shed light on processes operating in the roots of presently active volcanoes. The Reyðarártindur pluton, Southeast Iceland is an example of a fossil shallow magma reservoir that fed eruptions. The different chapters in this thesis examine th...
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Uppsala universitet, Mineralogi, petrologi och tektonik
2022
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ftuppsalauniv:oai:DiVA.org:uu-472813 2023-05-15T16:49:39+02:00 Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland Rhodes, Emma 2022 application/pdf http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-472813 eng eng Uppsala universitet, Mineralogi, petrologi och tektonik Centre of Natural Hazards and Disaster Science Uppsala Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 2151 orcid:0000-0002-5006-5596 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-472813 urn:isbn:978-91-513-1505-8 info:eu-repo/semantics/openAccess magma magma emplacement magma reservoir floor subsidence piecemeal subsidence granite pluton cap-rock magma mingling magma plumbing systems volcanic and igneous plumbing systems eruption Geology Geologi Doctoral thesis, comprehensive summary info:eu-repo/semantics/doctoralThesis text 2022 ftuppsalauniv 2023-02-23T21:59:24Z Field observations of extinct and exposed magma reservoirs shed light on processes operating in the roots of presently active volcanoes. The Reyðarártindur pluton, Southeast Iceland is an example of a fossil shallow magma reservoir that fed eruptions. The different chapters in this thesis examine the accumulation of magma, and processes occurring during the development and evolution of the magma reservoir from different methodological perspectives. A final model for the evolution of the Reyðarártindur pluton is then presented. The majority of the pluton consists of one voluminous rock unit, the Main Granite, that formed by rapid magma emplacement. However, a local zone of geochemically distinct, but related further Granite Enclaves and Quartz Monzonite Enclaves attest to variations in the composition of the underlying source reservoir. Space for the ca. 2.5 km3 of magma in the pluton was made by piecemeal floor subsidence, which began with multiple dykes that then propagated laterally to form flat-roofed intrusions at different depths. During the first stages of magma emplacement, shattering, sintering and sanidinite-facies contact metamorphism affected a ca. 10 m thick zone of the basalt host rock at the magma reservoir roof. The resulting hornfels was stronger than the original altered basalt, and contained zero porosity and permeability. It thus formed a ‘cap-rock’ to the magma reservoir, limiting heat, volatile and fluid transfer until fractured and faulted at a later stage. The magma reservoir erupted at least once, causing local subsidence of the roof, which would have been observable at the Earth’s surface. Recharge of the magma reservoir by the same Quartz Monzonite and further Granite as exposed in the Reyðará River led to overpressure and eruption. We envisage that cooling and sealing of the piecemeal subsidence network preceded eruption, causing overpressure with magma recharge. The eruptive lifetime of the magma reservoir was limited to ca. 1000 years. This timeframe is much less than the duration of ... Doctoral or Postdoctoral Thesis Iceland Uppsala University: Publications (DiVA) Reyðarártindur ENVELOPE(-14.725,-14.725,64.437,64.437) |
institution |
Open Polar |
collection |
Uppsala University: Publications (DiVA) |
op_collection_id |
ftuppsalauniv |
language |
English |
topic |
magma magma emplacement magma reservoir floor subsidence piecemeal subsidence granite pluton cap-rock magma mingling magma plumbing systems volcanic and igneous plumbing systems eruption Geology Geologi |
spellingShingle |
magma magma emplacement magma reservoir floor subsidence piecemeal subsidence granite pluton cap-rock magma mingling magma plumbing systems volcanic and igneous plumbing systems eruption Geology Geologi Rhodes, Emma Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland |
topic_facet |
magma magma emplacement magma reservoir floor subsidence piecemeal subsidence granite pluton cap-rock magma mingling magma plumbing systems volcanic and igneous plumbing systems eruption Geology Geologi |
description |
Field observations of extinct and exposed magma reservoirs shed light on processes operating in the roots of presently active volcanoes. The Reyðarártindur pluton, Southeast Iceland is an example of a fossil shallow magma reservoir that fed eruptions. The different chapters in this thesis examine the accumulation of magma, and processes occurring during the development and evolution of the magma reservoir from different methodological perspectives. A final model for the evolution of the Reyðarártindur pluton is then presented. The majority of the pluton consists of one voluminous rock unit, the Main Granite, that formed by rapid magma emplacement. However, a local zone of geochemically distinct, but related further Granite Enclaves and Quartz Monzonite Enclaves attest to variations in the composition of the underlying source reservoir. Space for the ca. 2.5 km3 of magma in the pluton was made by piecemeal floor subsidence, which began with multiple dykes that then propagated laterally to form flat-roofed intrusions at different depths. During the first stages of magma emplacement, shattering, sintering and sanidinite-facies contact metamorphism affected a ca. 10 m thick zone of the basalt host rock at the magma reservoir roof. The resulting hornfels was stronger than the original altered basalt, and contained zero porosity and permeability. It thus formed a ‘cap-rock’ to the magma reservoir, limiting heat, volatile and fluid transfer until fractured and faulted at a later stage. The magma reservoir erupted at least once, causing local subsidence of the roof, which would have been observable at the Earth’s surface. Recharge of the magma reservoir by the same Quartz Monzonite and further Granite as exposed in the Reyðará River led to overpressure and eruption. We envisage that cooling and sealing of the piecemeal subsidence network preceded eruption, causing overpressure with magma recharge. The eruptive lifetime of the magma reservoir was limited to ca. 1000 years. This timeframe is much less than the duration of ... |
format |
Doctoral or Postdoctoral Thesis |
author |
Rhodes, Emma |
author_facet |
Rhodes, Emma |
author_sort |
Rhodes, Emma |
title |
Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland |
title_short |
Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland |
title_full |
Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland |
title_fullStr |
Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland |
title_full_unstemmed |
Evolution of a silicic magma reservoir in the upper crust : Reyðarártindur pluton, Southeast Iceland |
title_sort |
evolution of a silicic magma reservoir in the upper crust : reyðarártindur pluton, southeast iceland |
publisher |
Uppsala universitet, Mineralogi, petrologi och tektonik |
publishDate |
2022 |
url |
http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-472813 |
long_lat |
ENVELOPE(-14.725,-14.725,64.437,64.437) |
geographic |
Reyðarártindur |
geographic_facet |
Reyðarártindur |
genre |
Iceland |
genre_facet |
Iceland |
op_relation |
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 2151 orcid:0000-0002-5006-5596 http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-472813 urn:isbn:978-91-513-1505-8 |
op_rights |
info:eu-repo/semantics/openAccess |
_version_ |
1766039819957305344 |