Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust
An elementary (major and trace elements) and isotopic (87Sr/86Sr, 143Nd/144Nd and δ18O) geochemical study has been achieved in order to determine and to quantify the petrogenetic mechanisms that gave rise to silicic magmas in Iceland. The target of this approach consists not only of understanding th...
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Language: | French |
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ftclermontuniv:oai:HAL:tel-00717368v1 2023-06-11T04:13:00+02:00 Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust Etude géochimique des magmas acides d'Islande : mode de genèse, implications sur l'évolution géodynamique islandaise et sur la formation de la proto-croûte continentale Martin, Erwan Institut des Sciences de la Terre de Paris (iSTeP) Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) Laboratoire Magmas et Volcans (LMV) Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS) Université Blaise Pascal - Clermont-Ferrand II Olgeir Sigmarsson 2006-12-08 https://theses.hal.science/tel-00717368 https://theses.hal.science/tel-00717368/document https://theses.hal.science/tel-00717368/file/2006CLF21709.pdf fr fre HAL CCSD NNT: 2006CLF21709 tel-00717368 https://theses.hal.science/tel-00717368 https://theses.hal.science/tel-00717368/document https://theses.hal.science/tel-00717368/file/2006CLF21709.pdf info:eu-repo/semantics/OpenAccess https://theses.hal.science/tel-00717368 Sciences de la Terre. Université Blaise Pascal - Clermont-Ferrand II, 2006. Français. ⟨NNT : 2006CLF21709⟩ volcanisme Islande [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/doctoralThesis Theses 2006 ftclermontuniv 2023-05-02T22:42:20Z An elementary (major and trace elements) and isotopic (87Sr/86Sr, 143Nd/144Nd and δ18O) geochemical study has been achieved in order to determine and to quantify the petrogenetic mechanisms that gave rise to silicic magmas in Iceland. The target of this approach consists not only of understanding the genesis of these magmas but also in addressing their significance in terms of Iceland geodynamic evolution. The main results of this thesis are as follows: In course of Iceland history, most of the silicic rocks appear to have been generated by partial melting of the hydrated metabasaltic crust in a rift zone environment. In this place, the interaction between hot spot and mid-oceanic ridge is important resulting in a geothermal gradient high enough to exceed the solidus temperature of the partially hydrated basaltic crust. However, at the periphery of the island (i.e. Snæfellsnes Peninsula and Öræfajökull volcanic system), far from both the mantle plume centre and the rift-zone, the geothermal gradient is lower, precluding to step over the solidus temperature of hydrated metabasalts. This situation favoured the genesis of silicic magmas by fractional crystallisation (with possibly slight crustal assimilation).The link that exists between the composition of silicic rocks and the geodynamic environment of their genesis has been used together with age determination in order to establish the time-space geodynamic evolution of Iceland. The proposed model is based on the fact that mid-Atlantic ridge migrate relatively to the plume centre and on the "accretion - over lapping" mechanism that best accounts for the abnormally great width of Iceland. Iceland demonstrates that oceanic plateaus can give rise to significant volumes (towards 10%) of silicic magmas; in other words, it can be a potential environment for continental crust genesis in a purely oceanic environment. A comparison between these "continental" rock compositions from recent oceanic plateaus and primitive continental crust one (TTG) shows that, in spite of ... Doctoral or Postdoctoral Thesis Iceland Islande HAL Clermont Auvergne (Université Blaise Pascal Clermont-Ferrand/Université d'Auvergne) Mid-Atlantic Ridge |
institution |
Open Polar |
collection |
HAL Clermont Auvergne (Université Blaise Pascal Clermont-Ferrand/Université d'Auvergne) |
op_collection_id |
ftclermontuniv |
language |
French |
topic |
volcanisme Islande [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
spellingShingle |
volcanisme Islande [SDU.STU]Sciences of the Universe [physics]/Earth Sciences Martin, Erwan Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust |
topic_facet |
volcanisme Islande [SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
An elementary (major and trace elements) and isotopic (87Sr/86Sr, 143Nd/144Nd and δ18O) geochemical study has been achieved in order to determine and to quantify the petrogenetic mechanisms that gave rise to silicic magmas in Iceland. The target of this approach consists not only of understanding the genesis of these magmas but also in addressing their significance in terms of Iceland geodynamic evolution. The main results of this thesis are as follows: In course of Iceland history, most of the silicic rocks appear to have been generated by partial melting of the hydrated metabasaltic crust in a rift zone environment. In this place, the interaction between hot spot and mid-oceanic ridge is important resulting in a geothermal gradient high enough to exceed the solidus temperature of the partially hydrated basaltic crust. However, at the periphery of the island (i.e. Snæfellsnes Peninsula and Öræfajökull volcanic system), far from both the mantle plume centre and the rift-zone, the geothermal gradient is lower, precluding to step over the solidus temperature of hydrated metabasalts. This situation favoured the genesis of silicic magmas by fractional crystallisation (with possibly slight crustal assimilation).The link that exists between the composition of silicic rocks and the geodynamic environment of their genesis has been used together with age determination in order to establish the time-space geodynamic evolution of Iceland. The proposed model is based on the fact that mid-Atlantic ridge migrate relatively to the plume centre and on the "accretion - over lapping" mechanism that best accounts for the abnormally great width of Iceland. Iceland demonstrates that oceanic plateaus can give rise to significant volumes (towards 10%) of silicic magmas; in other words, it can be a potential environment for continental crust genesis in a purely oceanic environment. A comparison between these "continental" rock compositions from recent oceanic plateaus and primitive continental crust one (TTG) shows that, in spite of ... |
author2 |
Institut des Sciences de la Terre de Paris (iSTeP) Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS) Laboratoire Magmas et Volcans (LMV) Observatoire de Physique du Globe de Clermont-Ferrand (OPGC) Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS) Université Blaise Pascal - Clermont-Ferrand II Olgeir Sigmarsson |
format |
Doctoral or Postdoctoral Thesis |
author |
Martin, Erwan |
author_facet |
Martin, Erwan |
author_sort |
Martin, Erwan |
title |
Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust |
title_short |
Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust |
title_full |
Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust |
title_fullStr |
Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust |
title_full_unstemmed |
Geochemical study of silicic magmas from Iceland : genesis mechanism, implications for the Icelandic geodynamic evolution and for the formation of the primitive continental crust |
title_sort |
geochemical study of silicic magmas from iceland : genesis mechanism, implications for the icelandic geodynamic evolution and for the formation of the primitive continental crust |
publisher |
HAL CCSD |
publishDate |
2006 |
url |
https://theses.hal.science/tel-00717368 https://theses.hal.science/tel-00717368/document https://theses.hal.science/tel-00717368/file/2006CLF21709.pdf |
geographic |
Mid-Atlantic Ridge |
geographic_facet |
Mid-Atlantic Ridge |
genre |
Iceland Islande |
genre_facet |
Iceland Islande |
op_source |
https://theses.hal.science/tel-00717368 Sciences de la Terre. Université Blaise Pascal - Clermont-Ferrand II, 2006. Français. ⟨NNT : 2006CLF21709⟩ |
op_relation |
NNT: 2006CLF21709 tel-00717368 https://theses.hal.science/tel-00717368 https://theses.hal.science/tel-00717368/document https://theses.hal.science/tel-00717368/file/2006CLF21709.pdf |
op_rights |
info:eu-repo/semantics/OpenAccess |
_version_ |
1768389503470272512 |