Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks
International audience Mafic rocks consist of strong minerals (e.g. clinopyroxene, plagioclase) that can only be deformed by crystal plastic mechanisms at high temperatures (>800°C). Yet, mafic rocks do show extensive deformation by non-brittle mechanisms when they have only reached lower tempera...
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HAL CCSD
2021
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Online Access: | https://hal.science/hal-03554520 https://hal.science/hal-03554520/document https://hal.science/hal-03554520/file/EGU21-12360-print.pdf https://doi.org/10.5194/egusphere-egu21-12360 |
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ftbrgm:oai:HAL:hal-03554520v1 |
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BRGM: HAL (Bureau de Recherches Géologiques et Minières) |
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ftbrgm |
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English |
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[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
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[SDU.STU]Sciences of the Universe [physics]/Earth Sciences Lee, Amicia Stünitz, Holger Soret, Mathieu Battisti, Matheus Ariel Konopásek, Jiří Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
topic_facet |
[SDU.STU]Sciences of the Universe [physics]/Earth Sciences |
description |
International audience Mafic rocks consist of strong minerals (e.g. clinopyroxene, plagioclase) that can only be deformed by crystal plastic mechanisms at high temperatures (>800°C). Yet, mafic rocks do show extensive deformation by non-brittle mechanisms when they have only reached lower temperatures (~650°C). In many of such cases, the deformation is accommodated by an interaction of deformation with simultaneous mineral reactions. Here we show that dissolution-precipitation creep plays a major role in deformation of gabbro lenses at mid and upper amphibolite facies conditions.The Kågen gabbro in the North Norwegian Caledonides intruded the Vaddas Nappe at 439 Ma at pressures of 7-9 kbar, temperatures of 650-900°C, and depths of ∼26-34 km. The Kågen gabbro on south Arnøya is comprised of undeformed gabbro lenses with sheared margins wrapping around them. This contribution analyses the evolution of the microstructures and metamorphism from the low strain gabbro lenses to high strain mylonites at margins of the lenses. Microstructural and textural data indicate that dissolution-precipitation creep is the dominant deformation mechanism, where dissolution of the gabbro took place in reacting phases of clinopyroxene and plagioclase, and precipitation took place in the form of new minerals: new plagioclase and clinopyroxene, amphibole, and garnet. Amphibole shows a strong CPO that is primarily controlled by its preferential growth in the extension direction. Synchronous deformation and mineral reactions of clinopyroxene suggests mafic rocks can become mechanically weak during the general transformation weakening process, i.e. the interaction of mineral reaction and deformation by diffusion creep. The weakening is directly connected to a fluid-assisted transformation process that facilitates diffusion creep deformation of strong minerals at far lower stresses and temperatures than dislocation creep. Initially strong lithologies can become weak, provided that reactions can proceed during deformation, the ... |
author2 |
University of Tromsø (UiT) Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO) Bureau de Recherches Géologiques et Minières (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) Géodynamique - UMR7327 Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) |
format |
Conference Object |
author |
Lee, Amicia Stünitz, Holger Soret, Mathieu Battisti, Matheus Ariel Konopásek, Jiří |
author_facet |
Lee, Amicia Stünitz, Holger Soret, Mathieu Battisti, Matheus Ariel Konopásek, Jiří |
author_sort |
Lee, Amicia |
title |
Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
title_short |
Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
title_full |
Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
title_fullStr |
Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
title_full_unstemmed |
Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
title_sort |
creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks |
publisher |
HAL CCSD |
publishDate |
2021 |
url |
https://hal.science/hal-03554520 https://hal.science/hal-03554520/document https://hal.science/hal-03554520/file/EGU21-12360-print.pdf https://doi.org/10.5194/egusphere-egu21-12360 |
op_coverage |
Online, France |
genre |
Arnøya |
genre_facet |
Arnøya |
op_source |
vEGU21: Gather Online https://hal.science/hal-03554520 vEGU21: Gather Online, Apr 2021, Online, France. ⟨10.5194/egusphere-egu21-12360⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-12360 hal-03554520 https://hal.science/hal-03554520 https://hal.science/hal-03554520/document https://hal.science/hal-03554520/file/EGU21-12360-print.pdf BIBCODE: 2021EGUGA.2312360L doi:10.5194/egusphere-egu21-12360 |
op_rights |
http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess |
op_doi |
https://doi.org/10.5194/egusphere-egu21-12360 |
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1799476159406145536 |
spelling |
ftbrgm:oai:HAL:hal-03554520v1 2024-05-19T07:36:58+00:00 Creeping gabbro: dissolution-precipitation creep facilitating deformation in mafic rocks Lee, Amicia Stünitz, Holger Soret, Mathieu Battisti, Matheus Ariel Konopásek, Jiří University of Tromsø (UiT) Institut des Sciences de la Terre d'Orléans - UMR7327 (ISTO) Bureau de Recherches Géologiques et Minières (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC) Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS) Géodynamique - UMR7327 Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Bureau de Recherches Géologiques et Minières (BRGM)-Observatoire des Sciences de l'Univers en région Centre (OSUC) Université Paris Sciences et Lettres (PSL)-Université Paris Sciences et Lettres (PSL)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université d'Orléans (UO)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS) Online, France 2021-04-19 https://hal.science/hal-03554520 https://hal.science/hal-03554520/document https://hal.science/hal-03554520/file/EGU21-12360-print.pdf https://doi.org/10.5194/egusphere-egu21-12360 en eng HAL CCSD info:eu-repo/semantics/altIdentifier/doi/10.5194/egusphere-egu21-12360 hal-03554520 https://hal.science/hal-03554520 https://hal.science/hal-03554520/document https://hal.science/hal-03554520/file/EGU21-12360-print.pdf BIBCODE: 2021EGUGA.2312360L doi:10.5194/egusphere-egu21-12360 http://creativecommons.org/licenses/by/ info:eu-repo/semantics/OpenAccess vEGU21: Gather Online https://hal.science/hal-03554520 vEGU21: Gather Online, Apr 2021, Online, France. ⟨10.5194/egusphere-egu21-12360⟩ [SDU.STU]Sciences of the Universe [physics]/Earth Sciences info:eu-repo/semantics/conferenceObject Conference papers 2021 ftbrgm https://doi.org/10.5194/egusphere-egu21-12360 2024-05-02T00:12:28Z International audience Mafic rocks consist of strong minerals (e.g. clinopyroxene, plagioclase) that can only be deformed by crystal plastic mechanisms at high temperatures (>800°C). Yet, mafic rocks do show extensive deformation by non-brittle mechanisms when they have only reached lower temperatures (~650°C). In many of such cases, the deformation is accommodated by an interaction of deformation with simultaneous mineral reactions. Here we show that dissolution-precipitation creep plays a major role in deformation of gabbro lenses at mid and upper amphibolite facies conditions.The Kågen gabbro in the North Norwegian Caledonides intruded the Vaddas Nappe at 439 Ma at pressures of 7-9 kbar, temperatures of 650-900°C, and depths of ∼26-34 km. The Kågen gabbro on south Arnøya is comprised of undeformed gabbro lenses with sheared margins wrapping around them. This contribution analyses the evolution of the microstructures and metamorphism from the low strain gabbro lenses to high strain mylonites at margins of the lenses. Microstructural and textural data indicate that dissolution-precipitation creep is the dominant deformation mechanism, where dissolution of the gabbro took place in reacting phases of clinopyroxene and plagioclase, and precipitation took place in the form of new minerals: new plagioclase and clinopyroxene, amphibole, and garnet. Amphibole shows a strong CPO that is primarily controlled by its preferential growth in the extension direction. Synchronous deformation and mineral reactions of clinopyroxene suggests mafic rocks can become mechanically weak during the general transformation weakening process, i.e. the interaction of mineral reaction and deformation by diffusion creep. The weakening is directly connected to a fluid-assisted transformation process that facilitates diffusion creep deformation of strong minerals at far lower stresses and temperatures than dislocation creep. Initially strong lithologies can become weak, provided that reactions can proceed during deformation, the ... Conference Object Arnøya BRGM: HAL (Bureau de Recherches Géologiques et Minières) |