Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures
International audience The rheology of mafic rocks buried at high to ultra-high-pressure conditions remains enigmatic. Minerals stable at these conditions are mechanically very strong (garnet, omphacite, glaucophane, zoisite, kyanite). Yet, viscous shear zones are commonly reported at depths in foss...
Main Authors: | , , , , |
---|---|
Other Authors: | , , , , , , , , , , |
Format: | Conference Object |
Language: | English |
Published: |
HAL CCSD
2022
|
Subjects: | |
Online Access: | https://insu.hal.science/insu-04092121 |
id |
ftobservparis:oai:HAL:insu-04092121v1 |
---|---|
record_format |
openpolar |
institution |
Open Polar |
collection |
Archive de l'Observatoire de Paris (HAL) |
op_collection_id |
ftobservparis |
language |
English |
topic |
[SDU]Sciences of the Universe [physics] |
spellingShingle |
[SDU]Sciences of the Universe [physics] Soret, Mathieu Stunitz, Holger Précigout, Jacques Lee, Amicia Lisbeth Raimbourg, Hugues Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures |
topic_facet |
[SDU]Sciences of the Universe [physics] |
description |
International audience The rheology of mafic rocks buried at high to ultra-high-pressure conditions remains enigmatic. Minerals stable at these conditions are mechanically very strong (garnet, omphacite, glaucophane, zoisite, kyanite). Yet, viscous shear zones are commonly reported at depths in fossil collisional and subduction zones. The weakening observed in these shear zones is interpreted as being induced by a transition from grain size insensitive to grain size sensitive creep, in particular with the activation of the dissolution–precipitation creep. However, the exact interplay between deformation, mineral reaction and fluid/mass transfer remains poorly-known. We have conducted a first series of deformation experiments at eclogite-facies conditions on a 2-phase aggregate representative of mafic rocks. Shear experiments were performed in a new generation of Griggs-type apparatus (Univ. Orléans) at 850°C, and 2.1 GPa with a shear strain rate of 10⁻6 s⁻¹. The starting material consists of mixed powders with < 100 µm sized grains of plagioclase and clinopyroxene from an undeformed sample of the Kågen Gabbro in Northern Norway. Experiments have been conducted with 'as is' (dried at 110°C) starting material and with 0.2% added water. The mechanical data indicate that the samples are first very strong with a peak differential stress at 1.4 GPa. Then, a significant weakening is observed with a stress decrease by 0.5 GPa. The high-strain sample is characterized by a strain gradient increasing toward the center of the shear zone. Metamorphic reactions occur throughout the sample, but the high-strain areas contain considerably more reaction products than the low-strain areas. The nucleation of new phases leads to a drastic grain size reduction and phase mixing, whose intensities are positively correlated with the strain intensity. The nature, distribution and fabric of the mineral products vary also progressively with the strain intensity. Our preliminary results indicate that strain at eclogite-facies ... |
author2 |
Université d'Orléans (UO) 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) The Arctic University of Norway Tromsø, Norway (UiT) 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 |
Soret, Mathieu Stunitz, Holger Précigout, Jacques Lee, Amicia Lisbeth Raimbourg, Hugues |
author_facet |
Soret, Mathieu Stunitz, Holger Précigout, Jacques Lee, Amicia Lisbeth Raimbourg, Hugues |
author_sort |
Soret, Mathieu |
title |
Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures |
title_short |
Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures |
title_full |
Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures |
title_fullStr |
Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures |
title_full_unstemmed |
Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures |
title_sort |
strain localization and weakening during eclogite-facies transformation in experimentally deformed plagioclase-pyroxene mixtures |
publisher |
HAL CCSD |
publishDate |
2022 |
url |
https://insu.hal.science/insu-04092121 |
op_coverage |
à renseigner, Unknown Region |
genre |
Northern Norway |
genre_facet |
Northern Norway |
op_source |
AGU Fall Meeting 2022 https://insu.hal.science/insu-04092121 AGU Fall Meeting 2022, 2022, à renseigner, Unknown Region |
op_relation |
insu-04092121 https://insu.hal.science/insu-04092121 BIBCODE: 2022AGUFMMR25B0074S |
_version_ |
1799486146221178880 |
spelling |
ftobservparis:oai:HAL:insu-04092121v1 2024-05-19T07:46:01+00:00 Strain Localization and Weakening during Eclogite-Facies Transformation in Experimentally Deformed Plagioclase-Pyroxene Mixtures Soret, Mathieu Stunitz, Holger Précigout, Jacques Lee, Amicia Lisbeth Raimbourg, Hugues Université d'Orléans (UO) 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) The Arctic University of Norway Tromsø, Norway (UiT) 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) à renseigner, Unknown Region 2022 https://insu.hal.science/insu-04092121 en eng HAL CCSD insu-04092121 https://insu.hal.science/insu-04092121 BIBCODE: 2022AGUFMMR25B0074S AGU Fall Meeting 2022 https://insu.hal.science/insu-04092121 AGU Fall Meeting 2022, 2022, à renseigner, Unknown Region [SDU]Sciences of the Universe [physics] info:eu-repo/semantics/conferenceObject Conference papers 2022 ftobservparis 2024-05-01T23:56:23Z International audience The rheology of mafic rocks buried at high to ultra-high-pressure conditions remains enigmatic. Minerals stable at these conditions are mechanically very strong (garnet, omphacite, glaucophane, zoisite, kyanite). Yet, viscous shear zones are commonly reported at depths in fossil collisional and subduction zones. The weakening observed in these shear zones is interpreted as being induced by a transition from grain size insensitive to grain size sensitive creep, in particular with the activation of the dissolution–precipitation creep. However, the exact interplay between deformation, mineral reaction and fluid/mass transfer remains poorly-known. We have conducted a first series of deformation experiments at eclogite-facies conditions on a 2-phase aggregate representative of mafic rocks. Shear experiments were performed in a new generation of Griggs-type apparatus (Univ. Orléans) at 850°C, and 2.1 GPa with a shear strain rate of 10⁻6 s⁻¹. The starting material consists of mixed powders with < 100 µm sized grains of plagioclase and clinopyroxene from an undeformed sample of the Kågen Gabbro in Northern Norway. Experiments have been conducted with 'as is' (dried at 110°C) starting material and with 0.2% added water. The mechanical data indicate that the samples are first very strong with a peak differential stress at 1.4 GPa. Then, a significant weakening is observed with a stress decrease by 0.5 GPa. The high-strain sample is characterized by a strain gradient increasing toward the center of the shear zone. Metamorphic reactions occur throughout the sample, but the high-strain areas contain considerably more reaction products than the low-strain areas. The nucleation of new phases leads to a drastic grain size reduction and phase mixing, whose intensities are positively correlated with the strain intensity. The nature, distribution and fabric of the mineral products vary also progressively with the strain intensity. Our preliminary results indicate that strain at eclogite-facies ... Conference Object Northern Norway Archive de l'Observatoire de Paris (HAL) |