Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica
International audience The Mertz shear zone (MSZ) is a lithospheric scale structure that recorded mid-crustal deformation during the 1.7 Ga orogeny. We performed a microstructural and crystallographic preferred orientation (CPO) study of samples from both mylonites and tectonic boudins that constitu...
Published in: | Tectonophysics |
---|---|
Main Authors: | , , , , , |
Other Authors: | , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2016
|
Subjects: | |
Online Access: | https://hal-emse.ccsd.cnrs.fr/emse-01505345 https://doi.org/10.1016/j.tecto.2016.05.011 |
id |
ftinsu:oai:HAL:emse-01505345v1 |
---|---|
record_format |
openpolar |
institution |
Open Polar |
collection |
Institut national des sciences de l'Univers: HAL-INSU |
op_collection_id |
ftinsu |
language |
English |
topic |
Crustal deformation Shear zone Microstructures Crystallographic preferred orientation (CPO) East Antarctica Strain localization LATTICE-PREFERRED ORIENTATION AMPHIBOLE-RICH ROCKS MAGMA EMPLACEMENT METAMORPHIC BELT ORTHO-PYROXENE LOWER-CRUSTAL UPPER-MANTLE PALEOPROTEROZOIC TECTONICS CRYSTALLOGRAPHIC FABRICS MAGNETIC-SUSCEPTIBILITY [SPI.MAT]Engineering Sciences [physics]/Materials |
spellingShingle |
Crustal deformation Shear zone Microstructures Crystallographic preferred orientation (CPO) East Antarctica Strain localization LATTICE-PREFERRED ORIENTATION AMPHIBOLE-RICH ROCKS MAGMA EMPLACEMENT METAMORPHIC BELT ORTHO-PYROXENE LOWER-CRUSTAL UPPER-MANTLE PALEOPROTEROZOIC TECTONICS CRYSTALLOGRAPHIC FABRICS MAGNETIC-SUSCEPTIBILITY [SPI.MAT]Engineering Sciences [physics]/Materials Lamarque, Gaëlle Bascou, Jerôme Maurice, Claire Cottin, Jean-Yves Riel, Nicolas, Ménot, René-Pierre Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica |
topic_facet |
Crustal deformation Shear zone Microstructures Crystallographic preferred orientation (CPO) East Antarctica Strain localization LATTICE-PREFERRED ORIENTATION AMPHIBOLE-RICH ROCKS MAGMA EMPLACEMENT METAMORPHIC BELT ORTHO-PYROXENE LOWER-CRUSTAL UPPER-MANTLE PALEOPROTEROZOIC TECTONICS CRYSTALLOGRAPHIC FABRICS MAGNETIC-SUSCEPTIBILITY [SPI.MAT]Engineering Sciences [physics]/Materials |
description |
International audience The Mertz shear zone (MSZ) is a lithospheric scale structure that recorded mid-crustal deformation during the 1.7 Ga orogeny. We performed a microstructural and crystallographic preferred orientation (CPO) study of samples from both mylonites and tectonic boudins that constitute relics of the Terre Adelie Craton (TAC). The deformation is highly accommodated in the MSZ by anastomosed shear bands, which become more scattered elsewhere in the TAC. Most of the MSZ amphibolite-facies mylonites display similar CPO, thermal conditions, intensity of deformation and dominant shear strain. Preserved granulite-facies boudins show both coaxial and non coaxial strains related to the previous 2.45 Ga event. This former deformation is more penetrative and less localized and shows a deformation gradient, later affected by a major phase of recrystallization during retrogression at 2.42 Ga. Both MSZ samples and granulite-facies tectonic boudins present microstructures that reflect a variety of deformation mechanisms associated with the rock creep that induce contrasted CPO of minerals (quartz, feldspar, biotite, amphibole and orthopyroxene). In particular, we highlight the development of an "uncommon" CPO in orthopyroxene from weakly deformed samples characterized by (010)-planes oriented parallel to the foliation plane, [001]-axes parallel to the stretching lineation and clustering of [100]-axes near the Y structural direction. Lastly, we computed the seismic properties of the amphibolite and granulite facies rocks in the MSZ area in order to evaluate the contribution of the deformed intermediate and lower continental crust to the seismic anisotropy recorded above the MSZ. Our results reveal that (i) the low content of amphibole and biotite in the rock formations of the TAC, and (ii) the interactions between the CPO of the different mineralogical phases, generate a seismically isotropic crust. Thus, the seismic anisotropy recorded by the seismic stations of the TAC, including the MSZ, must be due to ... |
author2 |
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) Centre Science des Matériaux et des Structures (SMS-ENSMSE) École des Mines de Saint-Étienne (Mines Saint-Étienne MSE) Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT) Laboratoire Georges Friedel (LGF-ENSMSE) Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS) PMM-ENSMSE- Département Physique et Mécanique des Matériaux Department of Earth Sciences Durham Durham University |
format |
Article in Journal/Newspaper |
author |
Lamarque, Gaëlle Bascou, Jerôme Maurice, Claire Cottin, Jean-Yves Riel, Nicolas, Ménot, René-Pierre |
author_facet |
Lamarque, Gaëlle Bascou, Jerôme Maurice, Claire Cottin, Jean-Yves Riel, Nicolas, Ménot, René-Pierre |
author_sort |
Lamarque, Gaëlle |
title |
Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica |
title_short |
Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica |
title_full |
Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica |
title_fullStr |
Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica |
title_full_unstemmed |
Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica |
title_sort |
microstructures, deformation mechanisms and seismic properties of a palaeoproterozoic shear zone: the mertz shear zone, east-antarctica |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://hal-emse.ccsd.cnrs.fr/emse-01505345 https://doi.org/10.1016/j.tecto.2016.05.011 |
long_lat |
ENVELOPE(-59.517,-59.517,-62.500,-62.500) ENVELOPE(-112.453,-112.453,57.591,57.591) |
geographic |
East Antarctica Tac The ''Y'' |
geographic_facet |
East Antarctica Tac The ''Y'' |
genre |
Antarc* Antarctica East Antarctica |
genre_facet |
Antarc* Antarctica East Antarctica |
op_source |
ISSN: 0040-1951 EISSN: 1879-3266 Tectonophysics https://hal-emse.ccsd.cnrs.fr/emse-01505345 Tectonophysics, 2016, 680, pp.174-191 ⟨10.1016/j.tecto.2016.05.011⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.tecto.2016.05.011 emse-01505345 https://hal-emse.ccsd.cnrs.fr/emse-01505345 doi:10.1016/j.tecto.2016.05.011 |
op_doi |
https://doi.org/10.1016/j.tecto.2016.05.011 |
container_title |
Tectonophysics |
container_volume |
680 |
container_start_page |
174 |
op_container_end_page |
191 |
_version_ |
1769010470852755456 |
spelling |
ftinsu:oai:HAL:emse-01505345v1 2023-06-18T03:37:42+02:00 Microstructures, deformation mechanisms and seismic properties of a Palaeoproterozoic shear zone: The Mertz shear zone, East-Antarctica Lamarque, Gaëlle Bascou, Jerôme Maurice, Claire Cottin, Jean-Yves Riel, Nicolas, Ménot, René-Pierre 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) Centre Science des Matériaux et des Structures (SMS-ENSMSE) École des Mines de Saint-Étienne (Mines Saint-Étienne MSE) Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT) Laboratoire Georges Friedel (LGF-ENSMSE) Institut Mines-Télécom Paris (IMT)-Institut Mines-Télécom Paris (IMT)-Université de Lyon-Centre National de la Recherche Scientifique (CNRS) PMM-ENSMSE- Département Physique et Mécanique des Matériaux Department of Earth Sciences Durham Durham University 2016-06-12 https://hal-emse.ccsd.cnrs.fr/emse-01505345 https://doi.org/10.1016/j.tecto.2016.05.011 en eng HAL CCSD Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.tecto.2016.05.011 emse-01505345 https://hal-emse.ccsd.cnrs.fr/emse-01505345 doi:10.1016/j.tecto.2016.05.011 ISSN: 0040-1951 EISSN: 1879-3266 Tectonophysics https://hal-emse.ccsd.cnrs.fr/emse-01505345 Tectonophysics, 2016, 680, pp.174-191 ⟨10.1016/j.tecto.2016.05.011⟩ Crustal deformation Shear zone Microstructures Crystallographic preferred orientation (CPO) East Antarctica Strain localization LATTICE-PREFERRED ORIENTATION AMPHIBOLE-RICH ROCKS MAGMA EMPLACEMENT METAMORPHIC BELT ORTHO-PYROXENE LOWER-CRUSTAL UPPER-MANTLE PALEOPROTEROZOIC TECTONICS CRYSTALLOGRAPHIC FABRICS MAGNETIC-SUSCEPTIBILITY [SPI.MAT]Engineering Sciences [physics]/Materials info:eu-repo/semantics/article Journal articles 2016 ftinsu https://doi.org/10.1016/j.tecto.2016.05.011 2023-06-06T00:46:51Z International audience The Mertz shear zone (MSZ) is a lithospheric scale structure that recorded mid-crustal deformation during the 1.7 Ga orogeny. We performed a microstructural and crystallographic preferred orientation (CPO) study of samples from both mylonites and tectonic boudins that constitute relics of the Terre Adelie Craton (TAC). The deformation is highly accommodated in the MSZ by anastomosed shear bands, which become more scattered elsewhere in the TAC. Most of the MSZ amphibolite-facies mylonites display similar CPO, thermal conditions, intensity of deformation and dominant shear strain. Preserved granulite-facies boudins show both coaxial and non coaxial strains related to the previous 2.45 Ga event. This former deformation is more penetrative and less localized and shows a deformation gradient, later affected by a major phase of recrystallization during retrogression at 2.42 Ga. Both MSZ samples and granulite-facies tectonic boudins present microstructures that reflect a variety of deformation mechanisms associated with the rock creep that induce contrasted CPO of minerals (quartz, feldspar, biotite, amphibole and orthopyroxene). In particular, we highlight the development of an "uncommon" CPO in orthopyroxene from weakly deformed samples characterized by (010)-planes oriented parallel to the foliation plane, [001]-axes parallel to the stretching lineation and clustering of [100]-axes near the Y structural direction. Lastly, we computed the seismic properties of the amphibolite and granulite facies rocks in the MSZ area in order to evaluate the contribution of the deformed intermediate and lower continental crust to the seismic anisotropy recorded above the MSZ. Our results reveal that (i) the low content of amphibole and biotite in the rock formations of the TAC, and (ii) the interactions between the CPO of the different mineralogical phases, generate a seismically isotropic crust. Thus, the seismic anisotropy recorded by the seismic stations of the TAC, including the MSZ, must be due to ... Article in Journal/Newspaper Antarc* Antarctica East Antarctica Institut national des sciences de l'Univers: HAL-INSU East Antarctica Tac ENVELOPE(-59.517,-59.517,-62.500,-62.500) The ''Y'' ENVELOPE(-112.453,-112.453,57.591,57.591) Tectonophysics 680 174 191 |