Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica
Microfabrics of mylonitic orthopyroxene-bearing quartzofeldspatic granulites from central Dronning Maud Land, Antarctica, have been investigated to evaluate the deformation behaviour at lower crustal conditions. The microfabric is characterized by a fine-grained matrix of dispersed feldspar, quartz...
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ftethz:oai:www.research-collection.ethz.ch:20.500.11850/444399 2023-05-15T14:03:33+02:00 Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica Engvik, Ane K. Mertens, Cornelia Trepmann, Claudia A. 2020-12 application/application/pdf https://hdl.handle.net/20.500.11850/444399 https://doi.org/10.3929/ethz-b-000444399 en eng Elsevier info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jsg.2020.104196 info:eu-repo/semantics/altIdentifier/wos/000595250500012 http://hdl.handle.net/20.500.11850/444399 doi:10.3929/ethz-b-000444399 info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International CC-BY Journal of Structural Geology, 141 Orthopyroxene Granulite Microfabric Diffusional creep Episodic deformation Shear zone info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion 2020 ftethz https://doi.org/20.500.11850/444399 https://doi.org/10.3929/ethz-b-000444399 https://doi.org/10.1016/j.jsg.2020.104196 2022-04-25T14:14:24Z Microfabrics of mylonitic orthopyroxene-bearing quartzofeldspatic granulites from central Dronning Maud Land, Antarctica, have been investigated to evaluate the deformation behaviour at lower crustal conditions. The microfabric is characterized by a fine-grained matrix of dispersed feldspar, quartz and orthopyroxene, which contains monophase elongate quartz and feldspar aggregates, so-called ribbons, and elongate monocrystalline orthopyroxene ribbon grains. The observed crystallographic preferred orientation (CPO) of orthopyroxene ribbon grains that contain clinopyroxene exsolution lamellae in (100) and kink bands in equidimensional porphyroclasts indicate (100)[001] dislocation glide. Fine-grained matrix orthopyroxene formed by deformation of porphyroclasts and growth in strain shadows during diffusional creep, indicating a separate stage of deformation and reaction. Although dislocation creep of coarse ribbon quartz is indicated by sutured grain boundaries at high angle to the ribbon boundary and few subgrains, the weak CPO is rather unspecific. Fine-grained matrix quartz shows no indication of dislocation creep. We suggest that epitactic growth during quartz-producing mineral reactions played a major role for ribbon formation during diffusional creep. Our study demonstrates the importance of episodic deformation and metamorphic reactions in lower continental crust with transient high stresses allowing for dislocation glide of orthopyroxene enclosed in a fine-grained polyphase matrix undergoing diffusional creep on long term. ISSN:0191-8141 Article in Journal/Newspaper Antarc* Antarctica Dronning Maud Land ETH Zürich Research Collection Dronning Maud Land |
institution |
Open Polar |
collection |
ETH Zürich Research Collection |
op_collection_id |
ftethz |
language |
English |
topic |
Orthopyroxene Granulite Microfabric Diffusional creep Episodic deformation Shear zone |
spellingShingle |
Orthopyroxene Granulite Microfabric Diffusional creep Episodic deformation Shear zone Engvik, Ane K. Mertens, Cornelia Trepmann, Claudia A. Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica |
topic_facet |
Orthopyroxene Granulite Microfabric Diffusional creep Episodic deformation Shear zone |
description |
Microfabrics of mylonitic orthopyroxene-bearing quartzofeldspatic granulites from central Dronning Maud Land, Antarctica, have been investigated to evaluate the deformation behaviour at lower crustal conditions. The microfabric is characterized by a fine-grained matrix of dispersed feldspar, quartz and orthopyroxene, which contains monophase elongate quartz and feldspar aggregates, so-called ribbons, and elongate monocrystalline orthopyroxene ribbon grains. The observed crystallographic preferred orientation (CPO) of orthopyroxene ribbon grains that contain clinopyroxene exsolution lamellae in (100) and kink bands in equidimensional porphyroclasts indicate (100)[001] dislocation glide. Fine-grained matrix orthopyroxene formed by deformation of porphyroclasts and growth in strain shadows during diffusional creep, indicating a separate stage of deformation and reaction. Although dislocation creep of coarse ribbon quartz is indicated by sutured grain boundaries at high angle to the ribbon boundary and few subgrains, the weak CPO is rather unspecific. Fine-grained matrix quartz shows no indication of dislocation creep. We suggest that epitactic growth during quartz-producing mineral reactions played a major role for ribbon formation during diffusional creep. Our study demonstrates the importance of episodic deformation and metamorphic reactions in lower continental crust with transient high stresses allowing for dislocation glide of orthopyroxene enclosed in a fine-grained polyphase matrix undergoing diffusional creep on long term. ISSN:0191-8141 |
format |
Article in Journal/Newspaper |
author |
Engvik, Ane K. Mertens, Cornelia Trepmann, Claudia A. |
author_facet |
Engvik, Ane K. Mertens, Cornelia Trepmann, Claudia A. |
author_sort |
Engvik, Ane K. |
title |
Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica |
title_short |
Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica |
title_full |
Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica |
title_fullStr |
Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica |
title_full_unstemmed |
Episodic deformation and reactions in mylonitic high-grade metamorphic granulites from Dronning Maud Land, Antarctica |
title_sort |
episodic deformation and reactions in mylonitic high-grade metamorphic granulites from dronning maud land, antarctica |
publisher |
Elsevier |
publishDate |
2020 |
url |
https://hdl.handle.net/20.500.11850/444399 https://doi.org/10.3929/ethz-b-000444399 |
geographic |
Dronning Maud Land |
geographic_facet |
Dronning Maud Land |
genre |
Antarc* Antarctica Dronning Maud Land |
genre_facet |
Antarc* Antarctica Dronning Maud Land |
op_source |
Journal of Structural Geology, 141 |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1016/j.jsg.2020.104196 info:eu-repo/semantics/altIdentifier/wos/000595250500012 http://hdl.handle.net/20.500.11850/444399 doi:10.3929/ethz-b-000444399 |
op_rights |
info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/4.0/ Creative Commons Attribution 4.0 International |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/20.500.11850/444399 https://doi.org/10.3929/ethz-b-000444399 https://doi.org/10.1016/j.jsg.2020.104196 |
_version_ |
1766274238379982848 |