Metamorphic evolution of the Great Slave Lake shear zone
Funder: Natural Environment Research Council; Id: http://dx.doi.org/10.13039/501100000270 Funder: Natural Sciences and Engineering Research Council of Canada; Id: http://dx.doi.org/10.13039/501100000038 Abstract: The Palaeoproterozoic Great Slave Lake shear zone (GSLsz) is a crustal‐scale strike‐sli...
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Journal of Metamorphic Geology
2021
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ftunivcam:oai:www.repository.cam.ac.uk:1810/324010 2023-10-29T02:36:32+01:00 Metamorphic evolution of the Great Slave Lake shear zone Dyck, Brendan Goddard, Rellie M. Wallis, David Hansen, Lars N. Martel, Edith 2021-06-17T20:33:48Z text/xml application/pdf https://www.repository.cam.ac.uk/handle/1810/324010 https://doi.org/10.17863/CAM.71470 en eng Journal of Metamorphic Geology https://www.repository.cam.ac.uk/handle/1810/324010 doi:10.17863/CAM.71470 ORIGINAL ARTICLE ORIGINAL ARTICLES mylonite phase equilibria modelling shear zone thermometry Article 2021 ftunivcam https://doi.org/10.17863/CAM.71470 2023-10-05T22:20:20Z Funder: Natural Environment Research Council; Id: http://dx.doi.org/10.13039/501100000270 Funder: Natural Sciences and Engineering Research Council of Canada; Id: http://dx.doi.org/10.13039/501100000038 Abstract: The Palaeoproterozoic Great Slave Lake shear zone (GSLsz) is a crustal‐scale strike‐slip structure, with a total length of >1,000 km and a width of ~25 km, that separates the Archean Rae and Slave cratons. The range of metamorphic rocks now exposed at the surface encompasses granulite facies mylonite through to lower‐greenschist facies ultramylonite and cataclasite, providing a potential type example of fault‐zone structure in the middle and lower crust. However, the metamorphic evolution of the units remains poorly quantified, hindering detailed structural and tectonic interpretations. Here, we use phase equilibria modelling and thermobarometry to determine the metamorphic conditions recorded by pelitic, mafic and felsic GSLsz mylonites. Samples from the entire range of granulite–greenschist facies units preserve evidence for nested clockwise pressure–temperature paths that are consistent with a single orogenic cycle. Our findings indicate that the northern Rae margin underwent pervasive crustal thickening with peak pressures in metasedimentary rocks reaching ~1.1 GPa. The crustal thermal gradient at the onset of thickening was ~650°C/GPa, whereas the final stages of equilibrium recorded by fine‐grained matrix minerals in all samples collectively define a metamorphic field gradient of ~1,000°C/GPa. Deformation microstructures are consistent with the main phase of dextral shear having been synchronous with or following peak metamorphism. The history of metamorphism and exhumation of the GSLsz is consistent with the Sibson–Scholz model for shear zones, with a narrowing of the deforming zone and the progressive overprinting of higher‐grade assemblages during exhumation through shallower crustal levels. Article in Journal/Newspaper Great Slave Lake Apollo - University of Cambridge Repository |
institution |
Open Polar |
collection |
Apollo - University of Cambridge Repository |
op_collection_id |
ftunivcam |
language |
English |
topic |
ORIGINAL ARTICLE ORIGINAL ARTICLES mylonite phase equilibria modelling shear zone thermometry |
spellingShingle |
ORIGINAL ARTICLE ORIGINAL ARTICLES mylonite phase equilibria modelling shear zone thermometry Dyck, Brendan Goddard, Rellie M. Wallis, David Hansen, Lars N. Martel, Edith Metamorphic evolution of the Great Slave Lake shear zone |
topic_facet |
ORIGINAL ARTICLE ORIGINAL ARTICLES mylonite phase equilibria modelling shear zone thermometry |
description |
Funder: Natural Environment Research Council; Id: http://dx.doi.org/10.13039/501100000270 Funder: Natural Sciences and Engineering Research Council of Canada; Id: http://dx.doi.org/10.13039/501100000038 Abstract: The Palaeoproterozoic Great Slave Lake shear zone (GSLsz) is a crustal‐scale strike‐slip structure, with a total length of >1,000 km and a width of ~25 km, that separates the Archean Rae and Slave cratons. The range of metamorphic rocks now exposed at the surface encompasses granulite facies mylonite through to lower‐greenschist facies ultramylonite and cataclasite, providing a potential type example of fault‐zone structure in the middle and lower crust. However, the metamorphic evolution of the units remains poorly quantified, hindering detailed structural and tectonic interpretations. Here, we use phase equilibria modelling and thermobarometry to determine the metamorphic conditions recorded by pelitic, mafic and felsic GSLsz mylonites. Samples from the entire range of granulite–greenschist facies units preserve evidence for nested clockwise pressure–temperature paths that are consistent with a single orogenic cycle. Our findings indicate that the northern Rae margin underwent pervasive crustal thickening with peak pressures in metasedimentary rocks reaching ~1.1 GPa. The crustal thermal gradient at the onset of thickening was ~650°C/GPa, whereas the final stages of equilibrium recorded by fine‐grained matrix minerals in all samples collectively define a metamorphic field gradient of ~1,000°C/GPa. Deformation microstructures are consistent with the main phase of dextral shear having been synchronous with or following peak metamorphism. The history of metamorphism and exhumation of the GSLsz is consistent with the Sibson–Scholz model for shear zones, with a narrowing of the deforming zone and the progressive overprinting of higher‐grade assemblages during exhumation through shallower crustal levels. |
format |
Article in Journal/Newspaper |
author |
Dyck, Brendan Goddard, Rellie M. Wallis, David Hansen, Lars N. Martel, Edith |
author_facet |
Dyck, Brendan Goddard, Rellie M. Wallis, David Hansen, Lars N. Martel, Edith |
author_sort |
Dyck, Brendan |
title |
Metamorphic evolution of the Great Slave Lake shear zone |
title_short |
Metamorphic evolution of the Great Slave Lake shear zone |
title_full |
Metamorphic evolution of the Great Slave Lake shear zone |
title_fullStr |
Metamorphic evolution of the Great Slave Lake shear zone |
title_full_unstemmed |
Metamorphic evolution of the Great Slave Lake shear zone |
title_sort |
metamorphic evolution of the great slave lake shear zone |
publisher |
Journal of Metamorphic Geology |
publishDate |
2021 |
url |
https://www.repository.cam.ac.uk/handle/1810/324010 https://doi.org/10.17863/CAM.71470 |
genre |
Great Slave Lake |
genre_facet |
Great Slave Lake |
op_relation |
https://www.repository.cam.ac.uk/handle/1810/324010 doi:10.17863/CAM.71470 |
op_doi |
https://doi.org/10.17863/CAM.71470 |
_version_ |
1781060537450233856 |