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dc.contributor.authorDyck, Brendanen
dc.contributor.authorGoddard, RMen
dc.contributor.authorWallis, Daviden
dc.contributor.authorHansen, Lars Nen
dc.contributor.authorMartel, Edithen
dc.date.accessioned2020-10-20T23:30:39Z
dc.date.available2020-10-20T23:30:39Z
dc.identifier.issn0263-4929
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/311735
dc.description.abstractThe Paleoproterozoic Great Slave Lake shear zone (GSLsz) is a crustal-scale strike-slip structure, with a total length >1000 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 ~650ºC·GPa-1, whereas, the final stages of equilibrium recorded by fine-grained matrix minerals in all samples collectively define a metamorphic field gradient of ~1000ºC·GPa-1. 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.
dc.publisherWiley-Blackwell
dc.rightsAll rights reserved
dc.rights.uri
dc.titleMetamorphic evolution of the Great Slave Lake shear zoneen
dc.typeArticle
prism.publicationNameJournal of Metamorphic Geologyen
dc.identifier.doi10.17863/CAM.58825
dcterms.dateAccepted2020-10-14en
rioxxterms.versionAM
rioxxterms.licenseref.urihttp://www.rioxx.net/licenses/all-rights-reserveden
rioxxterms.licenseref.startdate2020-10-14en
dc.contributor.orcidWallis, David [0000-0001-9212-3734]
rioxxterms.typeJournal Article/Reviewen
cam.orpheus.counter16*
rioxxterms.freetoread.startdate2023-10-20


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