Metamorphic evolution of the Great Slave Lake shear zone

Dyck, Brendan and Goddard, R. M. and Wallis, D. and Hansen, L. N. and Martel, E. (2020) Metamorphic evolution of the Great Slave Lake shear zone. Journal of Metamorphic Geology. ISSN 0263-4929 DOI https://doi.org/10.1111/jmg.12576

[img] Text
Manuscript_respository.pdf - Accepted Version
Restricted to Registered users only until 24 October 2021.

Download (6MB) | Request a copy
[img]
Preview
Image
jmg12576-sup-0001-figs1.jpg - Supplemental Material

Download (2MB) | Preview
[img]
Preview
Image
jmg12576-sup-0002-figs2-01.jpg - Supplemental Material

Download (1MB) | Preview
[img]
Preview
Image
jmg12576-sup-0003-figs2-02.jpg - Supplemental Material

Download (2MB) | Preview
[img]
Preview
Image
jmg12576-sup-0004-figs2-03.jpg - Supplemental Material

Download (1MB) | Preview
[img]
Preview
Image
jmg12576-sup-0005-figs2-04.jpg - Supplemental Material

Download (1MB) | Preview
[img]
Preview
Image
jmg12576-sup-0006-figs2-05.jpg - Supplemental Material

Download (1MB) | Preview
[img]
Preview
Image
jmg12576-sup-0007-figs2-06.jpg - Supplemental Material

Download (2MB) | Preview
[img] Image
jmg12576-sup-0008-figs3.eps - Supplemental Material

Download (2MB)
[img] Text
jmg12576-sup-0009-appendixs1.docx - Supplemental Material

Download (13kB)
Official URL: https://onlinelibrary.wiley.com/doi/epdf/10.1111/j...

Abstract

The 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.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
Divisions: 05 - Petrology - Igneous, Metamorphic and Volcanic Studies
08 - Green Open Access
Journal or Publication Title: Journal of Metamorphic Geology
Identification Number: https://doi.org/10.1111/jmg.12576
Depositing User: Sarah Humbert
Date Deposited: 24 Oct 2020 21:29
Last Modified: 24 Oct 2020 21:29
URI: http://eprints.esc.cam.ac.uk/id/eprint/4900

Actions (login required)

View Item View Item

About cookies