Metamorphic evolution of the Great Slave Lake shear zone ...

• Main Authors: Dyck, B, Goddard, RM, Wallis, D, Hansen, LN, Martel, E
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2021
• Subjects: mylonite; phase equilibria modelling; shear zone; thermometry; Great Slave Lake
• Online Access: https://dx.doi.org/10.17863/cam.58825; https://www.repository.cam.ac.uk/handle/1810/311735

AbstractThe 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 ...