Constraining the timing and duration of ductile deformation in the Great Slave Lake shear zone, Northwest Territories, Canada

The Paleoproterozoic Great Slave Lake shear zone (GSLsz) is a crustal-scale dextral transcurrent structure that accommodated up to 700 km of oblique convergence between the Rae and Slave cratons during the assembly of the supercontinent Nuna. Although previous geochronologic work indirectly dates the onset of shear to ca. 1950 Ma, little is known about the precise timing and duration of ductile shear on the structure. The goal of this project was to establish the timing and duration of ductile deformation in the GSLsz through a combination of field mapping, petrography and in situ U-Pb dating of fabric- linked accessory minerals via LA-ICP-MS. Apatite and titanite in samples collected across the GSLsz record a near continuous history of ductile shear spanning from ca. 1920 to 1740 Ma. These revised ages for ductile shear in the GSLsz are broadly coincident with other regional tectonic events linked to the formation of supercontinent Nuna.