High-pressure, ultrahigh-temperature 1.9 Ga metamorphism of the Kramanituar Complex, Snowbird Tectonic Zone, Rae Craton, Canada

The high-pressure ( P ) granulite–facies Kramanituar Complex, dominated by a metagabbroic–anorthositic suite with subordinate sillimanite- and kyanite-bearing diatexite and charnockite, is one of several complexes that demarcate the 1000 km-long Snowbird Tectonic Zone. Ti-in-quartz (TiQ) and Zr-in-rutile (ZiR) thermometry on inclusions in garnet in mafic and pelitic rocks establish that temperatures ( T ) exceeded 990–1000 °C, ~ 100 °C higher than recorded by Fe–Mg exchange thermometers. At 1000 °C, thermobarometry and forward modelling of both mafic and pelitic rocks from the complex define 14–15 kbar pressures, where TiQ and ZiR temperatures are in good agreement. The occurrence in diatexite of sparse prograde F-bearing biotite and high- T rutile inclusions in garnet rims, not cores, can be accounted for with a high-Ti solubility biotite model and the presence of fluorine. Forward modelling suggests that heterogeneities in both the composition and zoning of garnet reflect the effects of melt loss on bulk composition. Gabbroic rocks with coronitic and symplectitic reaction textures record high- T decompression to 8 kbar and 800 °C, also reflected by matrix quartz ribbons in diatexite which yield TiQ values between 655 and 824 °C at 8 kbar. Combined results define a clockwise P – T path for the complex at 1910–1896 Ma. South of the complex, a contemporaneous clockwise P – T path is recorded in semipelitic rocks that reached peak conditions of 690 °C and 8.1 kbar. Overall, results support tectonic reworking of the thickened (> 50 km) Rae margin from ca. 1910 Ma, culminating in ca. 1902 Ma mantle-derived mafic magmatism and rapid exhumation, potentially triggered by slab breakoff or lithospheric delamination.