Mesoproterozoic syntectonic garnet within Belt Supergroup metamorphic tectonites: Evidence of Grenville-age metamorphism and deformation along northwest Laurentia

► Northern Idaho contains Belt Supergroup equivalent metamorphic tectonites. ► This study utilized Lu-Hf garnet geochronology and porphyroblast-fabric relationships. ► The Belt Supergroup underwent two episodes of Proterozoic deformation and metamorphism. ► M1 metamorphism and D1 deformation occurred in the Belt Supergroup at 1.4-1.3 Ga. ► Grenvillian age (1.1-1.0 Ga) metamorphism (M2) and deformation (D2) overprinted M1/D1.