The Nolan-Zemlak domain boundary in the southwestern Rae Province separates ca. 2.6 Ga granodioritic to granitic rocks (Nolan suite) of the Nolan lithotectonic domain to the north from an assemblage of ca. 2.52 Ga ultramafic-intermediate plutonic rocks (Zemlak suite) and ca. 2.3 Ga granitoids, and derived gneisses, of the Zemlak domain to the south, the latter representing part of the Taltson basement complex (TBC). The restriction of the Zemlak suite to south of the domain boundary suggests that its emplacement was structurally controlled, an inference supported by recognition of pre-2.52 Ga deformation in Nolan domain. This paper reports the results of U-Pb and Lu-Hf isotopic analysis of zircon, coupled with multi-element whole-rock geochemical analysis, for the Nolan and Zemlak suites, plus a younger suite of leucogranites that stitch the domain boundary. Both the Nolan and Zemlak suites have geochemical-isotopic signatures consistent with subduction-related magmatism, but the ca. 2.52 Ga Zemlak suite is distinguished by anomalously low Th concentrations, attributed to minimal sediment flux into the mantle wedge. Zircon rims from Nolan granites record ca. 2.52 Ga metamorphism ascribed to intrusion of the Zemlak suite. Regionally, these observations are best explained by the subduction-related accretion of the Zemlak terrane, part of a larger Paleo-Mesoarchean crustal block now embedded within the TBC, to a ‘proto-Rae’ cratonic core. A model is presented wherein circa 2.64–2.58 Ga (Nolan age) continental arc magmatism was generated via north-dipping subduction below the proto-Rae craton leading to eventual collision/accretion of the outboard Paleo-Mesoarchean block. Collisional suturing occurred by ca. 2.57 Ga, as recorded by both local and regional metamorphic ages. Following collision, subduction is inferred to have stepped outward, directed beneath the now amalgamated Nolan and Paleo-Mesoarchean (Zemlak/TBC) terrane with further arc magmatism represented by the ca. 2.52 Ga Zemlak suite. Thereafter, arc magmatism continued along the west-southwest margin of Rae craton from ca. 2.47 Ga to 2.4 Ga, likely the expression of Arrowsmith orogeny. Terminal collision ending the Arrowsmith orogenic cycle resulted in reactivation of the boundary zone and formation of the South Tazin Lake shear zone coeval with 2.37 Ga metamorphism and leucogranite emplacement.