The palaeoproterozoic Southeastern Churchill Province of Labrador-Quebec, Canada: Orogenic development as a consequence of oblique collision and indentation

Palaeoproterozoic orogenic development in the northeastern Canadian Shield was controlled by the successive, oblique collision of the Archaean Nain (North Atlantic) and Superior cratons with a southwards projecting promontory of the Archaean Rae Province (part of the northern Churchill Province hinterland). By this process the Rae Province became sutured to the Nain craton by the Torngat Orogen and to the Superior craton by the New Quebec Orogen, resulting in the formation of a 400 km wide orogenic belt known as the Southeastern Churchill Province (SECP). Initial rifting at 2.45-2.1 Ga, and early (arc?) magmatism and deformation at 2.3-1.9 Ga, were restricted to the Rae Province. They were followed by arc magmatism in the Torngat Orogen at c. 1.91-1.88 Ga and Rae\Nain collision 1.87-1.86 Ga, which resulted in the formation of an orogen with east- and west-verging structures. Arc magmatism in the New Quebec Orogen commenced at c. 1.845 Ga and was succeeded by Rae\Superior collision and widespread deformation across the SECP at c. 1.83 Ga. Deformation at this time was dominated by west-vergent thrusting in the New Quebec Orogen and Rae Province, and by renewed east-vergent thrusting in Torngat Orogen. Deformation was then progressively transferred to major sinistral (1.845-1.82 Ga in the eastern SECP) and dextral (1.83-1.80 Ga? in the western SECP) shear systems that accommodated continued northwards motion of the Nain and Superior cratons relative to the Rae Province. Juvenile crust expelled by thrusting effectively doubled crustal thickness in parts of the Rae Province and the northwestern edge of the Nain craton. Late stage development (1.8-1.71 Ga), was restricted to the margins of the SECP, where deformation was associated with renewed outward-directed overthrusting and transcurrent shear in conjunction with uplift of the orogenic core.