Distributed crustal shortening followed by transpressional shearing in the Superior Province, northeastern Canada: A Late Archean analogy to modern accretionary plate margins?

The Canadian Superior Province has become one of the key test pieces to discuss tectonic processes and mechanisms crustal growth in Late Archean. consists a >2.8 Ga proto-cratonic core intruded by voluminous arc-like plutons surrounded series narrow, elongate ca. 2.8–2.7 juvenile belts, also referred as terranes or domains. seem wrap around generally young outward, but kinematics geodynamic causes their assembly remain debated. In this paper, we examine Radisson pluton northeastern Québec, which southern, outer edge presumed magmatic arc (Bienville domain) along its ~WNW–ESE-trending boundary with crust (La Grande domain). pluton, dominated porphyritic monzogranite quartz monzonite, was emplaced at 2712 Ma exhibits complex internal structure resulting from superposed solid-state deformations. An early margin-parallel ~WNW–ESE foliation containing steep lineation, recognized anisotropy magnetic susceptibility (AMS), is interpreted recording vertical stretching horizontal flattening highly crystallized magma, either due emplacement and/or pure shear transpression. More widespread, however, lineation within same that post-emplacement, still syn-magmatic, strain (~NNE–SSW shortening boundary-parallel stretching). Upon cooling, localized dextral S–C mylonite zones accommodated further whereas undeformed late-stage felsic dikes cross-cut fabric an angle margins. We suggest structural succession, reproduced numerical modeling, local-scale signal two-stage Province: frontal, NNE-directed terrane convergence attachment cratonic nucleus, operating ‘hot’ regime plutonism, followed more shearing parallel boundaries. latter phase recorded proto-craton margin outboard Abitibi greenstone belt virtually time (ca. 2700–2690 Ma). combination, evolution similar deformation distributed over broad region resemble modern large hot orogens formed plate-tectonic regime.