Structural development of the Snow Lake Allochthon and its role in the evolution of the southeastern Trans-Hudson Orogen in Manitoba, central Canada

The Snow Lake Allochthon is a zone of tectonic interleaving of sedimentary rocks of an inverted marginal basin (Kisseynew Domain) with island-arc and oceanic rocks. It is located in the southeastern part of the exposed intern al zone of the Paleoproterozoic Trans-Hudson Orogen in Manitoba, Canada, ne ar the external zone (Superior collision zone or Thompson Belt), which cons titutes the local boundary between the Trans-Hudson Orogen and the Archean Superior Craton. The Snow Lake Allochthon formed, was deformed, and was met amorphosed up to high grade at low to medium pressure during the Hudsonian orogeny as a result of the collision of Archean cratons similar to 1.84-1.7 7 Ga. Four generations of folds (F-1-F-4) that formed in at least three suc cessive kinematic frames over a period of more than 30 Ma are described. Is oclinal to transposed southerly verging F1-2 structures are refolded by lar ge, open to tight F-3 folds and, locally, by open to tight F-4 folds. The a xes of the F1-2 folds are parallel or near parallel to the axes of F-3 fold s, owing to progressive reorientation of the F1-2 axes during south- to sou thwest-directed tectonic transport, followed by F-3 refolding around the pr evious linear anisotropy. A tectonic model is presented that reconciles the distinct tectono-metamorphic developments in the Snow Lake Allochthon and the adjacent part of the Kisseynew Domain on the one hand, and in the Thomp son Belt on the other, during final collision of the Trans-Hudson Orogen wi th the Superior Craton.