Lithostratigraphy and map-scale structure in the western Cape Smith Belt, northern Quebec: a tentative correlation between two tectonic domains

• Published in: Canadian Journal of Earth Sciences
• Main Author: Barrette, Paul D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: National Research Council of Canada. NRC Research Press 1994
• Subjects: Cape Smith; Hudson; Hudson Bay; Lac Lanyan
• Online Access: https://doi.org/10.1139/e94-087; https://nrc-publications.canada.ca/eng/view/object/?id=8dbfb5af-c8bc-4ce0-8ac8-0a2f8436d270; https://nrc-publications.canada.ca/fra/voir/objet/?id=8dbfb5af-c8bc-4ce0-8ac8-0a2f8436d270

Field investigations in the western part of the Cape Smith Belt outlined four fault-bounded lithological assemblages tectonically overlying foliated to gneissic granitoids of the Archean Superior Province. These assemblages comprise sequences of pillowed volcanic rocks, sedimentary rocks of pelitic and psammitic composition, and volcaniclastic rocks. They are juxtaposed along the Lanyan Lake Fault against a structurally thickened sequence of mafic to ultramafic pillowed volcanic suite belonging to the Chukotat Group. The occurrence of volcaniclastic horizons in the uppermost levels of the Chukotat Group may indicate a northward facies transition from sea-floor volcanism to arc sedimentation, the latter corresponding to the Parent Group. A major pluton intruding the upper Chukotat Group, if assigned to the younger Narsajuaq intrusive suite, provides support for an 1844 – 1826 Ma link between two tectonic domains, formerly considered "suspect." These domains lie on either side of the Bergeron Fault in the east and central parts of the Cape Smith Belt. This fault, formerly interpreted as extending to Hudson Bay, was not recognized in this work. Thrust faulting, involving three kilometre-thick imbricate slices enclosing the Superior Province, was followed by the development of the Cape Smith Synclinorium with overturning of its northern limb, forelimb faulting, and large-scale folding along northwest-trending axes. Des travaux de terrain dans la partie occidentale de la Bande du Cap Smith ont démontré l'existence de quatre assemblages lithologiques délimités par des failles et reposant en contact tectonique sur le socle archéen de la Province du lac Supérieur. Ces assemblages sont composés de volcanites mafiques coussinées, de roches sédimentaires silteuses et argileuses et de volcaniclastites. Ils sont séparés du Groupe de Chukotat par la Faille du lac Lanyan. Ce groupe est composé d'une séquence structuralement imbriquée de basaltes coussinés de composition mafique à ultramafique. La présence de roches ...