Neoarchean continental crust formation and Paleoproterozoic deformation of the central Rae craton, Committee Bay belt, Nunavut

• Published in: Canadian Journal of Earth Sciences
• Main Authors: Sanborn-Barrie, M., Davis, W.J., Berman, R.G., Rayner, N., Skulski, T., Sandeman, H.
• Other Authors: Corfu, Fernando
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 2014
• Subjects: Nunavut; Arrowsmith; Committee Bay
• Online Access: http://dx.doi.org/10.1139/cjes-2014-0010; http://www.nrcresearchpress.com/doi/full-xml/10.1139/cjes-2014-0010; http://www.nrcresearchpress.com/doi/pdf/10.1139/cjes-2014-0010

Integrated mapping, structural analysis, and U–Pb geochronology of the Committee Bay area, Nunavut, establish a record of Neoarchean crustal growth followed by penetrative Paleoproterozoic deformation. Supracrustal rocks include a lower ca. 2.73 Ga mafic–ultramafic volcanic-dominated sequence, a middle, economically significant 2.71 Ga intermediate volcanic-bearing sequence with intercalated sulphidized, gold-bearing iron formation, and an upper <2.69 Ga clastic ± komatiite–quartzite sequence. Following an 80 million year hiatus, this succession was intruded by voluminous ca. 2.61–2.57 Ga granodiorite–tonalite–granite ± diorite, which do not appear to have thermally or tectonically affected the supracrustal belt. Instead, three generations of structures record polyphase Paleoproterozoic deformation of the region. D 1 structures are consistent with a doubly vergent structural fan developed at ca. 2.35 Ga in response to the Arrowsmith orogeny that affected the western Rae margin. Penetrative D 2 structures dominate the map pattern and include northeast-trending, southeast-dipping folds and fabrics within which gold is localized. The general southeast dips of S 2 and inclined, northwest-vergent attitude of F 2 reflect northwest-directed shortening at 1.84–1.82 Ga. The absence of syn-D 2 plutonic rocks in the west and central Committee Bay belt support amphibolite-facies metamorphism as a response to crustal thickening, which, in turn, led to syn-D 2 crustal melting in the east. Regionally extensive upright to northwest-vergent D 2 structures and associated ca. 1.85–1.82 Ga tectonometamorphism across the Rae craton are attributed to an early stage of the Hudsonian orogeny involving microcontinent collision(s) with its southeastern margin. D 3 folds and dextral shearing at ca. 1780 Ma accommodated localized, late-stage compressional strain during final amalgamation of Laurentia.