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TitleNeoarchean continental crust formation and Paleoproterozoic deformation of the central Rae craton, Committee Bay belt, Nunavut
AuthorSanborn-Barrie, M; Davis, W J; Berman, R G; Rayner, N; Skulski, T; Sandeman, H
SourceCanadian Journal of Earth Sciences vol. 51, no. 6, 2014 p. 635-667, https://doi.org/10.1139/cjes-2014-0010 (Open Access)
Year2014
Alt SeriesEarth Sciences Sector, Contribution Series 20140046
PublisherCanadian Science Publishing
Documentserial
Lang.English
Mediaon-line; digital
File formatpdf; html
ProvinceNunavut
NTS56J/09; 56J/11; 56J/12; 56J/13; 56J/14; 56J/15; 56J/16; 56K; 56O/01; 56O/02; 56O/03; 56O/04; 56O/05; 56O/06; 56O/07; 56O/08; 56P
AreaCommittee Bay
Lat/Long WENS -94.0000 -88.0000 68.0000 66.0000
Subjectsgeochronology; structural geology; stratigraphy; deformation; continental crust; uranium lead dates; structural analyses; lithology; stratigraphic correlations; mineralization; gold; plutonic rocks; granodiorites; monzo-granites; dykes; Archean; Rae craton; Committee Bay belt; Precambrian; Proterozoic
Illustrationsgeological sketch maps
ProgramGeomapping for Energy & Minerals (GEM) - Geo-mapping Frontiers, GEM: Geo-mapping for Energy and Minerals
AbstractIntegrated 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 a 80 Myr hiatus, this succession was intruded by voluminous ca. 2.61-2.57 Ga granodiorite-tonalite-granite±diorite, which does not appear to have exerted a controlling thermal or tectonic influence on the supracrustal belt. Instead, three generations of structures record polyphase Paleoproterozoic deformation of the region. D1 structures are consistent with a doubly vergent structural fan developed at ca. 2.35 Ga as a response to the Arrowsmith Orogeny which affected the western Rae margin. Penetrative D2 structures include northeast-trending, southeast-dipping folds and fabrics, within which gold is localized. The general southeast dips of S2 and inclined, northwest-vergent attitude of F2 reflect northwest-directed shortening at 1.84-1.82 Ga. The absence of syn-D2 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-D2 crustal melting in the east. Regionally extensive upright to northwest-vergent D2 structures and associated ca. 1.85-1.82 Ga tectono-metamorphism across the Rae craton are attributed to an early stage of the Hudsonian orogeny involving microcontinent collision(s) with its southeastern margin. D3 folds and dextral shearing at ca. 1780 Ma accommodated localized, late-stage compressional strain during final amalgamation of Laurentia.
Summary(Plain Language Summary, not published)
Mapping, measuring structures and dating rocks in central Nunavut established the presence of a greenstone belt formed 2.73 billion years ago, that was intruded by magma 2.6 billion years ago and then deformed much later. Formation of the belt by volcanic and sedimentary processes generated three units, the middle of which is gold mineralized. Following a 80 million year hiatus, voluminous ca. 2.61-2.57 Ga magmas intruded, but didn't deform the belt. Rather, three generations of structures were imposed much later. The earliest structures record compression (Arrowsmith Orogeny) about 2.35 billion years ago. The dominant, second generation of structures includes folds and fabrics within which gold is localized. These reflect regional NW-directed shortening 1.84 billion years ago, attributed to continent collision (Hudsonian Orogeny). Localized shear zones about 1.78 billion years old reflect late-stage compression during the final stages of amalgamation of the North American continent.
GEOSCAN ID293949