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TitleArchean and Paleoproterozoic fault history of the Big Lake shear zone, MacQuoid-Gibson lakes area, Nunavut
LicencePlease note the adoption of the Open Government Licence - Canada supersedes any previous licences.
AuthorRyan, J J; Hanmer, S; Sandeman, H A; Tella, S
SourceGeological Survey of Canada, Current Research (Online) no. 2000-C6, 2000, 11 pages, Open Access logo Open Access
PublisherNatural Resources Canada
Mediaon-line; digital; CD-ROM
RelatedThis publication is contained in Current Research 2000
File formatpdf
NTS55M/09; 55M/16; 55N/11; 55N/12; 55N/13; 55N/14
AreaBig Lake; MacQuoid Lake; Gibson Lake; Squiggly Lake; Chesterfield Inlet; Cross Bay
Lat/Long WENS -94.5000 -93.0000 64.0000 63.5000
Subjectsstructural geology; igneous and metamorphic petrology; Archean; faults; shear zones; structural features; structural interpretations; metamorphic facies; mylonites; lithology; metamorphic rocks; dykes; igneous rocks; gneisses; amphibolite facies; granulite facies; anorthosites; deformation; total field magnetics; Big lake shear zone; Precambrian; Proterozoic
Illustrationssketch maps; stereograms; photographs
ProgramWestern Churchill NATMAP Project
Released2000 01 01
AbstractThe Big lake shear zone in the MacQuoid Gibson lakes area comprises diverse mylonitic rocks with a complex tectonothermal history. The shear zone has an exposed strike length of 50 km, with abrupt termination to the west. Central and eastern segments of the shear zone consist of dextral, amphibolite-facies, porphyroclastic mylonite and annealed straight gneiss. The western segment, however, is cored by variably retrogressed granulite-facies mafic and anorthositic ultramylonite, within amphibolite-facies wall rocks, and has a more complex kinematic history. The granulite-facies rocks are spatially associated with the anorthosite sheets, which are interpreted here as the dominant heat source of the localized high-grade event. The ultramylonite units are crosscut by undeformed ca. 2.19 Ga MacQuoid dykes, constraining the high-grade, high-strain event to be older. Regional aeromagnetic data illustrate that the western segment is truncated by two faults of (?)Proterozoic age.

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