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TitleU-Pb zircon ages and field relationships of Archean basement and Proterozoic intrusions, south-central Wopmay Orogen, NWT: implications for tectonic assignments
AuthorJackson, V A; van Breemen, O; Ootes, L; Bleeker, W; Bennett, V; Davis, W D; Ketchum, J; Smar, L
SourceCanadian Journal of Earth Sciences vol. 50, 2013 p. 979-1006,
Alt SeriesEarth Sciences Sector, Contribution Series 20130154
PublisherNational Research Council
Mediapaper; on-line; digital
File formatpdf
ProvinceNorthwest Territories; Nunavut
NTS75; 76; 85; 86
AreaSlave Craton
Lat/Long WENS-120.0000 -104.0000 68.0000 62.0000
Subjectsgeochronology; geochemistry; igneous and metamorphic petrology; structural geology; tectonics; plutons; orogenies; orogenesis; bedrock geology; zircon; kinematic analysis; deformation; Archean; metamorphism; plate tectonics; Proterozoic
Illustrationslocation maps; geological sketch maps; photographs; tables; graphs; geochemical plots
ProgramGeomapping for Energy and Minerals (GEM) - Minerals Component, GEM: Geo-mapping for Energy and Minerals
AbstractNew field and U-Pb zircon data from the south-central Wopmay Orogen (south of 65°N) establish crystallization ages of basement and plutonic phases and bring to the forefront questions on the architecture of the orogen. The complex and extensive >3300-2575 Ma basement domain was derived from the adjacent Slave craton. Paleoproterozoic supracrustal rocks, dominated by an extensive pelitic-psammitic sequence with basal arenite, conglomerate, and carbonate, unconformably overlie this basement. Pre- to post-kinematic Paleoproterozoic plutons intrude both basement and overlying strata and crystallized at 1877, 1867-1862, and 1858-1850 Ma. The first pulse of plutonism constrains an early generation of metamorphism and deformation to younger than 1877 Ma and is corroborated by metamorphic zircon in Archean basement. The interval from 1867 to 1862 Ma brackets ductile deformation in granite and granodiorite intrusions; although corresponding structure in the metasedimentary strata is equivocal. Post-kinematic ca. 1858-1850 Ma plutons were coeval with localized high-grade metamorphism and concomitant recrystallization of Archean basement. The absence of older (>1880 Ma) phases of the Hepburn intrusive suite in south-central Wopmay Orogen demonstrates a previously unrecognized north-south plutonic dichotomy and that the historical assignment of Calderian metamorphism to ca. 1885 Ma may be too old. The designation of part of the area to a klippe of Hottah terrane is not compatible with field and zircon age data which shows that basement and the overlying strata can be tied directly to the Slave craton. The study raises questions regarding the tectonic relationship between the Hottah terrane and Slave craton.
Summary(Plain Language Summary, not published)
New field and U-Pb zircon data from the south-central Wopmay Orogen establish crystallization ages of ancient continental crust and granitoid intrusions, throwing light on the architecture and geological history of this 1900 million year eroded mountain belt in the northwestern Canadian Shield. This collaborative GEM project between the Northwest Territories Geoscience Office and the Geological Survey of Canada links previous mapping in the northern and southern parts of the Wopmay Orogen. The belt hosts numerous promising mineral showings and the new geological framework will stimulate and guide future mineral exloration.