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TitleU-Pb geochronology and geochemistry of the Povungnituk Group of the Cape Smith Belt: part of a craton-scale circa 2.0 Ga Minto-Povungnituk Large Igneous Province, northern Superior craton
 
AuthorKastek, N; Ernst, R E; Cousens, B L; Kamo, S L; Bleeker, WORCID logo; Söderlund, U; Baragar, W R A; Sylvester, P
SourceLithos vol. 320-321, 2018 p. 315-331, https://doi.org/10.1016/j.lithos.2018.09.026
Year2018
Alt SeriesNatural Resources Canada, Contribution Series 20190226
PublisherElsevier
Documentserial
Lang.English
Mediapaper; on-line; digital
File formatpdf; html; xlsx (Microsoft® Excel®); jpg
ProvinceQuebec
NTS25E/03; 25E/04; 25E/05; 25E/06; 25E/12; 35B/13; 35B/14; 35B/15; 35B/16; 35C/11; 35C/12; 35C/13; 35C/14; 35C/15; 35C/16; 35D/15; 35D/16; 35F/01; 35F/02; 35F/03; 35F/04; 35F/05; 35F/06; 35F/07; 35F/08; 35F/09; 35F/10; 35F/11; 35F/12; 35G; 35H
AreaNunavik
Lat/Long WENS -79.0000 -71.0000 62.0000 60.5000
Subjectsgeochronology; geochemistry; Science and Technology; Nature and Environment; radiometric dating; uranium lead dating; tectonic history; magmatism; intrusions; sills; dykes; emplacement; thermal history; bedrock geology; lithology; mafic rocks; igneous rocks; volcanic rocks; basalts; lava flows; intrusive rocks; dolerites; sedimentary rocks; metamorphic rocks; paleomagnetism; paleogeography; ophiolites; baddeleyite; mantle; lithosphere; geochemical analyses; trace element analyses; major element analyses; isotopic studies; isotope ratios; field relations; models; modelling; Archean; Paleoproterozoic; Povungnituk Group; Cape Smith Belt; Minto-Povungnituk Large Igneous Province; Superior Craton; Beauparlant Formation; Cecilia Formation; Watts Group; Minto Dykes; Eskimo Formation; Lac Leclair Alkaline Complex; Kenty Lake Alkaline Complex; Korak Sill; Inukjuak Dykes; Nastapoka Basalts; Persillon Volcanics; Lac Shpogan Dykes; Precambrian; Proterozoic
Illustrationslocation maps; geoscientific sketch maps; profiles; tables; Concordia diagrams; plots; models
ProgramTargeted Geoscience Initiative (TGI-5) Nickel-copper-PGE-chromium ore systems - deposit controls in cratonic areas
Released2018 09 27
AbstractMagmatism of the Povungnituk Group of the Cape Smith Belt, northern Superior craton, was formed in three stages: (i) early alkaline magmatism and associated carbonatites (undated), (ii) a main flood basalt sequence (Beauparlant Formation) (constrained between 2040 and 1991 Ma), and (iii) a late stage alkaline pulse (Cecilia Formation) (ca. 1959 Ma). We suggest that the main stage of magmatic activity (middle pulse) was of short duration.
A new U-Pb baddeleyite age of 1998 ± 6 Ma is obtained from a dolerite sill intruding the uppermost section of the Beauparlant Formation. This age has regional significance because it matches the previously obtained 1998 ± 2 Ma age for the Watts Group (Purtuniq) ophiolite of the northern Cape Smith Belt and the 1998 ±2 Ma U-Pb age of the Minto dykes intruding the craton to the south. These coeval units, along with additional units correlated on paleomagnetic grounds (Eskimo Formation), are interpreted to define a large igneous province (LIP), extending over an area of N400,000 km2, which we herein define as the Minto-Povungnituk LIP.
Geochemical comparison between the Watts Group ophiolite, Minto dykes and the mafic Povungnituk Group shows significant differences allowing these data to be divided into two groups and domains within the LIP. A northern domain, comprising the Povungnituk and Watts groups, shows mixing between a depleted mantle source and a more enriched mantle plume-sourced melt. A southern domain comprising the Minto dykes and the paleomagnetically linked Eskimo Formation shows signs of an even more enriched source, while these magmas also show the effect of crustal contamination.
Two distinct source mechanisms can be responsible for the observed geochemical differences between the two domains. First, a difference in lithospheric sources, where melting of different portions of Superior craton lithosphere caused the different melt signatures in the interior of the craton. In this case magmatism in the two domains is only related by having the same heat source (e.g., a mantle plume) interpreted to be located on the northwestern side of the northern Superior craton. Second, two distinct deep mantle sources that remained separated within the ascending plume. This is analogous to some current hotspots interpreted to sample both large low shear velocity provinces (LLSVP) and adjacent ambient deep mantle. This latter interpretation would allow for the use of bilateral chemistry in LIPs as a potential tool for the recognition and mapping of the LLSVP boundaries throughout Earth's history.
GEOSCAN ID321391

 
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