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TitleU-Pb zircon geochronology of Archean greenstone belts (Mary River Group) and surrounding Archean to Paleoproterozoic rocks, northern Baffin Island, Nunavut
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AuthorSkipton, D R; Wodicka, N; McNicoll, V; Saumur, B M; St-Onge, M R; Young, M D
SourceGeological Survey of Canada, Open File 8585, 2019., https://doi.org/10.4095/314938 (Open Access)
Year2019
PublisherNatural Resources Canada
Documentopen file
Lang.English
Mediaon-line; digital
File formatreadme
File formatpdf (Adobe® Reader®); rtf; xlsx (Microsoft® Excel®)
ProvinceNunavut
NTS37E/03; 37E/04; 37E/05; 37E/06; 37E/11; 37E/12; 37E/13; 37E/14; 37F; 37G; 38B/01; 38B/02; 38B/03; 38B/04; 38B/05; 38B/06; 38B/07; 38B/08; 38B/09; 38B/10; 38B/11; 38B/12; 38B/14SE; 38B/14SW; 38B/15SE; 38B/15SW; 38B/16SE; 38B/16SW; 48A/01; 48A/08NE; 48A/08SE; 48A/09SE
AreaBaffin Island; Mary River; Pond Inlet; Steensby Inlet; Barnes Ice Cap
Lat/Long WENS -80.7500 -74.0000 72.8333 70.0000
Subjectsregional geology; stratigraphy; tectonics; geochronology; economic geology; Archean; greenstone belts; radiometric dating; uranium lead dating; zircon dates; lead lead dates; mineral potential; tectonic history; volcanism; depositional history; intrusions; sills; emplacement; metamorphism; deformation; thermal history; bedrock geology; basement geology; lithology; metamorphic rocks; gneisses; metavolcanic rocks; metarhyolites; metasedimentary rocks; psammites; quartzites; orthogneisses; igneous rocks; intrusive rocks; granodiorites; monzo-granites; diorites; tonalites; leucogranites; gabbros; leucogabbros; mafic intrusive rocks; felsic intrusive rocks; correlations; Mary River Group; Paleoproterozoic; Rae Craton; Laurentia; Mary River Iron Mine; Arrowsmith Orogen; Ellesmere Orogeny; Inglefield Orogeny; Trans-Hudson Orogen; metaplutonic rocks; syenogranites; siliciclastic rocks; sensitive high-resolution ion microprobe analyses; SHRIMP; thermal ionization mass spectrometry analyses; TIMS; metadacites; supracrustal rocks; Phanerozoic; Precambrian; Proterozoic
Illustrationsgeoscientific sketch maps; tables; photomicrographs; Concordia diagrams; photographs; histograms; graphs
ProgramBaffin Bedrock Mapping, GEM2: Geo-mapping for Energy and Minerals
Released2019 08 08
AbstractPrior to 1:100,000-scale geological mapping conducted in 2017-2018, northern Baffin Island remained a major knowledge gap in the understanding of the northern Rae craton and the tectonic assembly of northeastern Laurentia. Geochronological data in the region was sparse; only four published U-Pb dates existed in the mapping area (~67,000 km2). Resolving the geology and age of the Archean Mary River Group - host to the Mary River iron mine - and the surrounding felsic-to-intermediate gneiss has key implications for the regional tectonic history and mineral prospectivity. In this study, we present new U-Pb zircon ages for 16 samples, including: 3 metavolcanic rocks and a quartzite from the Mary River Group; 2 psammite samples from newly discovered strata near Pond Inlet; 8 felsic-to-intermediate metaplutonic rocks; and 2 mafic metaplutonic rocks. Gneissic granodiorite to quartz diorite that forms the basement to the Mary River Group is dated herein at ca. 2901-2892 Ma. Taking into account previously published data, the age of gneissic basement beneath the Mary River Group is considered to be ca. 2901-2775 Ma. New ages of felsic-intermediate metavolcanic rocks from the Mary River Group define two phases of volcanism at ca. 2830 Ma and ca. 2760-2718 Ma, whereas quartzite from the Mary River Group has a maximum depositional age of ca. 2705 Ma. Psammite from the Pond Inlet area has a similar maximum depositional age of ca. 2720 Ma. Monzogranite and granodiorite and, less commonly, tonalite define an extensive ca. 2731-2706 Ma felsic plutonic suite. Mafic metaplutonic rocks near Pond Inlet, including a layered maficultramafic intrusion, yielded ages of ca. <2720 and >2655 Ma. Late, post-kinematic syenogranite was emplaced at ca. 1792 Ma. U-Pb dates of metamorphic zircon indicate that portions of northern Baffin Island experienced metamorphism during ca. 2.6-2.5 Ga, ca. 1926-1878, and 1850-1820 Ma. The new U-Pb zircon data reinforces lithological and tectonic correlations between northern Baffin Island and the Rae craton in Arctic Canada and West Greenland. Metamorphic U-Pb zircon data also suggest that northern Baffin Island may record tectonothermal activity associated with the Arrowsmith, Ellesmere-Inglefield, and/or Trans-Hudson orogens.
Summary(Plain Language Summary, not published)
Prior to geological mapping conducted in 2017¿2018, northern Baffin Island represented a major knowledge gap in the understanding of the geological history of the eastern Canadian Arctic. The recent mapping has identified and documented the various rock types in the area, including felsic igneous rocks and the Mary River Group, a succession of ancient volcanic and sedimentary rocks that host the world-class Mary River iron mine. Determining the ages of the rocks using a technique based on the radiogenic decay of isotopes (U-Pb zircon geochronology) is important for understanding the geological framework of northern Baffin Island. In this study, we present 16 new U-Pb ages, which show that the Mary River Group was deposited between ~2.8 and 2.7 billion years ago, felsic rocks beneath the Mary River Group were emplaced between ~2.9 and 2.8 billion years ago, and other granitic rocks were emplaced later, at ~2.7 billion years ago. The new geochronological data reinforce correlations between northern Baffin Island and similar rocks located in the Canadian Arctic and in West Greenland.
GEOSCAN ID314938