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TitleU-Pb, Lu-Hf and REE in zircon from 3.2 to 2.6 Ga Archean gneisses of the Repulse Bay block, Melville Peninsula, Nunavut
AuthorLaFlamme, C; McFarlane, C R M; Corrigan, DORCID logo
SourcePrecambrian Research vol. 252, 2014 p. 223-239,
Alt SeriesNatural Resources Canada, Contribution Series 20182210
PublisherElsevier BV
Mediapaper; on-line; digital
File formatpdf
ProgramGEM: Geo-mapping for Energy and Minerals Melville Peninsula
Released2014 10 01
AbstractCombined in situ U-Pb and Lu-Hf isotope, and REE analyses of zircons from the tonalite-trondhjemite-granodiorite (TTG)-type gneisses and granitoids within the Repulse Bay block (RBb) of Melville Peninsula, Nunavut, reveal that the block is composed of ca. 2.86 Ga and 2.73-2.71 Ga granitoids that formed by reworking of a 3.25-3.10 Ga basaltic crust. The interpretation is supported by initial eHf values for ca. 2.86 Ga and ca. 2.73-2.71 Ga gneisses of -2.7 to -0.7 and -4.8 to -2.3, respectively, and the preservation of high uranium xenocrystic cores at 3.15 ± 0.05 Ga Neoarchean plutonism also occurred at ca. 2.69-2.66 Ga, and is characterized by two pyroxene-bearing charnockite-enderbite and hornblende-biotite granitoid intrusions that yield initial eHf values that range from -7.1 to +1.0 demonstrating that they were derived from juvenile magmas with significant assimilation of the existing crust. The pyroxene- and non pyroxene-bearing granitoids also contain elevated LREE in zircon, a feature that is interpreted to reflect metasomatism of the source. This study also demonstrates that in the RBb, the results of Lu-Hf isotopes in zircon combined with in situ U-Pb geochronology from inherited zircon cores, differ from the results of whole rock Sm-Nd isotopes.

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