U–Pb, Lu–Hf and REE in zircon from 3.2 to 2.6 Ga Archean gneisses of the Repulse Bay block, Melville Peninsula, Nunavut

• High grade TTG terrane in Rae domain.
• Zircons measured for U–Pb, Lu–Hf and trace elements by LA-(MC)-ICPMS.
• Derivation of TTG crust at 2.86 and 2.73–2.71 Ga from a 3.25–3.15 Ga mafic crust.
• Generation of charnockite–granite magmatism at 2.69–2.66 Ga from a juvenile source.

Combined 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 ɛHf 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 ɛHf 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.