Crustal evolution of the western Minto Block, northern Superior Province, Canada

Geochemical and Nd isotope data are presented for suites of Meso- to Late Archean (2.7–2.9 Ga) granitoid rocks from the western Minto Block of the northeast Canadian Superior Province. The samples provide coverage of the Inukjuak and Tikkerutuk domains and include biotite, amphibole and/or orthopyroxene-bearing tonalites, granodiorites and granites from tonalite–trondhjemite–granodiorite (TTG) and monzodiorite suites. Both suites are characterized by strong light rare earth element (REE) and large-ion lithophile (LIL) element enrichment, variably negative to positive Eu anomalies and moderate heavy REE depletion. High La/Yb and Sr/Y ratios with correspondingly low Yb and Y concentrations in both suites likely reflect parental melts that left residual garnet. Correlations between Eu anomalies and fractionation indices suggest that compositional variations in both suites reflect plagioclase accumulation in tonalite samples and plagioclase and Fe–Ti oxide fractionation among granitic samples. The Nd isotope compositions range from ɛNd values of +2 to −10, the largest range found among granitoids of the Minto Block, and indicate the presence of a crustal contaminant of ca. 3.8 Ga in age. There is a decrease in ɛNd values from east to west across the studied region and a measurable decrease across Tikkerutuk and Inukjuak domain boundary. This suggests increasing addition of an older crustal component in the Inukjuak domain, possibly as a result of recycling of Early Archean crust from the nearby ca. 3.8 Ga Nuvvuagittuq sequence.