Ujaraaluk Unit (Nuvvuagittuq greenstone belt)
The Ujaraaluk unit is the dominant lithological unit in the Nuvvuagittuq greenstone belt (formerly called Porpoise Cove greenstone belt) in Northeastern Canada. It is interpreted to be as old as 4.39 Ga, which would make it the oldest vestige of crust preserved on Earth (O’Neil et al. 2008, 2012). The Ujaraaluk unit is an amphibolite composed of variable proportions of cummingtonite – plagioclase – biotite ± quartz ± garnet ± anthophyllite (O’Neil et al. 2011). The abundance of cummingtonite gives the Ujaraaluk unit an unusual light beige color compared to most other dark green to black hornblende-dominated greenstone belts in the Northeastern Superior Province. The Ujaraaluk unit was formerly named “Faux-amphibolite” due to this unusual aspect (O’Neil et al. 2007).
The Ujaraaluk is mafic in composition ranging from basaltic to basaltic andesite. It is divided into three distinct geochemical groups following a chemostratigraphy within the Nuvvuagittuq greenstone belt (O’Neil et al. 2011...
KeywordsGreenstone Belt Ultramafic Cumulate Trace Element Profile Geochemical Group Tholeiitic Affinity
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