La ceinture supracrustale d'Ukaliq

Les échantillons de cette étude ont été collectés sur l'enclave d'Ukaliq (Figure II-14) qui se situe environ à une dizaine de kilomètres au nord de Nuvvuagittuq. Il s'agit d'une séquence volcano-sédimentaire de faible épaisseur (50 m), présentant une stratigraphie relativement intacte (Caro et al., 2017). Comme l'ensemble du complexe d'Inuksuac, cette séquence a été métamorphisée sous faciès amphibolite (Cates and Mojzsis, 2009). La ceinture supracrustale d'Ukaliq (USB) est composée d'intercalations de roches volcaniques (métabasaltes, métakomatiites) et sédimentaires (BIF, quartzite), morcelées par l'intrusion tardive de leucogranites. La ceinture est enclavée par des TTGs de la suite de Voizel (3.45 Ga 3.65 Ga) et par des granitoides potassiques Neoarchéens de la suite de Boizard. Les roches mafiques de cette ceinture présentent des caractéristiques géochimiques similaires à celles

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observées dans la ceinture de Nuvvuagittuq, confirmant leur appartenance à une même génération de ceintures supracrustales. Toutefois, contrairement, aux roches de Nuvvuagittuq, les métabasaltes d'Ukaliq ne semblent pas avoir subi d'altération hydrothermale, et la présence d'amphibolites à cummingtonite reste marginale au sein de la séquence. Les caractéristiques pétro-géochimiques des roches d'Ukaliq seront présentées plus en détail dans le chapitre IV de ce manuscrit.

Figure II-13 : Géochronologie U-Pb des zircons de quartzites détritiques et métapélites de la ceinture de Nuvvuagittuq (Cates et al., 2013).

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