Archean crustal evolution in the central Minto block, northern Quebec

The central Minto block contains three volcano-sedimentary successions. Near Lake Qalluviartuuq, an isotopically primitive (2.83GaεNd +3.8 to +2.3) 2.83 Ga volcano-plutonic sequence comprises depleted tholeiitic basalts, anorthositic gabbro, and diorite-granodiorite that is unconformably overlain by <2.77 Ga conglomerates. Overlying the conglomerate is a more evolved (2.76GaεNd +1.8) calc-alkaline sequence of pillow basalts, andesites, and peridotite cut by 2.73 Ga diorite. To the west, and in inferred tectonic contact, the sediment-dominated Kogaluc sequence includes both isotopically evolved calc-alkaline rocks (2.76GaεNd +1.6 to -0.1) including <2.76 Ga rhyolitic tuff, pillowed andesites, and 2.76 Ga quartz-feldspar porphyry, and less abundant, depleted tholeiitic basalts (2.76 GaF-Nd +2.4). These are interlain with sedimentary rocks including banded iron-formation, quartzite, and metagreywacke. Calc-alkaline batholiths include 2.78 Ga pyroxene-bearing intermediate and felsic plutons (2.78GaεNd <+2.7) and younger, peraluminous tonalites (εNd <+1.3). Late, 2.73 Ga peraluminous granitoids are isotopically evolved (2.725GaεNd - 1. 6). (author). 19 refs., 4 tabs., 5 figs