Results of integrated geological and aeromagnetic mapping, and recent exploration, Henik and Hurwitz groups, Noomut River, Northwest Territories (Nunavut)

Abstract

Henik Group (Neoarchean) supracrustal rocks, including iron-formation marker horizons, were deposited in a deep- water lava plain-slope-basin setting across at least 6000 km2 in central Ennadai-Rankin greenstone belt. Hurwitz Group (2.45-2.11 Ga) rocks record continental to marine intracratonic-basin sedimentation. Archean rocks experienced synplutonic folding, faulting, and metamorphism (D1, probably Archean), east-northeast- trending folding that was followed by dextral faulting (D2; Paleoproterozoic(?)) and cross faulting (D3). At recently discovered prospects in the Henik Group, gold (with disseminated pyrite and pyrrhotite) is concentrated in quartz veins and carbonate-pyrite alteration zones in gabbro (`Esker' prospect); quartz-carbonate-chlorite veins in magnetite iron-formation interbedded with turbiditic semipelite ± felsic tuff (`Ironside' prospect); quartz-carbonate veins in iron carbonate- quartz-albite schist, apparently derived from metasomatism of variolitic pillow lava (`Napartok' prospect); and quartz-carbonate-biotite veins in magnetite iron-formation interbedded with turbiditic semipelite (`River' prospect). All four prospects appear to be related to D2 or later structures.