Initiation of similar to 2.45-2.1 Ga intracratonic basin sedimentation of the Hurwitz Group, Keewatin Hinterland, Northwest Territories, Canada

Continental to shallow-marine rocks of the Hurwitz Group, exposed as outliers across the Hearne Province in northern Canada, were deposited between similar to 2.45 and 2.11 Ga on a 3.3-2.6 Ga granite-greenstone basement. Initiation of the Hurwitz Basin was characterized by low relief and rates of subsidence that never progressed beyond the intensity of regional sagging. During stage 1, polymictic conglomerate (lower Noomut Formation) was deposited in palaeovalleys cut into Archaean basement, and subarkose to quartz arenite +/- quartz pebble conglomerate (upper Noomut Formation) was deposited on a low-relief sand plain. Abundant first-cycle quartz-rich sandstones are attributed to intense humid climate weathering in low-relief source areas and at sites of temporary storage, as well as to repeated fluvial and eolian reworking. Interbedding of pyritic palaeoplacers and continental redbeds denotes fluctuating levels of atmospheric oxygen; disappearance of pyritic palaeoplacers upsection signifies ultimate changeover to an atmosphere with sustained free oxygen. Stage 2 (Padlei Formation) was marked by a climatic shift toward cold (glacial?) conditions as indicated by dropstones, greywacke (till?) pellets and possible ikaite pseudo-morphs in lacustrine rhythmites. Stage 3 (Kinga Formation) represents a return to wet/warm conditions with fluvial (+/- eolian) deposition of subarkose and quartz arenite on a low-relief sand plain (Maguse Member) and deposition of supermature quartz arenite in a vast (100,000 k(m)2 minimum), shallow-water lake or series of lakes (Whiterock Member). Local chert beds at the top of the Kinga Formation (Hawk Hill Member) formed by spring discharge due to regional, gravity-driven, convective groundwater flow. An intracratonic setting is implied by: (1) a symmetric, basin-centred fill; (2) absence of features indicating a shelf-slope break; (3) absence of rift rocks; (4) a prolonged slow-subsidence history; (5) likely correlation with other continental to shallow-marine deposits scattered across the Keewatin Hinterland; and (6) positioning 1000-2000 km away from closest coeval passive margin sequences. We speculate that Hurwitz Basin formed due to lithospheric stretching related to a large-scale mantle upwelling during the protracted breakup of an earliest Palaeoproterozoic supercontinent ('Kenorland').