Late pleistocene chronology of glacial lake old crow and the north-west margin of the laurentide ice sheet

Abstract

Late Pleistocene advances of the Laurentide Ice Sheet in the northern Cordillera diverted westward the regional preglacial arctic drainage of the Porcupine River, northern Yukon, Canada. Glacial advance caused flooding of glacial Lake Old Crow which occupied Old Crow Basin, originally inundated by the northward diversion of Peel River drainage by a lobe of the Laurentide Ice Sheet that occupied Bonnet Plume Depression to the headwaters of Eagle River during the ice sheet maximum. Further glacial lake transgression expanded into Bell, Driftwood and Bluefish basins and Upper Rat River valley, covering an area of c. 13,000 km2. Radiocarbon dates from an exposure along the south-western edge of Bluefish Basin place ages on the deposition of near-shore deltaic sediments associated with the maximum glacial Lake Old Crow transgression, c. 18.8–16.4 ka BP. A synthesis of regional stratigraphic and geochronological data indicates two phases of glacial Lake Old Crow transgression; Stage 1, c. 35–22 ka BP, correlative to the all-time maximum advance of Laurentide ice; and Stage 2, c. 22–16 ka BP, correlative to the Katherine Creek phase readvance. Final drainage of glacial Lake Old Crow by 14.8 ka BP caused rearrangement of the regional drainage, establishing the present Porcupine River as a tributary of the Yukon River system into Alaska.