Ice-flow evolution of the Labrador Sector of the Laurentide Ice Sheet: a review, with new evidence from northern Quebec

Outcrops bearing stained, striated facets indicative of north-northeastward moving ice, truncated by unstained, striated facets indicative of various younger hows occur in the Caniapiscau area of north-central Quebec. This is the first report of differential staining of striated facets in the region . We propose that the staining occurred in an ice-free interval of probable interglacial age. This early ice flow probably occurred during ice retreat toward the Quebec highlands. Ice flow and glacial transport data from the southern Hudson Bay and James Bay basins indicate that the next major regio nal ice flow was toward the northwest and resulted from the expansion of an Early Wisconsinan glacier in the Quebec highlands. The northern part of th is flow was diverted northwestward through Hudson Bay, and the southern par t southwestward across James Bay, following a progressive counterclockwise rotation of flow. A zone of intersection (ZI) of two major glacier bedform systems, often referred to as the horseshoe-shaped Labrador Ice Divide, rep resents the head of a large northward convergent ice-flow system that exten ded to Ungava Bay and beyond. The Ungava flow propagated southward and capt ured the head of the opposing flow from an outflow centre located east of C aniaspiscau reservoir. We propose that this capture event correlates with t he Gold Cove Advance in Ungava Bay and on Baffin Island at about 9900 14C y r BP, It is the largest advance of Quebec-Labrador ice yet proposed for the region. This correlation is based on the relative ice-flow chronology, acc ommodation of glacial lakes Naskaupi and McLean in the deglaciation sequenc e, the constraints placed on Last Glacial Maximum (LGM) ice configuration b y the postglacial uplift pattern and events in the deep-sea record. Therefo re, the Ungava ice-flow pattern is not a relict pre-Wisconsinan glacial lan dscape as recently proposed. (C) 1999 Elsevier Science Ltd. All rights rese rved.