Ice-flow patterns and glacial transport in the eastern Hudson Bay region: implications for the late Quaternary dynamics of the Laurentide Ice Sheet

Abstract

Recent field surveys in the eastern Hudson Bay region have led to the discovery of regional ice-flow sequences that require a significant reassessment of the late Quaternary dynamics of the Laurentide Ice Sheet. Two regional ice-flow phases can be recognized from till compositional data and from crosscutting relationships observed on striated bedrock surfaces: the oldest is directed toward the northwest and north-northwest, while the youngest is directed toward the west and includes a late-glacial deflection toward the southwest. The wide regional distribution of striae formed during the early northwestward glacial movement together with the recognition of palimpsest glacial dispersal trains associated with this phase suggest that it was a long-lived, time-transgressive regional event. The ensuing glacial movement is a regionally dominant westward ice-flow phase during which several large glacial dispersal trains were formed downglacier from distinctive bedrock sources. The largest of these trains extends westward over a distance of 120 km from Lac à l'Eau Claire to Hudson Bay. Regional glacial transport data as well as glacial and deglacial landforms indicate that this was a long-lived glacial phase, likely lasting throughout the Late Wisconsinan glacial maximum and until déglaciation about 8000 BP. The erosional and depositional record of the northwestward ice-flow event is quite comparable to that of the ensuing glacial phase, and it is thus thought to represent the Early Wisconsinan glacial maximum. In view of the large regional extent of the northwestward ice-flow phase, it must postdate the early buildup of the ice sheet. Along the southeastern Hudson Bay coast, the Late Wisconsinan westward glacial movement was followed by a southwestward deflection that was likely caused by glacial streaming prior to 8000 BP in James Bay, in response to calving and surging into Glacial Lake Ojibway.

Late Quaternary Deglaciation, Glaciomarine Sedimentation and Glacioisostatic Recovery in the Rivière Nastapoka Area, Eastern Hudson Bay, Northern Québec

“…Fluted till, striae, chattermarks, roches moutonnées and drumlins indicate a general westward (270°) flow that correspond to the regional ice flow reported in Parent et al (1995). Flutings are located >200 m asl and concentrated in the NE sector of the study area, although some are present north of Rivière du Nord (Fig.…”

“…However, in the terrestrial coastal sectors of eastern Hudson Bay, only a small number of papers (HillaireMarcel, 1976;Hillaire-Marcel et al, 1981;Allard and Seguin, 1985;Parent and Paradis, 1994;Parent et al, 1995) have addressed the regional history of ice retreat. Recently, Lajeunesse andAllard (2002, 2003) reported on the presence of a series of emerged ice-proximal glaciomarine fans that were deposited during a short period of stabilization of the ice margin in the Rivière Nastapoka area in association with the first phase of deglaciation of southeastern Hudson Bay.…”

Ice-Flow Chronology and Palimpsest, Long-Distance Dispersal of Indicator Clasts, North of the St. Lawrence River Valley, Quebec

“…South of the line, cross-striations record a clockwise shift in ice flow from an early southeastward flow to a late southwestward flow. While ice flow and glacial transport data toward the northwest exist north of the line, including the Hudson Bay area (Henderson, 1989;Thorleifson et al, 1993;Parent et al, 1995;Roy, 1998), data south of the line are limited to the Lake MistassiniChibougamau area, and are found mostly north of (or close to) the Grenville Front (De Corta, 1988;Cadieux, 1986;Prichonnet et al, 1984;Beaudry, 1994). The only exception is the work of Dionne (1973) who suspected the presence of Mistassini erratics in till in the Lake Saint-Jean area and later (Dionne, 1986(Dionne, , 1994 traced Mistassini erratics, up to 400 km to the southeast of Lake Mistassini, in the Tadoussac area.…”

Erratiques de dolomie au Cap Colombier, sur la haute Côte-Nord du Saint-Laurent estuarien

“…Bien qu'il soit difficile de préciser la période durant laquelle les glaces se sont effectivement écoulées vers le SE et ont déplacé les cailloux de dolomie, nous pensons que la période comprise entre 13 et 11 ka a été favorable (Vincent, 1989). Selon certains auteurs (Prichonnet et al, 1984 ;Bouchard et Martineau, 1985 ;Parent et al, 1995), l'écoulement des glaces vers le SE à partir d'une ligne de partage située au NO du lac Mistassini serait ancien et antérieur à l'écoule-ment vers le sud et le sud-ouest dans la région de Chiboug a m a u . To u t e f o i s , d ' a p r è s n o s d o n n é e s e t l e s connaissances actuelles, l'écoulement vers le SE, entre le lac Mistassini et Tadoussac (Dionne, 1994 ;Veillette et al, 1999 ;Dionne et Bernatchez, 2000b), aurait persisté jusqu'à la fin du Wisconsinien, une langue de glace occupant encore l'embouchure du Saguenay vers 11-11,5 ka (Dionne et Occhietti, 1996).…”