Laurentide Ice-Flow Patterns: A Historical Review, and Implications of the Dispersal of Belcher Islands Erratics

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>This paper deals with the evolution of ideas concerning the configuration of flow patterns of the great inland ice sheets east of the Cordillera. The interpretations of overall extent of Laurentide ice have changed little in a century (except in the Arctic) but the manner of growth, centres of outflow, and ice-flow patterns, remain somewhat controversial. Present geological data however, clearly favour the notion of multiple centres of ice flow. The first map of the extent of the North American ice cover was published in 1881. A multi-domed concept of the ice sheet was illustrated in an 1894 sketch-map of radial flow from dispersal areas east and west of Hudson Bay. The first large format glacial map of North America was published in 1913. The binary concept of the ice sheet was in vogue until 1943 when a single centre in Hudson Bay was proposed, based on the westward growth of ice from Labrador/Québec. This Hudson dome concept persisted but was not illustrated until 1977. By this time it was evident from dispersal studies that the single dome concept was not viable. Dispersal studies clearly indicate long-continued westward ice flow from Québec into and across southern Hudson Bay, as well as eastward flow from Keewatin into the northern part of the bay. Computer-type modelling of the Laurentide ice sheet(s) further indicates their complex nature. The distribution of two indicator erratics from the Proterozoicage Belcher Island Fold Belt Group help constrain ice flow models. These erratics have been dispersed widely to the west, southwest and south by the Labrador Sector of more than one Laurentide ice sheet. They are abundant across the Paleozoic terrain of the Hudson-James Bay lowland, but decrease in abundance across the adjoining Archean upland. Similar erratics are common in northern Manitoba in the zone of confluence between Labrador and Keewatin Sector ice. Scattered occurences across the Prairies occur within the realm of south-flowing Keewatin ice. As these erratics are not known, and presumably not present, in Keewatin, they indicate redirection and deposition by Keewatin ice following one or more older advances of Labrador ice. The distribution of indicator erratics thus test our concepts of ice sheet growth.</jats:p>

Patterns of ice recession and ice stream activity for the MIS 2 Laurentide Ice Sheet in Manitoba, Canada

“…Ice from the Quebec-Labrador dome also crossed into Manitoba (Dyke & Prest 1987a;Dredge & Cowan 1989b). The nature of interaction between these two dispersal centres has been a long-debated topic (Prest 1990), that includes theories of a separate dome (Tyrrell 1914), an ice divide (Dyke & Prest 1987a) or an ice saddle (Dyke & Prest 1987a;Dyke & Dredge 1989). During MIS 2-4, ice flowing from the Hudson Bay Ice Saddle was strong enough to divert the Keewatinsourced southeast-trending ice flow in northeastern Manitoba to south-trending and then southwesttrending (phases 6, 7 and 8 of Gauthier et al 2019).…”

Occurrence, significance and origin of banded iron formation erratics south of lake Mistassini, Quebec, Canada

“…Dans ce secteur, les surfaces rocheuses striées et la composition des tills révèlent uniquement des écoulements nord-nord-ouest, ouest et sud-ouest (Parent et al, 1995). Les roches de ce secteur ont été dispersées essentiellement vers l'ouest, le sud-ouest et le sud (Shilts, 1980 ;Prest, 1990), et elles n'ont jamais atteint la région du lac Mistassini (Bouchard & Martineau, 1985 ;Bouchard et al, 1989 ;. En outre, la présence d'une ligne de partage des glaces nord-est -sud-ouest, à l'ouest du bassin de Mistassini ( fig.…”

Quaternary geology and environmental geochemistry of the Flin Flon Region, Manitoba and Saskatchewan.

“…The old westward event(s) recognized in the area must have been from a centre of outflow located on the eastern side of Hudson Bay at least once prior to the last main glaciation. This would account for the presence of distinctive greywacke erratics in the Prairies, derived from the Omarolluk Fm which outcrop in eastern Hudson Bay (Prest, 1990).…”

“…whereas it progressively flattens as the till veneer increases to a thick, streamlined blanket south of Suggi Lake. (Prest, 1990), compared to till of Keewatin provenance, and 3) the presence of exotic HBL carbonate debris in surface till located directly up-ice, within the area of the radial flow originating near Sipiwesk Lake (Matile and Thorleifson, 1997). Labradorean till also contains a local component as indicated by the abundance of angular carbonate pebbles over large bedrock plateaus covered by relatively thin drift (Fig.…”