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TitleUncovering the hidden part of a large ice stream of the Laurentide Ice Sheet, northern Ontario, Canada
AuthorVeillette, J J; Roy, M; Paulen, R C; Ménard, M; St-Jacques, G
SourceQuaternary Science Reviews vol. 155, 2017 p. 136-158,
Alt SeriesEarth Sciences Sector, Contribution Series 20160101
Mediapaper; on-line; digital
File formatpdf
ProvinceOntario; Quebec
NTS32M; 32L; 32E; 42A; 42H; 42I; 42P; 42G; 42J; 42O
AreaHearst; Kapuskasing
Lat/Long WENS -84.0000 -78.0000 52.0000 49.0000
Subjectsdeglaciation; striations; Laurentide Ice Sheet; Lake Ojibway; cross-striations; relict striations; ice stream; glacial surge; Continental records of glaciations
Illustrationssatellite imagery; location maps; photographs; diagrams
ProgramHudson/Ungava, Northeastern Quebec-Labrador, surficial geology, GEM2: Geo-mapping for Energy and Minerals
Released2016 11 24
AbstractThe Glacial Map of Canada shows an enigmatic ice-flow anomaly (Area A) covering about 10 000 km2 in the Hearst/Kapuskasing area of northern Ontario which prompted this investigation. It consists of streamlined landforms and striations indicative of a major ice movement toward 130º oriented at right angle to another one toward 220º. Both are late glacial flows but long-lasting disagreement exists regarding their relative age, some argue that the east-southeast (130º) flow is the youngest and others that it is the oldest. The analysis of aerial photographs and satellite images in conjunction with a detailed survey of cross-striated surfaces over an area of about 30 000 km2 within and around Area A clearly indicate that the 130º flow preceded the 220º flow. The conflicting interpretations on the relative age of the two flows within Area A are attributed mainly to the sporadic occurrence of relict striated surfaces formed by older southwestward (220º- 240º) Wisconsinan ice flows that have locally escaped destruction by late glacial flows with the result that the southwestward flows are older (Wisconsinan) at some sites and younger (late glacial 220º) at others relative to the 130º flow. When considered with other factors like the maximum elevation reached by the youngest late glacial flow, these evidences indicate that Area A is simply the outcropping southern and distal part of a much larger, east-southeast ice-flow system, the Winisk ice stream, first identified west of James Bay. The distal part of the ice stream, except for Area A, escaped detection by remote sensing methods because depositional and erosional features associated with it are masked by deposits laid down by the younger (220º, Cochrane) ice flow and/or by postglacial marine and organic deposits (or were destroyed by it). The only reliable indicators of the passage of the ice stream in this "buried" section of its extent are east-southeast relict striations crossed by striations toward the southwest. While the east-southeast striations indicate that the advancing ice stream preceded the late Cochrane 220º flow, the mapping of several thousand iceberg furrows in Quebec and Ontario, indicating movement toward the east and overprinted on flutes formed by the last glacial flow, suggests that the ice stream also outlasted the Cochrane episode. It probably calved in Lake Ojibway from a position to the northwest of Hearst, Ontario, until final drainage as indicated by ice-rafted debris found at the surface and in the upper part of cores from sub bottom lake sediment. The removal of large volumes of ice in the marginal part of the retreating ice sheet by the eastward progression of the ice stream accelerated deglaciation, and eventually triggered the Cochrane surges. With this southern component the Winisk ice stream becomes the largest terrestrial ice stream in the Hudson Bay basin. These new results clarify the sequence of events associated with the problematic chronology of Cochrane surges.
Summary(Plain Language Summary, not published)
This paper is a summation of both TGI-3 and GEM-2 research on ice streams (i.e., fast flowing glacier ice) propagating out from the Keewatin and Labrador ice centres during deglaciation. The result from these two ice centres which had independent, fast-flowing lobes of ice has produced a complex surficial history and terrain, which has been subject to various interpretations and controversy since the 1960s. This work bring together recent research from TGI-3 and GEM-2, as well as, legacy field data over the past 15 years by the lead author. It will help piece together the regional deglacial history, which in turn, will assist mineral and diamond exploration in the Hudson & James Bay lowlands of Quebec and Ontario.