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TitleDispersal Trains Produced by Ice Streams: an Example from Strange Lake, Quebec and Labrador
AuthorPaulen, R C; Stokes, C R; Rice, J R; Dubé-Loubert, H; McClenaghan, M B
Source 2015 p. 69-70
LinksOnline - En ligne (whole publication, pdf 2.08 MB)
Alt SeriesEarth Sciences Sector, Contribution Series 20150139
PublisherCANQUA (St. John's, Canada)
MeetingCANQUA, 2015; St John's; CA; August 16, 2015
File formatpdf
ProgramHudson/Ungava, Northeastern Quebec-Labrador, surficial geology, GEM2: Geo-mapping for Energy and Minerals
Large tracts of northern Canada were impacted by a large number of land-terminating and coastal-terminating palaeo-ice streams during deglaciation of the Laurentide Ice Sheet. In soft-bedded areas, subglacial landforms can be used to map the spatial extent of ice stream tracks (e.g., mega-scale glacial lineations, ice stream shear margin moraines). Over hard-bed areas, the bedform imprint of ice streams is, perhaps, less obvious. However, sediment dispersal trains, coupled with erosive corridors of streamlined terrain, provide a potentially powerful means of identifying “hard-bedded” ice streams. The Strange Lake dispersal train, in northern Quebec and Labrador, has a remarkably linear ribbon-like dispersal pattern trending 40 km down ice (northeast) from a mineralized rare earth element (REE) peralkaline intrusion. The train was originally attributed as a product of a consistent late-Wisconsin regional flow regime. Recent mapping of Laurentide Ice Sheet streams by Margold and others (2015), places the Strange Lake train directly within the Kogaluk River ice stream (IS #187), one of a number of ice streams that operated near the centre of the Labrador dome and drained into the Atlantic Ocean. There are numerous mega-scale glacial lineations (up to 5000 m long, with length:width ratios exceeding 12 and higher) within the mapped dispersal train. The dispersal train shows a remarkable linear consistency with REE element concentrations in till tens of kilometres down ice from the mineral source, a phenomenon similarly observed with the carbonate dispersal trains formed by streaming ice in Nunavut. Thus, whilst drift prospecting methods have traditionally considered long term steady-state ice flow as the primary method for transport of glacial debris from a mineralized source, we argue that changes in glacial erosion, transport distances and diffusion rates are factors that should be considered when mapping and interpreting glacial dispersal trains in palaeo-ice stream corridors.
Summary(Plain Language Summary, not published)
This is a presentation re-examining a published dispersal train from a rare-earth deposit (Strange Lake) in northern Labrador, in the context of fast flowing ice and our better understanding of glacial dynamics during deglaciation of the Laurentide Ice Sheet. This presentation is directly linked to ongoing research in the GEM2 Hudson-Ungava Project, Core Zone Surficial Activity.