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TitleLandform-sediment associations within 'subglacial meltwater corridors' reflect channelised subglacial hydraulic conditions during deglaciation on the Canadian Shield
AuthorHaiblen, A M; Ward, B C; Campbell, J E; Normandeau, P X
SourceAmerican Geophysical Union, Fall Meeting 2016, abstracts; C33A-0758, 2016 p. 1 Open Access logo Open Access
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20160293
PublisherAmerican Geophysical Union
Meeting2016 American Geophysical Union Fall Meeting; San Francisco, CA; US; December 12-16, 2016
DocumentWeb site
Mediaon-line; digital
File formathtml; pdf
ProgramGEM2: Geo-mapping for Energy and Minerals South Rae Province Bedrock/Surficial geology
Released2016 12 01
AbstractEsker networks have traditionally been invoked to represent the channelised subglacial drainage system in shield terrains. However, eskers are only one sediment-landform association found within `subglacial meltwater corridors': tracts where till has been eroded, bedrock is exposed and glaciofluvial sediments have been deposited in a time-transgressive manner. These regularly-spaced corridors parallel deglacial ice flow directions, have up-and-down profiles, and can cross modern drainage divides. Our LiDAR- and field-based mapping in the Slave and South Rae regions of Northwest Territories, west of the Keewatin Ice Divide, reveals that the most common sediment-landform association in many of these subglacial meltwater corridors is not eskers, but mounds and ridges that are up to 30 m high and 300 m wide. These mounds and ridges typically occur in groups of 20 to 200. Eskers have been observed to drape some mounds and ridges, thus, they must form subglacially. These mounds and ridges are commonly cored with diamicton that is similar in composition and structure to regional till. They are occasionally draped with well-sorted, stratified glaciofluvial sediments. The simplest interpretation for the genesis of these landforms is that regional till was eroded during meltwater corridor formation, after which glaciofluvial deposition occurred in some areas. The hydraulic conditions required to create these mounds and ridges are different to those required for esker formation. Thus, subglacial meltwater corridors, not just the eskers that they sometimes contain, should be considered when parameters are developed for numerical models relating to subglacial drainage systems in shield terrains. Determining the genesis of landforms found within meltwater corridors will improve our understanding of hydraulic conditions in the subglacial channelised drainage system during late-stage ice-sheet retreat and decay.
Summary(Plain Language Summary, not published)
This abstract is for a talk presented at the 2016 American Geophysical Union annual meeting. The talk highlights a study of unique sediment-landform assemblages associated with landscape corridors that drained meltwater beneath the Laurentide Ice Sheet as it retreated from the Slave and south Rae regions, Northwest Territories. Understanding the composition and genesis of the landforms will improve our understanding of subglacial hydraulic conditions and imform ice sheet reconstruction and deglacial models. In addition, this information will inform mineral industry on how to apply drift prospecting in such landscapes.

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