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TitleMega-scale glacial lineations formed by ice shelf grounding in the Canadian Beaufort Sea during multiple glaciations
AuthorRiedel, M; Dallimore, S RORCID logo; Wamsteeker, M; Taylor, G; King, E L; Rohr, K M M; Jin, Y K; Hong, J K
SourceEarth Surface Processes and Landforms 2021 p. 1-18, Open Access logo Open Access
Alt SeriesNatural Resources Canada, Contribution Series 20200421
PublisherJohn Wiley & Sons on behalf of the British Society for Geomorphology
Mediapaper; on-line; digital
File formatpdf; html
AreaBeaufort Sea; Canada
Lat/Long WENS-155.0000 -112.0000 76.0000 68.0000
SubjectsScience and Technology; glaciers; glacial deposits; glacial features; Canadian Beaufort Sea
Illustrationslocation maps; diagrams; graphs; tables
ProgramPublic Safety Geoscience Beaufort Sea Exploration
Released2021 03 31
AbstractMega-scale glacial lineations formed by the raking of ice shelves across the seafloor have been reported from multiple polar regions. Here, we present the first evidence of continental slope situated buried lineations in the southern Canadian Beaufort Sea in present-day water depths of 220 to 800 m. Three separate surfaces with lineations are defined at sub-seafloor depths of 40 m to 390 m. All lineations are mostly parallel to the general trend of slope contours. The uppermost surface is recognized over a distance of 56 km. In water depths > 500 m the lineations are parallel to each other at a consistent direction (43°-44°). The second lineated surface is a regionally occurring erosional unconformity. This event has two sub-sets of lineations: mid-slope situated lineations oriented at 42°-48°, and lineations closer to the continental shelf break at 55°-59°. The third lineated surface is an unconformable horizon buried up to 390 m below seafloor with lineaments oriented between 30° and 55°. All three sets of lineations are interpreted to have been produced by ice-ploughing on the paleo-seafloor through the grounding of an ice shelf. Our observations are similar to those documented along the slope off northern Alaska, Chukchi Rise, and Lomonosov Ridge. Collectively, these observations support the concept of an extensive ice shelf across the Arctic Ocean that grounded locally along its margins during multiple glaciations, including during the penultimate (or an earlier) glaciation. The youngest set of lineations indicates ice movement to the southwest with a suggested source in Amundsen Gulf and/or M'Clure Strait. Tentative age considerations for these youngest lineations indicate the first evidence for an analogous extensive ice shelf configuration for the Last Glacial Maximum.
Summary(Plain Language Summary, not published)
The first evidence of continental slope situated glacial lineations in the Canadian Beaufort Sea are consistent with similar features reported in multiple Arctic seabed locations. Buttressing by a pan-arctic ice shelf or a perennial iceberg/sea ice melange apparently steered a component of the major continental ice sheet draining via Amundsen Gulf and other outlets. Part of this floated and part may have remained constantly grounded on the seabed. Attributed to raking of a large ice shelf across the seafloor, three separate horizons of mega-scale glacial lineations indicate for the first time that thick, continuous floating glacially-derived ice pertained at different glacial times. Further, their location contributes to corroborating the concept of a thick and expansive ice shelf and, again for the first time, suggests it also occurred during the Last Glacial Maximum, not only the previous.

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