Climate-driven thaw of permafrost preserved glacial landscapes, northwestern Canada
Ice-marginal glaciated landscapes demarcate former boundaries of the continental ice sheets. Throughout circumpolar regions, permafrost has preserved relict ground ice and glacigenic sediments, delaying the sequence of postglacial landscape change that transformed temperate environments millennia ea...
| Published in: | Geology |
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| Main Authors: | , , , , |
| Format: | Article in Journal/Newspaper |
| Language: | English |
| Published: |
Geology
2017
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| Subjects: | |
| Online Access: | https://doi.org/10.1130/G38626.1 https://dspace.library.uvic.ca//handle/1828/9884 |
| Summary: | Ice-marginal glaciated landscapes demarcate former boundaries of the continental ice sheets. Throughout circumpolar regions, permafrost has preserved relict ground ice and glacigenic sediments, delaying the sequence of postglacial landscape change that transformed temperate environments millennia earlier. Here we show that within 7 x 10(6) km(2) of glaciated permafrost terrain, extensive landscapes remain poised for major climate-driven change. Across northwestern Canada, 60-100-km-wide concentric swaths of thaw slump-affected terrain delineate the maximum and recessional positions of the Laurentide Ice Sheet. These landscapes comprise similar to 17% of continuous permafrost terrain in a 1.27 x 10(6) km(2) study area, indicating widespread preservation of late Pleistocene ground ice. These thaw slump, relict ground ice, and glacigenic terrain associations are also evident at the circumpolar scale. Recent intensification of thaw slumping across northwestern Canada has mobilized primary glacial sediments, triggering a cascade of fluvial, lacustrine, and coastal effects. These geologically significant processes, highlighted by the spatial distribution of thaw slumps and patterns of fluvial sediment mobilization, signal the climate-driven renewal of deglaciation and postglacial permafrost landscape evolution. This work was supported by the Northwest Territories (NWT) Geological Survey and the NWT Cumulative Impact Monitoring Program, Government of Northwest Territories, the Natural Sciences and Engineering Research Council of Canada, the Polar Continental Shelf Project, the Canada Foundation for Innovation, and the Climate Change Adaptation Program, Indigenous and Northern Affairs Canada. We thank Kelly Pierce for the cartography. Stimulating discussions with C.R. Burn, S. Lamoureux, J. Murton, and S. Wolfe are gratefully acknowledged. Constructive comments by Melissa Chipman and two anonymous reviewers improved this manuscript. Faculty Reviewed |
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