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CHARACTERIZING PERMAFROST VALLEY FILLS ALONG THE ALASKA HIGHWAY, SOUTHWEST YUKON
Session: Geophysical Investigation in Cold Regions / Investigations géophysiques en milieu nordique
Joel Pumple, University of Alberta (Canada)
Duane Froese, University of Alberta (Canada)
Fabrice Calmels, Yukon Research Centre (Canada)
In the Beaver Creek area of southwest Yukon, the Alaska Highway traverses both glaciated and non-glaciated terrain from the last glacial maximum. In this area permafrost characteristics are strongly influenced by regional glacial history including the distribution of relict Pleistocene permafrost. Here we characterize the distribution and history of permafrost in a valley fill along the Alaska Highway between Beaver Creek and the Alaska border using a multidisciplinary approach. Our surveys include Electrical Resistivity Tomography (ERT), permafrost drilling, cryostratigraphy, and geochemical analyses to define the boundaries and characteristics of the valley fill. Using ERT data we are able to map the distribution of relict syngenetic permafrost from the late Pleistocene within the valley fill, from areas where similar sediments have degraded and have been subsequently overlain by organic-rich sediment through the Holocene. Radiocarbon dating and stable isotope analyses of d18O and dD combined with detailed cryostratigraphy confirm that much of the ground ice is relict syngenetic ground ice from the late Pleistocene.
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