Origin, burial and preservation of late Pleistocene-age glacier ice in Arctic permafrost (Bylot Island, NU, Canada)

• Published in: The Cryosphere
• Main Authors: S. Coulombe, D. Fortier, D. Lacelle, M. Kanevskiy, Y. Shur
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2019
• Subjects: Environmental sciences; GE1-350; Geology; QE1-996.5; Arctic; Nunavut; Bylot Island; Canada; Barnes Ice Cap; glacier*; Ice; Ice cap; permafrost; The Cryosphere
• Online Access: https://doi.org/10.5194/tc-13-97-2019; https://doaj.org/article/612561caed7b4d9aaedc0691edb024ec

Over the past decades, observations of buried glacier ice exposed in coastal bluffs and headwalls of retrogressive thaw slumps of the Arctic have indicated that considerable amounts of late Pleistocene glacier ice survived the deglaciation and are still preserved in permafrost. In exposures, relict glacier ice and intrasedimental ice often coexist and look alike but their genesis is strikingly different. This paper aims to present a detailed description and infer the origin of a massive ice body preserved in the permafrost of Bylot Island (Nunavut). The massive ice exposure and core samples were described according to the cryostratigraphic approach, combining the analysis of permafrost cryofacies and cryostructures, ice crystallography, stable O-H isotopes and cation contents. The ice was clear to whitish in appearance with large crystals (cm) and small gas inclusions (mm) at crystal intersections, similar to observations of englacial ice facies commonly found on contemporary glaciers and ice sheets. However, the δ 18 O composition ( <math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>-</mo><mn mathvariant="normal">34.0</mn><mo>±</mo><mn mathvariant="normal">0.4</mn></mrow></math> <svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="58pt" height="10pt" class="svg-formula" dspmath="mathimg" md5hash="6c233401b15cd09b150017d0f113dbaa"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="tc-13-97-2019-ie00001.svg" width="58pt" height="10pt" src="tc-13-97-2019-ie00001.png"/></svg:svg> ‰) of the massive ice was markedly lower than contemporary glacier ice and was consistent with the late Pleistocene age ice in the Barnes Ice Cap. This ice predates the aggradation of the surrounding permafrost and can be used as an archive to infer palaeo-environmental conditions at the study site. As most of the glaciated Arctic landscapes are still strongly ...