The Cryosphere | 2019
Origin, burial and preservation of late Pleistocene-age glacier ice in Arctic permafrost (Bylot Island, NU, Canada)
Abstract
Abstract. Over the past decades, observations of buried glacier ice exposed in coastal\nbluffs and headwalls of retrogressive thaw slumps of the Arctic have\nindicated that considerable amounts of late Pleistocene glacier ice survived\nthe deglaciation and are still preserved in permafrost. In exposures, relict\nglacier ice and intrasedimental ice often coexist and look alike but their\ngenesis is strikingly different. This paper aims to present a detailed\ndescription and infer the origin of a massive ice body preserved in the\npermafrost of Bylot Island (Nunavut). The massive ice exposure and core\nsamples were described according to the cryostratigraphic approach, combining\nthe analysis of permafrost cryofacies and cryostructures, ice\ncrystallography, stable O-H isotopes and cation contents. The ice was clear\nto whitish in appearance with large crystals (cm) and small gas inclusions\n(mm) at crystal intersections, similar to observations of englacial ice\nfacies commonly found on contemporary glaciers and ice sheets. However, the\n δ18O composition ( - 34.0 ± 0.4 \u2009‰) of\nthe massive ice was markedly lower than contemporary glacier ice and was\nconsistent with the late Pleistocene age ice in the Barnes Ice Cap. This ice\npredates the aggradation of the surrounding permafrost and can be used as an\narchive to infer palaeo-environmental conditions at the study site. As most\nof the glaciated Arctic landscapes are still strongly determined by their\nglacial legacy, the melting of these large ice bodies could lead to extensive\nslope failures and settlement of the ground surface, with significant impact\non permafrost geosystem landscape dynamics, terrestrial and aquatic\necosystems and infrastructure.