Late Pleistocene and Holocene ice-wedge activity on the Blackstone Plateau, central Yukon, Canada

• Published in: Quaternary Research
• Main Authors: Grinter, Mike, Lacelle, Denis, Baranova, Natalia, Murseli, Sarah, Clark, Ian D.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press (CUP) 2018
• Subjects: General Earth and Planetary Sciences; Earth-Surface Processes; Arts and Humanities (miscellaneous); Arctic; Blackstone Plateau; Canada; Plateau Central; Yukon; Ice; permafrost; wedge*
• Online Access: http://dx.doi.org/10.1017/qua.2018.65; https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0033589418000650

Abstract Ice-wedge activity can be used to reconstruct past environmental conditions. We investigated the moisture source and timing of ice-wedge formation on the Blackstone Plateau. A section of permafrost exposed ice wedges that developed at two distinct depths: the first set formed syngenetically and penetrated alluvial silts from the top of permafrost; the second set, truncated by an erosional or thaw contact, was found solely in icy muddy gravels (>3.1 m depth). The δ 18 O and D-excess records of the ice wedges suggest that they formed from freezing of snow meltwater whose isotopic composition evolved during meltout. The 14 C DOC results suggest that climate was favorable to ice-wedge growth between 32,000–30,000 and 14,000–12,500 cal yr BP, but there was likely a hiatus during the last glacial maximum due to climate being too dry. During the early to mid-Holocene, ice wedges were inactive as a result of warmer and wetter climate. Ice wedge re-initiated around 6360 cal yr BP, with a peak in activity between 3980 and 920 cal yr BP, a period characterized by cool and moist climate. Overall, timing of ice-wedge activity was broadly consistent with the climate and vegetation evolution in the western Arctic.