ABSTRACT: Aufeis of the northern Yukon : evidence for perennial intrapermafrost flow?

CGRG Bibliography of Canadian Geomorphology
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Abstract

Unlike intrapermafrost groundwater flow in the cryosphere, evidence for supra-permafrost and sub-permafrost groundwater flow in the arctic has been described in considerable detail in the literature. However, growth of aufeis throughout the arctic winter may be evidence for intra-permafrost groundwater flow, and a tool to study the storage and water quality characteristics of talik aquifers. Aufeis in the mountainous regions of the northern Yukon are typically 2-3 m thick and areally extensive (<1 to >50 sq km) icings in steam channels, which form annually in zones of perennial groundwater. Their physiography and geochemistry provide insights to the processes of groundwater recharge, karstification and contributions to baseflow in arctic watersheds. A survey of aufeis in the Porcupine, Firth and Babbage River watersheds has been carried out to examine geochemical and isotopic parameters of the discharging groundwaters. Aufeis ice as wellas springs, surface waters and precipitation have been analysed. Stable isotopes indicate the seasonality of groundwater recharge is not biased towards spring snow melt, but rather towards annually averaged precipitation. Geochemistry demonstrates calcite saturation for these waters, and together with delta 13 C reflects upon the systematics of CO2 incorporation and carbonate dissolution during recharge. The temperature of discharge indicates that more deeply penetrating sub-permafrost groundwaters do not contribute significantly to flow. The thermal structure and heat flow mechanisms associated with intrapermafrost groundwater flow has significant implications with respect to rates of permafrost degradation under the scenario of global warming.

Bibliography of Canadian Geomorphology