The development of near-surface ground ice at Illisarvik, Richards Island, Northwest Territories.

摘要

Samples of near-surface permafrost were obtained in summer 2010 from 26 sites in the Illisarvik drained lake basin, three sites on lake basin terraces, and nine sites in the surrounding tundra on Richards Island, NWT, to investigate the growth of near-surface ground ice and the relations between controlling factors and ice formation. Active-layer records from the basin, tundra, and lake terrace were also examined. Active-layer thicknesses were positively associated with summer air temperatures, and in some lake basin areas, with winter snow depths. Excess-ice accumulation was highly variable in the basin and predominantly positively associated with active-layer moisture status, and, to a lesser extent, soil texture. Near-surface excess-ice contents in the tundra were much greater than in the basin, and ice enrichment was present at greater depths, likely a result of permafrost aggradation since the early-Holocene climatic optimum.