CGRG Bibliography of Canadian Geomorphology
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Author : Calmels, F.; and Allard, M.
Date : 2008.
Title : Permafrost structure, growth and decay through the study of a typical lithalsa in Nunavik, northern Quebec, Canada.
Publication : Joint Annual Meeting of the Canadian Geophysical Union and the Canadian Geomorphology Research Group. May 11-14, Banff, Alberta.
Issue :
Page(s) :
Abstract
The purpose of this study is to obtain some new knowledge concerning the ice segregation and frost heave processes taking place in a lithalsa. A tomodensitometric scanner was used to produce high resolution computer images of ice lenses, soil layers, faults, sedimentary structures and gas bubbles. Scan image analysis allows interpreting the ice lenses and soil cryo-structures resulting from permafrost aggradation. It also provides an accurate estimation of volumetric contents of ice and gas present in the permafrost. Isotopic analyses on the various phases of the permafrost (i.e. ice, gas, and soil) provide supplementary information. 18O, D and Tritium analyses were undertaken on ground ice and on surface water. Monitoring of the thermal regime of the lithalsa provides clues relative to gradients that drive ground water movements and ice lens growth. Compilation and interpretation of the data in a 3-D and temporal context suggest that the lithalsa grew under climate conditions slightly colder than those of the 20th Century. However, postaggradational water penetrated into the permafrost of the lithalsa. Ground temperature measurements reveal a decay since 2000 that is in large part induced by underground warming due to groundwater flow around the permafrost body. This decay shows up as an incipient thermokarst pond that became conspicuous starting in 2003.
Bibliography of Canadian Geomorphology