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TitreCharacteristics of discontinuous permafrost from ground temperature measurements and electrical resistivity tomography, southern Yukon, Canada
AuteurLewkowicz, A G; Etzelmuller, B; Smith, S L
SourcePermafrost and Periglacial Processes 2011, 23 pages,
Séries alt.Secteur des sciences de la Terre, Contribution externe 20100083
Documentpublication en série
Mediaen ligne; numérique; papier
SNRC105C; 105D; 115O
Lat/Long OENS-136.0000 -132.0000 61.0000 60.0000
Lat/Long OENS-140.0000 -138.0000 64.0000 63.0000
Sujetspergélisol; congélation du sol; glace fossile; températures au sol; résistivité électrique; résistivité; climat arctique; climat; fluctuations climatiques; Changement climatique; géologie des dépôts meubles/géomorphologie; géophysique; géologie de l'environnement
Illustrationslocation maps; tables; profiles; photographs
ProgrammeLes sciences de la Terre à l'appui de la caractérisation, à l'échelle nationale, des impacts des changements climatiques sur la masse continentale canadienne, Géosciences de changements climatiques
Résumé(disponible en anglais seulement)
Warm permafrost conditions (mean temperatures of -3°C to -0.1°C) were investigated in detail at 13 valley and mountain sites in the sporadic (10 - 50%) and extensive (50 - 90%) discontinuous permafrost zones in the southern half of the Yukon (60°N to 64°N), using a combination of ground temperature monitoring, electrical resistivity tomography (ERT), frost table probing and coring. Sites were selected to cover a wide range of substrates, vegetation types and ground ice contents. ERT profiling in the spring imaged both deep seasonal frost and perennially frozen ground. Deep active layers measured by probing at the end of summer were also detectable by ERT. Where ground temperatures indicated that the base of permafrost was at a depth of less than 25 m, vertical transitions in apparent resistivity were more sharply defined in coarse materials than in fine-grained deposits, probably because of differences in unfrozen moisture contents at temperatures just below 0°C. Apparent resistivity values related to excess ice fraction and ground temperatures were similar to those previously obtained in Mongolia and Iceland, but generally lower than in ice-rich rock glaciers in European studies. The observations revealed the complexity of site conditions where permafrost is discontinuous and the utility of ERT, in combination with other methods, to investigate permafrost thickness, spatial extent and ice content for infrastructure planning or climate change studies.