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TitreMapping ground ice potential in Canada
AuteurWolfe, S A; Duchesne, C; O'Neill, H B; Parker, R J H
SourceNorthwest Territories Geological Survey, Yellowknife Geoscience Forum Abstract and Summary Volume 2017, 2017 p. 118-119 (Accès ouvert)
LiensOnline - En ligne (complete volume - volume complet, pdf, 1.69 MB)
Année2017
Séries alt.Ressources naturelles Canada, Contribution externe 20170266
ÉditeurCommission géologique des Territoires du Nord-Ouest
Réunion2017 Yellowknife Geoscience Forum; Yellowknife, NT; CA; Novembre 14-16, 2017
Documentpublication en série
Lang.anglais
Mediapapier; en ligne; numérique
Référence reliéeCette publication est reliée les publications suivantes
Formatspdf
ProvinceCanada; Colombie-Britannique; Alberta; Saskatchewan; Manitoba; Ontario; Québec; Nouveau-Brunswick; Nouvelle-Écosse; Île-du-Prince-Édouard; Terre-Neuve-et-Labrador; Territoires du Nord-Ouest; Yukon; Nunavut
SNRC1; 2; 3; 10; 11; 12; 13; 14; 15; 16; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32; 33; 34; 35; 36; 37; 38; 39; 40; 41; 42; 43; 44; 45; 46; 47; 48; 49; 52; 53; 54; 55; 56; 57; 58; 59; 62; 63; 64; 65; 66; 67; 68; 69; 72; 73; 74; 75; 76; 77; 78; 79; 82; 83; 84; 85; 86; 87; 88; 89; 92; 93; 94; 95; 96; 97; 98; 99; 102; 103; 104; 105; 106; 107; 114O; 114P; 115; 116; 117; 120; 340; 560
Lat/Long OENS-141.0000 -50.0000 90.0000 41.7500
Sujetspergélisol; glace fossile; caractéristiques périglaciaires; action du gel; temperature; effets climatiques; milieu sédimentaire; sediments; tills; biomes; dégel du pergélisol; changement climatique; méthodologie; sédiments fluvioglaciaires; géologie des dépôts meubles/géomorphologie; paléontologie; géologie de l'environnement; Nature et environnement
ProgrammeGéosciences de changements climatiques, Pergélisols
Diffusé2017 11 01
Résumé(disponible en anglais seulement)
Ground ice is widespread in permafrost regions. The thaw of ground ice initiates different thermokarst processes depending on ice type, host sediments, and distribution. These processes are dramatically affecting landscapes and human activity in northern North America, but our current knowledge of ground ice distribution and the impacts associated with the thaw of ice-rich permafrost is inadequate.
The Permafrost Map of Canada (MCR 4177) is the primary source representing ground ice in Canada, but has limitations including poor differentiation of ground ice types and coarse spatial resolution. Mapping at the national scale necessarily includes extrapolation based on limited data and expert knowledge. Our objective is to present the methodology and early results from a new national-scale mapping effort of three common ground ice types: (1) segregated ice, (2) wedge ice, and (3) buried ice. The ground-ice potentials are based on knowledge of glacial and post-glacial sedimentary processes as well as past and present environments from existing national-scale datasets. These include the Surficial Geology of Canada (GSC CGM 195), the Deglaciation of North America (GSC Open File 1574), the Glacial Map of Canada (GSC Map 1253A), Paleovegetation Maps of Northern North America (GSC Open File 4682), and the Permafrost Map of Canada (MCR 4177).
Permafrost is commonly ice-rich due to segregated ice formed during initial permafrost aggradation, and its accumulation over time from repeated freezing and thawing of the active layer. Wedge ice forms within permafrost in regions where air temperatures are conducive to thermal contraction cracking of the ground. Buried ice, represented here primarily by glaciogenic ice, is preserved within permafrost by a sediment cover. The surficial geology, glaciation, paleo-biome, and permafrost map data combined with knowledge-based associations between environmental conditions and ground ice are used in a model within a GIS to determine ground ice potentials for these three ice types.
(1) Buried ice potentials are defined for 22 surficial sediment types. Potentials are highest within thick till, moderate within glaciofluvial sediments, and absent in sediment veneers and bedrock. Buried ice potential is reduced in areas of past inundation, and modified by paleo-biome distributions. The potentials are further modified by modern permafrost distribution. (2) Segregated ice potentials are assessed initially by the frost susceptibility of each surficial sediment type. Areas of marine inundation also define potential for saline permafrost. The potentials are then modified based on past biomes and present-day permafrost distributions. (3) Wedge ice potentials are initially based on the surficial material type, and the time exposed to biomes associated with conditions favourable to thermal contraction cracking. The potentials are then modified by the present-day permafrost distribution.
Preliminary maps for the three ground ice types are presented. These enhance the existing national-scale representation of ground ice on the Permafrost Map of Canada, and represent a fundamental step towards understanding the impacts that climate warming and permafrost thaw will have on permafrost regions in North America.
Sommaire(Résumé en langage clair et simple, non publié)
Cette étude présente les méthodes et les résultats de la nouvelle cartographie à l'échelle nationale de trois types de glace de sol. Les potentiels de glace de sol reposent sur la connaissance des processus sédimentaires glaciaires et postglaciaires et des environnements passés et présents. La carte du pergélisol du Canada représente une étape fondamentale vers la compréhension des impacts que le réchauffement climatique et le dégel du pergélisol auront sur les régions de pergélisol en Amérique du Nord.
GEOSCAN ID306194