|Title||Mapping ground ice potential in Canada|
|Author||Wolfe, S A; Duchesne, C; O'Neill, H B; Parker, R J H|
|Source||Northwest Territories Geological Survey, Yellowknife Geoscience Forum Abstract and Summary Volume 2017, 2017 p. 118-119 (Open Access)|
|Links||Online - En ligne (complete
volume - volume complet, pdf, 1.69 MB)|
|Alt Series||Natural Resources Canada, Contribution Series 20170266|
|Publisher||Northwest Territories Geological Survey|
|Meeting||2017 Yellowknife Geoscience Forum; Yellowknife, NT; CA; November 14-16, 2017|
|Media||paper; on-line; digital|
|Related||This publication is related to the following publications|
|Province||Canada; British Columbia; Alberta; Saskatchewan; Manitoba; Ontario; Quebec; New Brunswick; Nova Scotia; Prince Edward Island; Newfoundland and Labrador; Northwest Territories; Yukon; Nunavut|
|NTS||1; 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 WENS||-141.0000 -50.0000 90.0000 41.7500|
|Subjects||surficial geology/geomorphology; paleontology; environmental geology; Nature and Environment; permafrost; ground ice; periglacial features; frost action; temperature; climate effects; depositional
environment; sediments; tills; biomes; permafrost thaw; climate change; methodology; segregated ice; wedge ice; buried ice; geological mapping; datasets; glaciofluvial sediments|
|Released||2017 11 01|
|Abstract||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.
|Summary||(Plain Language Summary, not published)|
his study presents the methods and results of new national-scale mappiing of three ground ice types. The ground-ice potentials are based on knowledge of
glacial and post-glacial sedimentary processes and past and present environments. The Permafrost Map of Canada represents a fundamental step towards understanding the impacts that climate warming and permafrost thaw will have on permafrost regions in