| Title | Lithalsa distribution, morphology and landscape associations in the Great Slave Lowland, Northwest Territories, Canada |
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| Author | Wolfe, S A ;
Stevens, C W; Gaanderse, A J; Oldenborger, G A |
| Source | Geomorphology vol. 204, 2013 p. 302-313, https://doi.org/10.1016/j.geomorph.2013.08.014 |
| Image |  |
| Year | 2013 |
| Alt Series | Earth Sciences Sector, Contribution Series 20130119 |
| Publisher | Elsevier BV |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf; html |
| Province | Northwest Territories |
| NTS | 85J/07; 85J/08; 85J/09; 85J/10; 85J/11; 85J/12; 85J/13; 85J/14; 85J/15; 85J/16 |
| Area | Yellowknife; Great Slave Lake |
| Lat/Long WENS | -116.1667 -114.2500 62.8833 62.2500 |
| Subjects | surficial geology/geomorphology; geophysics; hydrogeology; environmental geology; stratigraphy; Nature and Environment; permafrost; ground ice; periglacial features; frost heaving; talik; ice lenses;
surface waters; streams; vegetation; remote sensing; photogrammetric techniques; airphoto interpretation; satellite imagery; geophysical logging; resistivity logging; boreholes; core samples; sediments; organic deposits; peatlands; glacial deposits;
marine sediments; silts; clays; sands; groundwater; climate; stratigraphic analyses; modelling; topography; Holocene; Recent; Great Slave Lowland; Great Slave Upland; lithalsas; glaciolacustrine sediments; lacustrine sediments; alluvial sediments;
glaciomarine sediments; Climate change; permafrost thaw; Land cover; Phanerozoic; Cenozoic; Quaternary |
| Illustrations | location maps; geoscientific sketch maps; photographs; aerial photographs; cross-sections; schematic cross-sections; lithologic sections; geophysical logs; plots; histograms; tables |
| Program | Climate Change Geoscience |
| Released | 2013 08 27 |
| Abstract | Lithalsas are permafrost mounds formed by ice segregation in mineral-rich soil that occur within the zone of discontinuous permafrost. Nearly 1800 lithalsas were mapped using archival aerial photographs
within the Great Slave Lowland, Northwest Territories, Canada. These are up to 8 m high and several hundred meters in length and width. One lithalsa, examined by electrical resistivity and boreholes, rises 4 to 6 m above an adjacent peatland, shows
clear evidence of ice-segregation at depth and ground heave of between 2.5 and 4.0 m, and is estimated to have formed within the past 700 years. Regionally, lithalsas are typically located adjacent to ponds and streams with mature forms vegetated by
deciduous (birch) forest or mixed (birch and spruce) forest with a herb-shrub understory and include circular, crescentic and linear forms. They are abundant within the Lowland region, which contains widespread glaciolacustrine, lacustrine and
alluvial fine-grained sediments. The lithalsas are most common within the first few tens of meters above the present level of Great Slave Lake, indicating that many are late Holocene, and some less than 1000 years, in age. A comparison with lithalsas
in contemporary environments reveals that comparatively warm but extensive discontinuous permafrost, fine-grained sediments (alluvial, lacustrine, marine or glaciomarine), and available groundwater supply provide the climatic and hydro-geological
parameters for the development of lithalsas in permafrost terrain. The identification of lithalsas in this region is important given their sensitivity to climate change and potential hazards to northern infrastructure upon thawing. |
| Summary | (Plain Language Summary, not published)
We undertook the first regional investigation of ice-rich terrain, known as lithalsas, found within the Great Slave Lowland of the Northwest Territories.
Lithalsas are permafrost mounds formed by ice lens growth in mineral soil that occur within the zone of discontinuous permafrost. In our study area, lithalsa mounds can be up to 8 m high and many hundreds of metres in length. We mapped nearly 1800 of
these in the Lowland area. Lithalsas are likely more common than previously recognized and are significant as they represent potentially ice-rich, thaw-sensitive, and frost-susceptible terrain that is sensitive to climatic and ecological
disturbances. |
| GEOSCAN ID | 292764 |
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