Composition and origin of a lithalsa related to lake‐level recession and Holocene terrestrial emergence, Northwest Territories, Canada. Issue 5 (15th January 2018)

• Record Type: Journal Article
• Authors: Gaanderse, Adrian J.R.; Wolfe, Stephen A.; Burn, Christopher R.
• Is Part Of: Earth surface processes and landforms. Volume 43:Issue 5(2018)
• Page Start: 1032
• Page End: 1043
• Publication Date: 2018-01-15
• Subjects: lithalsa -- ground ice -- stable isotopes -- soil geochemistry -- lake‐level recession; Geomorphology -- Periodicals; 551.4
• DOI: 10.1002/esp.4302
• Languages: English
• ISSNs: 0197-9337

Abstract

Abstract: Lithalsas of the Great Slave Lowland, Northwest Territories, occur within fine‐grained glaciolacustrine, lacustrine, and alluvial deposits. Detailed investigations of a lithalsa revealed that it is composed of ice‐rich sediments with ice lenses up to 0.2 m thick below 4 m depth. The observed ice accounted for about 2 m of the 4 m between the top of the lithalsa and adjacent terrain. The ice is isotopically similar to modern surface water, but enriched in δ 18 O relative to local precipitation. Total soluble cation concentrations are low in the basal, Shield‐derived and unweathered glaciolacustrine sediments of the lithalsa. Higher concentrations in the overlying Holocene‐aged lacustrine and alluvial deposits may be due to greater ion availability in Holocene surface waters. Increasing Cl ‐ and Na + concentrations in clays at depth likely relate to exclusion and migration of these dissolved ions in pore water during ice lens formation though total soluble cations remain comparatively low. The lithalsa developed 700 to 300 cal yr BP. A conceptual model of lithalsa formation and landscape evolution illustrates that this feature and more than 1800 other lithalsas in the region have developed in association with Holocene terrestrial emergence following lake‐level recession. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : Lithalsas of the Great Slave Lowland, Northwest Territories, occur within discontinuous permafrost in fine‐grained glaciolacustrine, lacustrine, and alluvial deposits. Detailed investigations at one lithalsa that developed 700 to 300 years age reveals that below 4 m depth it is composed of ice‐rich sediments. A conceptual model of lithalsa formation and landscape evolution illustrates that this feature and the more than 1800 other lithalsas in the region have developed in association with Holocene terrestrial emergence following lake‐level recession.