ABSTRACT: Integrated geophysical approach for the detection and assessment of massive ground ice at Parsons Lake, Northwest Territories and Herschel Island, Yukon Territory.

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Abstract

The nature and distribution of massive ground ice is one of the most unpredictable and problematic geological variables in near-surface deposits characterized by continuous permafrost. Site-speci?c information about massive ground ice distribution and structure can be obtained either by invasive techniques like drilling and excavation or by non-invasive low impact geophysical methods. This study concerns itself with the geophysical detection and assessment of massive ground ice on Herschel Island, Yukon Territory, as well as Parsons Lake, Northwest Territories, a potential hydrocarbon development site in the Mackenzie Delta. The survey methodology integrates 3 geophysical tools– capacitive-coupled resistivity (CCR), ground penetrating radar (GPR), and frequency domain electromagnetic sounding (FEM) – where the output from one system is used to help interpret and calibrate the other systems. Each of these systems has been used successfully to map various aspects of permafrost, but only a few studies have incorporated two or more systems in a complimentary fashion. The ultimate goal of this project is to correlate geophysical data with information available from multiple boreholes (e.g. ice content, soil texture, salinity, etc.). If speci?c properties of permafrost (e.g. ice content, ice structure, active layer depth, etc.) can be shown to be detectable with only geophysical tools, land use planners would be able to estimate the subsidence risk of an area using a cheaper, faster, and more environmentally friendly approach. Preliminary estimates of ground ice content and distribution will be used by colleagues at the Geological Survey of Canada (GSC) to model potential terrain response for a series of hydrocarbon development activities and potential long-term problems related to climate change at Parsons Lake. Mapping the distribution of massive ground ice at coastal sites on Herschel Island will provide a means of validation for parallels drawn between geophysical data and permafrost properties at Parsons Lake, but will also help colleagues from McGill assess the vulnerability of the island’s natural resources to climate change.

Bibliography of Canadian Geomorphology