Subsurface investigation of shallow-water permafrost located within the near-shore zone of the Mackenzie Delta, Northwest Territories, Canada

This thesis uses Ground Penetrating Radar (GPR) within a near-shore Arctic environment to define subsurface parameters and to determine the thermal interaction between seasonal ice and sub-bottom sediments. Subsurface data were acquired using GPR, drill, and temperature data over two consecutive winters. In total, four thermistor cables were successfully installed beneath bottom-fast ice along a seaward transect through an actively forming distributary mouth bar. At these sites, temperature measurements were recorded up to 10 m in depth over an 11 month period.; Ground penetrating radar was found to be well suited for imaging ice morphology, ice thickness, water bathymetry, sedimentary structures, and thermal boundaries. The high resolution subsurface images contributed to understanding the complex spatial distribution of seasonal ice and frozen and non-frozen sediment over an extensive area. The geophysical information along with drill and temperature data provided information regarding seasonal changes in the thermal regime during periods of ice cover and open water. Subsequently, a new origin of permafrost is suggested, described as shallow-water permafrost, which aggrades in sub-aqueous conditions where bottom-fast ice (BFI) seasonally forms a conductive link between cold air temperatures and the underlying sediment. This work contributes to a fundamental understanding of the complex thermal regime that exists in the near-shore zone of Arctic ice dominated deltas.