Permafrost-related landform-sediment assemblages, Grays Bay Road corridor region, NU, and implications for climate-resilient infrastructure.



Peter Morse – 



P.D. Morse – Geological Survey of Canada, Ottawa, ON, Canada
S.L. Smith – Geological Survey of Canada, Ottawa, ON, Canada
R.J. Parker – Geological Survey of Canada, Ottawa, ON, Canada



Knowledge of permafrost conditions is needed to develop climate-resilient northern infrastructure. Where present, permafrost constitutes a landscape foundation and geohazards can develop if it thaws. However, thaw effects are differential due to the heterogeneous distribution of ground temperatures, surficial and bedrock materials, and ice contents, which are, in turn, a function of landscape history. Little is known about permafrost conditions in the northern Slave Geological Province that will be encountered by the proposed Grays Bay Road route. To better understand them we use a landsystem approach, which considers the permafrost-related landform-sediment assemblages (not landforms or sediments in isolation) in this landscape and links them to the processes that formed them. These process-form models enable inferences on past and future landscape evolution. Here we present newly mapped landforms, and patterns in their spatial distributions, for 72% of the 1600 km2 area that is within 5 km of the proposed route. In combination with sparse sedimentological and cryostratigraphic records, we develop a set of preliminary landform–sediment assemblages. A notable assemblage is glaciofluvial deposits over massive ice, dissected by ice-wedge polygons. Demonstrating long-term creep, it has a high potential for thermal adjustment and potentially represents an important geohazard in this region.

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