Geomorphologic and Sedimentary Evolution of a Transgressive Thermokarst Coast, Mackenzie Delta Region, Canadian Beaufort Sea

Abstract

Transgression of a thermokarst coastline results in the development of a distinctive coastal morphology consisting of breached thermokarst lakes, separated by narrow headlands fringed by barrier-spit complexes and sandflats. A detailed description of the geomorphology and sediment facies of one such area east of North Head in the Canadian Beaufort Sea is combined with seismic and core analysis from the adjacent inner shelf to develop a sedimentologic model for use in interpolating geotechnical conditions in the region. The model proposes the sedimentary successions that develop during transgression in a number of sub-environments related to the thermokarst morphology. It differs from conventional shoreface evolution models in that thermokarst processes create additional accommodation space at the coastline. This extra space, formerly occupied by ground ice, is rapidly filled by coastal and shelf lithosomes, the latter consisting principally of mud from the nearby Mackenzie River.