Facies analysis and sedimentary architecture of a prograding sandy delta in an ice-contact glacial lake under normal- and forced-regression during ice retreat from the Lake Erie basin (Port Stanley area, Ontario)

Abstract

Landslide susceptibility mapping requires knowledge of geological criteria, including grain size and lithological boundaries. The north shore of Lake Erie (Ontario) is prone to landslides in areas with steep lake bluffs, such as in the Port Stanley area. Several regional stratigraphic models have been developed for the Lake Erie basin; however, the lithological heterogeneity (facies), sedimentary architecture, and interpreted depositional processes and environments in the Port Stanley area have not been reported in the literature. This paper presents new sedimentological data recorded in logs from lake bluffs in the Port Stanley (Hawk Cliff) area. This study applies a facies analysis approach to 1) understand the localized depositional processes and environments, 2) delineate the sedimentary architecture (geological framework), and 3) develop a facies model to characterize the depositional system. The sedimentary succession records nearly continuous deposition of glaciolacustrine and prodelta muds, sand, and diamicts that transition upward to delta slope sands, which are truncated by a distributary channel fill succession and delta front sediments. A facies model for a prograding sandy delta in an ice-contact glacial lake under normal- and forced-regression during overall ice retreat from the basin is proposed, which may facilitate correlation to process-related units elsewhere and provide insight to the broader geological history of the Lake Erie basin. The superposition of low-permeability muds at the base and overlying higher permeability sands results in water saturation at the mud-sand contact which, together with toe erosion, may contribute to landslide susceptibility along the north shore of Lake Erie.