Conner Arts HBSc Thesis Abstract

This research was focused on constructing a depositional model for the thick, massive sandstone layers present in the Pass Lake and Outan Island Formations of the 1.4Ga Sibley Group Delta, east of Thunder Bay, Ontario. Massive sandstone beds are not typically deposited in a distributary-mouth bar environment and are anomalous in this instance. To develop a depositional model, field mapping and core logging was conducted, and thin sections of samples were used to ascertain grain orientation in the massive sandstone. The results were compared to established literature on sediment gravity flows and prevegetated delta environments in order to discern the nature of the depositional mechanisms that resulted in the formation of the thick massive sandstone layers. It is likely that these layers were deposited by high-energy flood events that created turbulent flows of sediment and water, ranging from high density to moderate density. These flows would have deposited the sediment rapidly from suspension and consolidated quickly, creating largely ungraded deposits with poorly oriented grains. Understanding the Sibley Group massive sandstone may assist in identifying other types of flow deposits in both Precambrian and extraterrestrial environments.