The evolution of western Arctic landscape during the past 5 million years

Besides glacial erosion, there is no other more dramatic change in Arctic landscape in the past 5 million years than the deposition and incision of the Beaufort Formation sedimentary wedge in the western Canadian Arctic Archipelago (CAA). Sediments were eroded from the east and deposited onto western islands and into the Canada Basin and Beaufort Sea. The result was a voluminous wedge of stream sediments that extended over 1200 km from the Yukon to Meighen Island. Sediment thicknesses reach more than 3 km offshore, and the channels that separate the islands were filled above the contemporaneous high sea level. Because this occurred during a relatively warm global climate when water no longer circulated through the CAA to cool the island, the sediments were interbedded with forest beds and supported a wide variety of flora and fauna, including hemlock and camels. The significant effort to collect and analyse these records of Arctic paleoenvironmental change has demonstrated, for instance, how sensitive the Arctic climate is (2A°C of global warming translates to 15A°C warming on Ellesmere Island, due to various sea ice and other feedbacks). But was global warming the only condition necessary to trigger such a wide-scale landscape response? Did tectonic processes, sea level change, and subsidence of the western margin play primary roles? The proposed research aims to significantly improve the chronology of the Beaufort Formation and similarly-aged sediments around the western CAA. This will help place the many isolated paleoenvironmental records into a chronological framework and link disparities in the paleoclimate records to temporal differences or spatial variation. Further, a precise chronology will provide a means to i) test hypotheses regarding the controls on deposition and incision of the clastic wedge, ii) relate the coastal sediments to high terraces inland and submerged Canada Basin shelf sediments, and iii) evaluate what feedbacks (sea ice, opening of paleoceanographic gateways) were necessary for such a significant landscape and environmental change. Besides a significant impact on our understanding of these events, the insights into sediment flux and rates of the processes will inform models of Arctic Ocean sedimentation used for evaluating hydrocarbon potential.*