SGER: Using 4He/3He thermochronometry to quantify the rate and timing of Canadian Shield fjord incision

Using 4He/3He thermochronometry to quantify the rate and timing of Canadian Shield fjord incision Intellectual Merit - The relationship between topographic relief development and climate change has emerged as a critical topic in earth science. Linking relief generation to climate change, e.g. the onset of the Quaternary ice age, relies on a quantitative understanding of the pattern and timing of glacial erosion. Although alpine glacial erosion in active orogenic belts has been the focus of recent research, fjorded continental margins, arguably the sites of the most intense glacial incision, in which fjords >1 km deep have been inserted since the ice ages began, have yet to be examined in detail. The rates and spatial patterns of fjord insertion, and the feedbacks between ice sheet dynamics, topography, and glacial erosional processes are important components of Quaternary climate and landscape change. The aim of this research is to quantify the temporal and spatial evolution of a fjord inserted into the northern Canadian Shield by the Laurentide Ice Sheet. The research team will apply a novel tool, 4He/3He thermochronometry, to quantify the rate and pattern of formation of Clyde Inlet, a fjord on Baffin Island typical of dozens of other fjords rimming the Canadian Shield, and representative of fjords around both Greenland and Norway. Samples for 4He/3He thermochronometry will document the thermal history of Clyde Inlet, which in turn will constrain the long-term incision history of the fjord. Both fjord cross-section and fjord long-profile sample sets will be collected, which will potentially quantify both vertical exhumation and headward propagation rates of the fjord. The results of the proposed research represent a critical step toward the team's longer-term goal of improving the understanding of the feedbacks between ice sheet dynamics and landscape evolution. The erosional history of the fjord is the key observational constraint for numerical ice sheet simulations aimed at solving the complex feedbacks between topography and ice sheet behavior. The erosional history of fjords exerts a significant control on ice sheet thickness and configuration, the locations of major ice streams and their onset zones, and the overall stability and configuration of marine-based margins of ice sheets. Broader Impacts - This research will train one early-career scientist (Briner) and will expose graduate and undergraduate students at the Universities of Buffalo and Colorado to novel applications and exciting earth science problems. Research activities under this award will be made accessible to indigenous peoples by translating the goals and eventual results into Inuktitut, making posters that describe the research, and by offering public lectures in Iqaluit, the capital of Nunavut, and at Clyde River, our proposed field base. The team will continue their tradition of working with the people of Clyde River, including guides, the Hunter's and Trapper's Association and high school students. In addition, Anderson will continue his efforts to educate the broader public about glacial landscape evolution through involvement in ranger training programs at US National Parks in which glaciers have played significant roles in sculpting the landscape, and in generation of simulations that can serve both as educational tools in K-12 and college classrooms, and as dynamic content in National Park displays.