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

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Using 4He/3He thermochronometry to quantify the rate and timing of Canadian Shieldfjord incisionIntellectual Merit - The relationship between topographic relief development and climatechange has emerged as a critical topic in earth science. Linking relief generation to climatechange, e.g. the onset of the Quaternary ice age, relies on a quantitative understanding of thepattern and timing of glacial erosion. Although alpine glacial erosion in active orogenic belts hasbeen the focus of recent research, fjorded continental margins, arguably the sites of the mostintense 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 thefeedbacks between ice sheet dynamics, topography, and glacial erosional processes are importantcomponents of Quaternary climate and landscape change. The aim of this research is to quantifythe temporal and spatial evolution of a fjord inserted into the northern Canadian Shield by theLaurentide Ice Sheet. The research team will apply a novel tool, 4He/3He thermochronometry, toquantify the rate and pattern of formation of Clyde Inlet, a fjord on Baffin Island typical ofdozens of other fjords rimming the Canadian Shield, and representative of fjords around bothGreenland 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-sectionand fjord long-profile sample sets will be collected, which will potentially quantify both verticalexhumation and headward propagation rates of the fjord. The results of the proposed researchrepresent a critical step toward the team's longer-term goal of improving the understanding ofthe feedbacks between ice sheet dynamics and landscape evolution. The erosional history of thefjord is the key observational constraint for numerical ice sheet simulations aimed at solving thecomplex feedbacks between topography and ice sheet behavior. The erosional history of fjordsexerts a significant control on ice sheet thickness and configuration, the locations of major icestreams and their onset zones, and the overall stability and configuration of marine-basedmargins of ice sheets.Broader Impacts - This research will train one early-career scientist (Briner) and will exposegraduate and undergraduate students at the Universities of Buffalo and Colorado to novelapplications and exciting earth science problems. Research activities under this award will bemade 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 ofNunavut, and at Clyde River, our proposed field base. The team will continue their tradition ofworking with the people of Clyde River, including guides, the Hunter's and Trapper'sAssociation and high school students. In addition, Anderson will continue his efforts to educatethe broader public about glacial landscape evolution through involvement in ranger trainingprograms at US National Parks in which glaciers have played significant roles in sculpting thelandscape, and in generation of simulations that can serve both as educational tools in K-12 andcollege classrooms, and as dynamic content in National Park displays.