Development and application of cosmogenic nuclide methods to analyse Cenozoic landscape responses to climate and tectonic change

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The goal of my research program is to develop and apply innovative isotope geochronology strategies to study landscape responses to climate and tectonic forcing. We seek to improve our understanding of a dramatic large-scale Arctic landscape response to climate change in the Pliocene (5.3 to 2.6 Myr ago). Warmer global climate led to feedbacks (e.g. ice albedo) that increased Arctic mean annual temperatures (>10°) and changed precipitation patterns to allow forests (including Hemlock) to expand to Ellesmere Is. where fauna as diverse as camels evolved. Streams eroded and carried sediment from eastern and sub-Arctic sources, and constructed a westward-thickening wedge of sediment that extended >1200 km from Yukon to Meighen Is., filled the inter-island channels, and reached thicknesses >3 km offshore. Climate cooled, sea level fell with glaciation, incision of the Beaufort Formation isolated the islands once again, and the channel-radiator system was restored. Despite the profound impact of this Pliocene experiment, it is surprising how little we know about the conditions required and the rates of processes involved. With innovative approaches our research addresses questions and tests hypotheses regarding the triggers and rates of these landscape responses. New age estimates for Pliocene paleoenvironmental records currently unlinked to temperature time series or specific processes will help distinguish spatial from temporal differences in the paleoenvironmental and forest records. Estimates of timing, durations, and sediment flux rates and improved surface maps and a correlation with offshore (Iperk Formation) components will help us test hypotheses regarding the roles of global and regional climatic, tectonic, isostatic, and oceanographic forces. Considering that the potential for rapid sediment remobilization is significant in the Arctic where sediment availability is sensitive to permafrost thawing, could such a significant landscape response be re-triggered by the projected 2°C global warming this century? To what degree of impact on Arctic infrastructure, water quality, and harbor development? The results will also have direct implications for sediment models used for hydrocarbon evaluation in Beaufort Sea and Canada Basin.