POST-GLACIAL EROSIONAL RESPONSE OF A PERMAFROST LANDSCAPE ACROSS DECADAL TO MILLENNIAL TIMESCALES, AKLAVIK RANGE, ARCTIC CANADA

The Arctic is warming rapidly, which is leading to accelerated permafrost thaw and erosion on upland landscapes through a combination of landslides, debris flows, and fluvial erosion. This results in increased sediment delivery to downstream river systems and the communities that rely on them. The effects of warming temperatures on snowmelt and permafrost thaw are particularly acute on hillslope and bedrock systems, with changes in erosion rate recorded in the deposits of periglacial alluvial fans. We aim to compare the erosional response of one such landscape since the Last Glacial Maximum (LGM) to that from modern anthropogenic warming. To test this, we combine multiple geochronometers covering a range of timescales (10² to 10⁶ years) to quantify erosion rates and geomorphic response on a post-LGM alluvial fan system in the Northwest Territories of Arctic Canada. We use apatite and zircon (U-Th)/He thermochronology to constrain the tectonic background rock cooling and inferred erosion rate of the landscape, ¹⁰Be cosmogenic nuclide dating of glacial erratics to determine when the landscape was last glaciated, and both ¹⁴C dating and optically stimulated luminescence dating of quartz and feldspar sand and cobbles to determine the dominant timing of alluvial fan deposition and erosion rates across the fan. Although similar multiple chronometer approaches have been used across temperate catchment-fan systems to constrain the impacts of changing climate on erosion, this would be its first application to periglacial systems, arguably one of Earth’s most dynamic and fragile landscapes.