Spatial and Temporal Variability of Lake Accumulation Rates in Subarctic Northwest Territories, Canada

We examined the spatial and temporal variability of Holocene lake sediment accumulation at 22 sites from 18 lakes transecting boreal forest, tree line, and tundra zones in the central Northwest Territories, Canada. Over 140 radiocarbon dates were obtained, and accumulation rates (AR) were calculated at 100-year intervals from age-depth models constructed using the modeling software Clam. Sites with the shortest mean AR of 25±10yr/cm(1σ) occur primarily in the boreal zone. Sites with moderate (70±22yr/cm) and long (160±56yr/cm) AR are north of the treeline and display higher variability, strongly influenced by bathymetry. Many age-depth models are characterized by fluctuations in ARs that coincide with paleogeographical changes associated with proglacial lake evolution during the early Holocene, and subsequent climate changes inferred from proxy data. The insights gained on the spatial and temporal trends in ARs across the region are valuable for developing higher resolution age-depth models using the Bayesian software Bacon.