RECENT SEDIMENTATION OF A TRANSECT OF HIGH ARCTIC ISOLATION BASINS, QUEEN ELIZABETH ISLANDS, NUNAVUT, CANADA

An observed 20th Century global warming trend has spurred controversy concerning anthropogenic influence. In order to understand current trends in climate, researchers have looked to the past to reconstruct natural variability to understand the degree to which elevated greenhouse gas emissions are related to 20th Century warming. Annually laminated sediments preserved in high Arctic coastal lakes provide a high-resolution proxy for paleoenvironmental change, and may provide valuable information concerning this debate. Before deriving climate information from these sediments, however, it is important to understand the controls on the depositional processes. This study examines the recent sedimentation of five Arctic coastal lakes located on an east-west transect through Devon, Cornwallis, and Bathurst Island in the Queen Elizabeth Islands Archipelago (Q.E.I), Nunavut, Canada.

All studied lakes are all coastal inlets that have been isolated from the sea due to post-glacial uplift. These are termed ‘isolation basins,’ and each lake is at a different stage of isolation. Upon isolation, stagnant sea-water is trapped in the bottom, and the water column becomes density-stratified from freshwater input. Anoxic conditions in bottom-waters contribute to the preservation of undisturbed annually-laminated sediments or varves. Varves used together with radiometric dating provide information about sedimentation rates, and allow paleoenvironmental interpretation.

Surface cores recovered from each lake basin, sampling the most recent deposition, are currently being analyzed for varve thickness, percent grain size >63 mm, percent loss-on-ignition (% LOI), and percent biogenic silica. Thin sections from cores will be analyzed for varve structure and thickness. Completed analysis for % LOI reveals a systematic decrease in organic matter with increasing basin elevations. Grain-size anomalies show possible correlations between basins (which will be coupled with ¹⁴C and ²¹⁰Pb dates). Biogenic silica analysis is currently in progress to assess past productivity levels. Correlation of cores between lakes may provide high-resolution reconstructions of recent climate history in the southern Q.E.I., and current natural sedimentation processes.