Luminescence Timing of Paleoenvironmental Changes in Quaternary Lake Sediments from the Arctic Taymyr Peninsula, Siberia

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9909686BergThe arctic is a predicted highly sensitive region to future global climatic change, yet its harshness and remoteness have limited our knowledge of the geological record of past climatic/environmental changes in this region. The region of arctic Central Siberia is largely unexplored in this regard. German and Russian scientists have conducted geological, geochemical and geophysical studies over the last 6 years from the Taymyr Peninsula to the arctic islands of Severnaya Zemlya, on a south-north transect -1400 km long. Their objective has been to unravel the climatic and environmental history of northern Central Siberia over the last several tens of thousands of years. Long (up to -22 m) sediment cores have been recovered from several existing lakes, providing the most important paleoenvironmental data archive of the entire project, but they have proven to be difficult or impossible to date by the various radiocarbon procedures, mainly because of very low carbon concentration, or the presence of contaminating coal particles. The PI proposes to provide an alternative dating tool: infrared-stimulated-luminescence direct dating of the last exposure of sediment grains to daylight. Based on extensive experience with Alaskan and other North American lake cores, the PI will analyze in Reno about 29 lake-core samples with NSF support. Samples will first be collected (under separate funding) by the PI from a lake-core storage site in Potsdam, Germany. The proposed luminescence method has been shown to be accurate elsewhere, and with sediments much older than those expected in the Siberian lake cores. Luminescence dates are expected to provide the first direct, accurate chronology for these lake cores, and hence for the time series of several paleoenvironmental data sets already measured by German colleagues. These dates should also settle a controversy about the size (extent) of the last ice sheet (Eurasian Ice Sheet) in the area of central arctic Siberia. Glacial sediments are present in some of the lake cores, but the age of such sediments is unknown or highly speculative at present. Dating results are expected to provide also the first opportunity for across-Arctic-Ocean correlation to Quaternary pollen stratigraphies from Alaska that the PI has been involved with. Accurate time series of paleoenvironmental records from circum-arctic Quaternary sediments are essential for a fuller (quantitative) understanding of the past role of the arctic in global changes.