NATURE OF ARCTIC CHANGE OVER SEVERAL GLACIAL CYCLES REFLECTED IN SEDIMENT CORES FROM LAKE EL'GYGYTGYN, NE RUSSIA

Sediment piston cores from Lake El'gygytgyn (67°N, 172°E), a 3.6 million year old meteorite impact crater in northeastern Siberia, have been analyzed to extract a multi-proxy millennial-scale climate record extending to nearly 250 ka, with distinct fluctuations in sedimentological, physical, biochemical, and paleoecological parameters. Five major themes emerge from this research. First the pilot cores and seismic data show that El'gygytygn Crater Lake contains what is expected to be the longest, most continuous terrestrial record of past climate change in the entire Arctic back to the time of impact. Second, processes operating in the El'gygytygn basin lead to changes in the limnogeology and the biogeochemistry that reflect robust changes in precession-driven regional climate and paleoecology over a large part of the western Arctic. Third, the magnetic susceptibility record, controlled largely by changes in anoxia in the hypolimnon driving the dissolution of magnetite, and other proxies record numerous rapid change events. The recovered lake sediment contains both the best-resolved record of the last interglacial and the longest terrestrial record of millennial scale climate change in the Arctic, yielding a high fidelity multi-proxy record extending nearly 150,000 years beyond what has been obtained from the Greenland Ice Sheet. Fourth, the potential for evaluating teleconnections under different mean climate states is high. Despite the heterogeneous nature of recent Arctic climate change, millennial scale climate events in the North Atlantic/Greenland region are recorded in the most distal regions of the Arctic under variable boundary conditions. And finally, deep drilling of the complete depositional record to 3.5 Ma in Lake El'gygytgyn will offer new insights and, perhaps, surprises into the late Cenozoic evolution of Arctic climate for comparison with the new Lomonosov Ridge records.