CLIMATIC VARIABILITY OF THE LAST INTERGLACIAL DERIVED FROM A RUSSIAN ARCTIC CRATER LAKE

During May of 1998 a 13.0 m sediment core was retrieved from El’gygytgyn Crater Lake, located 100 km north of the Arctic Circle in northeast Siberia. The lake was formed by a 3.6 million year old meteorite impact, which generated a crater roughly 20 km in diameter. Geochronological age models of sediments from this core suggest that the upper 6.5 meters of the core represents ~150 ky of paleoenvironmental change from northeast Siberia (Nowaczyk et al., in press). The magnetic susceptibility record from the 1998 core shows a strong pattern of correlation with the Greenland Ice Sheet stable isotope record (GISP2) in the upper 6.0 meters of the core where significant age control exists, based upon optically stimulated luminescence ages (Forman and Pierson, unpublished data), magnetic events (Nowaczyk et al., in press), and significant shifts in pollen (Lozhkin et al., 2001). The marine isotopic stages derived from SPECMAP have been correlated to the magnetic susceptibility record of the 2000 core. Much of the current terrestrial study of marine isotopic stage 5 (MIS 5) and the Last Interglacial (LI, substage 5e) are confined to a few distinct long continental records predominately in Europe. The research presented here summarizes the LI signal from a key Arctic location . The climate signal contained within the sediments of the LI are particularly important, as the extensive length of the sediment record may provide a high resolution archive of interglacial climate patterns for comparison with the Holocene. As a result, a sedimentological record has been constructed for the interval spanning the LI. The core is almost entirely composed of silt and clay (25-85% silt and 20-75% clay) with a few intervals containing sand. Clay mineralogy analyses using x-ray diffraction show that the abundance of chlorite increases during colder periods within the upper 200 cm of the core, representing roughly the last 40ka (Asikainen, in progress). This work has been expanded to examine the interstadial/stadial substages of MIS 4-6. A series of gravity cores along a northwest transect were obtained during the 2000 return trip to the lake in 2000. Sediment and clay analyses on these shorter cores at varying water depths will provide insight on the spatial variability of sediment transport into El’gygytgyn Crater Lake.