ИСТИНА

The Seyaha yedoma is located on the eastern coast of Yamal Peninsula (70°10′00″ N, 72°30′30″ E). This sequence (height 22-24 m) is especially valuable for paleotemperature reconstruction because its accumulation was nearly continuous during 20 ka: from 30 to 11 ka BP and due to the abundance of multistage ice wedges. The previous oxygen isotope and radiocarbon results allowed dating the ice wedge formation from 21 to 11 ka BP. The pollen diagram of the large ice wedge represents three units corresponding to changes in taxa composition and their abundance. There are two trends of δ18О values; at the height from +12 to +14.2 m the range of δ18О values is about 1.5‰, from –24.18 to – 25.75 ‰, at the height from +14.2 to +15.8 m there is clear increasing of δ18О values vs the height by 2.6‰ from – 25.75 to –23.15 ‰. New isotope data reveal that the average January temperature was –34 to –40ºC from 23 to 15-18 ka BP. Certain tendency of bottom-up increase of δ18О values may be explained with increase of average winter and the average January temperature at the final stages of the ice wedge formation. There are 3 maxima of trace elements content in the upper fragment of ice wedge: at a height of 14.6-15.2 m – for Fe, Si, Mn, P, Ba, Sr, Zn, Ni, Cu, Cd, Mo, Sb, Pb; at a height of 13.5-13.8 m for Fe, Si, Mn, Zn, Ba, Sr; at a height of 12 m for Sb, Cd, Mo, Pb.