LONG-TERM ARCTIC PEATLAND DYNAMICS, VEGETATION AND CLIMATE HISTORY OFTHE PUR-TAZ REGION, WESTERN SIBERIA

Stratigraphic analyses of peal composition, LOI, pollen, spores, macro fossils, charcoal and AMS ages are used to reconstruct the peatland, v egetation and climatic dynamics in the Pur-Taz region of western Siber ia over 5000 years (9300-4500 BP). Section stratigraphy shows many cha nges from shallow lake sediment to different combinations of forested or open sedge, moss, and Equisetum fen and peatland environments. Macr ofossil and pollen data indicate that Larix sibirica and Betula pubesc ens trees were the first to arrive, followed by Picea obovata. The dom inance of Picea macrofossils 6000-5000 BP in the Pur-Taz peatland alon g with regional Picea pollen maxima indicate warmer conditions and mov ement of the spruce treeline northward at this time. The decline of po llen and macrofossils from all of these tree species in uppermost peal s suggests a change in the environment less favorable for their growth , perhaps cooler temperatures and/or less moisture. Of major significa nce is the evidence for old ages of the uppermost peals in this area o f Siberia, suggesting a real lack of peal accumulation in recent mille nnia or recent oxidation of uppermost peat.