GEOCHRONOLOGY OF LATE QUATERNARY EVENTS IN NORTHEASTERN RUSSIA

Radiocarbon-dated paleobotanical and palynological samples record comp lex changes of vegetation and climate in northeastern Russia during th e Late Pleistocene and Holocene. Since the Kargin Interval (middle Wis consin equivalent), which started 50 ka ago, we can distinguish two pe riods that were colder than the present. The Kirgilyakh was the earlie st Karginsk cool period, dating to 45-39 ka BP. The second significant cool period dates to 33-30 ka BP. The boundary between the Kargin Int erval and the last Late Pleistocene glaciation (Sartan, late Wisconsin equivalent) dates from 27 ka BP. The sharp change from herbaceous mos sy tundra (Sartan) to light-coniferous larch forests (Holocene) in nor theastern Russia dates to 12.5 ka ago. The Holocene thermal maximum, l inked to the expansion of woody plants into the modern barren-ground t undra, dates from 9.5-8 ka BP.