GEOCHRONOLOGY AND STRATIGRAPHY OF THE HOLOCENE LACUSTRINE-BOG DEPOSITS IN NORTHERN AND CENTRAL KAZAKHSTAN

A detailed stratigraphic subdivision of five sections of lacustrine-bo g deposits in northern and central Kazakhstan, based on comprehensive palynological data and radiocarbon datings, is obtained for this area for the first time. The time scale of climatic cycles and pollen zones covers the period from the Allerod until the present and shows a sati sfactory correlation between the vegetal and climatic phases and the B lytt-Sernander periodicity scale for the Holocene with Khotinskii's mo dification (1977, 1989). The two climatic optima established in the Ho locene are equally important: the early Atlantic optimum (8 to 7 ka) a nd the middle sub-Atlantic optimum (1.8 to 0.8 ka). The beginning of s apropel accumulation on a large scale in the freshwater lakes of the s teppe area in Kazakhstan (about 10 ka) is considered synchronous with a similar phenomenon in many lakes of the temperate belt of northern E urasia. This phase of accumulation, therefore, can be used as a strati graphic boundary between late and post-glacial time as well as for dis tant geographical correlations.