ЭВОЛЮЦИЯ ОЗЕРА ХАНКА И ОКРУЖАЮЩИХ ЛАНДШАФТОВ В МАКСИМУМ ПОХОЛОДАНИЯ ПОЗДНЕГО ПЛЕЙСТОЦЕНА

Abstract

The problems of the environmental development in the western part of the Khanka lowland and the evolution of Khanka Lake during the last glaciation maximum and the maximum lacustrine transgression in the Late Pleistocene are considered. Lithology and diatom data on lacustrine sediments indicate two depositional environments in the lake during the period 24.0–19.0 cal ka BP: 1) an oligotrophic-mesotrophic, moderately swamped shallow basin with variable water level; and 2) a relatively deep lake. The beginning of the maximum transgression (about 19.6 cal ka BP) was established. For the first time in the Late Pleistocene the lake level was 1.5–2.0 m higher than the present one. Four phases of vegetation development in the western part of the Khanka lowland were recognized: birch and larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II – dark coniferous taiga with dwarf pine and an admixture of broad-leaved trees (22.8–20.6 cal ka BP); III – spruce forests with dwarf pine, fir, larch and a rare admixture of oak (20.6-20.1 cal ka BP); and IV – light birch forests with alder and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two phases of cooling were reconstructed in the Khanka lowland: about 24.0 cal ka BP (maximum cooling) and 20.6 cal ka BP, and one phase of warming (about 22.8 cal ka BP). These events correlate well with the global records of the Greenland glaciers. The longest dry periods were established during 21.7–21.2 cal ka BP. The quantitative characteristics of climatic events were reconstructed based on the present-day vegetation analogues.