The Evolution of Lake Khanka and the Surrounding Landscapes at the Maximum of Late Pleistocene Cooling

Abstract

The issues of the environmental evolution of the western sector of the Khanka valley and the evolution of Lake Khanka are considered for the maxima of the last glaciation and Late Pleistocene lacustrine transgression. The lithological indicators and results of diatom analysis of lacustrine sediments of Lake Khanka indicate two sedimentation conditions over the period of 24.0–19.0 cal ka BP: an oligotrophic–mesotrophic moderately swampy shallow reservoir with an unstable level and a relatively deep lake. The maximum of the transgression occurred at ~19.6 cal ka BP, when the lake level was 1.5–2.0 m higher than at present for the first time. Four phases of the vegetation evolution in the western sector of the Khanka valley are distinguished: I, birch–larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II, dark coniferous taiga with dwarf pine and a small amount of broad-leaved trees (22.8–20.6 cal ka BP); III, spruce forests with dwarf pine, fir, larch, and rare oak (20.6–20.1 cal ka BP); and IV, light birch forests and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two cooling phases are registered at the Khanka valley (~24.0 cal ka BP (cooling maximum) and 20.6 cal ka BP) and one warming phase (∼22.8 cal ka BP), which are correlated with the detailed global Greenland glacier records. The driest periods occurred at 21.7–21.2 cal ka BP. The quantitative characteristics of climate events are reconstructed from modern plant analogs.