Development of Solontsovskie Lakes as indicator of humidity within Central Sikhote-Alin in the Late Holocene

Abstract

The stages of development of small Solontsovskie (Shanduyskie) Lakes located in the middle mountains of the Central Sikhote-Alin within large landslides, formed on the slopes of the paleovolcano, are identified on the basis of complex study of the sediment section of the Nizhnee Lake. The ecological-taxonomic composition of the diatom flora, the botanical composition of peat have been analyzed, and the tendencies of lacustrine sedimentation depending on the different scale of hydroclimatic changes in the Late Holocene have been established. The age model is based on 6 radiocarbon dates. The temporary resolution for the reconstructions is 30–60 years. A comparison of the development of Nizhnee and Izyubrinye Solontsi Lakes was carried out, the stages of watering and shallowing of lakes were identified on the basis of their dynamics, which made it possible to restore the change in moisture in the middle mountains. Organogenic deposits in lacustrine basins accumulated at high rates (up to 1.7–1.9 mm/ year). The most detailed data were obtained for the last 2.6 thousand cal. yr BP based on the study of the sediment section of the Nizhnee Lake, which responded more sensitively to changing climatic conditions. Frequent changes in diatom assemblages and peat-forming plants indicate unstable hydroclimatic conditions with varying degrees of watering and drainage up to complete overgrowth of water bodies. According to the data of diatom analysis, a successive change in the trophicity of the lake was traced. A frequent change of sphagnum mosses of different sections with different trophic preferences was established. The main reason for the change in the hydrological regime of the lakes was variations in precipitation during the short-term climatic changes. The correlation of the identified paleoclimatic events with global data has been carried out. Cooling periods, as a rule, were accompanied by a decrease in moisture, but the Little Ice Age was wet due to an increase in precipitation.