Geophysical processes and biosphere: article

Аnnotation: The history of lacustrine sedimentation in the Sevan depression is traced. The possibilities of using lacustrine sediments for the analysis of paleoclimate and neotectonic development of the region based on geological data are shown. The main reason for the preservation of the lacustrine regime in the Sevan depression was large lava flows, which repeatedly create dams in the NW part of the depression. Based on the conjugated analysis of three dated sections of sediments near the coast of Lake Sevan (Dzknaget, Norashen, Argichi), it was shown that the main factor determining the fluctuations of the lake level in the Holocene was the climate. It was established that during periods of transgression, shallow-lake and beach facies accumulated, and alluvial and subaerial technogenic (cultural layers) accumulated during periods of regression. In the Holocene sediments of Lake Sevan, synchronous transgressions of the Subarctic, Atlantic and Subatlantic periods and regression of the Вoreal and Subboreal periods are noted. Periods of transgression are associated with climate moistening and the development of tree-shrub vegetation in its catchment area, and regressions correspond to periods of decrease in humidity and reduction of this type of vegetation. The minimum rates of lacustrine sedimentation are typical for beach facies remote from river mouths (0.1-0.3 mm/year), maximum values for delta facies (0.7-1.5 mm/year). The obtained results can be used to analyze and forecast long-term trends in the development of the natural environment in the catchment area of Lake Sevan and changes in its level regime.