Accumulation of sedimentary matter at the present stage of lymnogenesis development in the territory of the southeastern part of the Fennoscandian crystal shield using the example of Lake Vendyurskoye

Abstract

The article is devoted to the study of modern processes of sedimentary matter accumulation in the lake Vendyurskoye. The lake was formed during the period of deglaciation of southeastern part of the Fennoscandian Shield around 12,400 – 9,000 cal yr BP and now it performs in typical landscape conditions of the northern taiga of the humid zone. New knowledge about modern sedimentogenesis was obtained on the basis of comprehensive studies of the lake in different seasons 2018-2023. The assessment of the landscape structure of the lake's catchment area was carried out, the morphology of lake basin was studied, observations of the distribution of suspended matter in the water column were carried out, suspensions entering the bottom were collected using sedimentation traps, the chemical composition of water, suspended solid and bottom sediments was studied. The thermohydrodynamic features of the lake were revealed and the influence of depth, wind and convective mixing, conductivity and temperature of water and algae development on the accumulation of suspensions in the lake basin in different seasons was estimated. The issues of transformation of suspended solid during deposition in water and early diagenetic transformations in bottom sediments are discussed. The variable nature of modern sedimentation processes in the lake is shown depending on the synoptic situation. The rates of sedimentary matter entering the bottom are estimated. The quantitative and qualitative characteristics of the chemical composition of water, suspended solid, and bottom sediments have been studied and their geochemical features determined by both natural and anthropogenic factors have been identified. It is shown that the chemical composition of the material currently entering the bottom sediments differs from the composition of bottom sediments in the content of organic matter, biogenic elements and microcomponents (Pb, Cd, Zn).

Keywords:

sedimentogenesis of the humid type, sedimentary matter, distribution and rate of accumulation sedimentary matter, geochemical composition of water, suspended solid and bottom sediments