An age and accumulation patterns of laminated sediments of Lake Kasplya (Smolensk region)

Abstract

Presented study aims to investigate paleolimnological conditions of Lake Kasplya in northwestern European Russia. An annually-laminated deposits were analyzed with 14C dating, thin section study and varve counting using a semi-automated method. An annual structure is expressed in one or two pairs of layers per year (light – diatomite and calcite, dark – organomineral detritus with pyrite concretions). Differences in the structure of Early Holocene and Middle Holocene varves indicate changing paleolimnological conditions of the water body, while the disappearance of varves around 6.7 thousand years ago suggests the cessation of stable lake stratification. Due to the peculiarities of sediment structure, the obtained varve chronology is older compared to the radiocarbon sedimentation model (3,5 thousand years versus 2,5 thousand years).