The Late Pleistocene–Early Holocene palaeoenvironmental evolution in the SE Baltic region: a new approach based on chironomid, geochemical and isotopic data from Kamyshovoye Lake, Russia

Abstract

The Kamyshovoye Lake sedimentary record in the southeastern Baltic Sea region was studied to reconstruct climatic fluctuations and the abiotic responses to them during the Lateglacial and Early Holocene. New results from chironomid, isotopic, palaeomagnetic and geochemical data analyses were correlated with earlier evidence of lithological and palynological changes in the Kamyshovoye Lake record. The section of the record that was studied covered the interval between 15 200 and 6500 cal. a BP. Palaeoclimatic reconstructions showed that during the Younger Dryas there was a two‐step decrease in the mean July temperature. The temperature dropped by 3 °C in the period from ̃12 650 to 12 300 cal. a BP, and then it dropped by another 0.5 °C to a minimum of 11.5 °C at 11 900 cal. a BP. During the Younger Dryas–Holocene transition, a temperature increase of 3 °C can be seen over a period of several centuries, inferred from the chironomid data. Further, the temperature curve showed that significant fluctuations continued until ̃9500 cal. a BP. During the coolings, the average July temperature dropped to values that were typical for the Younger Dryas, while values characteristic for the Allerød were only reached at around 9700 cal. a BP. After 9500 cal. a BP, a more stable, gradual increase in temperature was recorded. The short‐term Early Holocene climatic oscillations are clearly traced in the Kamyshovoye sequence, although the responses of the natural components are sometimes asynchronous. In the case of the Kamyshovoye study, the geochemical data seem to be a sensitive indicator of the climatic and environmental changes despite the absence of an evident response to the Holocene onset at ̃11 700 cal. a BP. Considerable changes in the geochemical pattern are recorded later, at ̃11 500 cal. a BP, coinciding with noticeable changes in the development of vegetation. The results obtained in this study contribute to a deeper understanding of how global climatic trends are manifested on a local scale.

Geochemical Approach to the Reconstruction of Sedimentation Processes in Kamyshovoye Lake (SE Baltic, Russia) during the Late Glacial and Holocene

“…The negative values of F2 indicate the predominance of oxic conditions. According to the age-depth model, the sedimentation in this interval took place during the Bølling-Allerød period, just after 15,000 cal y BP [6]. During this period, natural conditions were most likely uniform, contributing to a stable inflow of mineral fractions into the Kamyshovoye lake basin.…”

“…The southwestern part of the lake is drained by a river 8 m wide. The basin of the Kamyshovoye Lake is up to 90% filled with limnoglacial (silty clay) and lacustrine (clay gyttja and gyttja) deposits [6]. The Kamyshovoye Lake is located in a kettle hole, oriented from SW to NE, whose maximum length is 1200 m and width is 600 m. The total area is 0.26 km 2 .…”

“…The southwestern part of the lake is drained by a river 8 m wide. The basin of the Kamyshovoye Lake is up to 90% filled with limnoglacial (silty clay) and lacustrine (clay gyttja and gyttja) deposits [6].…”

“…The calibrated years were expressed in cal y BP, given at the 2-sigma confidence level (68.2%). Previously described by Druzhinina et al [3,6], biostratigraphic dates were also used for the model. Samples with obvious inversions, such as LU-6927, LU-6931, and POZ-60941, and dates with questionable results, such as POZ-60943 and POZ-60940, were not used for the age-depth model preparation.…”

“…The abiotic composition of bottom deposits can give reliable information about the surrounding catchment and physicochemical and biological processes [1]. A sufficiently large number of qualitative studies of vegetation changes during the Late Glacial and Holocene exist for the Kaliningrad Region, SE Baltic [2][3][4][5], which enabled us to carry out a comprehensive reconstruction of the natural conditions of the Kamyshovoye Lake surroundings during the Late Glacial to early Holocene transition [3,6]. This article presents the results of a geochemical analysis in combination with statistical processing, along with depth/age models for the entire core of the bottom sediments of the Kamyshovoye Lake (the Vishtynets with depth/age models for the entire core of the bottom sediments of the Kamyshovoye Lake (the Vishtynets Upland, Kaliningrad Region, Russia).…”