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

© 2020 Collegium Boreas. Published by John Wiley & Sons Ltd 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.