Holocene sediment record from Briaunis palaeolake, Eastern Lithuania: history of sedimentary environment and vegetation dynamics

Abstract

This paper presents new data describing the Holocene environmental history of the Briaunis palaeolake, Eastern Lithuania. Shortly before 9600 cal yr BP, sedimentation began in an oligotrophic deep-water basin, whereas the Early Holocene instability of the environmental regime caused the influx of detrital sediment into the basin. A birch forest dominated in the surrounding landscapes, and at ca. 9600 cal yr BP, the spread of Ulmus, Alnus, Populus and Corylus began, suggesting a short-lived climatic amelioration. A subsequent drop of the water table and increasing influx of the terrigenous material continued from 9600 to 9300-9200 cal yr BP. The ensuing climatic stability caused the formation of a deciduous forest and the regional spread of Picea. Some instability, i.e. a decline in the thermophilous species, as well as the appearance of boreal and northern alpine diatoms, could be associated with the so-called “8.2 ka event”. This reversal was followed by amelioration and prospering of the water plants typical of the Holocene climatic optimum from 7900 to 7200-7100 cal yr BP. At aproximatelly 6600-6500 cal yr BP, a small rise of the water table was documented and bog-forming processes dominated until ca. 3600-3400 cal yr BP, when a small-scale deepening of the basin occured.