Depositional environment and climate changes during the late Pleistocene as recorded by the Netiesos section in southern Lithuania

Abstract

The Netiesos section in southern Lithuania exposes a late Pleistocene sedimentary sequence at a depth of between 17 and 4 m. An interdisciplinary study of the section investigated the environmental changes that occurred in the study area during the greater part of Marine Isotope Stage (MIS) 5. Geochemical, thermoluminescence, palaeontological (plant macro-remain, diatoms, fishbones) and magnetic susceptibility analyses were performed on numerous sediment samples. Chronological control of the sequence was provided by electron spin resonance (ESR), infrared optically stimulated luminescence (IR-OSL) and conventional radiocarbon dating methods. This interdisciplinary approach enabled the subdivision of the section into stratigraphic units reflecting environmental changes. According to chronological data, the development of the Netiesos palaeolake began at the end of the Medininkai (Saalian) glaciation, which is thought to correlate with MIS 6, and continued up to the thermophilous deciduous forests phase of the subsequent last interglacial of MIS 5. Sediments of the final phase of the interglacial are missing, as are the initial and final phases of the following early Nemunas (Weichselian) cooling (MIS 4). The palaeomagnetic Blake Event was recorded in the interglacial sediments. One of the richest palaeofloras in the East Baltic region was observed representing the second half of MIS 5. The implications of the results for the regional late Pleistocene climato-chronostratigraphy are discussed.