WSTĘPNE BADANIA DIATOMOLOGICZNE OSADÓW JEZIORNYCH INTERGLACJAŁU AUGUSTOWSKIEGO Z PROFILI SUCHA WIŚE (POJEZIERZE EŁCKIE) I CZARNUCHA (RÓWNINA AUGUSTOWSKA), PÓŁNOCNO-WSCHODNIA POLSKA

Abstract

A PRELIMINARY DIATOMOLOGICAL STUDY OF AUGUSTOVIAN INTERGLACIAL LACUSTRINE DEPOSITS FROM THE SUCHA WIEŚ (EŁK LAKELAND) AND CZARNUCHA (AUGUSTÓW PLAIN) SECTIONS, NORTHEASTERN POLANDAbstract. The paper shows preliminary results of diatom analysis of Augustovian (Podlasian) Interglacial lacustrine-marsh deposits from the Sucha Wieś and Czarnucha sections located in the Augustów Plain, northeastern Poland, in connection with the results of palynological investigations. The deposits overlie Narevian glacial sediments and are overlain by Nidanian glacial deposits. On the basis of changes in taxa composition and the frequency of diatoms in the sections, five Local Diatom Assemblage Zones (L DAZ) have been distinguished in the lower portion of the Sucha Wieś section (DSW-1 to DSW-5) and in the Czarnucha section (DCz-1 to DCz-5). These zones represent 5 stages of the diatom succession, more fully pronounced in the Czarnucha section. During the first stage, apart from littoral periphytic diatoms, also planktonic diatoms are abundant (Aulacoseira and Stephanodiscus). During the second stage, the content of saline-water periphytic diatoms significantly increased (Fragilaria s.l.) indicating a lower water level in the lake. In the third and fourth stages, a gradual increase in the amount of planktonic diatoms (mainly Stephanodiscus spp.) indicates a deepening of the lake. The fifth stage is characterized by a renewed increase in the amount of periphytic diatoms typical of eutrophic lakes. The diatom succession from the Czarnucha section is similar to that from Sucha Wieś and, to a lesser extent, to the diatom succession known from lacustrine deposits of the Ferdynandovian Interglacial in Poland and the Belovezhian Interglacial in Belarus.