Okrzemki w osadach organogenicznych interglacjału ferdynandowskiego w Podlodowie (polska Środkowa

Barbara Marciniak



The site Podlodów is located about 18 km to the west of Kock (Fig. 1). It is represented by lake marl exposed at valley slope of the Świnka rivulet, a tributary to the Wieprz downstream from Podlodów. The marl was found by J. Łyczewska (14) who correlated it with interglacial sediments at Ferdynandów. This suggestion was confirmed by results of a preliminary pollen analysis by Z. Janczyk-Kopikowa (cf. 4, 7, 14) that indicated the lake marl from Podlodów to correspond to sediments of the lower climatic optimum of the Ferdynandów Interglacial (phytophase 3) in the section Ferdynandów B (3, 4). Sediments of this interglacial in Poland were located between the Warta and the Odra glaciations (14), and lately between the Wilga and the San glaciations (5, 6) or between the San 1 and the San 2 glaciations (13). It corresponds presumably to the Białowieża Interglacial in Byelorussia (10, 11, 15) and to Voigtstedt Interglacial in Germany (2). Quantitative and qualitative analysis of diatoms from the lake sediments at Podlodów enabled to distinguish 4 development phases (diatom phases PD1-PD4 in Fig. 2), in which numerous Aulacoseira granulata and A. ambigua were distinguished. They are freshwater and cosmopolitan species, at present common in plankton of different, mainly eutrophic reservoirs (22). The studied sediments contained, especially in the phase PD2, very common valves of Cyclotella cf. reczickiae and less common specimens, preliminary defined with use of electron microscope (Fig. 3) as Stephanodiscus "rotula/niagarae complex" sensu E. Theriot et al. (21). This group contains probably extinct diatoms, very close to the taxons described from sediments of the Białowieża Interglacial in Byelorussia (c! 8, 10, 15). They are also common in lake sediments of the Ferdynandów Interglacial at Ferdynandów (11) and less common at Bełchatów (16, 17). If compared with the previously studied sites of the Białowieża and Ferdynandów interglacials, the section at Podlodów represents mainly a deep facies of lake sediments. They were deposited during particularly favorable conditions for development of rich and varying flora of planktonic and nannoplanktonic diatoms (diatom phase PD2). Such conditions could exist at Podlodów, similarly as at Ferdynandów and Belchatów, particularly during the climatic optimum of the Ferdynandów Interglacial (3, 5, 11, 12, 16, 17).

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