Wistuliańskie osady jeziorne w Jaroszowie, Przedgórze
Abstract
VISTULIAN LAKE DEPOSITS IN JAROSZÓW, SUDETEN FORELAND (SW POLAND): PRELIMINARY RESULTS AND PERSPECTIVES FOR FUTURE INVESTIGATIONS
Summary
The paper describes three Vistulian lake basins from Jaroszów, SW Poland. The lacustrine sequences in all basins contain, from the bottom: laminated silt, massive silt and the uppermost sequence with silt (loess?), sandy silt, organic layers and calcareous gyttja. The lithofacial sequence shows that the lakes were smalI and shallow, at the begining with common inflows of deposits from the lake margin (solifluction). The latest phase of the lake development was characterized by autigenic, organicsedimentation and/or deposition of waterlain loess. The radiocarbon dating has indicated 19 250±310 BP age for the lower part of the uppermost sequence. Hence, it is concluded that the lacustrine sedimentation was during the Upper Pleniglacial of the Vistulian stage and simultaneously during the maximum extent of the ice-sheet being only 100 km north. The vegetation cover at that time was represented at Jaroszów by open forests with pine and birch and abundant herbs. The sediments from climatic pesimum(level with radiocarbon dating) have no pollen, but contain charcoal beds which document fires at that time.
Summary
The paper describes three Vistulian lake basins from Jaroszów, SW Poland. The lacustrine sequences in all basins contain, from the bottom: laminated silt, massive silt and the uppermost sequence with silt (loess?), sandy silt, organic layers and calcareous gyttja. The lithofacial sequence shows that the lakes were smalI and shallow, at the begining with common inflows of deposits from the lake margin (solifluction). The latest phase of the lake development was characterized by autigenic, organicsedimentation and/or deposition of waterlain loess. The radiocarbon dating has indicated 19 250±310 BP age for the lower part of the uppermost sequence. Hence, it is concluded that the lacustrine sedimentation was during the Upper Pleniglacial of the Vistulian stage and simultaneously during the maximum extent of the ice-sheet being only 100 km north. The vegetation cover at that time was represented at Jaroszów by open forests with pine and birch and abundant herbs. The sediments from climatic pesimum(level with radiocarbon dating) have no pollen, but contain charcoal beds which document fires at that time.