Sytuacja geologiczna osadów jeziornych interglaciału eemskiego w Grodzisku Mazowieckim

Abstract

GEOLOGICAL SITUATION OF EEMIAN INTERGLACIAL LACUSTRINE DEPOSITS AT GRODZISK MAZOWIECKI

Summary

Lacustrine deposits have been encountered during drilling activity and geological research at Grodzisk Mazowiecki, situated about 30 km south-west of Warsaw. Geological situation and palaeobotanical examinations made by Z. Janczyk-Kopikowa (1973) point to the Eemian Interglacial age of these deposits. The lacustrine deposits fill in here a glacier channel developed at the close of the Middle- Polish Glaciation. They are built up of clastic sediments at the battom, which pass higher up into organic formations. At the bottom part of the profile there are found fine-grained sands that correspond to the phytophases from Ea to Ec. These sands are covered with peats that were produced during the forest phytophase Ed, and with gyttja corresponding to the Interglacial climatic optimum, thus in the phytophases from Ee to Eg. At the beginning of the optimum, a melting of the buried dead ice took place during the phytophase Ee. This process changed both the configuration of the lake bottom and the original position of the part of these deposits from the early Eemian time. The profile ends with humus sands and peaty alluvium laid down during the phytophases Eh and Ei. These deposits in turn are overlain with the sands of alluvial cones of rivers that flow from the Mszczonów upland, southward cd Grodzisk Mazowiecki. The lacustrine deposits are underlain with the Eopleistocene formations (gravels, sand and silts), the South-Polish Glaciation formations (boulder clay), the Mazovian Interglacial formations (sands with gravels of fluvioglacial origin), and the Middle-Polish Glaciation formations (boulder clays of the Maximum Stage and the Mazowsze-Podlasie Stage, separated with the ice-dammed lake deposits and fluvioglacial deposits). The Quaternary formations rest on the Pliocene clays and silts, these on the Miocene sands and silts, and on the clastic, arenaceous-silty deposits of Palaeogene age (Danian-Oligocene).