Nowe stanowisko plejstoceńskich osadów morza krastudzkiego na Dolnym Powiślu

Abstract

W Kamionce kolo Kwidzyna stwierdzono osady morskie ogniwa krastudzkiego. Jest to drugie tego typu stanowisko na Dolnym Powiślu, po Krastudach, gdzie wyróżniono je po raz pierwszy. W Kamionce osady morskie znajdujące się w kilku profilach wiertniczych. Wykazują one daleko idącą zgodność lito stratygraficzną z profilem Krastud. Występowanie tych osadów w kolejnym stanowisku jest potwierdzeniem dotychczasowych wniosków o odrębnej transgresji morskiej, która nastąpiła na Dolnym Powiślu w interglacjale krastudzkim, młodszym od interglacjału eemskiego. THE NEW PLEISTOCENE SITE OF THE KRASTUDY SEA DEPOSITS IN THE LOWER POWIŚLETwo separate beds of marine deposits have been stated in the boreholes drilled in Kamionka near Kwidzyn in 1986 (Northern Poland) - Fig. 1. The lower bed has been known in the region for many years as the Tychnowy Horizon of the Eemian Interglacial (A. Makowska, 1979), the upper horizon is the Krastudy Horizon known yet from the only site in Krastudy (A. Makowska, 1986a). The latter consisting the "warm" mollusc fauna, in the base of separation in Lower Powiśle, of the Krastudy Interglacial, younger than the Eemian Interglacial and the Toruń Glaciation separated the both interglacials (A. Makowska, 1986a, b). These deposits have been known in 15 boreholes in Kamionka along the Liwa river valley, above the concurrent fluvioglacial erosive horizon of the close of the Pommeranian Phase of the North Polish Glaciation (Figs 1-3). The boreholes drilled through the whole Quaternary complex and partly went into the Paleocene and Cretaceous basement (Fig. 4). In the lower part of the Quaternary complex occur sandy deposits filling up the valley cut to 30 m in the basement (bed 1) from the Cromerian (Przasnysz) Interglacial. Above there are some till horizons and ice dammed lake deposits of the South and Middle Polish Glaciation (beds 2, 3,4 and 5). Above them there is a series of the Eemian Interglacial deposits from 12 to 57 m thick (Figs 4-8, beds 6-9), called the Lower Powiśle Formation (A. Makowska, 1979, 1986b), which is a lead stratigraphic series in Lower Powiśle. In its fully formed shape it contains two marine deposit horizons: the Sztum (older) and Tychnowy (younger), separated and covered with fluvial and fluvial-deltaic deposits. In Kamionka there is only the Tychnowy horizon (bed 8), due to the area lies beyond the Sztum horizon reach.Above the Lower Powiśle Eemian Formation occurs the complex of deposits formerly reckoned with the North Polish Glaciation, and nowadays according to the author's it contains the deposits of the Toruń Glaciation (bed 10), the Krastudy Interglacial forming the Gniew Intermorainic Formation (beds 11-14) and the Vistula Glaciation (beds 15 -17). Beyond the borehole area there is another bed of till and underlying intermorainic deposits of the Pommeranian Phase of the Vistula Glaciation (Fig. 2, beds 9 and 10). Within the Gniew Intermorainic Formation there is upper (related to the Eemian marine deposits) marine horizon (bed 13). It contains silty deposits with foraminifera and remains of other marine fauna and mollusc valves. Both the position of these deposits in the Quatemary profile and malakologic fauna included let make distinct correlation with the marine layer known Krastudy (Fig. 9). It may be accepted that it is the second marine deposit site of the Krastudy Horizon in Lower Powiśle. This confirms the early conclusions on marine transgression, that covered the area in the Krastudy Interglacial- younger than the Eemian Interglacial.