Wyniki badań laboratoryjnych plejstoceńskich osadów morskich z Krastud i Bukowa (Dolne Powiśle) na tle geomorfologii obszaru

Abstract

Przedstawiono wyniki analiz petrograficznych i litologicznych próbek z profili Bukowa i Krastud, zlokalizowanych w rejonie Mikołajek Pomorskich w strefie zasięgu fazy pomorskiej zlodowacenia północnopolskiego oraz omówiono geomorfologię obszaru badań. W osadach plejstoceńskich wyróżniono 19 poziomów litologiczno-stratygraficznych z okresu zlodowacenia środkowopolskiego, interglacjału eemskiego i zlodowacenia północnopolskiego, w dużym stopniu zgodnych z poziomami wydzielonymi w tych profilach przez A. Makowską, (1986). W obydwu stanowiskach znajdują, się osady morskie, które występują na złożu pierwotnym (eemskie i młodsze od eemu) lub w formie kier w glinach zwałowych zlodowacenia środkowopolskiego (holsztyńskie).LABORATORY TEST RFSULTS OF THE PLEISTOCENE MARINE SEDIMENTS FROM KRASTUDY AND BUKOWO (LOWER POWISLE) ON THE BACKGROUND OF REGIONAL GEOMORPHOLOGY The paper presents laboratory test results of samples taken from the boreholes in Krastudy and Bukowo, drilled for The Detailed Geological Map of Paland in scale 1:50000, sheet: Sztum. Both in Krastudy and Bukowo the Quaternary sediments were drilled through and the Palaeogen sediments reached. The area is situated within the North-Polish Glaciation - the Pomeranian Phase range. It is formed mainly by the postglacial upland with numerous frontal morains and dead ice morains upan it. Huge sandr fields occur on the a foreland of the morain series in the Sztum and Waplewo area. As a result of laboratory tests 19 levels of lithologically and genetically differentiated sediments have been distinguished from investigated boreholes. In the lowest part of the profile are found mixed silts and sands with marine Foraminifera (therefore they would be determined as the first site in Poland of the Holstein Sea sediments), boulder clays and their South-Polish Glaciation residua deposits with indexes of O/K 0.32-0.8, K/W 3.65-1.32, A/B 0.26-0.67, and also their Mid-Polish Glaciation residual deposits with other indexes. Different position of these sediments in the profile suggests the assumption that they lie on a secondary deposits .Above these sediments lie the Mid-Polish Glaciation boulder clays with the petrographic indexes O/K 1.68-1.93, K/W 0.55-0.64 and A/B 1.40-1.63 and clays and silts deposited in ice - barrier lakes. Detached blocks of the Holstein Sea sediments are found in the boulder clays in Krastudy. The sixty meter sediment of the Eemian Interglacial is found above the Mid-Polish Glaciation sediments. In the lower part of the Krastudy profile there are fluvial sands, clays and silts of ox-bow and lake-origins, in Bukowo however outwash fan sands with a large thickness. A level of silts with and ample cane-break and numerous microfauna - corresponding with so-called the Sztum Sea is found in the floor of the series in Krastudy and in the fan deposits in Bukowo. Sands, silts and clays of the matured rivers and their ox-bows are found higher and above them again silts, sands with Foraminifera and other marine fauna remains. They may be correlated with sediments of so-called the Tychnów Sea. The Eemian Interglacial profile is ended in fluvial sands, clays, silts, peats and lacustrine chalks. The lowest level of the North-Polish Glaciation is represented by boulder clays of the Torun Stadial with indexes of O/K 1.12, K/W 0.97, A/B 0.95. Above them occurs a series of silts, limnic ox-bow clays and fluvial sands of significant thickness. In the top of the series the lithological unvaried marine sediments with Foraminifera and other marine remains are found. The whole series is ranked with the Gniew Interstadial, and the marine sediments would be a new bed not stated in Poland before. The most upper parts of the profiles are composed of the Świecko Substadial boulder clays and their residual deposits with indexes of O/K 1.65, K/W 0.65 and A/B 0.95 and above occur the Grudziądz Subinterstadial fluvial sands and the Leszno-Poznań Substadial fluvioglacial sands. The investigated profile ends in boulder clays of the same substadial with the petrographic indexes of O/K 2.36, K/W 0.47 and A/B 1.77. Boulder clays and the Pomeranian Phase fluvioglacial sands were not tested.