Profil geologiczny otworu w Pagórkach koło Elbląga oraz znaczenie wyników badań pyłkowych jego osadów dla stratygrafii młodszego plejstocenu w Polsce

Aurelia Makowska

Abstrakt


GEOLOGIC SECTION OF THE BOREHOLE AT PAGÓRKI AND SIGNIFICANCE OF POLLEN ANALYSIS OF ITS DEPOSITS TO A STRATIGRAPHY OF THE LATE PLEISTOCENE IN POLAND

Summary
The borehole Pagórki was done in 1987 in the Elbląg Elevation (Fig. 1). General position of the borehole was described previously (16) in connection to the earlier studies in this area and in the Lower Vistula Region. Final results, of a pollen analysis of the Eemian part of the section (4) support a more reliable stratigraphic interpretation of the sediments and make it a more significant within the extents of the Post-Eemian glaciations in Poland. This section is also interesting as it contains two beds of marine sediments, separated by a tiII and other terrestrial deposits. The upper bed is composed of the Elbląg Clays, defined by the authoress as younger from the Eemian Interglacial (12, 17). The borehole was 355 m deep and went through the Quaternary complex (thickness of 299 m), entering the Tertiary (palaeocene) substrate (Fig. 1–I). The Quaternary complex is composed mainly of deposits of the Late Pleistocene age: Eemian and post-Eemian ones, that are 285 m thick. They are underlain by a thin till of the Middle Polish Glaciation. The upper part of the section is partly glaciotectonicaly deformed. The Late Pleistocene complex starts at the bottom with sediments of the Eemian Interglacial (sensu lato) and the post-Eemian ones, with two tills of two: Toruń (BII) and Wisła (BIV - V) glaciations, separated by a thick intertill (Kadyny) formation of the Krastudy Interglacial age. The latter contains marine Elbląg Clays with cool remains of molluscs and foraminifers (Fig. 2–I), and in other sires of the Lower Vistula Region also with warmer fauna (13). Eemian sediments sensu lato form a thick Lower Vistula formation (Fig. 2 – II) of a considerable thickness, deposited during the interval between the two glaciations. The middle part of the formation (B) is strictly of interglacial character which, beside others contains also marine sediments. The latter are connected with the Tychnowy Sea, correlated with the Eemian Sea of the Netherlands, Germany and Denmark. A middle part of the formation was pollen-analyzed (4); the pollen diagram presents transgression and recession of the Tychnowy Sea and transformation of this sea into a lake reservoir. It reflects presence of the Post-optimal cooling, corresponding with the first post-Eemian glaciation (The Toruń Glaciation in the Lower Vistula Region) and the following warming correlated in Poland with the Amersfoort Brorup (4, 17). Results of pollen studies at Pagórki are in general concordant with other previous investigations of the Lower Vistula formation in the Lower Vistula Region (1, 12, 13) and enable a distinct displacement of its upper limit outside the Brorup Interstade. They define also the age of the overlying glacial and inter-till sediments to be younger than the Brorup. In result these facts exclude presence of the so-called Kaszuby Stadial, interpreted as a glacial stade between the Eemian Interglacial and the Brorup (18-20).

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