Badania warstw pogranicznych kredy i trzeciorzędu w Polsce pozakarpackiej

Krystyna Pożaryska




In the light of micropalaeontological researches carried on in Poland by Pożaryska on materials from several European countries (Poland, Denmark, Sweden, Germany, Belgium, Holland, Soviet Union and Bulgaria) it seems quite definite that Danian represents the lowermost Paleocene and not the uppermost Cretaceous. This position of Danian, established as a result of researches on Foraminifera (K. Pożaryska 1965–l966), was confirmed by those on Ostracoda (J. Szczechura 1964–1965) and, in west Europe, also by the researches carried on by Deroo (1966). This author, studying both the uppermost Cretaceous and the lowermost Tertiary Ostracoda of the Limburg region and of the adjacent areas, confirmed the presence of a distinct, natural Cretaceous – Tertiary boundary between the Maastrichtian and Danian. The same phenomenon applies, as observed by Bramlette and Martini (1964), also to Nannoplankton. It is known that ammonites, true belemnites (Belemnitellidae), inoceramids, rudists and dinosaurs definitely became extinct at the end of the Maastrichtian, and never appeared in Danian. These doubtful cases, in which representatives of dinosaurs were reported to occur in Danian, were categorically disproved by Jeletzky (1962). Discredited were also the discoveries of inoceramids found in the Mediterranean region. It is requested on the above considerations that the position of Danian should be established, both in Europe and America, in the lowermost Paleocene. Consequently, the Cretaceous – Tertiary boundary must be fixed between the Maastrichtian and Danian. In Poland, this boundary is quite natural because, except for certain instances of distinct sedimentary hiatuses, the facies does not modify between the uppermost Maastrichtian (Żyrzyn beds) and Danian (Sochaczew beds), where the greatest change of fauna is observed.


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