Przyczynek do znajomości otwornic planktonicznych z podmenilitowych margli globigerinowych polskich Karpat zewnętrznych

Abstract

Opisano 25 gatunków otwornic planktonicznych z podmenilitowych margli globigerinowych polskich Karpat zewnętrznych. Na podstawie zbadanego zespołu wysunięto wnioski dotyczące środowiska sedymentacji tych utworów na przełomie eocenu i oligocenu.A CONTRIBUTION TO THE KNOWLEDGE OF PLANKTONIC FORAMINIFERS OF THE GLOBIGERINA SUBMENILLITE MARLS IN THE POLISH OUTER CARPATHIANS The Globigerina Submenillite Marls form characteristic lithostratigraphic horizon in the Polish Outer Carpathians, closing one of the stages in development of the Flysch geosyncline (Upper Cretaceous - Eocene stage). Up to the present, about 18 species of planktonic foraminifera have been described from this horizon (J. Blaicher, 1970). On the basis of stratigraphic ranges of these foraminifers, the strata were dated at the Eocene-Oligocene. Further studies showed the presence of 25 planktonic foraminifer species in the Globigerina Suhmenillite Marls (see Tables 1-2). Stratigraphic ranges of the species Turborotalia permicra (Blow et Banner), Globigerina angiporoides Hornibrook, G. sellii (Borsetti), G. tapuriensis Blow et Banner and G. vialovi Mjatliuk (see Table 1) give further support for the hypothesis of sedimentation of the Globigerina Marls at the turn of the Eocene and Oligocene. This conclusion is further supported by the dating based. on nannoplankton assemblages found in the Globigerina Submenillite Marls (S. Alexandrowicz, A. Kostecka, 1963; A. Radomski, 1967; B. Olszewska, M. Smagowicz, 1977). The assemblages comprise several characteristic species such as Isthmolithus recurvus Deflandre, Discoaster barbadiensis Tan Sin Hok, D. saipanensis Bramlette et Wilcoxon, and Spenolithus pseudoradians Bramlette et Wilcoxon. The isotopic age of bentonites occurring above the horizon of the Globigerina Submenillite Marls (34.6 Ma) seems to give support for the above datings based on microorganisms (T. Wieser, 1979). Specific composition of the foraminifer assemblages and the shares of individual species in foraminifer spectrum for the Globigerina Marls in the Polish Outer Carpathians; reflect both location of the Carpathian Basin at the periphery of the Tethys and the worldwide and local environmental changes which have taken place at the end of the Late Eocene.