Otwornice albu serii czorsztyńskiej (formacja z Chmielowej) Pienińskiego Pasa Skałkowego

Stefan Witold Alexandrowicz


Albian Foraminifera of the Czorsztyn Series (Chmielowa Formation) of the Pieniny Klippen Belt

Marls of the Chmielowa Formation are distinguished for the presence of rich microfauna in them. Studies on Foraminifera were carried out on 12 profiles (Fig. 1), described in detail by Birkenmajer (1963), of which two profiles were better exposed recently (Fig. 2). The Foraminifera assemblage comprises 53 species (Fig. 3—6). In this assemblage planktonie Foraminifera are prevailing quantitatively; their share in marls exceeds 50—60%, and is considerably higher in limeston.es. Arenaceous Foraminifera are infrequent, and among benthonic forms Nodosariidae are prevailing. Age determination of the Chmielowa Formation is possible owing to the presence of the species of a narrow stratigraphie range. They are presented by the benthonic Foraminifera: Gyroidina injracretacea Moroz., Osangularia infracretacea (Bukal.), Anomalina hostaensis Moroz., Gavelinella intermedia (Berth.) and Gavelinella schloenbachi (Reuss), reported from Albian deposits, and by the planktonic Foraminifera: Rotalipora ticinensis (Gand.) and Globigerinelloides breggiensis (Gand.), typical of Middle and Upper Albian deposits. In the uppermost part of the profileof red limestones and marls infrequent Praeglobotruncana delrioensis (Plum.) and Rotalipora balernaensis Gand. are found, and in the overlying marls of the Pomiedznik Formation there occur numerous Rotalipora apenninica (Renz) and Planomalina buxtorfi (Gand.). On these grounds the Chmielowa Formation can be included in the Middle and Upper Albian. The top of this formation may not reach the boundary between Albian and Cenomanien, which probably runs within the lower part of the Pomiedznik Formation. There have been, however, no evidences of the Lower Albian age of the red limestones and marls. The composition of the microfossil assemblage under description, a considerable share of benthonic Foraminifera and a great number of their species, point to favourable conditions of development of the stenotopic fauna during deposition of the Chmielowa Formation. The Foraminifera settled at the bottom below the wave base, at depths corresponding to sublittoral and neritic zones, are represented by numerous genera. A small admixture of the terrigene material in the deposit, as well as the plankton development on a large scale indicate that the red limestones and marls were formed as pelagic sediments on submarine rises within the Carpathian geosyncline. In the period preceding their deposition these were shoals on which no sediments had been formed for a long time.

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