Mikrofauna z warstw krośnieńskich z Liskowatego koło Ustrzyk Dolnych

Abstract

MICROFAUNA FROM THE KROSNO BEDS AT LISKOWATY NEAR USTRZYKI DOLNE

In the Krosno beds of the Skole unit, at Liskowaty, the authors encountered a rich microfauna. It was found in so-called shale horizon constituting the boundary horizon between lower and middle Krosno beds (according to the conception voiced by L Horwitz (1930a, b), L. Koszarski and K. Żytko (1959, 1961). The shale horizon, the regional extent of which within the Skole unit was recently stressed by J. Żgiet (1001), shows in the region of Liskowaty (southern flank of the Klewa antycline) a thickness, of approximately 15 m. This horizon consists of over ten fractionally laminated banks, beginning with fine-grained sandstone, or grey coarse-grained calcereous siltstone (Krosno shale), and ending with pelitic material in the shape of green and black shales. The siltstone banks contain very scanty microfauna, or none at all. Only in one bank of dark ashen-grey siltstone, 55 cm. in thickness, an abundant microfauna was discover. A list of the fauna is given in the Polish text.

Conclusions: The microfaunal assemblage from Liskowaty occupies the same positions as that from Leszczawa Górna (S. Gucik, J. Morgiel, 1960). The micro-fauna from Liskowaty and Leszczawa Górna is redeposited. It sems very likely that the bottom of the middle Krosno beds in the Polish part of the Skole unit corresponds to that of the Polanice (Kosmacz) beds. This interpretation is confirmed, inter alia, by the occurrence of Spiralis at the bottom of both members.

The microfauna from Liskowaty and Leszczawa Górna discloses the Oligocene-Miocene character. Even so, there appear forms that were reported up to now from. the Miocene only, i.e., Stilostomella scalaris (B a ł s c h.) and Valvutineria complanata (d' 0 r b.). On the basis of these forms it may be assumed that the beginning of sedimentation of the middle Krosno beds took place, in the Skole unit, already at the Miocene time.