Commune: Bircza (pow. przemyski, woj. podkarpackie)
Framework element or context represented:
Oligocene ichtiofauna and sedimentary environment. Biostratigraphy and paleosedymentology of Oligocene flysh Carpathians.
Primary geological/geomorphological interest:
The sequence of the Oligocene Menilite Beds with rich ichtiological fauna.
Comparative assessment justification:
It is unique site in the Skole Unit with the complete, stratotipical profile of the Menilite Beds of the whole Polish Carpathians.
Protection status and accessibility:
Outcrops are protected in the nature reserve “Krępak” (1991).
Character of site: Natural outcrops.
Area: c. 20 ha
Altitude: 350-425 m a.s.l.
Lithology: sandstones, other siliceous rocks, marls, shales
Discipline: Palaeobiology, Palaeoenvironment, Stratigraphy of Phanerozoic
Process Age: *all periods
Bedrock Age: Paleogene, *all periods
Description of primary interest:
The site “Na Krępaku” is situated along the Przemyśl – Bircza road and the outcrops in adjacent streams lying in part within the Krępak reserve. These sites enclose full profile of the Menilite Beds. The layers rest normally with the general strike about 170o and dips from 40 to 85o to W. The following members have been distinguished within the site: the Jamna Dolna Subchert Shale; the Borysław Sandstone; the Kotów Menilite Chert; the Dynów Marl; the Borek Nowy Sheet Shale with Chert; the Rudawka Tractionite Sandstone; the Krępak Green Shale; the Kliwa Sandstone; the Jasło Shale; the Łopianka Beds (ash-grey shales and micaceous sandstones); the Upper Menilite Shale with Upper Chert, and – belonging already to the Krosno Beds - the overlying Niebylec Shale with diatoms typical of the Piątkowa diatomite horizon. Within the Menilite Beds very rich fauna of fish – over 1,000 species – was collected and used to distinguish several ecostratygraphic ichtiofaunal zones: from IPM-1 in the subchert and chert strata to IPM-6 in the upper menilite shales. This division was extended onto the whole Carpathian arc and correlated with nannoplankton zonation on the basis of coccolithes present here: zones NN 21(?) to NN 25 as well as with the characteristic isochrone horizon of the Jasło Shale.
Literature:
JERZMAŃSKA A. 1968–Ichtyofaune des couches á ménilite (flysch des Karpathes). Acta Paleont. Pol., 13/3: 379-488. JERZMAŃSKA A. & KOTLARCZYK J. 1988–Podstawy podziału stratygraficznego serii menilitowo-krośnieńskiej Karpat za pomocą ichtiofauny. Proponowany profil stratotypowy warstw menilitowych w polskich Karpatach.(Polish only). In: Kotlarczyk J. & Pękala K. (reds) Przewodnik 59 Zjazdu Pol. Tow. Geol. w Przemyślu: 102-107. JUCHA S. & KOTLARCZYK J. 1961–La série des couches à Menilite et de couches de Krosno dans le flysch des Karpates. (French sum.). Prace Geol., PAN, 4: 1-115. KOTLARCZYK J. 1979–Zarys historii badań paleontologicznych Karpat przemyskich w minionym stuleciu. (Polish only). In: Kotlarczyk J. (red.) Badania Paleontologiczne Karpat Przemyskich. Materiały IV Krajowej Konferencji Paleontologów: 9-13. KOTLARCZYK J. 1988–Problemy sedymentologii, stratygrafii i tektoniki Karpat przemyskich oraz ich najbliższego przedpola. (Polish only). In: Kotlarczyk J. & Pękala K. (reds) Przewodnik 59 Zjazdu Pol. Tow. Geol. w Przemyślu: 23-62. KOTLARCZYK J. & JERZMAŃSKA A. 1976–Biostratygraphy of Menilite Beds of Skole unit from the Polish Flysch Carpathians. Bul. Acad. Pol. Sci., Ser. Sci. Terre, 24/1: 55-62. KOTLARCZYK J. & JARZMAŃSKA A. 1988–Lito- i biostratygrafia warstw menilitowych na Krępaku; Łupki z Niebylca z poziomem diatomitów z Piątkowej. (Polish only). In: Kotlarczyk J. & Pękala K. (reds) Przewodnik 59 Zjazdu Pol. Tow. Geol. w Przemyślu: 107-112. KOTLARCZYK J. & JERZMAŃSKA A. 1988–Ichtiofauna in Carpathian stratigraphy. (English sum.). Przegl. Geol., 36/6: 346-352.