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Taphonomy of Oligocene teleost fishes from the Outer Carpathians of Poland

Bieńkowska-Wasiluk M.

Acta Geologica Polonica

2010

Vol. 60, no. 4

479-533

The Oligocene ichthyotaphocoenoses from the Outer Carpathians of Poland are dominated by skeletons of actinopterygian (only teleost) fishes. Their taphonomy was studied in six localities of the Menilite-Krosno Series (Błażowa, Jamna Dolna 1, Jamna Dolna 2, Rudawka Rymanowska, Wola Czudecka, Wujskie). Over 1700 specimens of variably complete fish skeletons, representative of 20 actinopterygian families, were studied. The taphonomic analysis of the skeletal disarticulation and its pattern, deformations of the vertebral column (curved, broken), arrangement of jaws and fins, the spatial array of skeletons with regard to the embedding sediment, as well as identification of unusually preserved specimens, indicate that all of the ichthyotaphocoenoses have resulted from a long-term accumulation of fish carcasses at the burial place, at a very low sedimentation rate, under anoxic conditions in, and above, the sediment/water interface. Two assemblages from the Tylawa Limestone Horizon have acquired their unusually good preservation state due to the penetration of calcium carbonate into soft tissues of corpses at the burial place. in other deposits (shales, marls) the fish skeletons are more or less disarticulated as a result of decay in a calm environment. each of the ichthyotaphocoenoses displays some features indicative of mass mortality events (e.g. high density of individuals, the presence of individuals with jaws agape, high number of juveniles); none of them has a set of features indicating it unequivocally. The cause and/or conditions of death were not the same for all individuals. Only some individuals died instantaneously during mass mortalities, whereas the majority died over a period of time as a result of senility, diseases, or other circumstances. all of the ichthyotaphocoenoses show features typical of both necro- and thanatocoenoses. The associated flora and fauna, e.g., amphipods, land-derived dragonflies and bird feathers, indicate that the taphocoenoses originated as a result of accumulation of biotic remains from various environments. Fishes and associated remains settled on the bottom successively, and thus their assemblages display features typical of necrocoenoses. evidence of fish predation is reported for the first time from the Menilite-Krosno Series of Poland.

Granica oligocen/miocen w polskich Karpatach zewnętrznych na podstawie nanoplanktonu wapiennego

Garecka M.

Biuletyn Państwowego Instytutu Geologicznego

2008

nr 432

1-53

Badaniami objęto utwory serii menilitowo-krośnieńskiej jednostek śląskiej i skolskiej wschodniej części polskich Karpat Zewnętrznych powyżej korelacyjnych poziomów wapienia jasielskiego i/lub wapienia z Zagórza. W jednostce śląskiej granica oligocen/miocen przebiega w wyższej części warstw krośnieńskich dolnych, w południowej części jednostki - w otryckim regionie facjalnym, w wyższej części łupkowo-piaskowcowej serii nadotryckiej warstw krośnieńskich dolnych, natomiast w południowej części leskiego regionu facjalnego jednostki śląskiej - w obrębie serii przeławicających się pakietów gruboławicowych piaskowców i drobnorytmicznych osadów turbidytowych warstw krośnieńskich dolnych. W bardziej północnej części jednostki seria ta jest zastępowana przez kompleks gruboławicowych piaskowców facji leskiej i w wyższej części tego wydzielenia stwierdzono obecność gatunków mioceńskich. W jednostce skolskiej, w jej południowej części, granica przebiega w niższej części warstw krośnieńskich dolnych, a w bardziej północnej i zachodniej części tej jednostki - w obrębie warstw menilitowych. Jako gatunki wskaźnikowe dla wyznaczenia granicy oligocen/miocen zaproponowano: Helicosphaera mediterranea Muller, Helicosphaera recta Haq, Helicosphaera scissura Miller, Dictyococcites bisectus (Hay, Mohler et Wade) Bukry et Percival, Zygrhablithus bijugatus Deflandre i Sphenolithus delphix (Bukry).

The aim of this work was to establish the Oligocene/Miocene boundary in the eastern part of the Polish Outer Carpathians on the basis of calcareous nannoplankton analysis. The investigations focused on the Menilite-Krosno Series of the Silesian and Skole Units overlying the Jasło and/or Zagórz limestone chronohorizons. In the Silesian Unit, the Oligocene/ Miocene boundary is placed in the upper part of the Lower Krosno Beds. In the Otryt facial region (southern part of the Silesian Unit), this boundary runs within the upper part of the shaly-sandy Supra-Otryt series of the Lower Krosno Beds. In the southern part of the Lesko facial region, the boundary is established within a series of thick-bedded sandstones and fine-rythmical turbidite deposits of the Lower Krosno Beds. In the northern part of this region, the series is replaced by thick-bedded sandstones of the Lesko facies. Miocene taxa were recorded in the upper part of these deposits. In the southern part of the Skole Unit the Oligocene/Miocene boundary runs within the lower part of the Lower Krosno Beds, whereas in the more northern and western parts of the unit - within the Menilite Beds. Among taxa proposed as indicative for the Oligocene/Miocene boundary, Helicosphaera mediterranea Muller, Helicosphaera recta Haq, Helicosphaera scissura Miller, Dictyococcites bisectus (Hay, Mohler et Wade) Bukry et Percival, Zygrhablithus bijugatus Deflandre, Sphenolżthus delphix (Bukry) were recorded.