Zróżnicowanie batymetryczne i facjalne skamieniałości sladowych w poludniowej części płaszczowiny magurskiej (polskie Karpaty zewnętrzne)

Abstract

Przedstawiono próbę zastosowania modeli batymetrycznych A Seilachera i M. Książkiewicza oraz modelu facjalnego T.P, Crimesa do interpretacji zmienności skamieniałości śladowych w albsko-oligoceńskim fliszu strefy krynickiej i bystrzyckiej płaszczowiny magurskiej. W konfrontacji z wieloma przedstawionymi faktami modele te nie sprawdzają się, a model Crimesa tylko częściowo wyjaśnia rozmieszczenie ichnoasocjacji w badanych profilach. BATHYMETRIC AND FACIAL DIFFERENTIATION OF TRACE FOSSILS IN THE SOUTHERN PART OF THE MAGURA NAPPE IN THE POLISH OUTER CARPATHIANS  The Albian - Oligocene flysch formations of Sącz and Krynica zones of Magura Nappe (Polish Aysch Carpathians) contain several trace fossils (A. Uchman, 1990a) with notable share of Graphoglyptidae, typical for the Nereites ichnofacies (A. Seilacher, 1967). In Beloveža Beds Thallassinoides and Ophiomorpha - the typical forms of the ichnofacies - are often met. The Piwniczna Sandstones Member contains in the southern part the Cruziana ichnofacies, and in the northern part - the ichnofacies similar to Nereites. It is difficult, however, to accept that the formations of the same lithosome were formed at the depth so strongly differentiated, expressed by these ichnofacies. In such case the bathymetric differences in the sedimentary basin would reach about 1500 m at the distance of 30 km only. The ichnotaxa typical for shallow water, such as Rhizocorallium, Ophiomorpha, Thalassionides, Pelecypodichnus and others (A. Uchman. 1990a, b, 1991) exist often with bathypelagic ichnotaxa, as for instance Paleodictyon and others. According to T. P. Crimes et a1. (1981) the shallow-water forms exist in the flysch of inner deep-sea fan. Many of them appear in the distal thin- and middle-bedde flysch of the Beloveža beds and the Szczawnica Formation. Ophiomorpha exist plenitifully in the part of the Piwniczna Sanstones Member. Single beds in the Beloveža beds contain many Thalassinoides. It seems, that these ichnotaxa are not strictly dependent on the flysch subfacies. In spite of several discrepancies, the conception of T. P. Crimes describes well the general increase of the shallow-water forms with the increase of the proximity of the facies at the area of investigations. M. Książkiewicz (1911) correlated the data about the depth of foraminifers and the sedimentological features of the sediments with the supposition of the model of A. Seilacher. As a result, he constructed the bathymetric model for the chosen ichnotaxa. The issue data for this model are presently not fully actual. For instance, the vertical and horizontal distribution of the ichnotaxa is different from that given by M. Książkiewicz (A. Uchman, 1990a). This author considered unjustly the Ciężkowice Sandstones (Eocene) as the neritic-epibathyal deposits, using as a basis the existence of the diagonal bedding. New microfaunal and sedimentological data show, that these sandstones are the deep-water deposits, similar to most of Senonian - Eocene fonnations of the Carpathian Flysch. As we see, the hypotheses of A. Seilachcr, T. P. Crimes and M. Książkiewicz do not explain sufficiently the distribution of trace fossils at the area of investigations. It is possible to distinguish (A. Uchman, 1990a) several local ichnoassociations, controlled mostly by the oxygenation of the sediment, the erosion of the bottom, the quickness of sedimentation and/or availability of food.