Flysch formation in the Tertiary of the Polish Carpathians

Franciszek Bieda


Formacja fliszowa w trzeciorzędzie Karpat polskich

The Tertiary of the Polish Carpathians is represented by nummulitic and flysch formations. In the latter, organisms are poorly represented and agglutinating Foraminifera predominate. The paucity of fossils in flysch sediments may be explained by unfavourable conditions in fresh and brackish water for the preservation of shells, as a rule made up of an organic substance, as fossils. For animals, the deciding life factor is food, of which there is a great deal in shallow water. On the basis of the occurrence of Foraminifera in the Tertiary flysch of the Polish Carpathians, the areas of sedimentation of this flysch may be defined as follows. Sediments with exclusively agglutinating Foraminifera are lacustrine, reflecting fresh-water environments such as swamps, enclosed bays and river mouths, in which life conditions undergo rapid changes. Occurrences of mixed assemblages, that is, comprising agglutinating and small, calcareous Foraminifera, indicate a marine environment of the littoral and neritic zones. Occurrences of large Foraminifera which are rarely encountered in flysch, also suggest a shallow sea. On the other hand, assemblages of small, calcareous Foraminifera, together with nannoplankton, reflect the existence of pelagic marine conditions, with depths equivalent to those of the present-day bathyal zone.

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