Skamieniałości śladowe z warstw inoceramowych oraz utworów formacji szczawnickiej w strefie krynickiej i bystrzyckiej płaszczowiny magurskiej

Alfred Uchman

Abstrakt


TRACE FOSSILS OF THE LNOCERAMID BEDS AND THE SZCZAWNICA FORMATION IN THE KRYNICA AND BYSTRZYCA ZONES OF THE MAGURA NAPPE

Summary
Ichnoassociation composition of thin and medium, and occasional thick bedded silicic1astic flysch of the Inoceramian beds (informal unit, Senonian - Paleocene), as well as thin and medium bedded silicic1astic flysch of the Szczawnica Formation (Paleocene - Lower Eocene) have been examined. The ichnoassociation of the Inoceramian beds is dominated by postdepositional forms, such as: Chondrites, Planolites, and Helminthoida. Ichnoassociation of the Szczawnica Formation is dominated by postdepositional forms, such as: Chondrites, Planolites, Phycosiphon, Helminthoida, Tubulichnium, Zoophycos, and Spirorhaphe zumayensis. Predepositional forms, e.g., graphogliptides (Urohelminthoida, Paleodictyon, and others) as well as those produced by irregular echinoids (Taphrehelminthopsis, Scolicia) are very rare in the both units. Very scarce evidence of bottom erosion as well as relatively dark colour of interbedded mudstones and silts tones both suggest that low sediment oxygenation was the main factor controlling benthic life. The observed small scale changes of diversity and density of the trace fossils within the studied sections probably reflect changes in the sediment oxygenation. The ichnoassociations of the Inoceramian beds as well as those of the Szczawnica Formation are composed of the elements belonging to the Zoophycos, Nereites, and even the Cruziana ichnofacies. Such mixed composition of the ichnoassociations does not allow for any bathymetric determination.

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