Two ammonites from the Early Cretaceous deep-sea sediments of the Silesian Nappe, Polish Carpathians, and stratigraphic problems resulted from micropalaeontological dating of their sites

Abstract

Two ammonites Teschenites subflucticulus Reboulet and Criosarasinella mandovi Thieuloy have been found for the first time in the Flysch Carpathians. They occur in the so far poorly dated Early Cretaceous flysch deposits of the Silesian Nappe at Poznachowice Dolne, in the Upper Cieszyn Shale and the Hradiště (Grodziszcze) beds lithotypes, respectively. Teschenites subflucticulus points to Late Valanginian (Furcillata Zone), but nanno- plankton points to Late Hauterivian-Late Barremian and dinocysts to Late Hauterivian, all analyzed from the same sample. Criosarasinella mandovi points also to Late Valanginian (Furcillata Zone), what is not in contra- diction with the nannoplankton assemblage (Early Valanginian-Early Barremian) analyzed from the same bed, but dinocysts suggest Late Hauterivian. Preservation of the ammonites and sedimentary features of their host beds exclude redeposition. The difference in age by almost 3 Ma years between the ammonites and microfossils cannot be satisfactorily explained according to the current knowledge on their biostratigraphic meaning; it is left as it is as a dilemma.