International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

Biostratigraphy and paleoenvironment of the Upper Cretaceous deposits in the northern Tarcau Nappe (Eastern Carpathians) based on foraminifera and calcareous nannoplankton

Pages: 117 - 132

Authors: RALUCA BINDIU, SORIN FILIPESCU, RAMONA BALC

Abstract: Late Cretaceous foraminiferal and calcareous nannoplankton assemblages from the northern part of the Tarcau Nappe, Hangu Formation in the northern Eastern Carpathians are documented in order to reconstruct paleoenvironmental settings and biostratigraphy. The foraminiferal assemblages are dominated by flysch-type agglutinated taxa suggesting bathyal environments, close to the calcite compensation depth (CCD), and mesotrophic to oligotrophic conditions. The morphogroup analyses display variations in tubular and infaunal morphotypes suggesting different levels of oxygenation and seafloor disturbance caused by currents. Reddish hemipelagites containing only agglutinated foraminifera (dominant infaunal forms) occurring in the middle part of the section suggest an increase of water depth and changes in redox conditions. Based on foraminifera, the deposits were assigned to planktonic Globotruncana ventricosa and agglutinated Caudammina gigantea Zones. The first occurrence of Uniplanarius trifidus and last occurrence of Reinhardtites anthophorus demonstrate the presence of Late Campanian UC15cTP–UC16/CC21–CC23 calcareous nannoplankton Zones. Foraminiferal and nannofossil assemblages in the red beds have a high potential for stratigraphic correlation on a regional scale.

Keywords: Eastern Carpathians, paleoecology, biostratigraphy, morphogroup analysis, red beds, calcareous nannoplankton, agglutinated foraminifera

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