Correlation of the Middle Miocene deposits in SE Poland and western Ukraine based on foraminifera and calcareous nannoplankton

The aim of this study is to compare the assemblages of foraminifera and calcareous nannoplankton from the Middle Miocene sediments from SE Poland and western Ukraine. Detailed investigations revealed a high degree of similarity of foraminiferal assemblages of the Pecten/Spirialis beds of Poland and the Kosiv Formation of Ukraine. Assemblages from both areas are characterized by numerous arenaceous species of foraminifera (Hyperammina granulosa, Ammodiscus miocenicus, Haplophragmoides indentatus, H. laminatus), radiolarians, pteropods and index planktic species Velapertina indigena. High degrees of similarity also display assemblages from the Krakowiec beds (Poland) and the Dashava Formation (Ukraine). The lower parts of both subdivisions are characterized by the presence of Anomalinoides dividens. Saccammina sarmatica, Bolivina sarmatica, Brizalina nisporenica, and Porosononion granosum occur in the upper parts. Chloropycean Halicoryne morelleti is a characteristic element of the assemblages. The calcareous nannoplankton assemblages contain almost identical species. The deposits lying above the evaporites (which belong to the NN6 zone) are included into the NN6, undivided NN6-NN7, and NN7 zones. The gradual impoverishment of the species of the upper part of NN6 and the lower part of NN7 zones is observed. The assemblages of the Krakowiec beds and the upper part of the Kosiv and Dashava formations are of low species diversity and are mainly restricted to a few species with high abundance. The assemblage is composed of placoliths (Coccolithus and Reticulofenestra species), high number of the reworked nannofossils and damaged elements.