Vernyhorova, Y., Jamrich, M., Kyška-Pipík, R. & Hudáčková, N., 2026: Biostratigraphic framework of the Konkian-Sarmatian boundary based on microfossils from the well #20 Kerch Peninsula (Crimea) [Biostratigrafický rámec konsko-sarmatského rozhrania na základe mikrofosílií z vrtu č. 20 Kerčský polostrov (Krym)]. Mineralia Slovaca, 85, 1, 67 – 86.
DOI: https://doi.org/10.56623/ms.2026.58.1.4
Abstract: The Konkian-Sarmatian transition represents a major interval of biotic turnover and paleoenvironmental change in the Eastern Paratethys. This study investigates the upper Konkian and Lower Sarmatian deposits penetrated by well #20 on the western Kerch Peninsula (Crimea) using integrated analyses of benthic foraminifera, calcareous nannoplankton, mollusks, ostracods and rare planktic foraminifera. Three successive benthic foraminiferal assemblages were distinguished. The lower Konkian interval is characterized by assemblages containing Spiroloculina konkensis, Quinqueloculina minakovae group, and Elphidium kudakoense, together with the mollusks Limacina konkensis and L. andrussovi. The upper Konkian interval is dominated by Elphidium horridum and associated with Obsoletiformes lithopodolicus ruthenicus and Musculus sarmaticus. Early Sarmatian interval is marked by the appearance and common occurrence of Varidentella reussi, Articularia articulinoides, Articulina sarmatica, and Elphidium reginum. The transitional phase, termed the Konkian-Sarmatian Conversion Time (KSCT), represents a process of gradual basin reorganization. It is characterized by an abrupt decline in stenohaline elements occurring concurrently with the emergence of transitional mollusc and benthic foraminiferal species that appear in the late Konkian and span into the early phase of the Early Sarmatian. Calcareous nannoplankton assemblages containing Orthorhabdus rugosus, Cyclicargolithus floridanus, and common Reticulofenestra pseudoumbilicus, together with the absence of Sphenolithus heteromorphus, support assignment of the Konkian deposits to the NN6 Zone. The Early Sarmatian interval is characterized by abundant Braarudosphaera bigelowii, B. bigelowii ssp. parvula, and Holodiscolithus macroporus. The integrated microfossil and mollusc record documents a distinct turnover in biotic assemblages across the Konkian-Sarmatian transition and enables reliable correlation of the studied succession with regional Eastern Paratethyan stratigraphic schemes. The results contribute to a better understanding of the timing and character of biotic changes preceding and accompanying the establishment of Sarmatian environments.
Key words: Paratethys, Biostratigraphy, Serravallian, Foraminifera, Calcareous nannoplankton, Ostracods