Dinoflagellate cyst record of the Eocene-Oligocene boundary succession in flysch deposits at Leluchów, Carpathian Mountains, Poland

Abstract

Abstract Organic-walled dinoflagellate cysts from Eocene-Oligocene transitional deposits have been studied in a section at Leluchów, Flysch Carpathians, Poland. The Eocene-Oligocene boundary, as based on dinoflagellate cyst distribution, is placed in the upper part of the Leluchów Marl Member. The main biostratigraphic events associated with this boundary interval are the highest occurrence of Areosphaeridium michoudii and Areosphaeridium diktyoplokum , and the lowest occurrence of Wetzeliella gochtii . Distinct changes in dinoflagellate cyst assemblages and palynofacies across the Eocene-Oligocene boundary at Leluchów imply a drop in relative sea-level within the Carpathian flysch basin that might correlate with a major eustatic fall during the earliest Oligocene. A drop in sea surface temperature is recognized prior to the Eocene-Oligocene boundary, and evidence is presented for an increase in nutrient level and decrease in salinity within the photic zone during the earliest Oligocene.