Late Eocene (Priabonian) dinoflagellate cysts from Primorsky quarry, southeast Baltic coast, Kaliningrad Oblast, Russia

Abstract

Forty-seven rock samples from the stratotypes of three upper Paleogene formations – Prussian, Palvé, and Kurshskaya formations – were collected from the biggest amber deposit worldwide (Primorsky quarry, Kaliningrad Oblast SE Baltic coast), and have been palynologically analyzed. The presence of age-diagnostic dinoflagellate cyst species has allowed us to refine and update the previously questionable age of regional lithostratigraphical units. Based on the presence of Rhombodinium perforatum, the ‘Upper Wild Earth’ and ‘Upper Blue Earth’ members of the Prussian Formation correspond to the early Priabonian (Late Eocene) Rhombodinium perforatum Zone. The overlying ‘Upper Quicksand’ and ‘White Wall’ members of the Prussian Formation contain the key-species Thalassiphora reticulata, and are correlated with the latest Priabonian T. reticulata Zone. The overlying Palvé Fm (‘Green Wall’), comprises a dinoflagellate cyst assemblage very close to that recorded from the Prussian Formation, and also corresponds to the T. reticulata Zone, late Priabonian. The lower part of the Kurshskaya Formation – ‘Chocolate clays’ and lower ‘Brown sands’ members, contain an impoverished dinoflagellate cyst assemblages as a result of significant environmental changes. However, the common presence of Areosphaeridium diktyoplokum and Glaphyrocysta semitecta, along with an absence of early Oligocene key-species Wetzeliella gochtii or Chiropteridium galea, and pollen key-species Boehlensipollis hohli or Aglaoreidia cyclops, suggest the lower Kurshskaya Formation can be correlated with the uppermost Eocene, and very close to the Eocene/Oligocene boundary. Based on the revised stratigraphical ages presented here, we suggest an important regional marine transgression occurred during the Priabonian, which allowed the direct marine connection between the NW European Basin and Peri-Tethys via the Polish-Luthuanian Seaway. This was then followed by a regression at the end of Priabonian that culminated in a transition to continental sedimentation in the early Rupelian. A new dinoflagellate cyst species Oligokolpoma balticus sp. nov. is formally described.

Keywords:

• Late Eocene
• Priabonian
• amber deposits
• dinoflagellate cysts
• palynomorphs
• biostratigraphy
• palaeoenvironments
• Sambia Peninsula

Acknowledgments

We are grateful to M.I. Zatsepin, General Director of the Kaliningrad Amber Combine, for the access to the Amber quarry and the possibility to sample the section. We kindly thank chief geologists of the Amber Combine T.M. Khalitov and A.E. Korkin for their help in sampling of the section. Przemysław Gedl (Institute of Geological Sciences, Kraków) and Hartmut Shultz (Tubingen University) are thanked for their help in finding old German articles of Alfred Eisenack. Tatyana I. Chikina (Geological Institute, Moscow) is thanked for translation of German publication. Erica Crouch, Przemysław Gedl and Manuel Vieira are thanked for their careful and constructive reviews, which improved the paper. We also thank James Riding for his very helpful editorial suggestions.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The reported study was funded by the Russian Foundation for Basic Research and Governement of Kaliningrad Region according to the research project no. 19-45-390001. The research of AI and GA was carried out under the Russian State program no. 0135-2019-0045 (Geological Institute, Russian Academy of Sciences). The fieldtrip to the Amber Combine and the research of EM were funded by the Russian State program no. 0128-2021-0012 (Institute of Oceanology, Russian Academy of Sciences).

Notes on contributors

Alina I. Iakovleva

ALINA I. IAKOVLEVA obtained her PhD in 1999 at the Montpellier II University, France and her Dr. Sci. Habilitation in 2017 at the Geological Institute of Russian Academy of Sciences (Moscow). After Postdoc appointments at the National Autonomous University of Mexico (UNAM) and the Aarhus University (Denmark), she is currently a chief researcher at the Geological Institute in Moscow. In 2017, Alina was awarded Cavalier of the French Order of Academic Palms. Her research interests are focused on the systematics of Paleogene dinoflagellate cysts, and Paleogene biostratigraphy, palaeoecology and palaeogeography of Russia, France, Central Asia, Ukraine, the United Kingdom, and other regions.

Galina N. Aleksandrova

GALINA A. ALEKSANDROVA obtained her PhD in 2013 at the Geological Institute of Russian Academy of Sciences (Moscow). She is currently a researcher and scientific secretary at the Geological Institute in Moscow. Her research interests include the Mesozoic–Neogene palynostratigraphy (dinoflagellate cysts, pollen and spores) and palaeoecology of Russian Federation and Central Asia.

Eduard V. Mychko

EDUARD V. MYCHKO obtained his PhD in palaeontology in 2017 at the Moscow State University. He is a currently a researcher at the Atlantic Branch of the Institute of Oceanology of Russian Academy of Sciences and a senior researcher at the Museum of the World Ocean (Kaliningrad). His scientific interests are focused on the Baltic Paleogene stratigraphy and palaeontology.