Late Eocene to Early Oligocene palynostratigraphy of the Western Black Sea, Eastern Paratethys

Authors: RECEP HAYRETTİN SANCAY, ZÜHTÜ BATI

Abstract: The Eastern Thrace and Western Black Sea basins provide unique perspectives on the palaeogeographic reconstructions of the Paratethys. Although very thick and extensive Oligocene outcrops and well sections exist in the Thrace Basin, only a few comparable sections are available in the Black Sea onshore areas. In this study, five measured stratigraphic sections of Eocene to Oligocene age from the margins of the Western Black Sea were studied and palynomorph assemblages were identified quantitatively. Index dinoflagellate cyst events and a palynological biozonation as established in the Mediterranean were applied successfully. Priabonian units contain the Aal biozone, whereas Rupelian successions were represented by the Adi, Rac, Cin, and Hpu zones. Palynological analyses suggest that the youngest interval of the studied sections, the highest sample of Karaburun (2) and the upper part of Servez Beach, sit just above the Wetzeliella gochtii interval and are early-middle Rupelian in age (Cin and Hpu zones). The Karaburun (1) and the lower part of the Servez Beach sections represent W. gochtii-bearing intervals and are interpreted as early Rupelian in age (Rac, Cin, and Hpu zones). The Servez Road Dam section occurs below the W. gochtii interval. It is characterized by common occurrences of Glaphyrocysta semitecta and interpreted as earliest Rupelian in age (Adi and Rac zones). Finally, the Sazlıbosna section lies below the Glaphyrocysta semitecta zone and represents the oldest stratigraphic unit of the studied intervals. It yielded Eocene dinoflagellates such as Areoligera taulomasentosa, Areosphaeridium michoudii, Rhombodinium perforatum, Homotryblium pallidum, and Stoveracysta ornata and is interpreted as late Priabonian in age (Aal zone). Both palynomorph assemblages and organic matter constituents reflect shallow to open marine and nutrient-rich depositional conditions that occurred during Late Eocene?Early Oligocene time. The dominance of marine palynomorphs, without any indication of fresh water influx, might suggest that deposition took place before the isolation of the Paratethys, when the Western Black Sea region was still part of the Western Tethys during the earliest Oligocene (NP21-23).

Keywords: Black Sea, Paratethys, Eocene, Oligocene, palynology

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