Maastrichtian-Thanetian planktonic foraminiferal biostratigraphy and remarks on the K-Pg boundary in the southern Kocaeli Peninsula (NW Turkey)

• Published in: TURKISH JOURNAL OF EARTH SCIENCES
• Main Authors: Sarigul, Volkan, Hakyemez, Aynur, Tuysuz, Okan, Can Genc, Sengul, Yılmaz, İsmail Ömer, Özcan, Ercan
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: TURKISH JOURNAL OF EARTH SCIENCES 2017
• Subjects: Planktonic foraminifera
• Online Access: https://hdl.handle.net/11511/40514; https://doi.org/10.3906/yer-1602-23

The Kocaeli Peninsula (NW Turkey) provides one of the best exposed deep marine Upper Cretaceous-Palaeocene sections in north-western Anatolia. The biostratigraphic framework from three sections, namely Belen, Bulduk, and Toylar, in the southern part of the Kocaeli Peninsula is established by means of planktonic foraminifera. A very rich planktonic foraminiferal assemblage analysed both in thin sections and washed residues records a biozonation ranging from the Contusotruncana contusa (CF6) Zone (Maastrichtian) to the Globanomalina pseudomenardii (P4) Zone (Thanetian). Although a major part of the biozones in the studied interval is clearly defined, the upper three zones (CF1-3) of the latest Maastrichtian and the P0 and P1a zones of the earliest Palaeocene cannot be recognised. These unrecorded biozones are either completely missing or occurred within a very condensed interval in the studied sections. A hardground layer characterised by oxidation and extensive bioturbation might indicate a possible biostratigraphic gap spanning the CF1-3 zones of the uppermost Maastrichtian in the Belen and Bulduk sections. In the Toylar section, on the other hand, the CF1-3 zones still cannot be detected although a hardground layer is not observed. The biostratigraphic resolution across the Cretaceous-Palaeogene (K-Pg) boundary in the studied sections cannot be improved due to the condensed and well-cemented pelagic carbonates of the boundary interval.