Depositional Setting of Eastern Sakarya Zone (NE Türkiye): Late Cretaceous–Paleogene Period Biostratigraphy, Sedimentology and Tectono-Sedimentary Basin Evolution

This study reconstructs the late Campanian–Thanetian tectonic and sedimentary evolution of the Eastern Sakarya Zone Basin (Türkiye) during the closure of the Neotethys Ocean, through the integration of tectonic, biostratigraphic and sedimentary data from three distinct tectonic regions: a northern back-arc basin, a central magmatic arc and a southern fore-arc basin. Analysis reveals a northwest-southeast trending basin with pronounced lateral variations: sediment thickness increases west-to-east, while facies transition from pelagic (north) to neritic (south) carbonate. The succession records a shift from late Campanian–Danian pelagic back-arc carbonates, through a Maastrichtian–early Danian hiatus, to late Maastrichtian–Danian hemipelagic-neritic carbonates, culminating in a Selandian–Thanetian neritic platform. The study proposes the first integrated facies model for the Eastern Sakarya Zone, linking its stratigraphic architecture to regional geodynamics. This establishes a new tectonically controlled carbonate sedimentation model for the Eastern Sakarya Zone Basin, critical for understanding basin evolution from pelagic to neritic carbonate systems in a closing ocean setting.