Palynofacies and paleoenvironment of the Early Cretaceous deposits in the KoppehDagh Basin, Iran

We used the palynomorphs from the Early Cretaceous deposits in the Koppeh-Dagh Basin in the Neo-Tethyan province of northeastern Iran to investigate the site’s paleoenvironmental conditions and depositional settings. The AOM–Phytoclast–Palynomorph (APP) ternary diagram highlighted three distinct palynofacies: Type I, II, and IVa. We can accordingly conclude that the depositional environments of the basin included a highly proximal shelf, a marginal basin, and a shelf-to-basin transition. Palynofacies analysis of the Sarcheshmeh and Sanganeh formations of the Koppeh-Dagh Basin revealed that the two formations were deposited in a shallow marine setting characterized by conspicuous input of plant material from nearby land. By comparing these results with those from adjacent sections, two paleoenvironmental trends are present in the Koppeh-Dagh Basin: the eastern side was more turbulent, and the western side was quieter. A previous calcareous nannofossil analysis from the section has been used to date the studied interval of the Sarcheshmeh and Sanganeh Formations, indicating a Late Barremian to Late Albian age.