Biostratigraphy of the Gurpi Formation based on Calcareous nannofossil in the Kouh-e sefid anticline section, Izeh structural zone

The Gurpi Formation with a thickness of 190 m at the Kouh-e sefid anticline is investigated with regard to the calcareous nannofossils. In this section, Gurpi Formation is mainly consists of shale, marls and argillaceous limestones. As a result of this study, 21 genera and 41 species of calcareous nannofossil have been recognized. Based on distribution of index species calcareous nannofossils bio zones of have been recognized, including CC16-CC25 biozones, that corresponding to UC12-UC20aTP. According to the identified biozones, the age of the Gurpi Formation in this section is middle/late Santonian to early late Maastrichtian. The study in the Kouh-e sefid anticline, show that the sedimentation of Gurpi Formation has been started at the middle/late Santonian and to continue to the early late Maastrichtian.