عنوان مقاله [English]
Nannofossils and foraminifera planktonic have been short range stratigraphy and spread vast geographical because of that two fossils groups can be used for subdividing biostratigraphy. According to this, and due to the lack of any correlational paleontological study, the nannofossils of Gurpi Formation have been investigated in north of Gachsaran. This formation has been formed of marl. As a result of this study and based on the obtained nannofossils and foraminifera planktonic, the studied section is Late Santonian to Late Maastrichtian in age, that corresponding to CC16-CC26 Zones (Sissingh, 1977) and Dicarinella asymetrica- Globotruncanita elevata Zone toAbathomphalus mayaroensis Zone (James & wind, 1985).