Biostratigraphy of the Ilam Formation in Shah Nakhjir anticline section (South West of Ilam) based on planktonic foraminifera and correlation with Type section

In order to study the fossil contents of the Ilam Formation for biostratigraphical purposes in this study, a 172 meters thick section was measured and sampled at Shah Nakhjir Anticline. This sequence is mainly composed of marly limestone with interbed of shally marls. The lower contact of the formation with Surgah Formation and upper contact with Gurpi Formation are conformable. Thirty eight species belong to 16 genera were identified and 3 biozones were determined. These are: 1- Dicarinella asymetrica Total Range Zone. 2- Globotruncanita elevata Partial Range Zone. 3- Globotruncana ventricosa Interval Zone. Based on these assemblages, the age of this formation is Late Santonian – Middle Campanian. Biozones identified in this section compared with type section in Tang-e- Garab shows that the biozones and ages are similar in these two sections, and there are only differences in thickness of biozones.