The study area is located in Tang-e Bagh at Kuh-e Genu, approximately 69 km, northern Persian Gulf. The age relationships of Sarvak, Gurpi, and Pabdeh formations were unclear in the study area because of the low-resolution biostratigraphy. Therefore, 152 samples were collected. All samples contain well-preserved foraminifers that permit clarification of the age of these formations. Nine benthic species (5 genera) and sixty-eight planktonic foraminiferal species (29 genera) were identified that were arranged eleven biozones with high resolution of biostratigraphy. Biozone Ⅰ corresponds to the total range of Orbitolina qatarica in the Mauddud Member of Sarvak Formation, suggesting the Cenomanian (middle Cenomanian) age. The biozone Ⅱ is characterized by the total range of Dicarinella asymetrica in the basal part of Gurpi Formation, indicating the Santonian age. Therefore, there is a hiatus between the Sarvak and Gurpi formations that includes part of the Mauddud Member, the whole Ahmadi Member, and the Ilam Formation. This hiatus encompasses the late Cenomanian to Coniacian that is marked by a few meters of Fe-stained deposits in the Kuh-e Genu; the interval range zones Ⅲ to Ⅶ as well as Abathomphalus mayaroensis zone Ⅷ (TRZ) are present within the rest of Gurpi Formation and suggests the Campanian to Maastrichtian. The biozones IX-XI are present within the Pabdeh Formation that corresponds to a Not Zone and two interval range zones (P1b, P1c-P2), suggesting Danian. Based on microfacies, texture, and paleontological analysis, a deep-water environment suggests for Gurpi and Pabdeh formations and shallow marine conditions for Sarvak Formation.