Biostratigraphy and Lithostratigraphy of Pabdeh Formation is based on planktonic foraminifera in the section of Jahangirabad (south Ilam_ Zagros basin)

After the Late Cretaceous and during the Paleogene, with the sea level rising, the Zagros sedimentary basin is covered with a progressive sea in which the Pabdeh Formation is deposited. The dual function of this formation as a source of oil and its reservoir capacity due to the diversity of lithology and its location between the two reservoirs Asmari and Bangistan, and the age of this formation is one of the issues that has attracted the attention of geologists. In order to study the stratigraphic and biostratigraphic rock of the Pabdeh Formation, the Jahangirabad section in the northwest of Zagros sedimentary basin has been selected and sampled. 320 samples were taken, of which 230 samples were prepared by washing method, and 90 samples were prepared by thin section method and examined. Based on studies conducted in the Jahangirabad section, 25 genera and 110 species have been identified, and based on the identified fossils, 27 biozones and 7 sub-biozones have been identified. Based on the identified biozones, the age of the Pabdeh Formation in the Jahangirabad Danian Early-Late Chattian section has been obtained. Pabdeh Formation deposits in the Jahangirabad section have a thickness of 676 m (beginning of purple shale to anhydrite Kalhor) which includes units of purple shale (2 parts), marl limestone with lower limestone, limestone, and marl limestone with limestone It is high. In this section, the lower boundary of the Pabdeh Formation is continuous with shales and marls of Gurpi Formation, and its upper boundary is with continuous limestone of Asmari Formation.