1. Department of Science, Payame Noor University, Tehran, Iran;
2. Department of Geology, Islamic Azad University, Science and Research Branch, Tehran, Iran

The Asmari Formation consists of shallow marine sedimentary rocks deposited on ramp setting. Larger benthic foraminifera collected from Asmri Formation are dominated by hyaline and porcelanouse forms, including Amphistegina, Nummulites, Archaias, Astrotrillina, Miogypsinella, Miogypsinoides, Lepidocyclina, Operculina, Spiroclypeous and Miliolids. The presence of Nummulites cf. vascus in the lower part of the formation allows the age to be determined as Rupelian. The occurrence of Borelis pygmae is an index taxon of the Rupelian-Chattian and indicates Early Chattian of SBZ 21-22 in the study section. The first appearance of Miogypsinella akadagensis shows Late Chattian (SBZ 23) and defines the upper boundary of the SBZ 21-22. The new data are the first evidences showing that the shallow marine Asmari Formation is attributed to Oligocene (Rupelian-Chattian) age for this region.