Biostratigraphy of the Asmari Formation in northwest of Shiraz (Tang-e Jalab) on the basis of the large benthic foraminifera

The carbonate Asmari Formation is known as the most important oil reservoir rock in the Zagros Basin of Iran, which contains sedimentary rocks from the Oligocene to the Lower Miocene. A stratigraphic section of Asmari Formation was taken in the Tang-e Jalab, northwest of Shiraz in order to study the biostratigraphy. A total of 214 meters of sediments of this formation were studied which contains 8 lithostratigraphic rock unit. Index foraminifera were accurately identified by studying 80 microscopic thin sections. In the present study, a total of 46 genera and 32 species of foraminifera were identified and based on them, the biomarkers of the Asmari Formation were identified. In addition, two assemblage zones are identified as follows: Nummulites vascus, Nummulites fichteli, Nummulites intermedius Assemblage ZoneArchias asmaricus, Archias hensoni, Miogypsinoides complanatus Assemblage ZoneThe age of the Asmari Formation in the studied area is determined as Oligocene (Rupelian to Chatian).