Paleoecology and biostratigraphic data of the large benthic foraminifera in the Oligocene-Miocene Qom Formation in Kahak area, in the Urumieh-Dokhtar province in Iran

The Oligocene-Miocene Qom Formation was deposited in different thickness in the Central Iran, Urumiehh–Dokhtar magmatic arc and Sanandaj–Sirjan provinces in Iran. The Oligocene-Miocene Kahak section of the Qom Formation in the Urumiehh–Dokhtar magmatic arc has been studied, in order to biostratigraphic data of the large benthic foraminifera.
In the Kahak section, the foraminifera assemblages of the Qom Formation consist of Nummulites fichteli, Nummulites vascus, Eulepidina dilitata, Nephrolepidina sp., Neprolepidina tournoueri, Eulepidina sp., Pseudolituonella reicheli, Miogypsina sp., Miogypsina irregularis, Amphistegina sp., Operculina sp., Bozorginella qumiensis, Triloculina trigonula, Triloculina tricarinata, Peneroplis sp., Peneroplis thomasi, Dendritina ranji, Triloculina trigonula, Rotalia sp., Pyrgo sp., Elphidium sp., Borelis melo and Borelis curdica.
In the Kahak section of the Qom Formation, four assemblage biozones of the large benthic foraminifera have been recognized from Rupelian, Chattian, Aquitanian and Burdigalian stages. These biozones are similar to assemblage biozones of the Oligocene-Miocene Asmari Formation in the Zagros Basin in southwest of Iran. Distribution type of the Oligocene-Miocene foraminifera in the Kahak depositions of the Qom Formation indicates to depositional settings of the lagoon, open lagoon and shallow open marine paleoenvironments. There is some similarity of foraminifera assemblage in Qom Formation sediments with other locality of Tethys including Mediterranean and Indo-West Pacific.