MICROBIOSTRATIGRAPHY, MICROFACIES AND SEDIMENTARY ENVIRONMENT STUDIES OF TARBOUR FORMATION (SOUTHWEST OF IRAN)

During Campanian – Maestrichtian an association of Rudist-rich sediments was found along the south east of neothetys margins, this rock unit is called Tarbour Formation in the Zagros Mountains in Iran.

Tarbour is a Formation that developed extensively in Zagros Mountains. On the other hand, equal formations of Tarbour in other countries such as Iraq are famous oil resources. According to these reasons and following the previous studies and completion of previous studies, we needed some more comprehensive and newer studies in other areas in Zagros Mountains.

In order to study of Micropaleontology , Stratigraphy and Sedimentary of the upper cretaceous deposits in the Zagros Mountains, Kherameh section, located on south east of Shiraz (south west of Iran) was selected. More than 100 samples collected and studied by thin sections. Tarbur Formation deposits in this area with the 228 meters thickness is lied on the Gurpi Formation( a marl limestone and marl) and Sachun Formation is in the upper of Tarbour Formation . It is dominantly formed from carbonate rocks ,thick bedded to massive limestone.

The Micropaleontological study of above deposits led to recognition some genera and species of benthic foraminifera, such as Orbitoides concavatus, Lepidorbitoides minor, Orbitoides media, Minouxia lobata, Omphalocyclus macroporous, Nezzazatinella sp., Rotalia skourensis and etc.

According to foraminifers’ assemblage, the age of studied section was Maestrichtian. This section is comparable with omphalocyclus – loftusia assemblage zone of wynd(1965) that is used in Zagros Mountains by Iranian oil companies.

Based on field and sedimentology study, seven carbonate facies related to “Lagoon “, ” Bar ” and “Open marine” environment have been identified in Tarbour Formation.