Stratigraphy of the Shahbazan Formation in Lorestan basin

The Shahbazan Formation deposited in the Lorestan foreland basin and northeastern part of Dezful embayment zone during the Middle-Late Eocene age. In order to study the stratigraphy of the Shahbazan Formation, four surface sections of this formation in northeastern flank of Langar anticline, southeastern flank of Chenareh anticline, northeastern flank of Maleh Kuh anticline and southwestern flank of Poshte-Jangal anticline, have been selected. The Shahbazan Formation in Langar and Chenareh sections is composed of limestone with intercalation of dolomite. In other parts of the Lorestan such as Maleh kuh and Poshte Jangel, it consists of dolomite and intercalations of limestons. In these areas, the Shahbazan and Asmari formations form a prominent topographic unit and separating their boundary is often difficult to place, thus making it necessary to map the two formations as one unit. In this case, the two names are hyphenated as Shahbazan- Asmari Formation. According to study of benthic foraminifera in Chenareh and Langar sections, two biozone have been distinguished. The age of the Shahbazan Formation in these areas is determined as Middle- Late Eocene (Bartonian- Priabonian). In the Maleh Kuh section, the lower part of the Shahbazan- Asmari Formations is dolomitic but in the upper part it contains limestone beds with foraminifera that belong to two assemblage zones, in Aquitanian- Burdigalian age. In the Poshte Jangal section, the lower and middle parts of Shahbazan- Asmari formations are dolomitic but the upper part contains limestone beds with rare foraminifera which have been reported at the Chattian- Burdigalian beds of the Asmari Formation.