The middle Cretaceous Kazhdumi Formation, with a thickness of 222 m, belongs to the Bangestan Group and occurs in the Zagros folded zone in southwest Iran. The lower boundary with the Dariyan Formation is disconformable, which is recognized by iron oxides and glauconite. The recognized microfossils are Valvulammina sp., Scandonea sp., Daxia cenomana, Choffatela sp., Pseudolituonella reicheli and calcareous algae-Lithocodium aggregatum (which belongs to the Sarvak Formation), representing the beginning of Cenomanian. Other microfossils are: Ammobaculites goodlandensis, Marsonella trochus, Hemicyclammina sigali, Praechrysalidina infracretacea, Orbitolina gr. concava, Orbitolina (conicorbitolina) conica, Orbitolina subconcava, Salpingoporella sp., Trinocladus tripolitanus, Trinocladus sp., Permocalculus irenae and Dissocladella deserta. These microfossils can be classified into five assemblage zones.