OICC Press Iranian Journal of Earth Sciences 2228-785X 8 1 2022 12 22 Lithostratigraphy ,biostratigraphy of Paleocene-lower Eocene squences in Dezful embeyment, South West Iran 135 146 EN Fatemeh Moradian Department of Geology, Science and Research Branch,Islamic Azad University,Tehran ,Iran Darioush Baghbani Islamic Azad university ,Damavand branch Journal Article 2022 12 22 Paleocene and  Lower Eocene deposits in SW Iran are known as Pabdeh formation.Pabdeh formation is one of the most important lithostratigraphy unit as source rock has been deposited in Zagros basin over an extremely long period in time. The area under research is the Ghachsaran 55 subsurface Section located  from the Ghachsaran oil field in Dezful embeyment in zagros fold zone. The Lower boundry of this formation around Ghachsaran basin is identified by Gurpi formation. Study on lithostratigraphy of  Paleocene and  lower Eocene deposits have been led to the separation following  units: clay limestone section in gray colour,11m in thickness, clay limestone section 18m in thickness containing chert inter layers, silt clay limestone section 3m in thickness, The clay limestone section 3m in thickness containing chert interlayers, clay limestone section 4m in thickness . biostratigraphy investigation of Pabdeh formation have been led to the identification of 39 species and 9 genera of foraminifers.In addition , basis of Paleocene- Early Eocene planktonicforamimnifers  bioevent in Wade biozonation  such as Morozovella  velascoensis, Globanomalina pseudomenardii, Psudohastigerina wilcoxensis, Acarinina soldadoensis , Morozovella subbotinae , Morozovella  formosa , 9 biozones and 4 subzones are recogenized and these correlated with oldest biozones of (Wynd 1965) Beside,the bio-boundary of Paleocene and early Eocene is identified based on (Wade et al. 2011).