calcareous nannofossil assemblages of the boundary paleocene-eocene deposits (pabdeh formation) of the zagros, dezful embayment-mansouri oilfield have been studied in detail. it consists of shale and grey marlstone with inter layers of calcareous argillites and marly claystone. we present a study focused on changes in calcareous nannofossils of the pabdeh formation during the paleocene/eocene b...