In this research, the Turonian-early Campanian sedimentary succession of the Abderaz Formation with 510 m thick (comprising: light grey shale and marls) was studied in the type section in eastern Kopeh-Dagh basin. The statistical analysis of the morphotype groups of the identified planktonic foraminifers shows that most of them are shallow water forms (SWF) and deep water forms (DWF). The high planktonic to benthic ratio indicates particular oligotrophic condi- tions and sedimentation in relatively deeper zones of a marine environment. The salinity of sea water during Coniacian was in the minimum level, whereas it reached maximum in Coniacian-Santonian boundary. Comparing Planktonic as- semblages from the study formation with those from the Cretaceous biogeographical provinces reflects a close rela- tionship between the identified species and the planktonic forms of the Tethyan provinces.

Keywords