Investigation of Main Planktonic Foraminiferal Bio-Events in Surgah Formation at Pol-e-Dokhtar Area, South Western of Iran

Abstract

Surgah Formation at Male-kuh well section with 82 meters thickness has been studied at Pol-e-<br><br>Dokhtar area. Surgah Formation at mentioned section was composed of limestone and shaly limestone.<br><br>The lower and upper contacts of studied formation with Sarvak and Ilam formations are<br><br>conformed. Based planktonic foraminifera study 37 species belonging to 10 genera in frame of two<br><br>planktonic foraminiferal biozones were identified respectively as below: 1) Dicarinella concavata<br><br>Interval Zone; 2) Dicarinella asymetrica Total Range Zone. Finally, based on recent investigation<br><br>have been detected middle Turonian-Late Santonian age for studied section. According to (Robaszynski<br><br>and Caron 1979), the first occurrence of Dicarinella primitiva has been shown base of the<br><br>Coniacian stage. The first occurrence of Di. primitiva was placed under the Turonian-Coniacian<br><br>boundary. Robaszynski and Caron 1995 recorded the first occurrence of Dicarinella primitiva and<br><br>Dicarinella concavata were simultaneous and assigned to late Turonian which correlated with<br><br>ammonite’s species Subprionocyclus neptuni. In the correlation between ammonite and Dicarinella<br><br>primitiva at Tethyan realm first occurrence of Di. primitiva was close to the Middle-Late Turonian<br><br>sub stage. The base of Coniacian stage was identified based on the FODs of Archaeoglobigerina<br><br>cretacea and Dicarinella concavata from planktonic foraminifera with FOD of Cremnoceramus walterdorfensis<br><br>walterdorfensis from inoceramid group, while the base of Santonian stage recorded<br><br>using LOD of Dicarinella primitiva, Whiteinellids group with FODs of Dicarinella asymetrica and<br><br>Inoceramus aff. vistulensis (inoceramid species).