Biostratigraphy of Surgah Formation based on Planktonic Foraminifera in Maleh Kuh (well no.1) and Sarkan (well no.1) oil fields in Pol-e-Dokhtar area, Lorestan Province

In order to study biostratigraphy of the Surgah Formation in Zagros sedimentary basin، two subsurface sections of this formation in Maleh Kuh and Sarkan oil fields at Pol-e-Dokhtar area، Lorestan Province، have been selected. The thickness of Surgah Formation at Maleh kuh and Sarkan، was 82 and 46 meters respectively and is composed of shale with intercalation of limestone and calcareous shale. The lower and upper boundaries of Surgah Formation at mentioned wells with Sarvak and Ilam formations are conformably. According to study of planktonic foraminifera، 37 species belong to 10 genera in Maleh Kuh well and 32 species belong to 10 genera in Sarkan well، were recognized. On the bases of these fossils، 3 biozones have been distinguished as below: 1-Dicarinella primitiva (caron1978) Interval Range Zone2- Dicarinella concavata (Sigal1995) Interval Range Zone3- Dicarinella asymetrica (Postuma1971) Total Range ZoneFinally، based on the study of planktonic foraminifera، the age of late Middle Turonian- Late Santonian has been proposed for two subsurface sections of Surgah Formation.