Biozonation and Paleoecology Surgah Formation at Ilam  Dam Section, South Ilam

Akbari, T; Bakhshandeh, L

doi:10.22071/gsj.2015.42255

Biozonation and Paleoecology Surgah Formation at Ilam Dam Section, South Ilam

Document Type : Original Research Paper

Authors

T Akbari ¹

L Bakhshandeh ²

¹ M. Sc., Department of Geology, Ferdowsi University of Mashhad, Mashhad, Iran

² Ph.D., Science and Research Branch, Islamic Azad University, Tehran, Iran

10.22071/gsj.2015.42255

Abstract

Based on stratigraphic value of calcareous nannoplanktons in determing the age of sedimentary layers, they have been used for biostratigraphic studies of Surgah Formation in sadd Ilam (Ilam damp) section ,Kabir –Kuh of Ilam. This formation is composed mainly ot dark gray shales. In Type section , the thickness of the Surgah Formation is 153.7 m. 109 samples were taken from shaly layers and for the first time their calcareous nannofossils were studied.The result of taxonomic studies lead to identification of 16 family , 44 genera and 80 species. Based of first occurrence of the index species and the assemblages zones is nannofossil Zones CC13-CC15 or Uc₈- Uc₁₂ of standard pattern. Based on biozone,the Upper Cretaceous sediments in the study area are of the Turonian through Early Santonian ages.

Keywords

Nannofossil

Surgah Formation

Type section

Late Turonian

Early Santonian