Calcareous Nannofossil Biostratigraphy of Sarmord Formation (Lower-Upper Cretaceous) in Bekhme Anticline, Kurdistan  Region – Northeastern Iraq

The calcareous nannofossil biostratigraphy has been studied in the Sarmord Formation (Lower - Upper Cretaceous) at an exposed section in the southern limb of the Bekhme anticline, Kurdistan Region, northeastern Iraq. Lithologically, the formation consists of marl, marly limestone, and limestone represented by 52 samples. These rocks contain inadequate benthic foraminiferal fauna, green algae, echinoderms, and some bioclasts. 83 species of nannofossils belonging to 37 genera were identified. The relative abundance of calcareous nannofossils throughout the section varied from moderate to good. Six distinct zones and two subzones can be identified based on the stratigraphic distribution of the calcareous nannofossils. These are from ancient to recent:

Speetonia colligate Interval Zone (Part) (CC4)

Lithraphidites bollii Interval Zone (CC5)

Micrantholithus hoschulzii Partial range Zone (CC6)

Chiastozygus litterarius Interval Zone (CC7)

Hayesites irregularis Interval Subzone (CC7a)

Rhagdiscus angustus Interval Subzone (CC7b)

Prediscosphaera columnata Interval Zone (CC8)

Eiffellthus turriseiffeli Interval Zone (CC9)

The Calcareous nannofossil zones have been correlated with other zonal schemes extending from the late Early Hauterivian to the Early Cenomanian.