Biostratigraphy and Paleoecology of the Sinjar Formation (Late Paleocene- Early Eocene) in the Dokan and Sinjar Areas, Iraq


  • Noor T. Al-Taee Geology Department, College of Science, Mosul University, Iraq
  • Imad M. Ghafor Geology Department, Sulaimaniyah University, Iraq
  • Ali I. Al-Juboury Petroleum Engineering Department, College of Engineering, Al-Kitab University, Kirkuk, Iraq
  • David L. Dettman Environmental Isotope Laboratory, Dept. of Geosciences, Univ. of Arizona, Tucson, AZ 85721, USA



Benthic foraminifera, Biostratigraphy, Paleoecology, Sinjar Formation, Paleocene-Eocene, Iraq


Biostratigraphy of the Sinjar Formation is investigated in two sections (Dokan and Sinjar)
from northeastern and northwestern Iraq, respectively. Two hundred samples from all the
limestones and marl that form the main lithological components of the studied sections were
collected. The studied limestones and marl are rich in microfossils. Through thin sections, we
were able to identify thirty species of benthic foraminifera and fifteen species of other
microfossils (coral, algae, mollusca, bryozoa, and echinoids) at Dokan section, and fifty-one
species of benthic foraminifera and thirty species of other microfossils at Sinjar section. 3
biozones were distinguished from both sections 1-Biozone A: Kathina sp.- Lockhartia hunti
Assemblage zone (SBZ 5) (Dokan section); (Kathina pemavuti - Lockhartia hunti Assemblage
zone (Sinjar section), 2- Biozone B: Idalina sinjarica Total Range zone (SBZ 6-7) and 3-
Biozone C: Alveolina globosa- Alveolina pasitisilata Concurrent Range Zone (SBZ8-10).
These zones indicate the Late Paleocene –Early Eocene age of the Sinjar formation. The
biostratigraphic correlations in the studied sections are based on benthic foraminiferal
zonations. Showed the correlation comparison between the biostratigraphic zones of the
commonly used benthic zonal scheme around the Late Paleocene -Early Eocene in and outside
of Iraq. paleoecological studies suggest that the carbonate sedimentation of the Sinjar
Formation thrived in 18-25oC, with mesophotic to oligophobic light, under an oligotrophic to
mesotrophic middle ramp environment with normal marine to slightly saline and at water
depths from 40 - 80 m. Stable isotopic carbon (δ13C) and oxygen (δ18O) data revealed generally
hot conditions with high productivity during the deposition of the Sinjar Formation
accompanied by an abrupt change in paleoenvironmental conditions across the Paleocene-
Eocene contact.