Calcareous nannofossil stratigraphy of the Upper Cretaceous–lower Paleocene sequence from the Dokan section, Sulaimani, Kurdistan- Iraq

Soran O. A. Kharajiany1, Sherwood W. Wise, Jr.2 & Basim A. Al-Qayim 1

1University of Sulaimani, Kurdistan-Iraq
2Florida State University, Tallahassee, Florida, USA


The boundary of the Cretaceous/Tertiary in the Kurdistan region of Iraq is still under debate. Most previous studies consider the Danian sediments to be absent. This paper examines the
boundary in the Dokan area northwest of the Sulaimani city of Kurdistan in northern Iraq. This research analyzes calcareous nannofossil assemblages and the biostratigraphy of the
boundary. The sequence in the study section is characterized by alternations of olive green to greenish gray sandstone, siltstone, shale and marlstone of the Tanjero Formation of the late
Campanian- Maastrichtian and the overlying Kolosh Formation of the early Paleocene. The upper part of the section includes thick sandstone beds and a reworked bioclastic
conglomerate bed in addition to a dark- grey, silty calcareous shale. The study shows that deposition across the boundary is continuous. The boundary is biostratigraphically delineated
by the last occurrence of Maastrichtian taxon and the first occurrences of Biantholithus sparsus, Cruciplacolithus spp. and Coccolithus pelagicus of biozone NP1, which indicate no
hiatus. This succession highlights the occurrence of the early Danian sequence at the bottom of the Kolosh Formation.

Key Words: Dokan, K/T boundary, early Danian, NP1, Biantholithus sparsus, Tanjero, Kolosh, Sulaimani, Kurdistan/Iraq.


[1]Abdel-Kareem, M. R. "Planktonic foraminifera and stratigraphy of the Tanjero Formation (Maastrichtian), Northeastern Iraq", Journal of Micropaleontology, Vol. 32, No. 3, pp.215-231. (1986).

[2]Al-Qayim, B. A. "Evolution of flysch basin along the northeastern margin of the Arabian plate", 3rd conference on the geology of the Middle East (Geocome III), pp.347-373. (1994).

[3]Al-Qayim, A. B., Omar, A., and Koyi, H. "Tectonostratigraphy overview of the Zagros Suture Zone, Kurdistan Region, Northeast Iraq", Geoarabia/ Gulf Petrolink, Bahrain, Vol.17, No.4, pp.109-156. (2012).

[4]Al-Shaibani, S., Al-Qayim, B. A., and Salman, L. "Stratigraphic analysis of the Tertiary- Cretaceous contact, Dokan area, North Iraq", Journal of the Geological Society of Iraq, Vol.19, No.2. (1986).

[5]Bellen, R.C., Van Dunnington, H.V., Wetzel, R. and Morton, D. "Lexique Stratigraphique", Int.Asie, Iraq 3c, 10a, 333p, (1959).

[6]Bown, P. "Calcareous Nannofossil Biostratigraphy", (first edition), Chapman and Hill (Cambridge University Press), 314p, (1998).

[7]Buday, T. "Regional Geology of Iraq": Vol. 1, Stratigraphy, I.I.M Kassab and S.Z. Jassim (Eds.), D. G. Geological Surveys and Mining Investigation Publications, 445p, (1980).

[8]Jassim, S. Z., and Goff, J. C. "Geology of Iraq", Dolin, Prague and Moravian Museum, Brno, 341p, (2006).

[9]Karim, K. H. "Basin analysis of Tanjero Formation in Sulaimaniya area, NE-Iraq", Unpublished Ph.D. thesis, University of Sulaimani, 135p, (2004).

[10]Karim, K. H., and Surdashy, A. M. "Paleocurrent analysis of Upper Cretaceous foreland basin: a case study for Tanjero Formation in Sulaimanyia area, NE-Iraq", Journal of Iraqi Science, Vol. 5, No.1, pp.30-44. (2005).

[11]Karim, K. H. "Environment of Tanjero Formation as inferred from Sedimentary structures, Sulaimanya area, NE-Iraq", Journal of Academy Kurdistan, Vol. 4, No.1, pp.1-18. (2006).

[12]Sharbazheri, K. M. I. "Biostratigraphy and paleoecology of Cretaceous/Tertiary boundary in the Sulaimani region, Kurdistan, NE-Iraq", Unpublished Ph.D. thesis, University of Sulaimani, 121p, (2007).

[13]Sharbazheri, K. M., Ghafor, I. M. and Muhammed, Q. A. "Biostratigraphy of the Cretaceous/Tertiary boundary in the Sirwan Valley (Sulaimani Region, Kurdistan, NE Iraq)", Iraqi Bulletin of Geology and Mining Vol.7, No.3, pp.1-24. (2011).

[14] Starkie, S. P. "Calcareous Nannofossil Biostratigraphy and Depositional History of the Late Cretaceous to Early Miocene Sequence of Iraq", Unpublished PhD thesis, Department of geological science/ Postgraduate unit of Micropaleontology, University College of London/ London/UK, 325p, (1994).
[15]"The International Nannoplankton Association (INA) website", http://ina.tmsoc.org/, and/or http://ina.tmsoc.org/Nannotax3/ntax-chartS.html.ersity, (2013