Petrography and diagenetic history of the Kometan Formation (Upper Cretaceous) in the Imbricated Zone, Iraqi Kurdistan Region


Author : Irfan Sh. Asaad, Sardar M. BalakyPublication : Bulletin of the Geological Society of MalaysiaNumber : 70Page : 195-208Year : Nov 2020DOI : doi.org/10.7186/bgsm70202015


Description

Bulletin of the Geological Society of Malaysia, Volume 70, November 2020, pp. 195 - 208
 

Petrography and diagenetic history of the Kometan Formation (Upper Cretaceous) in the Imbricated Zone, Iraqi Kurdistan Region

Irfan Sh. Asaad1,*, Sardar M. Balaky2

1Department of Geology, College of Science, Salahaddin University-Erbil, Iraqi Kurdistan Region
2Department of Petroleum Geosciences, Faculty of Science, Soran University, Iraqi Kurdistan Region
*Corresponding author email address: irfan.asaad@su.edu.krd

Abstract: The petrography and diagenetic history of Upper Cretaceous Kometan Formation is investigated from its type locality in Kometan Village, Imbricated Zone, Kurdistan Region, Northeastern Iraq. The formation comprised 44 m of white weathered, light grey, thin to medium bedded fractured limestones with chert nodules and lenses in the upper part. The petrographic study of the formation is based on 50 thin sections and showed that the majority of limestones microfacies are carbonate mud (micrite). The skeletal grains include planktonic foraminifera, oligostegina, calcisphers, ostracods, pelecypods, larvae ammonoids and echinoderms. Non-skeletal grains include peloids only. The Kometan Formation has been subjected to several diagenetic processes such as: micritization, dolomitization, cementation, neomorphism, compaction, silicification, solution, phosphatization, glauconitization and fracturing. All these occurred during marine phreatic shallow burial stage and activated during intermediate to deep burial and uplifting in the late stages. The paragenetic history of the Kometan Formation has passed through four diagenetic environments including; marine, meteoric, burial and uplifting.
 

Keywords: Petrography, diagenetic stages, Kometan Formation, Kurdistan, Northern Iraq

DOI: https://doi.org/10.7186/bgsm70202015