Foraminiferal Biostratigraphy of the Uppermost Cretaceous Period, Duhok Area, Kurdistan Region, North of Iraq

Abdulrahman Bamerni

doi:10.46717/igj.54.2c.5ms-2021-09-24

Abstract

A relatively complete Late Maastrichtian succession of the upper part of the Shiranish Formation (Upper Cretaceous) in the Duhok area is investigated for the planktic foraminiferal assemblages. This studied interval consists mainly of bluish shale, marl, and thin beds of hard marly limestone all with grey-blue color. The upper contact of the Shiranish Formation is conformable with the overlies Danian Aaliji Formation. Based on the recorded planktic foraminifera and their ranges, the studied succession is subdivided into three main biozones of the latest Maastrichtian age, these zones are Pseudoguembelina hariaensis (CF3) Interval Zone, Pseudoguembelina palpebra (CF2) Interval Zone, and Plummerita hantkeninoides (CF1) Total Range Zone. These zones show continuous and complete Upper Cretaceous sediments, which are preserved in the Bade section of the Duhok area

Highlights

The explosion of the calcareous nanoplankton and foraminifera in the warm seas of the Cretaceous is widely reported, for the Tethys realm no precise zonation schemes of the marine fauna are available (Gradstein et al, 2020)
Henson (1940) in Bellen et al (1959) investigated the uppermost rock unit of the Cretaceous in Duhok and Zakho areas and assigned it as the Shiranish Formation of Maastrichtian age at top, and stated that the upper part of the Shiranish Formation in the type section is of a continuous sequence of blue marls and without any apparent angular unconformity, but thought that topmost beds of the original Shiranish Formation were removed by erosion and the formation at its top is of Upper Maastrichtian but not uppermost Maastrichtian age
The investigated uppermost Maastrichtian sediments of Bade section is 23.30 m in thickness, 2021, 54 (2C), 48-58 belong to the upper part of the Shiranish Formation (Henson, 1940 in Bellen et al, 1959)

Summary

Introduction

The explosion of the calcareous nanoplankton and foraminifera in the warm seas of the Cretaceous is widely reported, for the Tethys realm no precise zonation schemes of the marine fauna are available (Gradstein et al, 2020). According to Renne et al (2013) in Gradstein et al (2020) the base of the uppermost Cretaceous (Maastrichtian) started 72.17 Ma ago and the top of the Maastrichtian Stage is anchored to the well calibrated K/Pg boundary, placed at 66.04 Ma ago with a duration of 6.13 million years. The uppermost Cretaceous (Maastrichtian) deposits are represented by the upper part of the Shiranish Formation in the current study. AlOmari (1966, 1970) studied the foraminiferal fauna from the upper part of the Shiranish Formation in northwestern Iraq and proved to be of Maastrichtian age.

Methods

Results

Conclusion