Iraqi National Journal of Earth Science

Twenty Samples of Shiranish Formation from the well (K-306), Kirkuk area, northern Iraq, are collected and studied on the basis of stratigraphic ranges of the recorded calcareous nannofossils. Eighty-nine species in the studied section reveals five biozones arranged from oldest to youngest as follows:
1.Quadrum trifidum Interval Biozone (CC22) Part
2.Tranolithus phacelosus Interval Biozone (CC23)
3.Rienhardtites lives Interval Biozone (CC24)
4. Arkhangelskilla cymbiformis Interval Biozone (CC25)
5. Nephrolithus frequens Rang Biozone (CC26) Part
These Biozones are correlated with other calcareous nannofossils biozones, from both local and regional sections, leading to conclude the age of Campanian- Maastrichtian.

Structural study was carried on the eastern part of Bekhair anticline
(Duhok section ) to test the folding phases within the formations related to Cretaceous and Tertiary period .This study adopted the structural contour maps in fold geometrical and structural analysis by construction of the Cretaceous and Tertiary formation contacts. The fold axes for the different structural contours were drawn .
The study found that there was an anticlockwise rotation of seven degree in the fold axis direction .This result supported ( or agreed ) with the results obtained from fold geometric analysis by stereographic projection ,which indicates that the studied fold were underwent more than one phase of folding .

The microfacies analysis of the Shiranish Formation (Early-Late Maastrichtian) at the Bekhair anticline, Dohuk area, northern Iraq revealed that the succession is composed of alternation of seven microfacies, which are wholly micritic groundmass and rich in Planktonic Foraminifera. Based on the mode of vertical and lateral distribution, the present study deduced that this succession was deposited at Dohuk area by two environmental zones: upper-middle bathyal and outer shelf within one of the half-graben basin, which formed by Lisstric rifts. The latter was formed by the what so-called "piggy-back" basins at Foreland of the Arabian shelf. It is thought that the lithological and thickness variations at the bases of half-graben basin topography are due to tectonic irregularity

On the basis of the biocontents, lithological features and analysis of the microfacies, an attempt is made to establish the nature of paleoecology and depositional environments of some Upper Cretaceous formations from northwest and middle Iraq ,of which the successions are represented by the formations from the oldest to the youngest are Khasib, Tanuma, Sa'di, Mushorah, Hartha and Shiranish.A wide spectrum of environmental types distributed between deep and shallow marine environments. The implication of paleoecological interpretations for different Ostrscode species and other fossils recorded in the studied sections highlights the strong correlation between the environmental parameters in particular the depths and the lifestyle of these organisms including specific morphologies and faunal abundance.In addition to that from palaeocological point view the identified biocontents represent a southern shelf tythes fauna.

ABSTRACT Four new ostracod species belonging to the genus Cytherella Jones, 1849 described from the Upper Cretaceous succession of Hamrin area NE Iraq namely: Cytherella shiranishensis sp. nov; ; C. iraqiensis sp. nov.: C. mushoriensis sp. nov.; and C. kirkukiensis sp. nov. Keywords: Ostracoda; Cytherella; Cretaceous; Iraq.

Previously, the basin of Tanjero Formation (Campanian-Maastrichtian) has been given the setting of trench or miogeosyncline in which turbidite sedimentation had occurred. In the present study, conversely, many sedimentary structures are found that shows shallow environment of the lower and upper part of Tanjero Formation.These sedimentary structures revealed that during deposition of these parts the sea level is so lowered that the sediments are affected repeatedly by storms surges. These storms reworked sediments to form storm deposits (Tempestite) or to be transported to deeper water and deposited as turbidite. The recoded sedimentary structures are such as hummocky- cross stratification, interference and longitudinal ripple marks, plant debris
and grass body fossils in addition to clean sandstone (Arenite).

Tanjero Formation is an Upper Cretaceous (Campanian-Maastrichtian) unit, which crops out within the Imbricated and High Folded Zones in Northeastern Iraq. Its outcrop stretches as narrow northwest-southeast belt near and parallel to the Iranian border. The formation mainly consists of alternation of clastic rocks of sandstone, marl and calcareous shale with occurrence of very thick conglomerate and biogenic limestones.
In this study many sedimentary structures are found in the Tanjero Formation, which have paleocurrent importance. These structures are cross bedding interference ripple marks, imbricated pebbles, elongate rudist and belemnite, plant debris, sole marks, valleys and channels. Most of these structures are found in the lower part. The paleocurrent analyses, as revealed by these structures, are presented in rose and stereonet diagrams, which show south and southwest directions.
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