The Yamama Formation was studied in three wells (Fh-1, Fh-2, and Fh-3) within Faihaa oil field, south Iraq. Thin sections were studied by using the polarizing microscope examination in order to determine microfossils and biozone. Thirty-five species of benthic foraminifera were recognized, including four index species. In addition,  twelve species of calcareous green algae were recognized, including  two index species. Other fossils that were recognized in Yamama Formation include Gastropoda, Bryozoa, Coral, Rudist, and Pelecypoda.

Six biozones were observed, which are Charentia cuvillieri sp. (Range Zone of Berriasian age), Psudochryalidina infracretacea

The Dammam Formation in S and SW of Iraq is an Eocene carbonate succession consisting of limestone and dolostone. Two boreholes are selected in Al-Najaf and Al-Samawa area to investigate the biostratigraphy. The biostratigraphy of Dammam Formation consist of 22 species which belong to 13 genera of fossils foraminifera.
Two biozones were distinguished in Dammam Formation depending on benthonic foraminifera Nummulites. These biozones are; Nummulites gizehensis range zone and Alveolina sp. – Coskinolina sp. assemblage zone. According to thESE biozones the age of Dammam Formation represent Middle Eocene , whereas absent of these biozone represent Early and Late Eocene.

A detailed systematic study of calcareous nannofossils was carried out for the Jaddala Formation in (Aj-10) well, Central Iraq. Seventy one species belong to twenty four genera of calcareous nannofossils were identified including sixty two of them were previously named and nine species were identified for the first time and they would not be given names until more information is obtained in the future to support this identification.
It is a recorded of five biostratigraphic zone, which suggested the age of the Jaddala Formation to be of early to late Eocene. The recorded biozone includes the following: Reticulofenestra dictyoda (Deflandre in Deflandre & Fert, 1954) Stradner & Edwards, 1968 Partial Range Biozone (CNE 5); Discoa

The Mauddud Formation was one of the important and widespread Lower Cretaceous period formations in Iraq. It has been studied in three wells (EB. 55, EB. 58, and EB. 59) within the East Baghdad Oil Field, Baghdad, central Iraq. 280 thin sections were studied by microscope to determine fauna, the formation composed of limestone and dolomitized limestone in some parts which tends to be marl in some parts, forty species and genus of benthic foraminifera have been identified beside algae and other fossils, three biozones have been identified in the range which is: Orbitolina qatarica range zone (Late Albian), Orbitolina sefini range zone (Late Albian – Early Cenomanian) and Orbitolina concava range zone (Early Cenomanian), The age of

     Geochemical proxies provide detailed information on depositional environment and diagenetic processes. The main objectives of the present study are the evaluation of the paleoenvironment and diagenetic conditions of selected three sections of the Shiranish Formation (Late Campanian-Maastrichtian) in Dokan-Sulaymaniyah, Kurdistan Region, northeast of Iraq. The major and some trace elements were analysed by X-Ray Fluoresces. These geochemical results showed a positive correlation of SiO₂, Al₂O₃, Fe₂O₃, MgO and TiO₂ between each other due to the influence of detrital influx from the active oceanic margins and thrust belts of the northeast Arabian Plate. The terrigeno

    Shiranish has been studied at Hijran section near Erbil city, NE Iraq. Fifty two thin-sections were prepared to study them under polarized microscope, to determine the petrographic component, organic content and digenetic processes. Rock units subdivided into four rock beds, as follows: dolostone, foraminiferal biomicrite, poorly washed biomicrite and micrite. Vertical succession of Shiranish Formation refers to off-shore quite marine environment.

Upper Cretaceous Oceanic Red Beds (CORBs) are pelagic sediment deposits that deposited in the Upper Cretaceous basin, with widespread in part of the world as well as in Iraq. This research investigates the deposition of cyclic marl and marly limestone CORBs of six selected sections at the active southern margin of the Tethys during the Late Campanian - Maastrichtian with petrography, microfacies, and depositional environment.
The measurement of carbonate content (CaCO3 %) in the rocks, 180 samples of all the geological sections were studied twice for each sample and the average readings were taken.
This examination proved the following major oxides wt. % concentrations domination SiO2, CaO, Al2 O3 and Fe2O3 with average values of 3

Shiranish formation has been divided into two microfacies units: 1 - Many biowackestone facies and 2 - maly packstone using planktonic foraminifera and other carbonate components in the rock cutting and core slides. Microfacies reflect marin deep shelf margin in the lower part of the formation, the upper part was deeper. The thickness of the formation is determined, depending on addition to the presence of echinoderm framents debris and spines. This is in disagreement with the 195 ft thickness reported by the Oil Exploration Company The age of the formation is estimated depending on the recognized biostratigraphic zone using the index fossils to be Upper - Middle Mastrichtion.

     Yamama Formation is the most important and widespread Lower Cretaceous Formation in Iraq. Yamama Formation in the Luhais well-12 and Rifaee well-1 are composed of dolomitized in some places and foraminifera and algae bearing limestone, 19 genera and species of foraminifera, 10 genera and species of algae. Two biozones were distinguished Pseudochrysalidina arabica Range zone and Pseudocyclammina lituus Range zone. The age of the formation was determined as Berriasian – Valanginian according to these biozones of Foraminifera. In this study, bryozoa, Gastropoda and Pelecypoda are recorded but less than Foraminifera.