The Upper Cretaceous Shiranish Formation of Shkawtua Village, Mergasur area, Iraqi Kurdistan region consists of alternating mixed siliciclastic and carbonate strata interpreted as an outer shelf open marine (basinal) depositional environment. Fourteen thin sections were studied under polarized microscope to determine the petrographic component, fauna content, and microfacies analysis. The study tries to compare this formation with its equivalences throughout the region. Rock units are divided into: marly limestone, marlstone, and dolostone. The major petrographic constituents are: micrite, pseudospar, replacement dolomite, and fossils. Fossils are the main particles within mudstone, wackestone, and packstone microfacies types. The occurrence of some planktonic foraminifera such as globigerina cretacea, archaeoglobigerina cretacea, and rotalipora cushmani (rotalia sp.) suggests an Upper Cretaceous age.