Stratigraphy of Sadi Formation ( Santonian) and its Relationship toKometan Formation from North and Mid Part of Iraq

Abstract

The litho-facies of Sa'di Formation is characterized by chalky and marly limestone with thick-wall rotaliids and algal facies of shallow marine environments of Santonian age. These facies are distributed in the mid -secter of Iraq, which is parallel to the Tigris river. While in Late Santonian the upper facies of Sa'di Formation was replaced by extensive Globotruncanal facies of pelagic environment of Kometan Formation, due to sea level change, which is accordant with in changing of paleo-topography of basin configuration. Two biozones are defined for the complete section of Sadi formation as: 1- Rotalia skourensis Zone (Late Santonian). 2- Dissocladella undulata Zone (Early Santonian). The second one is changing laterally to the Dicarinella concavata Zone for the same formation. Overplayed by Dicarinella asymetrica Zone from Late Santonian of Kometan Formation. While the Sadi Formation was disappear in the eastern part of the Iraq and replaced by kometan formation.