干旱区生态环境知识资源中心

The present work deals with a study of the Dammam and Euphrates formations in two outcrops in the southern desert of Iraq. Forty-five thin sections and rock samples are described and interpreted. The laboratory study reveals that these formations are composed of fossiliferous limestone and breccia. There are five biozones that had been distinguished in the studied area; three of them were described in the first section and they are as follows: Nummulites partschi range zone, Orbitolites complanatus range zone, and Nummulites gizehensis-N. intermedius concurrent range zone. And the two others were described in the second section: Discocyclina archias range zone and Miogypsina globulina-Borealis melo melo concurrent range zone. Depending on these biozones, the age of the Dammam formation is represented by the Middle-Upper Eocene, and the Euphrates formation by the Lower Miocene. According to faunal occurrence, paleoecological analysis had been done with details. Then, many facies could be described in the studied sections arrival to reconstruct paleoenvironment setting that all of the two studied formation deposited, which is reef-core reef-fore reef in the Dammam formation and inner to middle shelf in the Euphrates formation.