Nummulite Biozonation of Dammam Formation During the Eocene Epoch from Samawa and Nasiriya Cities, Southwestern Desert of Iraq

Abstract

The lithology of the Dammam Formation is limestone, dolomitic limestone, and dolomite rocks, which are also used as raw materials in the manufacture of cement. The shallow marine environment gave it these characteristics. The Eocene succession was described and illustrated in two complete sections in the Samawah and Nasiriyah regions. Determine the age of the formation accurately in the form of multiple biozones. Biostrtigraphicaly, the Dammam Formation was divided into six main biozones include 1. Nummulites deserti- Nummulites fraasi range zone: Early Eocene (E.Ypresian age), 2. Nummulites lucasanus range zone: Early Eocene (L.Ypresian age), 3. Nummulites globulus- Nummulites Zettie: Middle Eocene (E. Lutetian age), 4.Nummulites gizehensis- Nummulites discorbinus- Nummulites planulatus Assemblage Zone: Middle Eocene (L.Lutetian) age this zone is divided into three subbiozones a) Lockhartia alveolata Interval subzone: Middle Eocene (early Late Lutetian age); b) Nummulites milacaput range subzone: Middle Eocene (middle Late Lutetian age); c) Nummulites elevate range subzone: Middle Eocene (late Late Lutetian) age, 5. Nummulites striatus range Zone Middle Eocene (Bartonian), and finally 6. Nummulites incressatus range Zone: L.Eocene age (Priabonian). The study emphasizes the different sedimentation times of the Dammam Formation during the Eocene epoch across various sections in Iraq. It details the identification of biozones in the E.Eocene (Ypresian) and M.Eocene (Lutetian) ages, along with the lack of precise age determination for the Bartonian and Priabonian ages. The study suggests that the Bartonian age may start with the appearance of N. striatus and transition to the Priabonian age with the presence of N. incressatus.