Lithofacies and Age Determination Study of Fatha Formation in Mushak, Salah Al-Din Government, Northern Iraq

An exposure section of the Fatha Formation (Middle Miocene) was studied in the Mushak area, Baiji, Northern Iraq. A section of 35m thick consists of sequences of limestones, green marls, red claystone and gypsum. These sequences are repeated within the section and have a thickness of 35 m. As for the stratigraphic boundaries, the lower contact is unconformity with the Pila Spi Formation, while the upper boundary is conformity with the Injana Formation. The Paleontological study of limestone rocks was carried out by examining thin section of (15) samples. Three microfacies appears: Bioclastic Lime Packstone, Peloidal Lime Wackestone, and Lime Mudstone Microfacies that pointed to subtidal to restricted lagoon and open marine. The recorded calcareous nannofossil assemblages include one biozone which are from the lower to the upper part of the section: Sphenolithus heteromorphus Interval Biozone (CN4). Following the standard biozonation of sissingh (1977), This biozone concludes the age of the Middle Miocene (Langhian).