Abstract
X-ray diffraction analyses and petrographic study of marl samples belonging to the Al-Fat`ha Formation (Middle Miocene) from four selected localities in northern Iraq, revealed the presence of the minerals, carbonates (calcite and dolomite), quartz, plagioclase feldspars and the clay minerals illite, chlorite, kaolinite and montmorillonite. The origin and diagenesis of the non clay and clay minerals are discussed. Clay minerals, fossil contents and associated evaporite sediments revealed that the environment of deposition of marl sediments at the studied localities were hyper-saline and semi-arid marine lagoonal environment.