Paleoenvironmental Indicators of Clay Mineralsin Miocene Sediments, Northern Iraq

Clay mineralogy of the Miocene successions taken from northern Iraq constitute an important paleoenvironmental indication for the evolution of these sediments. Palygorskite is a common mineral especially in the lower Miocene sediments of Euphrates formation and the upper detrital part of the Fat'ha Formation belonging to the middle Miocene. Scanning Electron Microscope (SEM) study indicated that this mineral, was formed authigenically by neoformation in suitable chemical conditions within the evaporitic environments. Other minerals (kaoloinite and illite) have been most probable formed in detrital system and were preserved in those evaporitic conditions. Common kaolinites in the Injana clastic Formation (Upper Miocene) as well as its habit in SEM images are indicators for its detrital origin in such continental sediments.