The mineralogical study using X-ray diffraction (XRD) supported by scanning electron microscopic (SEM) examination and energy-dispersive spectroscopy (EDS) on the claystone of the Kolosh Formation from northern Iraq was conducted to Shows the provenance history of rocks. Chlorite, montmorillonite, illite, palygorskite, and kaolinite were recorded in different amounts in the study area. The association of montmorillonite and chlorite in the claystone of the Kolosh Formation (Paleocene) refers to the marine environment. Chlorite and montmorillonite are the common minerals in the Kolosh Formation with less common of illite, kaolinite and palygorskite. These clay minerals are of authigenic, detrital and diagenetically origin, which are controlled mainly by the source rocks, paleoclimatic conditions and the burial diagenesis. The clay minerals assemblages refer to be derived mainly from Fe-Mg rich with minor Si-Al rich silicate minerals, which are very common in the ophiolites associated with the basic igneous rocks. These rocks composed the major lithological units in the Zagros Thrust Belt of NE Iraq.
