Clay minerals of Shiranish Formation in, Erbil, Duhok northern Iraq

Abstract

In the Upper Cretaceous of northern Iraq (upper Campanian-Maastrichtian), the Shiranish Formation is examined for clay minerals using X-ray diffraction in the Duhok (Sandor section) and Erbil cities (Lailuk section). In the marl section of the Shiranish Formation, the layers of chlorite, illite, kaolinite, palygorskite, and a mixed layer of montmorillonite-chlorite strata were discovered to have formed antigenically. The variation in minerals indicates the Cretaceous’ changing climate. Palygorskite is a result of leaching processes that are more successful due to variations in the parent rocks. The transition of palygorskite from montmorillonite and illite can occasionally be impacted by post-depositional diagenetic processes. Because of the warm conditions that supply the eroded clastic materials from earlier successions of Cretaceous in the area, chlorite, mixed-layers, and illite may have predominated over kaolinite. The variation in source rocks and drainage conditions is reflected in the variation of clay minerals in the investigated sequence, which could improve leaching rate processes.