Depositional Environment of Khurmala / Sinjar Formation from Two Selected Sections, Northern Iraq

In Northern Iraq, the Khurmala Formation sections at Sundor in Duhok City and the Shiraswar section in Erbil City have been studied from a sedimentary point of view. The formation's thickness is 53 meters in the Sundor section and roughly 13.5 meters in the Shiraswar section. Petrographic analysis of 48 thin sections of the Khurmala Formation shows that the majority of skeletal grains are of shallow marine environment and consist of fossils as benthonic foraminifera, pelecypod, bryozoan, red algae, coral, and non-skeletal granules including peloids, oolite and lithoclasts (intraclasts and extraclast). Three main microfacies and five lithofacies are identified based on field observations and petrographic analysis of the formation. These include lime mudstone, lime wackestone, lime packstone microfacies, and red algae bindstone lithofacies, coral framestone lithofacies, algal lime bindstone lithofacies, cross bedding bearing carbonate sand lithofacies and intraformational conglomerate lithofacies. The results of the current study indicate that the carbonate succession have been deposited in a spectrum of sedimentary environments, as most of the facies are located between the tidal flats environment to the upper parts of the slope environment, and it should be noted that the facies diagnosed in the carbonate succession exposed in the Shiraswar section differ in most of them from those diagnosed in the Sundor section, and they reflect the deposition of the reef environment, which calls for changing the name of these carbonate succession exposed in the Shiraswar section from the Khurmala Formation to the Sinjar Formation.The results of the current study indicate that the carbonate succession have been deposited in a spectrum of sedimentary environments, as most of the facies are located between the tidal flats environment to the upper parts of the slope environment, and it should be noted that the facies diagnosed in the carbonate succession exposed in the Shiraswar section differ in most of them from those diagnosed in the Sundor section and they reflect the deposition of the reef environment, which calls for changing the name of these carbonate succession exposed in the Shiraswar section from the Khurmala formation to the Sinjar formation.