Microfacies and depositional environment of the Asmari Formation in the Izeh zone

In this study, microfacies features of the Asmari Formation have been studied. The study area is located in the Izeh zone, in the vicinity of Izeh city. Accordingly four outcrop sections (Halayjan, Kuh Shur, Kuh-e Bad and Gharibi Ha) have been sampled and investigated. Due to unique tectonical characteristic and lateral as well as spatial variations of the outcrops, different facies have been deposited across the Asmari Formation platform in the study area. Based on the sedimentary structures, texture, skeletal and non-skeletal grains, 11 microfacies have been recognized which have been deposited in three different sub environments including open marine, shoal and lagoon. Based on this reaserch, for the Asmari Formation, three independent depositional models have been considered during the Chattian, Aquitanian and Burdigalian. On the basis of the results of this study, during the Chattian, Aquitanian and Burdigalian the Asmari Formation has been deposited in a homoclinal ramp system. During the Burdigalian toward the NE of study area (Gharibi Ha section), the shallow water deposits are abruptly overlain by pelagic limestone. Therefore, during the Burdigalian toward the NE of study area, probably, the carbonate ramp has been changed to drowned carbonate platform. It is interpreted as the result of a regional tilting that started in the late of the Burdigalian. During the Chattian in the Gharibi Ha area, the base of the carbonate Asmari Formation transits into the marl-dominated Pabdeh Formation towards the Halayjan area which could be concerned as an analogue to investigate about the stratigraphic oil traps potential in the Izeh zone.