رخساره ها و محيط رسوبي سازند مبارك در منطقه كياسر جنوب شرق ساري

Microfacies and Sedimentary Environment of Mobarak Formation in Kiasar, Southeastern Sari

In order to study facies and sedimentary environment of Mobarak Formation in Kiasar, 75 km Southeastern Sari, a stratigraphy section , 250 m thick, was selected, which included thin to thick layers of limestone and of dolomite, shale and marl. Its lower contact includes shale and thin to thick layers of limestone with hemoclinal conformity overlies Geirud Formation (Upper Devonian) and its upper contact includes thick beds of shale covered by disconformity with sandstone of Dorud Formation (Lower Permian). For field sampling, the best path was chosen, and following sampling and studying the petrographic characteristics, thin sections were supplied from samples, and the microscopic features of the samples were studied. This study shows that these sediments may have been deposited in hemoclinal ramp that consists of 4 microfacies assemblages and 19 subfacies. These lithofacies indicate that sedimentation must have occurred in open marine, bar, lagoon and tidal flat subenvironments.