Microfacies and depositional environment of Jeribe Formation (Middle Miocene) in the selected sections in Bekhair anticline, northwestern Kurdistan region of Iraq

Abstract

Microfacies analysis and depositional environment of Jeribe Formation (early Middle Miocene) were studied for the first time in two outcrops (Karin and Qadia villages) within the Bekhair anticline in the High Folded Zone, Zakho area, northwestern part of Kurdistan region-northern Iraq. In the Bekhair anticline, the Jeribe Formation overlies the Dhiban Formation and underlies the Fatha Formation with gradational and conformable boundaries. Based on field observations two informal lithostratigraphic units were identified: a thick massive dolomitic limestone unit, and a fractured limestone unit. The petrographic diagnosis of 27 thin sections show a variety of shallow marine derivative fossils with non-skeletal grains like peloids, ooids, intraclasts, and quartz grains. Relying on the detailed microfacies analysis, five major microfacies types including lime mudstone, lime wackestone, lime packstone, grainstone, and boundstone were identified and then divided into eleven sub-microfacies types according to dominant grain types. They were integrated according to their environmental differentiation into two facies associations which are: intertidal and lagoon. From the sum of field observation and facies analysis, the depositional environment of the Jeribe Formation was a shallow marine environment, deposited in the intertidal setting in the lower part and changed to a semi-restricted lagoonal environment toward the upper part.