Depositional Model of the Sarki Formation (Early Jurassic) in Sule area, Hendren Anticline, Northeastern Iraq

The succession of the Sarki Formation (Early Jurassic) is studied in an outcrop section near the Sule village in northeastern Iraq within the High Folded Zone. The formation consists of dolomitic limestone, massive dolomite including stylolite, layers of limestone containing bedded stromatolites, interbedded black to gray and yellow shale in the lower and middle units. Petrographically, the formation consists of skeletal grains as represented by bivalves and gastropods, ostracod shells, stromatolites, some sponge spines, and calcispheres, as well as non-skeletal grains represented by ooids, intra and extra clasts and peloids. Field work has revealed that four rock lithofacies could be identified: the gray shale rock lithofacies, the yellow shale lithofacies, the brecciated dolomitic limestone lithofacies, and the laminated stromatolite lithofacies. Based on the petrographic components, five main microfacies are distinguished: the mudstone limestone microfacies, the wackstone microfacies, packstone microfacies, grainstone microfacies, and boundstone microfacies, which in turn are divided into eleven submicrofacies. All of these facies reflect the deposition in a shallow marine environment that extends into three secondary environments: the pertidal environment, lagoon environment, and oolitic sand shoal barrier environment. The paleogeography setting reveals that the formation sequences were deposited in shallow environments within the restricted basins that were formed as a result of affecting to tectonic movements that led to fluctuations in sea level which helped in creating sedimentary basins during the Early Jurassic period. Finally, a sedimentalogical model for the formation is drawn.