Palynological characteristics of Middle– Late Jurassic strata (Dalichai Formation) in Binalud Mountains, NE Iran

The Dalichai Formation with an age of Middle– Late Jurassic has been studied palynologically in Binalud Mountains, NE Iran. For this purpose two sections are selected in the east (Ghoroneh section) and the west (Navia section) of the area. The formation has been measured 710 m thick in the east and 1062 m thick in the west and sampled systematically. The Dalichai Formation mainly is composed of alternation of grey shale and marl with a lot of nodules in the lower part that followed by medium-thick bedded light grey limestone with intercalations of shale and marl that terminated to marl, marly limestone and thin- medium bedded limestone in the upper part. The formation disconformably overlies the Shemshak Formation and is in turn overlain by the very thick limestones of the Lar Formation with a transitional boundary in both sections. Palynological studies led to identification of rich assemblages of dinoflagellate cysts based on which a palynozonation with six identical palynozones were established for Ghoroneh section and five palynozones in Navia section. Palynofacies reflecting the depositional setting for the sections indicate however some changes between the west and the east of the range. Palynological contents of the samples plotted on Tyson diagrams show fluctuation in depth from shelf to basin transition during the depositional course of the formation in Middle– Upper Jurassic. The zonations established are compared with that of Northwest Europe and Central Alborz Mountains.