Palynostratigraphy of the Dalichai Formation in Darjazin section, North of Semnan

The Dalichai Formation in Darjazin section in NE Semnan with a thickness of 631 meters consisting of an alternation of bulish-gray was studied.This formation overlies the Shemshak formation disconformity with conglomerate bed and it has gradually been covered by the thick-beded limestones of the Lar formation. Based on the presence and stratigraphic distribution of the most dominant miospore, Klukisporites variegatus and Callialasporites dampieri of pollen areidentified in the Dalichai (late Bajocian - Callovian) and Presence of some index dinoflagellate species led to identification of three biozones in the Dalichai Formation. These include in ascending order, Cribroperidinium crispum Total Range Biozone (late Bajocian), Dichadogonyaulax sellwoodii Interval Biozone (Bathonian - early Callovian), Ctenididinium continuum Interval Biozone (early to middle Callovian). This biozonation corresponds largely to those established in Northwest Europe and Northwestern Tethys and reveals the marine connection between North of Iran with Northwest Europe and the Northwestern Tethys during the Middle Jurassic.