Depositional History and Sequence Stratigraphy of the Tirgan Formation (Barremian _ Aptian) in the Zavin section, NE Iran

The tirgan formation (barremian _aptian) is exposed in the kopet dagh in northeast iran. one stratigraphic section in zavinwas measured with a thickness of 110 meters. this formation in section consists of three parts (including lower carbonate, limy shale_ marl and upper carbonate rocks). based on the study of 94 thin sections, 10 carbonate and 2 siliciclastic lithofacies have beenidentified. carbonate lithofacies were deposited in a ramp platform in fore-shoal, shoal, lagoon and tidal flat environments. sea levelchanges during the early cretaceous time led to the formation of different large scale depositional sequences zavin (two). thepresent data can help in the reconstruction of the tectonic history of the area during early cretaceous time.