Depositional history and sequence stratigraphy of Tirgan formation (Barremian-Aptian) in central Kopet Dagh, NE Iran.

The Tirgan Formation (Barremian - Aptian) is exposed in the Kopet Dagh in northeast Iran. Two stratigraphic sections in Radkan and Chenaran were measured. Their thickness are 238 m and 119 m, respectively. This formation in measured sections consists of three parts (including lower carbonate, middle limy shale - marl and upper carbonate rocks). Based on study of 164 thin-sections, 15 carbonate and 2 siliciclastic lithofacies have been identified. Carbonate lithofacies are deposited in a ramp platform in fore shoal, shoal, lagoon and tidal flat environments. Sea level changes during lower Cretaceous led to the formation of different large-scale depositional sequences Radkan (two) and Chenaran (two) respectively. The present study highlights the reconstruction of tectonic history of the area during lower Cretaceous. [ABSTRACT FROM AUTHOR]