Biostratigraphy of Tirgan Formation at Jozak and Chaman-Bid areas-west of Kopet-Dagh Basin

Tirgan Formation (Lower Cretaceous) in the Kopet-Dagh Basin consists mainly of oolitic, Orbitolina, dolomitic limestones that conformably overlies and underlies the Shurijeh and Sarcheshmeh formations, respectively. Upper contact of Tirgan Formation at reference section with Abderaz Formation is faulty. Two stratigraphic sections at Jozak and Chaman-Bid were measured and sampled. Based on biostratigraphical studies, two benthonic foraminifera and calcareous green algae fossil assemblages have been identified. These assemblages include of 19 genera and 11 species of benthonic foraminifera and 1 genus and 1 species of calcareous green algae at Jozak section and 20 genera and 10 species of benthonic foraminifera and 2 genera and 2 species of calcareous green algae at Chaman-Bid section in west of Kopet-Dagh basin. This study has been suggested the Barremian-Lower Aptian (Bedulian) age for the Tirgan Formation at these localities that is corresponded whith age of central basin.