Application of benthic foraminifera and calcareous algae in determination of the biostratigraphic boundary of the Barremian-Aptian: A case study on the Tirgan Formation, West of Kopet-Dagh sedimentary basin

Large benthic foraminifera and dasycladalean green algae are the most common and important (micro) fossils in Lower Cretaceous shallow-water sediments of the Tethyan Realm. In this paper, we introduced such taxa and their importance in age dating of Lower Cretaceous strata in the Kopet-Dagh sedimentary basin. Also, according to determinations of index taxa (fauna and flora) in this period, the biostratigraphic boundary of Late Barremian-Early Aptian can be defined in the west Kopet-Dagh sedimentary basin for the first time. In addition, according to the FO and LO of the index taxa, 5 biozones are determined in the studied section which show Late Barremian-Early Aptian age for the studied stratigraphic sections.