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.