Introducing some echinoderms from the Tirgan Formation, Kopeh-Dagh Basin, NE of Iran

Abstract

A stratigraphic section from the Tirgan Formation was selected in Arkan village nearby Bojnourd city in order to study echinoderm fauna systematically. Many specimens of echinoderms, especially toxasteridae which is associated with brachiopods were collected and studied systematically in this paper. Microscopie slides were also prepared and studied. All slides contain benthic foraminifers and calcareous algae as well as gastropod and coral fragments. Based upon diagnostic micro and macro fossils, a Barremian-Aptian age is assigned to the Tirgan Formation which suggests Urgonien facies type indicating shallow water of open marine environment The Urgonien is named after the village with this name in the east of Tarascon, France. This facies type is characteristic of shallow-water carbonate facies which was accumulated along the Tethys northern shelf from the Barremian to the late Albian. The facies consists of hard, white-gray limestones which contains Orbitolina (foraminifers) and transitional sediments – detrital or siliceous limestones (Foury, 1968).