فهرست نشریات علمی دسترسی آزاد ایران

For the first time, an assemblage of cryptospores, which includes 10 species belonging to nine genera, from the Upper Ordovicianstrata, is being reported, in Iran. These cryptospore assemblages were recovered from the upper part of Ghelli Formation., from theeastern Alborz Mountain range. These peri-Gondwanan cryptospores have been classified based on their morphology (monad, truedyad, pseudodyad, true attached, and loose tetrads). The results of the present study support previous findings that there are nosignificant differences between similar-aged cryptospore assemblages of the peri-Gondwanan, Baltic provinces and other parts of theworld. Based on the presence of the chitinozoan index of the northern Gondwana (Spinachitina oulebsiri), the index acritarchs, and thepresent cryptospores, a late Hirnantian (Late Ordovician) age is proposed to the top of the Ghelli Formation. The cryptospores seem tobe transported from an adjacent land area and the lack of land-derived elements in the up-section may indicate an increased distanceoffshore.