Nannostratigraphy and investigation of depositional conditions of the contact between Aitamir and Abderaz formations in east and west of Kopet Dagh

In this paper، the calcareous nannofossils at the contact between Aitamir and Abderaz Formations in Dobaradar and Hammam Qaleh sections in the east and Qalehzoo and Sheykh sections in the west Kopet Dagh basin، for consideration of biostratigraphy and paleaoecology، were studied. On the basis of paleontological studies، 22 genera and 33 species in Dobaradar section، 25 genera and 37 species in Hammam Qaleh section، 9 genera and 13 species in Qalehzoo section and 17 genera and 22 species in Sheykh section، were detected، photographed and counted and the biozonation of studied regions have been determined. On the basis of these biozones، the age of the boundary between Aitamir and Abderaz formations in the Dobaradar and Hammam Qaleh sections is Late Santonian and the age of this boundary in Qalehzoo and Sheykh sections is Early Campanian. The increases in abundance from east to west and paleoecological interpretation show that the depth of the Kopet Dagh basin increased from east to west. Based on reduced diversity and abundance of species in the west، it can be stated that environmental conditions in the east were better for living calcareous nannoplanktons than west Kopet Dagh.