Carbon and Oxygen stable isotopes in Sarcheshmeh and Sanganeh Formations at the west Kopet Dagh basin

This research is focused on isotopic analysis data of Sarcheshmeh and Sanganeh Formations in Takal Kuh area in west Kopet Dagh. Based on stratigraphic and paleontologic studies of ammonites, Late Barremian- early Aptian age for Sarcheshmeh and early Aptian age for Sanganeh formations were suggested in study area. Carbon and oxygen isotopes values were analyzed for 35 samples. Variation of carbon isotopes in studied sections were correlated with biostratigraphic data and compared with isotopic data of Aptian type section in Europe and some other sections in Tethys. This correlation shows well similarities. Moreover, based on isotopic and paleontologic data, basal shale of the Sanganeh Formation is interpreted as OAE1a (Oceanic Anoxic Event) which is correlated with Deshayesites deshayesi biozone. Calculated temperature of ambient water during deposition of Barremian-Aptian deposits is supported by paleogeographic maps of Kopet-Dagh.