Introduction: The Cenomanian-Turonian boundary in the Koppeh-Dagh Basin (NE Iran) have spread out from west to east. The purpose of this study is to record sea-level changes and palaeo-climate history of the late Cenomanian-early Turonian interval in the eastern part of the Kopet-Dagh Basin (Taherabad section) using geochemical anomalies and minerals signatures. Methods: Two geochemical proxies including Δ13C (pCO2 index) and δ18O have been analyzed for palaeo-climate interpretation. Also, detrital index and kaolinite values were measured to determine humidity and chemical weathering in the study section. Results: Our results indicate variations in palaeo-climate indices including two cool intervals surrounded by warm periods in the study succession. The δ13C curve represents two main positive peaks in the cool intervals at the upper part of Rotalipora cushmani and middle part of Whiteinella archaeocretacea biozones. Conclusion We conclude that according to aquifer-eustasy hypothesis the cool and dryer intervals, which are characterized by decreased detrital input and kaolinite contents in the studied section, are associated with aquifer discharge and sea-level rise. Inversely, the warm and humid episodes are consistent with increased precipitation and chemical weathering, resulting aquifer charge and sea-level fall. The sequence boundaries in the studied succession are positioned at upper part of R. cushmani and middle part of W. archaeocretacea zones and can be correlated with Ce5 and Tu1 global events.

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