چينه نگاري سكانسي سازند آيتامير (آلبين- سنومانين) در ناوديس هاي شيخ و بي بهره غرب حوضه رسوبي كپه داغ

Sequence stratigraphy of the Aitamir Formation (Albian-Cenomanian) in Sheikh and Bi-bahreh synclines in the west Kopeh-Dagh basin

The Kopeh-Dagh Basin is located in northeastern Iran and southern Turkmenistan. The Aitamir Formation (Albian-Cenomanian) is deposited in this basin. Based on four measured stratigraphic sections, depositional environments and relative sea level changes of the Aitamir Formation have been interpreted. Petrographic studies and field observations led to identification of carbonates and siliciclastic (mudstone and sandstone) lithofacies. Carbonate rocks are deposited in semi-restricted lagoon, lower shoreface and open marine sub-environments, while the siliciclastics are deposited in lagoon, bars, shoreface and open marine condition. Sequence stratigraphic analysis led to identification of two (Sheikh Section) and three depositional sequences (Sorkhozoo section) in the west and three (Gadganloo section) and four (Passkooh section) depositional sequences in the east parts of the study area. Comparison of interpreted sea-level curve of Albian-Cenomanian time in the Kopeh-Dagh Basin with the global sea-level curve show some similarities and differences. These differences can be related to regional tectonic settings and sediment loading within the study area. Paleogeography reconstructions during the Albian-Cenomanian times are presented in nine Block diagrams. We hope these data can be used in paleogeographic interpretation of Middle Cretaceous time in other places.