Palynostratigraphy of the Sanganeh Formation at the East and Central Kopeh-Dagh Basin based on dinoflagellate cysts

The Sanganeh Formation (Lower Cretaceous) has cropped out across the Kopeh-Dagh Basin. The formation conformably overly the Aptian Sarcheshmeh Formation and is in turn overlain conformably by glauconitic sandstone of the Aitamir Formation. The considered formation in eastern and central parts of the basin comprises predominantly dark shale with some interbeds of limestone and siltstone. In order to analyse dinoflagellate content of this rock unit، four stratigraphic sections from east to the center of the basin including Karizak (320m)، Mozduran (355m)، Sanganeh (550m)، and Qarah-Su (580m) were measured and sampled palynologically. A total of 370 rock samples taken from the four sections were processed palynologically and scanned under a light microscope. Of these، two sections including Karizak and Mozduran were barren of any preserved dinocysts while، the samples from other two sections (Sanganeh and Qarah-Su) yielded a relatively diverse and well preserved assemblage. According to the recognized dinocysts، two zones DZ1 and DZ2 were established in Sanganeh and Qarah-Su sections. The differentiated dinozones were coincident to Odontochitina operculata and Pseudoceratium turneri which are index for late Aptian-early Albian for the Sanganeh Formation at the mentioned stratigraphic sections. In addition، distribution and dispersion of dinoflagellate cyst contents indicate an increasing trend of the depth from east to the central parts of the Kopeh-Dagh Basin.