标题：Biostratigraphy of the Abderaz Formation Based on Heterohelicids, at Six Stratigraphical Sections in East and Center of the Kopeh-Dagh Sedimentary Basin, Northeastern of Iran
摘要：In this study, Abderaz Formation at six stratigraphical sections, in east and center of the Kopeh-Dagh sedimentary basin, has been investigated, based on biserial planktonic foraminifera. Totally, 831 samples, with 3 meter distance, were gathered from a sequence with 2800 meter thickness. Also 4 genera and 17 species of biserial planktonic foraminifera have been identified and two biozones and two subzones recognized. Based on obtained data, the age of Early Turonian-Earliest Campanian for the Padeha, Abderaz village and Shorab sections, Midle Turonian-Earliest Campanian for type section, Early Turonian-Late Santonian for Qarehso section and Early Turonian-Earliest Santonian for Hajgelichkhan section were determined. The least amount of plank-tonic foraminifera was identified at Hajgelichkhan, while the maximum amount recognized at Qarehso section.
