Stratigraphy of the Gurpi Formation in Kuh-e Siah anticline and its comparison with Tang-e Bulfares and Aghar anticline sections

Planktonic foraminifera are useful in determining the relative age of the Upper Cretaceous strata. Based on distribution of planktonic foraminifera in Kuh-e Siah section (212 m thickness)، eight biozones have been recognized including Dicarinella concavata Interval Zone (Earliest Santonian)، Dicarinella asymetrica Total Range Zone (Santonian to Earliest Campanian)، Globotruncanita elevata Partial Range Zone (Early Campanian)، Globotruncana ventricosa Interval Zone (Middle to Late Campanian)، Radotruncana calcarata Total Range Zone (Late Campanian)، Globotruncanella havanensis Partial Range Zone (Late Campanian)، Globotruncana aegyptiaca Interval Zone (Late to Latest Campanian) and Gansserina gansseri Interval Zone (Latest Campanian to Early Maastrichtian). The study of the Gurpi Formation at Kuh-e Siah anticline and its comparison with the Tang-e Bulfares (Early Santonian to Middle Maastrichtion) and Aghar anticline (Late Santonian to Middle Maastrichtioan) sections، show that the sedimentation of the Gurpi Formation has been started in Dehdasht area (Kuh-eSiah section) at the Earliest Santonian time، while in the Bulfares and Aghar sections، sedimentation started at the Early Santonian and Late Santonian time respectively. Three morph type groups of planktonic foraminifera were recognized during the Santonian to Maastrichtian at the Kuh-e Siah anticline. The results of this study were similar with depth fluctuations of sedimentary basin in Bulfares and Aghar sections that can be affected by global changes in sea level.