Document Type : Original Research Paper
Authors
1 Ph.D., Islamic Azad University, North Tehran Branch, Tehran, Iran
2 Ph.D., Geological Survey of Iran, Tehran, Iran
3 Professor, Islamic Azad University, North Tehran Branch, Tehran, Iran
Abstract
In this study the Upper Cretaceous sediments in the Zagrous Basins Fars province,the Pyrgheib Section,for the purpose of Biostratighraphy and sea level change studies were investigated. These sediments with about 206 m thickness consist of Limestone, Shale, Marl and limy marl. The investigated foraminifera led to identification of 70 species of planktonic foraminifera that belong to 16genera. Based on planktonic foraminifera the Upper Cretaceous deposits were divided into 6 biozone which are cosmopolitan and respectively are:biozone1 - Dicarinella concavata Interval Zone,Biozone2- Dicarinella asymetrica Total Range Zone,Biozone3- Globotruncanita elevata Partial range zone Biozone4- Globotruncana ventricosa Interval Zone,Biozone5- Radotruncana calcarata Interval zone. Biozone6- Globotruncanella havanensis Partial range zone ,Biozone7- Globotruncana aegyptiaca Interval zone. Biozone8- Gansserina gansseri Interval zone, Biozone9- Contusotruncana contusa Interval Zone. The Upper Cretaceous sediments in the study area on the basis of Planktonic Foraminifera are of the Late middle Coniacian to theLate Maastrichtian ages. According to the Morphotype groups of planktonic foraminifera deeping the basin from the Coniacian to the Middle Santonian is seen .However, in the late Santonian shallowing the basin and again in the Early Campanian deeping the basin, in the Late Campanian and close to the Campanian-Maastrichtian boundary shallowing the basin and a sea regression is observed.
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