Biostratigraphyof the Ziyarat Formation based on calcareous nannofossils in the Tochal section, Alborz sedimentary basin (Central Alborz)

In this study, biostratigraphy of the the Ziyarat Formation was investigated based on calcareous nanoplankton in the Tochal section (southeast of Tehran). In this section the Ziyarat Formation conformably overlies the Fajan conglomerate and is overlain the Karaj Formation. The thickness of the formation in Tochal section with four rock units is 212 meters and it mainly consists of limestone, and marl. In this study, investigation of 105 prepared samples and calcareous nannoplanktons has led to the identification of 37 species belonging to 16 genera. Based on the first and last occurences of nannofossil species and assemblage species such as Discoaster sublodoensis, Nannotetrina fulgens, Tribrachiatus orthostylus, Discoaster lodoensis and Tribrachiatus contortus the NP9-NP15 and CNP11-CNE9 biozones in the Ziyarat Fsormation were determined. The nannofossil biozones and their stratigraphic location indicate the age of the late Paleocene - middle Eocene (Thanetian- Lutetian) for the Ziyarat Formation in the Tochal section.
In this study, biostratigraphy of the the Ziyarat Formation was investigated based on calcareous nanoplankton in the Tochal section (southeast of Tehran). In this section the Ziyarat Formation conformably overlies the Fajan conglomerate and is overlain the Karaj Formation. The thickness of the formation in Tochal section with four rock units is 212 meters and it mainly consists of limestone, and marl. In this study, investigation of 105 prepared samples and calcareous nannoplanktons has led to the identification of 37 species belonging to 16 genera. Based on the first and last occurences of nannofossil species and assemblage species such as Discoaster sublodoensis, Nannotetrina fulgens, Tribrachiatus orthostylus, Discoaster lodoensis and Tribrachiatus contortus the NP9-NP15 and CNP11-CNE9 biozones in the Ziyarat Fsormation were determined. The nannofossil biozones and their stratigraphic location indicate the age of the late Paleocene - middle Eocene (Thanetian- Lutetian) for the Ziyarat Formation in the Tochal section. Tochal section.