calcareous nannofossils biostratigraphy and paleoecology of the last layers related to eastern alborz cretaceous deposits in cheshmeh gholghol section

coccolithophores are important primary producers in the modern world ocean and were almost certainly important in the mesozoic oceans, prior to the evolution and rise of diatoms in the phytoplankton. calcareous nannofossils are abundant, planktonic, rapidly evolving and largely cosmopolitan, so they are a good tool for biostratigraphy and paleoecology studies especially in the cretaceous system. according to these specifications and due to the lack of precise paleontological study, the nannofossils of the last layers related to eastern alborz cretaceous deposits have been investigated in cheshmeh gholghol section. using polarize microscope, 23 genera and 51 species were identified in this section. based on identify nannofossils, the age of this section is late santonian- late maasrichtian corresponding to cc16- cc26 (sissingh, 1977). on the bases of paleoecological interpretation, the last layers related to eastern alborz cretaceous deposits were deposited in shallow marine environment in relatively low latitude, warm climate condition and basin shalloer toward fajan formation.