hossein khonchaman

The early-mid Cretaceous carbonate sequences in the northeast of Rafsanjan city contain abundant and diverse foraminifera assemblages. A stratigraphic section of these sequences has been sampled for biostratigraphical and paleoenvironmental studies. The studied section was subdivided into two informal lower and upper units based on lithological characteristics. The former is composed of coloured marls intercalated with a few limestone intercalations. Planktonic foraminifera, oligosteginids and radiolarian are most components of it. The upper unit consists of fossiliferous limestones with intercalation of marls, rich in benthic foraminifera and calcareous algae that form cliff walls. The lower unit is characterised by r-selected hedbergellids, reflecting nutrient-rich/eutrophic marine environments. Whiles an abundance of cone-shaped orbitolinids, calcareous algae, and invertebrate organisms (echinoids, corals, and Mollusca) reflect deposition in the photic zone of shallow water marine platforms with stable temperature and salinity conditions. The biostratigraphic data allow us to date the Lower Cretaceous successions between Barremian and probably the early Cenomanian. One planktonic and five benthonic foraminiferal biozones are identified which include:Hedbergella spp. Assemblage ZonePalorbitolina lenticularis ZonePraeorbitolina spp. Assemblage ZoneMesorbitolina parva ZoneMesorbitolina texana ZoneMesorbitolina subconcava Zone