Biostratigraphy of Albian Sediments (Kazhdumi Formation) in Zagros Area (Southwest of Iran)

To investigate biostratigraphy of Albian sediments (Kazhdumi Formation) in the Zagros Basin, 280 samples in four sections were prepared which are nominated as Murshan-e-Bala, Fahliyan-e-Pain, Kupon and Tale-e-Afghani. Stratigraphic distribution of identified foraminifers confirms well developed orbitolinids which are associated with other Albian benthic foraminifers in all studied sections. The orbitolinids are recognized in surrounding strata [Dariyan (at the base which is marked by an oxidized zone) and Sarvak Formations (on the top, as gradtional contact)] as well as the Kazhdumi Formation. Obtained biostratigraphic data show that Early Albian is marked by the presence of Hemicyclammina sigali , which co-occurs with Mesorbitolina texana and Mesorbitolina subconcava , whereas Conicorbitolina conica and Meorbitolina parva support Late Albian age of the studied sections. Calcareous algae are associated with both benthic faunal assemblages. Albian planktons occur in the studied sections which are identified as Favusella washitensis and Calcisphaerula inomminata subzones. The stratigraphic position of planktons actually indicates vertical displacement in the sedimentary basin during Albian time. Other associated Albian pelagic foraminifera are identified which are obviously recognized in three sections of the Kazhdumi Formation. The presence of pelagic species in the study section of the Kazhdumi Formation indicates basement faulting during the Albian period.