Nannostratigraphy in the Pabdeh and Asmari formations transition in Kuh-e Asmari section, evidence for biostratigraphic hiatus (east of Tethys Ocean)

Biostratigraphic analysis based on calcareous nannofossils was undertaken in Kuh-e Asmari section, located in the southeastern Masjed Soleyman in Zagros Basin. In this regard, for the first time the calcareous nannofossils of upper part of the Pabdeh Formation and lower part of the Asmari Formation have been studied. The stratigraphic interval studied includes shale, marl, tufa and stromatolite facies in upper part of the Pabdeh Formation, these deposits are covered by transitional zone (shale and marl) of the lower part of the Asmari Formation. In this study, for the first time, Paleogene calcareous nannofossil assemblages comprising 47 species belonging to 16 genera were identified. This confirms the existence of bio zones NP22, NP23 (upper part of the Pabdeh Formation) and NP25, NN1, NN2 (lower part of the Asmari Formation), which suggests the age of early Oligocene (Rupelian) for the top of the Pabdeh Formation and late Oligocene (Chatian)-early Miocene (Aquitanian) for the lower part of the Asmari Formation. Therefore, a biostratigraphic hiatus has been determined between Pabdeh and Asmari formations.