Investigating bio-events and time expansion of Calcareous nannofossils in the upper part of the Gurpi Formation and lower part of the Pabdeh Formation, northwestern Shiraz

n this study, calcareous nannofossils are investigated in the upper part of the Gurpi Formation and lower part of the Pabdeh Formation at the Par-e Nobar section located in the northwest of Shiraz. The thickness of the studied section is about 41 m. The upper part of the Gurpi Formation is mainly composed of shales and pelagic limestones while the lower part of the Pabdeh Formation consists of shale facies. As a result, 32 species and 22 genera of calcareous nannofossils were detected. According to the first and last occurrence of index species and fossil assemblages, two bio-zones including Nephrolithus frequens Zone (CC26/ UC20dTP) and Markalius inversus Zone (NP1) are recognized in the upper part of the Gurpi Formation, respectively. Fasciculithus tympaniformis Zone (NP5) and Heliolithus kleinpellii Zone (NP6) are reported for the first time from the lower part of the Pabdeh Formation, respectively. Based on the identified calcareous nannofossils zones, the age of the upper part of the Gurpi Formation is the latest Maastrichtian–early Danian, and the lower part of the Pabdeh Formation is the middle Paleocene/Selandian. Therefore, according to the nannofossil data, the boundary between the two formations is unconformable.