First Report of Ornatorotaliidae Family Representative species and Paleocene-Eocene Biostratigraphy in Hasan Abad section, southeast of Birjand, East of Iran

The present study aimed to investigate the biostratigraphic studies of Hasan Abad section (two sections), located in the southeast of Birjand in the east of Iran. The thickness of the first section of Hasan Abad is 74 meters, and the second section is 62 meters thick, including conglomerate, sandstone, calcareous sandstone, sandy limestone, limestone, and nummulitic limestone. The base of these sections is overlaid on the ophiolites, and their tops are erodedIn total, 21 genera and 29 species of benthic foraminifera were identified in the first section, and four biozones were consequently determined. These biozones included the Daviensina sp. interval zone, Alveolina ellipsoidalis interval zone, Nummulites globulus interval zone and Nummulites subramondi interval zone. In the second section, 16 genera and 21 species were identified, and three biozones were introduced based on the identified foraminifera, including Kathina selveri interval zone, Alveolina ellipsoidalis interval zone and Nummulites globulus interval zone. According to the identified biozones and foraminiferal assemblages, the age of the studied sequence was speculated to be the first section of Hasan Abad, Thanetian? - Early Cuisian and in the second section the Thanetian -Early Cuisian. Two new species of the Ornatorotaliidae family, Granorotalia sublobata and Ornatorotalia granum, are the first records from the east of Iran.