Nannostratigraphy of deposits attributed to Gurpi-Pabdeh Formations boundary located in Izeh and Dezful embayment border, Zagros

The calcareous nannofossils are important in determining the relative age of the Mesozoic and Cenozoic layers.To study Cretaceous-Paleogene boundary, the section in East Ramhormoz were studied based on calcareous nanofossils. In this interval, were studied sediment thickness of 40 meters of shale and limestone and in this study, for the first time were identified 39 species of nannofossils. As a result this study were identified bio zones include Reinhardtites Levis Zone (UC18/CC24) and Arkhangelskiella cymbiformis (CC25/UC19) with Late Cretaceous ageand Heliolithus kleinpelli Zone (NP6) with Selandian/Thanetian age. Based on the zones obtained, the transition period examined is Maastrichtian-Selandian/Thanetian (Middle/Late Paleocene) and was determined the boundary between the Cretaceous to Paleogene of discontinuity type.