In this study, the late-Maastrichtian and early-Paleocene transition at the Ziarat-Kola section has been investigated to recognize the biostratigraphy and paleoenvironmental changes. We applied a high-resolution quantitative study by using planktic foraminifera taxa and benthic foraminiferal morphotypes. Sixty-five species belong to twenty-eight genera were identified and seven biozones were differentiated. These biozones are 1. Racemiguembelina fructicosa, 2. Pseudoguembelina hariaensis, 3. Pseudoguembelina palpebra, 4. Parvularugoglobigerina eugubina, 5. Parasubbotina pseudobulloides, 6. Subbotina triloclinoides, 7. Globonomalina compressa-Preamurica inconstans. In the late Maastrichtian, benthic and planktic foraminifera are well mixed of epifauna/infauna morphotypes and diversified suggesting a stable and mesotrophic environment. By contrast, the early Paleocene is marked by high values of epifaunal benthic morphogroups, and extinction of Cretaceous species suggesting highly unstable and variable conditions, partly due to the dramatic collapse of calcareous primary producers. Additionally, four different zones were determined based on the benthic foraminifera morphogroups that show several changes in oxygen and organic matter flux during this time. Also, analysis of planktic foraminifera genera in this section indicating a close similarity with assemblages in Tethyan provinces.
This study contributes a new methods to understand the biostratigraphy and ageing the rock samples in late Cretaceous of eastern Tethys. Also, This study is one of very few studies which have investigated the pal ecology and oxygen changes in Campanian-Maastrichtian sediments by using the plank tic and benthic foraminfera that are small microorganism.