Biostratigraphy plays a vital role in hydrocarbon exploration and paleoclimate studies by providing precise age control and correlation across sedimentary basins. Planktonic and benthic foraminiferal zonations, especially those developed for the Cenozoic, are widely used in marine sequences. Planktonic forams such as Globigerina, Globorotalia, and Morozovella are critical for open marine stratigraphy, while Large Benthic Foraminifera (LBF)—like Nummulites, Miogypsina, and Lepidocyclina—are used extensively in shallow carbonate platforms for dating and environmental interpretations.Similarly, calcareous nannofossil zonations, such as Martini (1971) and Okada & Bukry (1980), offer high-resolution chronostratigraphy, especially useful in fine-grained, deep-marine deposits. Species like Discoaster, Coccolithus, and Emiliania help detect climatic events like the PETM or MMCO.Together, foraminiferal and nannofossil zonations enable precise sequence stratigraphy, paleoenvironmental reconstructions, and identification of potential reservoir, source, and seal intervals in hydrocarbon-bearing basins.