Eocene planktonic foraminifera from the north Eastern Desert, Egypt: Biostratigraphic, paleoenvironmental and sequence stratigraphy implications

The Eocene succession at Beni Suef -El Zaafarana District in north Eastern Desert is rich in planktonic foraminiferal assemblages.The main objectives of this work are to use the planktonic foraminifera to recognize the biostratigraphy for the Middle-Upper Eocene succession in the study area.Seventy planktonic foraminiferal species belonging to 20 genera and seven families are identified from the Eocene El Fashn and Beni Suef formations.Three planktonic foraminiferal biozones are recognized.These are from older to younger Morozovelloides crassatus Zone (late Middle Eocene) that is recorded from El Fashn Formation, Globigerinatheka semiinvoluta Zone (latest Middle Eocene -Late Eocene) and Globigerinatheka index Zone (Late Eocene age) that are recorded from the Beni Suef Formation while the Maadi Formation is found barren in planktonic foraminifera.These zones are correlated with those from nearby areas in Egypt and the Mediterranean regions.The Middle/Upper Eocene (Bartonian/Priabonian) boundary is discussed here in detail.The percentage of the planktonic foraminifera in the total foraminiferal content (P %) points to a change in water depth.There was a significant decrease in the planktonic/benthic foraminiferal ratio from the late Middle Eocene El Fashn Formation to the Late Eocene Maadi Formation at Beni Suef -El Zaafarana District.This ratio change supports a shallowing upward in paleodepth.Based on the lithology, planktonic/benthic ratio and the obtained water depth, the studied Eocene succession could be subdivided into four depositional sequences.These sequences agree with the global eustatic sea-level and the depositional sequences in nearby areas.