Global Climate Recovery and Marine Ecosystem Shifts Across the Oligocene–Miocene Transition:Foraminiferal Evidence From the Offshore Nile Delta,EgyptOA

Oligocene-Miocene transition(OMT)~23 million years ago was a critical global climatic change,involving Mil glaciation and later recovery.Multi-proxy,high-resolution investigation into foraminiferal assemblages from the offshore Nile Delta in the eastern Mediterranean(PFMD-2R well) reconstructs significant regional late Oligocene to Miocene paleoenvironmental change.We report a marked postglacial warming and a significant increase in nutrient availability from the cool,oligotrophic,low-oxygen Chattian conditions characterised by stressed assemblages with Globigerina glutinata to the warm,extremely productive,well-oxygenated Burdigalian with diverse tropical-subtropical species such as Paragloborotalia semivera.The Aquitanian is characterised as a dynamic,transitory phase.Planktonic foraminifers were resilient,exhibiting high diversity throughout.Conversely,benthic assemblages were radically compromised in the Chattian,recovering later and indicative of a foundational inequality in ecosystem sensitivity.Paradoxically,this recovery correlated with a general shallowing trend of the water depth.Multivariate analyses affirm significant ecological reshaping attributable to post-Mil climatic restoration.These semi-restricted-basin findings document the sophisticated interaction between global climatic forcing and regional responses in the ocean,stressing divergent biota recovery pathways between pelagic and ground-dwelling biota.