Paleoenvironments and Paleoclimate Reconstructions of the Middle–Upper Eocene Rocks in the North–West Fayum Area (Western Desert, Egypt): Insights from Geochemical Data

This study deals with the reconstruction of the paleoenvironment and the paleoclimate situation of the middle–upper Eocene sediments in the northwest Fayum area. The reconstruction is based on comprehensive stratigraphical and geochemical analyses of major oxides and trace elements for selected sediment samples from the Gehannam Formation (Bartonian–Priabonian), the Birket Qarun and the Qasr El Sagha formations (Priabonian). The sedimentological features coupled with paleo-redox trace elemental ratios (Ni/Co, V/Cr, U/Th, V/(V + Ni), and Cu/Zn), paleosalinity (Sr/Ba, Mg/Al ×100, Ca/Al), and paleowater depth (Fe/Mn) proxies, indicate that deposition took place in a shallow marine agitated environment with high oxygen levels. Paleoclimate indicators (Sr/Cu, Rb/Sr, K₂O₃/Al₂O₃, Ga/Rb, C-value, CIA, and CIW) suggest warm and prevailing arid climatic conditions, with minor humid periods at some intervals. The observed low values of the total organic carbon (TOC) are attributed to significant high sediment influx, predominant oxygenated conditions, and poor primary productivity, which is further confirmed by low values of paleoprimary productivity proxies (P, Ni/Al, Cu/Al, P/Al and P/Ti, and Ba_bio ratios). These findings enhance our understanding of the Eocene environments and provide insights into sedimentation processes during this period.