Emergent features in northern Western Desert, Egypt: proxies for progressive uplifting of the Tethys platform and the related palaeoclimate shifts since the latest Cretaceous

Abstract

The study elucidates the progressive emergence of the southern Tethys platform in Egypt and the associated palaeoclimatic changes, with a focus on their relevance to regional climatic events from the latest Cretaceous through the Late Eocene. The investigation focuses on shoaling and subaerial exposure features identified near the K/Pg boundary, at the top of the Middle Eocene, and within the Upper Eocene rock succession exposed along the western flank of the Giza Pyramids Plateau, northern Western Desert. Key indicators of subaerial exposure include post- and latest-Cretaceous karst pockets, bauxite-filled karst fissures, terra rossa-rich debris flow deposits, dissolution features, and characteristic patterns of dolostone dissolution and dedolomitization. Furthermore, the presence of a shoaling-upward stacking pattern, characterized by abundant Microcodium aggregates within the mixed siliciclastic-carbonate deposits of the Upper Eocene Wadi Hof Formation, underscores the repeated emergence of the southern margin of the Tethys platform in Egypt during this interval. Following the deposition of Upper Eocene–Lower Oligocene marginal marine facies and a subsequent regression, the study area transitioned into a terrestrial environment. This setting was later shaped by Miocene fluvial systems, which deposited extensive clastic sediments across the region. Since the latest Cretaceous, the northern Western Desert has undergone marked climatic shifts. Initially, warm and humid tropical to subtropical conditions aligns with MECO dominated until the Middle Eocene, as indicated by karstification and pedogenesis features. By the Late Eocene, the climate had transitioned to cooler, arid to semi-arid conditions, evidenced by the presence of Microcodium aggregates, indicators of calcic paleosol formation.