Facies analysis and sequence stratigraphy of the Eocene successions, east Beni Suef area, eastern Desert, Egypt

Abstract

Three Eocene stratigraphic successions east of the Beni Suef area are described and measured. These successions are made up of four rock units that are from base to top: Qarara (upper Lutetian), El Fashn (Bartonian), Beni Suef, and Maadi (Priabonian) formations. A detailed facies and sequence analysis unravels the stratigraphic framework and constructs a depositional model for the Middle-Upper Eocene succession. Ten microfacies types were grouped into four facies associations on a homoclinal ramp that compose the Upper Lutetian-Priabonian succession exposed in the east Beni Suef area. The depositional environment varied from a shallow to deep ramp setting. Four third-order depositional sequences were identified in the studied sections. The sequence boundaries are paleosoil horizons that can be traced throughout the entire outcrop area. Missing biozones are also evidence of the sequence boundaries. The history of these sequences mirrors the eustatic sea-level changes and the local tectonics in the region. Each sequence comprises facies associations that make up lowstand and/or transgressive and highstand systems tracts. The lowstand systems tract (LST) deposits are mainly sandstone facies and in Sequences 3 and 4 at Gabal Abyiad and Gabal Homret Shaibun respectively. The transgressive systems tract (TST) of Sequence 1 is dominated by nummulitic facies at Gabal Diya. The shale, mudstone and wackestone facies with planktic foraminifera and echinoids dominate the TST of Sequences 2 and 3 at Gabal Abyiad and Gabal Homret Shaibun respectively. The highstand systems tract (HST) of the studied sections is characterized by benthic foraminifera and bryozoan wackestone and packstone facies.