Subsurface Miocene sequence stratigraphic framework in the Nile Delta, Egypt

The Miocene depositional history of the Nile Delta is dominated by fluvial–deltaic, marginal marine and marine shelf sedimentation. It exhibits radical lateral facies changes due to its tectonic setting. Different attributions in age assignments characterise the Miocene Nile Delta due to the lack of large vertical facies changes, which consists mainly of siliciclastic with different environments. This study uses integrating lithologic, biostratigraphic, gamma-ray log and benthic foraminiferal biofacies, at four boreholes (Tanta-1, Rommana-1X, El-Fayrouz and Rosetta-7) in the Nile Delta, Egypt. Planktonic foraminifera allow subdivision of the Miocene Nile Delta succession into 12 planktonic biozones and benthic species are used in paleobathymetic estimates. Eight third-order Nile Delta Miocene sequences are bounded by eight major sequence boundaries, that can be correlated within and outside Egypt based upon planktonic foraminifera biostratigraphy. Chattian/Aquitanian (SB1) and Aquitanian/Burdigalian (SB2), intra-Burdigalian (SB3), Burdigalian/Langian (SB4), Langian/Serravallian (SB5), Serravallian/Tortonian (SB6) Tortonian/Messinian (SB7) and intra-Messinian (SB8): these boundaries in the Nile Delta are controlled by either eustatic processes and/or tectonic events. Each sequence contains a transgressive system tract bounded above by a maximum-flooding surface, and a highstand system tract. The lowstand systems tract and falling-stage systems tract is the main gas reservoir in the Nile Delta and recorded only below the Tortonian/Messinian and intra-Messinian sequence boundaries, that are marked by deep incisions and truncations. Variable patterns in the timing of regional deposition and erosion indicate different tectonic and sedimentary regimes, that encompass progressively greater periods of time southward in the Nile Delta.