Depositional Setting of the Seafloor and Near-Surface Interval on the Nile Cone, Deepwater Egypt: A View Using 3D Data from the Northeastern Mediterranean (NEMED) Seismic Survey

By

R.C. Shipp¹, J.A. Nott¹, J.L. Gibson¹

(1) Shell International E&P, Inc, Houston, TX

 Investigation of southern Northeastern Mediterranean (NEMED) Deepwater Block offshore of Egypt (on a large 3D seismic survey of ~7000 km2) to assess potential drilling hazards provided an opportunity to conduct a regional study of the seafloor and near-surface stratigraphy (upper 500 ms of seismic data) seaward of the Nile Delta in 900 to 2200 m of water depth. Analysis of the seafloor morphology revealed two distinct styles. The western two-thirds of the survey is characterized by flat first-order topography that is highly crenulated on a second-order scale of 1 to 10 m. Significant structural relief that exceeds 250 m in a well-developed graben system characterizes the eastern third of the survey. The near-subsurface interval reflects equally diverse stratigraphic patterns. Highly channelized packages dominate one stratigraphic near-surface interval of the western survey. Most channels features are single channel-levee systems, but one prominent channel-belt system exists. Ponded-fan sequences dominate the near-surface eastern survey. These fans occupy minibasins that occur throughout the near-surface section. Review of the deeper subsurface section indicates the thickness of Upper Miocene (Messinian) evaporites correlates well with the map and stratigraphic thickness of Quaternary and Upper Pliocene section. The structural control of evaporite thickness seems to be the primary control of seafloor morphology and near-surface stratigraphy. The striking variation of morphology and stratigraphy along strike is an exceptional example of the structural control of sedimentation, rarely observed in continental slope settings.