ABSTRACT

The availability of onshore and offshore three-dimensional seismic surveys facilitated detailed seismic sequence-stratigraphic interpretation of a large swath of the western Nile Delta evolution since the late Oligocene. The resulting sequence-stratigraphic framework is calibrated against more than 60 wells. The interpretation of repetitive sequence boundaries, that is, unconformities, on seismic sections was constrained by high-resolution abundance and diversity within biostratigraphic data sets and lithofacies-stacking patterns interpreted from well logs.

Our series of depositional facies maps reflect environments of undifferentiated lowstand and transgressive systems tracts, that is, depositional elements interpreted between the lower bounding unconformity surface (sequence boundary) and maximum flooding surface above. These typically constitute terrestrial distributary channels and floodplains landward of strike-aligned lowstand deltas and marine shoreline deposits at and over the relict shelf break area of the underlying sequence boundary. Basinward deep-marine shales, slope channels, splays, fans, and terminal channel lobes define the remainder of the deposition over the rather extensive deep-marine slope apron region of the western Nile Delta. Incised valleys, canyons, and broad slope channels often confine any of the above-mentioned depositional facies at the lower bounding unconformity of each sequence.

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