--> Abstract: Quaternary Depositional History of the Central and Western Nile Fan, Offshore Egypt, by C. Simon Newton, R. Craig Shipp, Grant D. Wach, and David C. Mosher; #90039 (2005)

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Quaternary Depositional History of the Central and Western Nile Fan, Offshore Egypt

C. Simon Newton1, R. Craig Shipp2, Grant D. Wach1, and David C. Mosher3
1 Dalhousie University, Halifax, NS
2 Shell International E&P, Inc, Houston, TX
3 Geological Survey of Canada Atlantic, Dartmouth, NS

Conventional 2D and 3D seismic exploration data are used to develop the Quaternary stratigraphy and assess controls on sedimentation processes for the deep water Nile Fan, offshore Egypt. The deep water Nile Fan is a high sedimentation rate environment in an active seismogenic zone. The Quaternary section, locally up to a kilometer thick, is dominated by submarine channel systems and mass transport deposits. Regional mapping within the central and western Nile Fan from conventional seismic data reveals the presence of seven large mass transport complexes each displacing greater than 100 km3 of sediment. These data show a link between extremely large slope failure events and development of submarine canyons and channel systems. Trigger mechanisms for catastrophic slope failure are uncertain, but are likely related to a combination of high sedimentation rates causing low vertical effective stresses and ground shaking due to seismicity.

Each large slope failure initiates on the upper slope creating an extensive region of sediment evacuation, leaving a headwall scarp accompanied by a thick accumulation of mass transport deposits on the mid-slope. Submarine canyons appear to establish on the upper slope within the headwall scarp immediately following a major slope failure event. These canyons then serve as the principal conduits for sediment transport to deepwater. By this mechanism, large slope failures may mark major shifts in deepwater turbidite depocenters that can be traced on regional seismic data. In exploring for hydrocarbons in turbidite basins, it is necessary, therefore, to understand this relationship between catastrophic sediment failure, canyon formation and turbidite deposition.

AAPG Search and Discovery Article #90039©2005 AAPG Calgary, Alberta, June 16-19, 2005