Morphology of the Nile Deep-sea Fan from Combined Swath Bathymetry and 3D Seismic Data First Arrivals

By

Olivier Sardou¹, Jean Mascle², Lies Loncke³, Paul Boucher⁴, Vince Felt⁴

(1) Géosciences Azur, 06235 Villefranche/Mer, France (2) Geosciences Azur, 06235 Villefranche-sur-Mer, France (3) Géosciences Azur, 06235 Villefranche-sur-mer, France (4) BP Amoco, Houston, TX

 A bathymetric synthesis of the Nile marine fan, from the shelf to the northern bordering abyssal plain, has been compiled using different data sets: swath bathymetry from scientific surveys using respectively Simrad EM12 and EM300 dual systems, and first arrivals from 3D surveys made available by BP-Amoco Egypt along the shelf and upper slope. Locally, in deeper areas, this detailed map has been completed using regional ICBM data. This compilation allows one to define and illustrate different morphological provinces, and particularly to stress the drastic contrast between an Eastern province whose morphology is clearly controlled by active tectonics, and a Western domain, chiefly characterized by important channel-levee systems in prolongation with the onshore-offshore Rosetta feeding sytem. Four 3D views of selected areas allow to better visualize key-processes of the deep-sea fan: (1) A first one shows the detailed morphology of the Rosetta canyon, that cuts the continental shelf from a depth of 60 meters up to the upper slope, and constitutes the main active turbiditic path for the deep-sea fan. (2) A second 3D block shows, in the same province, the contrasted morphology induced by combined growth faults and “mud-volcanoes” features, probably releasing huge quantities of fluids. (3) Eastwards, the Eratosthenes seamount appears cut by normal and strike-slip active faults that are triggering well-imaged sedimentary destabilizations. (4) Offshore of the Nile Damietta branch, the morphology of the Eastern province is strongly controlled by a complex interplay between salt-related polygonal slope basins, sub-linear tectonic faults, and large, almost circular, mud structures.