Institution: | aGéosciences Azur, BP 48, 06235, Villefranche-sur-Mer, France bUniversité Bordeaux 1, UMR-CNRS 5805 EPOC, av. des facultés, 33405 Talence cedex, France cUniversité de Picardie Jules Verne, UMR 8110, Dept de Géologie, 80000 Amiens, France |
Abstract: | In the Nile deep-sea turbidite system (NDSTS), the province fed by the Rosetta branch of the Nile delta is characterised by the recurrent activity of gravity processes. Seven mass-transport deposits (MTDs) were recognised from the upper to the mid slope, downstream from imbricated scars (~ 30 km-long, ~ 200 m high) running along the shelf edge nearby the Rosetta canyon. Extending on surfaces between 200 and 5000 km2, with estimated volumes from 3 to 500 km3, these MTDs represent about 40% (up to 90% locally) of the total Pleistocene–Holocene sedimentary thickness. Three types of MTDs can be distinguished on the basis of their scale. Each has also a distinctive internal configuration and distribution within the Rosetta depositional setting. Age estimates of two MTDs point towards relationships between climate and submarine mass failures through sea-level changes, sediment supply, or a combination of both. Additionally, the presence of gas in the sediment and earthquake shaking may have concurred to trigger large-scale failures on the low slope angles (1°–2°) of the Rosetta area. |