The ‘Fleuve Manche’: the submarine sedimentary features from the outer shelf to the deep‐sea fans

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Abstract
Bathymetric, seismic and coring surveys have been carried out since the beginning of the 1990s on the outer shelf, the slope and the continental rise of the Western Approaches margin. Most of the sedimentary features studied belong to a sedimentary system built up since the Oligocene and fed by a palaeoriver, the ‘Fleuve Manche’ that flowed in the English Channel during eustatic lowstands. A geomorphological map details the spatial distributions of the palaeovalleys on the outer shelf, the drainage‐basin‐like organised canyons on the slope and the channel–levee and lobe complexes on the rise. The obvious channel–canyon connections and the assessed palaeovalley–canyon links demonstrate that the ‘Fleuve Manche’ was the single source for terrigeneous fluxes of the Armorican Deep Sea Fan when it was one of two sources of the Celtic Deep Sea Fan. Amongst parameters controlling the sedimentation, two factors play a major role. (i) Subsidence controlled the possibly Messinian riverine incision, the turbidite activities during lowstands, as well as marine infilling of the seawards part of the ‘Fleuve Manche’. (ii) Quaternary sedimentary supplies were influenced by the melting ice‐sheets and the connections with the onshore catchment basins. Copyright © 2003 John Wiley & Sons, Ltd.