Morphologies in River-Connected Canyons: Examples from Northeast Atlantic and
Gaudin, Matthieu1, Pierre Cirac1, Serge Berné2, Thierry Mulder1 (1) Université Bordeaux 1, Talence, France (2) Ifremer, Plouzané, France
The canyons of Capbreton and Bourcart are located on the
Atlantic Ocean and occidental
During lowstands, Capbreton and Bourcart canyons were both
connected to rivers which supplied large amount of sediments derived from the
erosion of Pyrenees and
The Capbreton canyon morphology evolves owing to perennial, highly erosive, gravity driven mass movements flowing down the axial channel. They induce meander migrations and abandonment, slope failures and contribute to the initiation and evolution of “terraces”. These terraces are interpreted as typical sedimentary levees, slump deposits or nested levees.
During sea-level fall, the Bourcart canyon excavated under the combined effect of erosion by gravity driven currents and retrogressive failures. The sediment supply during glacial maximum leads to an entire or partial filling of the head of the canyon up to 400 m thick. This infill comprises slope failure, sedimentary levees and chaotic facies. With the rising of the sea level and river disconnection, direct supplies ended, and the present morphology is preserved.