Numerical models of continental and submarine erosion: application to the northern Ligurian Margin (Southern Alps, France/Italy)
Résumé
We present a new numerical surface process model allowing us to take into account submarine erosion processes due either to submarine landslides or to hyperpycnal currents. A first set of models show that the frequency of hyperpycnal flows influences the development of submarine canyons at the mouth of continental rivers. Further experiments show that an increase in submarine slope leads to faster regressive canyon erosion and a more dentritic canyon network, whereas increasing the height of the unstable sediment pile located on the shelf break leads to wider and less dendritic canyons. The models are then applied to the western segment of the north Ligurian margin (northwestern Mediterranean), which displays numerous submarine canyons with various sizes and morphologies. From west to east, canyon longitudinal profiles as well as margin-perpendicular profiles progressively change from moderately steep, concave-up shapes to steeper linear to convex-up shapes suggesting increasing eastward margin uplift. Moreover, the foot of the margin is affected by a marked slope increase with evidences of mass transport due to landslides. Numerical models which reproduce well the North Ligurian margin morphologic features indicate that the western part of the margin is submitted to rather low (i.e. 0.4 mm yr−1) uplift and intense submarine erosion due to frequent hyperpycnal currents, whereas the eastern part bears more rapid (i.e. 0.7 mm yr−1) uplift and has little or no hyperpycnal currents. Copyright © 2014 John Wiley & Sons, Ltd.