Landslide and gravity flow features and processes of the Nazaré and Setúbal Canyons, west Iberian margin

Abstract

The Nazaré and Setúbal Canyons of the west Iberian margin are highly complex seafloor environments, displaying a range of sedimentary features and processes that reflect the transition from erosive upper to depositional lower canyon. Upper sections are characterised by a deeply incised, narrow, V-shaped thalweg, and frequent localised intra-canyon slope failures. Lower sections have a U-shaped floor with heterogeneous sediment distribution. Two types of gravity flow are observed: thin-bedded, finegrained deposits that may be the result of frequent turbidity currents generated by high sediment supply to canyon heads, and thicker, siliciclastic coarse sandy turbidites, probably generated by larger earthquake-triggered slope failures on much longer timescales. Our results highlight the complex interplay of sedimentary processes operating within major canyon systems.