Morphology and sediment dynamics of the northern Catalan continental shelf, northwestern Mediterranean Sea

Abstract

The northern Catalan continental shelf, in the northwestern Mediterranean Sea, extends along 200 km from the Cap de Creus submarine canyon to the Llobregat Delta, in the vicinity of the city of Barcelona. In this paper we present the results of a systematic investigation of this area by means of very high-resolution multibeam bathymetry to fully assess its morphological variability. The causative factors and processes determining such variability are subsequently interpreted. The shelf is divided in three segments by two prominent submarine canyons: the northernmost Roses Shelf is separated from the intermediate La Planassa Shelf by the La Fonera Canyon, while the boundary between the La Planassa Shelf and the southernmost Barcelona Shelf is marked by the Blanes Canyon. These two canyons are deeply incised in the continental margin, with their heads located at only 0.8 and 5 km from the shore, respectively.

The seafloor character reflects the influence of external controlling factors on the geomorphology and sedi- ment dynamics of the northern continental shelf of Catalonia. These factors are the geological setting, the vol- ume and nature of sediment input, and the type and characteristics of processes leading to sediment

redistribution, such as dense shelf water cascading (DSWC) and eastern storms. The interaction of all these factors determines sediment dynamics and allows subdividing the northern Catalan continental shelf into three segments: the erosional–depositional Roses Shelf to the north, the non-depositional La Planassa Shelf in the middle, and the depositional Barcelona Shelf to the south. Erosional features off the Cap de Creus Peninsula and an along-shelf subdued channel in the outer shelf illustrate prevailing sediment dynamics in

the Roses segment, which is dominated by erosional processes, local sediment accumulations and the south- ward bypass of sediment. The rocky character of the seafloor immediately north of the Blanes Canyon head

demonstrates that neither significant sediment inputs from the Tordera River nor from the northern sources reach the southern part of the La Planassa Shelf. Palaeo-shorelines depict a number of paleodeltas with steep delta fronts on the drowned Barcelona Shelf.