Aitor Rumin-Caparrós, CRG Marine Geosciences, University of Barcelona, Spain
Miquel Canals, CRG Marine Geosciences, University of Barcelona, Spain
Anna Sanchez-Vidal, CRG Marine Geosciences, University of Barcelona, Spain
Galderic Lastras,CRG Marine Geosciences, University of Barcelona, Spain
Antoni Calafat, CRG Marine Geosciences, University of Barcelona, Spain
César González-Pola, Instituto Español de Oceanografía, Gijón, Spain
The Avilés Canyon system: morphology and sediment transport
The Avilés submarine canyon system is one of the largest in Europe. It INCISEs the high-energy central Cantabrian margin in the Bay of Biscay extending down to the Biscay abyssal plain where it opens at 4765 m of water depth. It displays a complex morphology with three main branches, namely Avilés, El Corbiro and La Gaviera, and a large number of smaller tributaries, of which the most significant ones are those forming La Vallina branches entering the main Avilés Canyon trunk through its western side. Several of the reaches of the Avilés Canyon systems have a fairly evident structural control.
A detailed multibeam bathymetry mapping of this canyon system was carried out in the frame of the Spanish DOS MARES research project, jointly with a year-round (from March 2012 to April 2013) monitoring of environmental variables and particle fluxes. Furthermore, remote sensing images and meteorological and hydrographical data were also incorporated, thus constituting one of the most complete datasets on a large submarine canyon in Spain’s Atlantic margins.
In this contribution we will present the main results of such a study, with a focus in the information provided by seafloor backscatter imagery and its fit with the measured particle fluxes and the main factors controlling them. Particle fluxes are mainly driven by direct delivery of river-sourced material to a narrow continental shelf and by major resuspension events caused by large waves and near bottom currents developing at the occasion of the rather frequent severe storms that commonly occur in the Cantabrian Sea. Atmospheric and oceanographic conditions and associated Ekman transport largely determine whether or not sedimentary particles may easily reach the main canyon head, with two main modes that tend to follow a seasonal pattern. Tides add an extra amount of energy to the prevailing bottom currents within each transport mode, thus contributing to a permanent background of suspended particles in near-bottom waters and to the winnowing of the finer fraction, especially in the main canyon heads and upper courses. Organic matter, opal and calcium carbonate fluxes representing more than 30% of the total mass flux translate the impact of seasonal high primary production events. We will finally consider the atmospheric teleconnections linking the oceanographic conditions in the Cantabrian margin with those in the Northwestern Mediterranean margin, where other submarine canyons were monitored in parallel.
Theme 1: Canyon processes in the space-time continuum (formation, evolution, circulation)
Bay of Biscay, sediment transport; geomorphology; Avilés Canyon