Flux and composition of settling particles across the continental margin of the Gulf of Lion: the role of dense shelf water cascading

Abstract

Abstract. Settling particles were collected using sediment traps deployed along three transects in the Lacaze-Duthiers and Cap de Creus canyons and the adjacent southern open slope from

Trophic state of benthic deep-sea ecosystems from two different continental margins off Iberia

“…1000 m and 1900 m depth (in the same stations investigated in the present study), provided evidence that, during the DSWC events occurring during winter/early spring 2005 and 2006, Cap de Creus canyon and the adjacent southern open slope received high amounts of organic material (up to ca. 75 % of the total annual organic matter fluxes; SanchezVidal et al, 2008SanchezVidal et al, , 2009Pasqual et al, 2010). Such huge inputs of organic material to the deep margin and basin are represented not only by organic particles of marine origin (due to the phytoplankton bloom occurring concomitantly on the shelf), but also by large amounts of organic particles of terrestrial origin (i.e.…”

“…Such huge inputs of organic material to the deep margin and basin are represented not only by organic particles of marine origin (due to the phytoplankton bloom occurring concomitantly on the shelf), but also by large amounts of organic particles of terrestrial origin (i.e. mainly from the Rhone River) resuspended on the shelf and transported down canyon and down slope Sanchez-Vidal et al, 2008Pasqual et al, 2010). Moreover, stable isotope and biochemical analyses revelead that this organic material settling on the seafloor was relatively labile (Sanchez-Vidal et al, 2008.…”

“…These events, driven by exceptionally strong, dry northern winds, spread down to the Catalan margin with maximum near-bottom current velocities of ca. 1 m s −1 Palanques et al, 2012) conveying large amounts of organic material into Cap de Creus canyon and the adjacent southern open slope Sanchez-Vidal et al, 2008Pasqual et al, 2010). Primary production in the Gulf of Lion ranges between 78 and 142 g C m −2 yr −1 (Lefevre et al, 1997).…”

A 500 kyr record of global sea-level oscillations in the Gulf of Lion, Mediterranean Sea: new insights into MIS 3 sea-level variability

“…In addition to northerly wind-induced DSWC, deep-water formation also occurs offshore during windy winters, where it may lead to deep convection (Millot, 1999). However, the sediment load involved in offshore convection is very low when compared to DSWC and major coastal storms, both constituting the most effective processes of sediment export from the shelf to the basin, mainly through submarine canyons Palanques et al, 2006;Pasqual et al, 2010;Sanchez-Vidal et al, 2008.…”

“…The inundation of the shelf during interglacial periods generated a relatively thin layer of water that was highly sensitive to atmospheric forcing, which may trigger the remobilisation of sedimentary particles temporarily stored on the shelf, as it happens during the present day highstand Canals et al, 2006;Dufois et al, 2008). Recent studies have demonstrated that nowadays northern cold, strong and persistent winds lead to DSWC down-slope at high speed (up to 1 m s −1 or more) during late winter and early spring months in the GoL coarser fraction efficiently scours and erodes the shelf edge and canyon heads and upper courses (Gaudin et al, 2006;Lastras et al, 2007;Pasqual et al, 2010;Puig et al, 2008;Sanchez-Vidal et al, 2008). Activation in the past of continental shelf erosive processes like DSWC probably did not lead to significant sediment accumulation in upper slope interfluves, but favoured the winnowing of fines and the supply of coarse lithic particles that, in combination with low sedimentation rates, contributed to generate CLs.…”