The Alboran Sea is a river and eolian influenced margin characterized by recent depositional and erosive contourite features over the continental margins and deep basins. Their formation has been governed by the action of four superimposed water masses. The surficial one is the Atlantic Water (AW) and the other underlying three are of Mediterranean origin; from top to bottom they comprise the Winter Intermediate Water (WIW), Levantine Intermediate Water (LIW), and Western Mediterranean Deep Water (WMDW). The combined geomorphologic, seismic and oceanographic observations allowed to suggest that the most common processes responsible of the formation of contourites are attributed to: 1) turbulence (e.g., internal waves) along the water mass interphases, mostly those with the most enhanced contrast density (AW and WIW+LIW; LIW+WMDW) as well as their vertical displacement with time; 2) the occurrence of solitons related both to the AW circulation along the shelf-break and the Mediterranean waters interaction with morphological highs; 3) local helicoidal cores when LIW and WMDW meet with numerous highs; 4) topographic steering of the WMDW; 5) cyclonic recirculation on the WMDW: and 6) piracy of fine sediment transported within the gravity flows. When river and eolian sediments arrive to the sea they are quickly and largely dispersed first by the AW and later down by Mediterranean waters. Sediment dispersal is favored by the nepheloid layers formation along the water-masses interphases. These layers are also fed by resuspension of sediment when internal waves and solitons interact with the seafloor and local bottom current enhances, and by sequestration of fine sediment from gravity flows. The fast settling of the suspended particles would occur when current velocities decrease. Thus, nepheloid layers represent probably the major way of sediment transport at different water depths and depositing basinward with predominant along-slope component

This study is supported by the projects CTM 2008-06399-C04/MAR, CTM 2012-39599-C03, IGCP 619, INQUA 1204, ACTIONS MARGES program and EUROFLEETS Programme (FP7/2007-2013) under grant agreement n° [228344]

Ercilla, Gemma ... et al.-- 30th IAS Meeting of Sedimentology, 2-5 September 2013, Manchester

Peer Reviewed