First evidence of a main channel generated by the Mediterranean Outflow Water after its exit from the Gibraltar Strait

Abstract

An extensive terrace comprising sandy sheeted drifts characterises the proximal sector (close to the Straits of Gibraltar) of the Contourite Depositional System (CDS) of the Gulf of Cadiz and the western continental margin of Portugal. A novel morphosedimentary study over this terrace has been executed based on new multibeam echosounder data, seismic profiles, and surficial sediments samples collected during the CONTOURIBER-1 Cruise (2010). Based on that study, an impressive large channel laterally connected with the central part of the Strait of Gibraltar (Camarinal Sill) has been identified. It is associated southwestward with a huge contourite levee (sand bank), which has been generated by overflow processes related to the Mediterranean Outflow Water (MOW). In the middle to the distal part of the terrace, there are other minor channels, erosional scour alignments and depositional features. The mapping of all these features coupled with CTD data allows to further understand the pathway and deceleration of the MOW, in addition to aid the conceptual identification of contourite terrace.