The sandy channel–lobe depositional systems in the Gulf of Cadiz: Gravity processes forced by contour current processes

Abstract

The sedimentation in the Gulf of Cadiz (NE Atlantic Ocean) is significantly controlled by the Mediterranean Outflow Water (MOW). Along its pathway onto the continental slope, the MOW is canalized by contourite channels, some of them feeding gravity sandy channel–lobe depositional systems firstly recognized in previous study [Habgood et al., 2003. Deep-water sediment wave fields, bottom current sand channels and gravity flow channel–lobe systems: Gulf of Cadiz, NE Atlantic. Sedimentology 50(3), 483–510.]. Using very high resolution acoustic data and cores, a detailed characterization and a new evolution pattern of these channel–lobe depositional systems is established. Complex internal geometry of the lobes shows several depositional units revealing a polyphase evolution of these systems, with a general progradation punctuated by retrogradation and avulsion phases. A gravity origin controlled by contouritic processes and climatic changes is demonstrated for the feeding and the evolution of these sandy channel–lobe depositional systems. Climate oscillations, via the MOW variations, act as a major forcing of the activity of the channel–lobe depositional systems during the Late Quaternary.