Late Miocene contourite depositional system of the Gulf of Cádiz: The sedimentary signature of the paleo-Mediterranean Outflow Water

Abstract

Late Miocene contourite deposits related to the paleo-Mediterranean Outflow Water (MOW) were identified in the Betic and Rifian corridors prior to the restriction of the Mediterranean-Atlantic gateway during the latest Miocene. In this study, we identified for the first time their downstream continuation in the Gulf of Cádiz through seismic stratigraphic analysis and the interpretation of contourite diagnostic features. The late Miocene contourite depositional system (CDS) consists of three stages (initial-, growth-, and maintenance-drift) which recorded the late Tortonian to early Messinian evolution from weak to vigorous bottom current flow in the Gulf of Cádiz prior to its cessation in the middle to late Messinian, represented by the buried-drift stage. Development of the CDS in the Gulf of Cádiz is coeval to a period when the continental margins were affected by regional deformation. Tectonism and diapirism, on top of sedimentary and climatic factors, exerted control on drift distribution and dimensions. However, dataset limitations hindered detailed analysis on the effect of deformation on CDS evolution. Overall, the long-term evolution of the late Miocene CDS across the Gulf of Cádiz towards the West Iberian margin suggests strengthening of paleo-MOW during the late Miocene which has significant impact on the North Atlantic ocean circulation and the late Miocene global cooling trend.