Origen de los depósitos contorníticos en los márgenes Ibérico y Marroquí del Golfo de Cádiz

Resum

The interaction of the Mediterranean Outflow Water with the adjacent continental margins determines the evolution of the contourite features that exist in the northern and southern sides of the Gulf of Cadiz. This study is based on two cores, 2 m in length, each obtained from one side of the Gulf of Cadiz (TG-2 on the Moroccan margin; and GC01A on the Iberian margin). The multi-proxy analysis helped characterize the sediment facies and confirm the presence of contourites in both areas; we combined detailed sedimentary descriptions, physical properties (multi-sensor core logger), digital-scan photography, continuous-XRF element abundances (calibrated with few discrete sample concentrations), and mineralogy. Particular proportions of major and trace elements characterise the different contouritic facies associations. Oxygen and carbon isotopes on planktonic (G. bulloides) and benthic (C. packyderma) foraminifera allowed the identification of the water masses depositing the contourites. Core TG-2 records 4 contourites, the basal one exceeding 50 cm, and dated 12, 6 ± 55 Ky BP. These studies provide insights into the origin of contourites in the Gulf of Cadiz, the water masses implied in contourite deposition in the Moroccan and Iberian margins, and on the millennial–scale climate control on both onset and evolution.