Mediterranean Outflow Water dynamics into the Gulf of Cadiz since yhe Pleistocene.

• Main Author: Moal-Darrigade, Paul
• Other Authors: Environnements et Paléoenvironnements OCéaniques (EPOC), Observatoire aquitain des sciences de l'univers (OASU), Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Sciences et Technologies - Bordeaux 1 (UB)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-École Pratique des Hautes Études (EPHE), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université de Bordeaux, Emmanuelle Ducassou, Jacques Giraudeau
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2022
• Subjects: Drill sites; Contourites; Contourite drifts; Contour current; Drifts contouritiques; Courant de contour; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; North Atlantic
• Online Access: https://theses.hal.science/tel-03698468; https://theses.hal.science/tel-03698468/document; https://theses.hal.science/tel-03698468/file/MOAL_PAUL_2022.pdf

Sedimentation in the middle slope of the Gulf of Cadiz is strongly influenced by Mediterranean Outflow Water (MOW). The relationship between MOW, the Atlantic Meridional Overturning Circulation (AMOC) and climate variations in the North Atlantic is a major and complex issue. This PhD work focuses on the sedimentary characteristics of contourite drifts in the Gulf of Cadiz. Contourites are sedimentary bodies that can offer precious information on the variability of bottom current patterns and are used here to reveal the dynamics of the MOW since the Early Pleistocene. This study is mainly based on sedimentary archives collected during Integrated Ocean Drilling Program Expedition 339 "Mediterranean Outflow" (2011-2012) and marine sediment cores collected during oceanographic mission CADISAR (2001). The present work identifies the sources of clay minerals composing the deposits in the Cadiz contourite system as being fluvial inputs from the Guadalquivir and North African aeolian dust. Furthermore, it highlights the role of surface ocean circulation and MOW current in the distribution of clay minerals in the Gulf of Cadiz. The high resolution clay mineralogy and grain size measurements, along with ostracod assemblages performed as part of this work in sedimentary archives collected at various depth in the Cadiz contourite system have refined our understanding of the MOW circulation pattern for the last climatic cycle. Older sedimentary series covering Marine Isotopic Stadial (MIS) 12-11 show that the general circulation pattern established for MOW was also true for the most recent climatic analogue. Finally, high-resolution grain size measurements and clay assemblages over a long sedimentary series from the Faro Drift—dated with a novel isotope stratigraphy—evidence that the Faro Drift was established in three phases and reveal new details on the dynamics of the MOW since the Lower Pleistocene (1.2 Ma). La sédimentation de la pente moyenne du Golfe de Cadix est fortement influencée par l’écoulement d’un courant de ...