Description of a contourite depositional system on the Demerara Plateau: Results from geophysical data and sediment cores

• Published in: Marine Geology
• Main Authors: Tallobre, Cédric, Loncke, Lies, Bassetti, Maria-Angela, Giresse, Pierre, Bayon, Germain, Buscail, Roselyne, Durrieu de Madron, Xavier, Bourrin, François, Vanhaesebroucke, Marc, Sotin, Christine, Iguanes Scientific Party, The
• Other Authors: Centre de Formation et de Recherche sur les Environnements Méditérranéens (CEFREM), Université de Perpignan Via Domitia (UPVD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Géosciences Marines (GM), Institut Français de Recherche pour l'Exploitation de la Mer (IFREMER)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2016
• Subjects: Marginal plateau; Contourite; Comet tail; Demerara Plateau; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; NADW; North Atlantic Deep Water; North Atlantic
• Online Access: https://hal-univ-perp.archives-ouvertes.fr/hal-01336536; https://hal-univ-perp.archives-ouvertes.fr/hal-01336536/document; https://hal-univ-perp.archives-ouvertes.fr/hal-01336536/file/41220.pdf; https://doi.org/10.1016/j.margeo.2016.01.003

International audience The Demerara Plateau, belonging to the passive transform margin of French Guiana, was investigated during the IGUANES cruise in 2013. The objectives of the cruise were to explore the poorly-known surficial sedimentary column overlying thick mass transport deposits as well as to understand the factors controlling recent sedimentation. The presence of numerous bedforms at the seafloor was observed thanks to newly acquired IGUANES bathymetric, high resolution seismic and chirp data, while sediment cores allowed the characterization of the deposits covering the mass transport deposits. Modern oceanographic conditions were determined in situ, using mooring monitoring over a 10-month period. Our data indicate the presence of a Contourite Depositional System along the Demerara Plateau, most likely related to bottom current activity of the North Atlantic Deep Water (NADW). However, at the regional scale, large longitudinal waves parallel the NADW flow. Their shape and orientation seem to be inherited from interactions between bottom currents and paleomorphologies expressed at the top of mass transport deposits. Their evolution is possibly driven by the intensity of bottom current activity that might have changed over time. Overall, this work presents an integrated approach combining seismic and sedimentological evidence to study the processes at the origin of contourite formation in the Demerara Plateau. Other regional factors, such as local slope values and slope instability, also control sedimentation.