Sedimentary expression of internal waves on Quaternary contouritic processes along the Irish and Moroccan Atlantic margins

• Main Author: Delivet, Stanislas
• Other Authors: Van Rooij, David, Louwye, Stephen
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Ghent University. Faculty of Sciences 2017
• Subjects: Earth and Environmental Sciences; Antarctic; The Antarctic; Antarc*
• Online Access: https://biblio.ugent.be/publication/8514402; http://hdl.handle.net/1854/LU-8514402; https://biblio.ugent.be/publication/8514402/file/8514412

This dissertation focuses on the mechanisms in which bottom currents dominated by internal wave processes controlled the large-scale architecture and sedimentary facies of marine sediments. Along the southern Irish margin, the build-up of large-scale sediment waves occurred throughout the Pleistocene, mainly ranging water depths between 1200 and 1600 m. This wave field could be attributed to the presence of energetic bottom currents, driven by enhanced internal wave and tide processes. The onset of these bottom currents was controlled by the introduction of the Mediterranean Outflow Water. The sedimentological analysis of the wave field at DSDP site 548 evidenced that the bottom current regime was climatically modulated over the past 500 ky. Enhanced bottom currents prevailed during interglacials, while they were reduced during glacials, which could be attributed to shifts in the Mediterranean Outflow Water northward advection. Energetic and variable internal tidal bottom currents have also influenced the sedimentation along the Atlantic Moroccan margin. At about 650 m water depth, the variable influence of the Antarctic Intermediate Water is thought to have driven the climatically modulated bottom current regime. Over the last 50 ky, enhanced bottom currents prevailed during Heinrich Events, Dansgaard-Oeschger stadials, and have caused erosional and/or non-depositional conditions with the onset and during most of the Last Glacial Maximum. At 1000 m water depth, energetic to erosive bottom currents gradually developed as the glacial stages became more pronounced over the past 1500 ky. Increased influence of Mediterranean eddies forced by sea-level decrease is thought to have driven the bottom current variability and internal wave processes over this period. This study highlights how changes in the general oceanic circulation pattern control local internal waves processes. These have a dramatic influence on the local sedimentation pattern and constitute important erosional processes. Furthermore, the presence of ...