Sedimentary evolution of the Le Danois contourite drift systems (southern Bay of Biscay, NE Atlantic): A reconstruction of the Atlantic Mediterranean Water circulation since the Pliocene

• Published in: Marine Geology
• Main Authors: Liu, Shan, Hernández-Molina, Francisco J., Ercilla, Gemma, Van Rooij, D.
• Other Authors: China Scholarship Council, European Commission, Royal Holloway, University of London, Ministerio de Economía y Competitividad (España), Agencia Estatal de Investigación (España)
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Elsevier 2020
• Subjects: Seismic stratigraphy; Contourite depositional systems; Bottom currents; Continental margin evolution; Southern Bay of Biscay; North Atlantic
• Online Access: http://hdl.handle.net/10261/217467; https://doi.org/10.1016/j.margeo.2020.106217; https://doi.org/10.13039/501100003329; https://doi.org/10.13039/501100004543; https://doi.org/10.13039/501100000780; https://doi.org/10.13039/501100011033

19 pages, 11 figures, 1 table The evolution of the Le Danois contourite depositional systems (CDS) during the Pliocene and Quaternary was investigated based on high-resolution seismic reflection data. From old to young, six seismic units (U1–U6) bounded by major discontinuities (H1–H6) were identified. Regarding variations of the bottom-current circulation, four evolution stages of the Le Danois CDS were identified, including onset (~5.3 to 3.5–3.0 Ma), initial (3.5–3.0 to 2.5–2.1 Ma), intermediate (2.5–2.1 to 0.9–0.7 Ma) and drift-growth (0.9–0.7 Ma to present day) stages. The CDS associated with the Atlantic Mediterranean Water (AMW) along the middle continental slope initiated at ~3.5–3 Ma and was widely built after the Mid-Pleistocene Transition (MPT; 0.9–07 Ma). At a shallower water depth, a second CDS associated with the Eastern North Atlantic Central Water (ENACW) started to develop from the late Quaternary (~0.47 Ma) onwards. In the AMW-related drift system, the Le Danois Drift was generated both under glacial and interglacial climatic oscilations. Repeated internal structures in unit 5 that consist of acoustically transparent lower parts, moderate amplitude upper parts and high amplitude erosional surfaces at the top, are compared with interglacial/glacial cycles since the middle Pleistocene to the present day. These cyclic features suggest coarsening-upward sequences of the Le Danois Drift and processes related to enhanced AMW during glacial stages. The estimated sedimentation rate of the Le Danois CDS reached a maximum during the MPT (at least ~27 cm/ky) and then decreased until present-day (~5 cm/ky). Variations of sedimentary stacking patterns and processes of the Le Danois CDS imply full domination of the intermediate water mass along the central Atlantic and southwest European continental slopes from the late Pliocene (~3.5–3.0 Ma) onwards This study was carried out within the framework of a Chinese Scholarship Council “CSC Grant” (201506410062). This study built on achievements of project ESF ...