A synthesis of the sedimentary evolution of the Demerara Plateau (Central Atlantic Ocean) from the late Albian to the Holocene

• Published in: Marine and Petroleum Geology
• Main Authors: Fanget, Anne-sophie, Loncke, Lies, Pattier, France, Marsset, Tania, Roest, Walter, Tallobre, Cédric, Durrieu De Madron, Xavier, Hernandez Molina, F. Javier
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier BV 2020
• Subjects: Marginal plateau; Demerara Plateau; Contourite; Bottom currents; Mass transport deposits; Atlantic Ocean; Plateau Central; North Atlantic Deep Water; North Atlantic
• Online Access: https://archimer.ifremer.fr/doc/00599/71125/69439.pdf; https://doi.org/10.1016/j.marpetgeo.2019.104195; https://archimer.ifremer.fr/doc/00599/71125/

The Demerara Plateau, off the French Guiana and Surinam margin, corresponds to a prominent sub-horizontal marginal plateau. The interpretation of a large set of seismic data acquired along the Demerara Plateau and integration with previous seismic stratigraphy and drill studies enables a better understanding of the sedimentary evolution of the outer Demerara marginal plateau. Since the end of the transform activity (late Albian), three sedimentary evolutionary stages have been identified. 1) The Pre-contourite Stage (late Albian to early Miocene) is strongly controlled by the structure of the margin that influences the distribution pattern of post-transform deposits through differential thermal subsidence between transform and divergent segments. 2) The Transitional Stage (middle Miocene to early Pliocene) is expressed as a current-controlled erosive surface resulting from the onset of bottom-current interactions due to the establishment and strengthening of the modern thermohaline circulation that is coeval with the progressive closure of the Isthmus of Panama. 3) The Contourite Stage (middle Pliocene to Holocene) is characterized by the development of a contourite depositional system that is linked to the activity of the North Atlantic Deep Water circulation and by a complex interaction between alongslope and downslope processes. Our study highlights that marginal plateaus might be particularly prone to develop contourite features since they regionally influence ocean current dynamics in guiding and accelerating bottom contour currents. Marginal plateaus should thus be considered as a key target to study bottom current dynamics and paleocirculation patterns.