Echofacies interpretation of Pleistocene to Holocene contourites on the Demerara plateau and abyssal plain - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Interpretation-A Journal of Subsurface Characterization Année : 2021

Echofacies interpretation of Pleistocene to Holocene contourites on the Demerara plateau and abyssal plain

Cédric Tallobre
  • Fonction : Auteur
Lies Loncke
  • Fonction : Auteur
Laurence Droz
  • Fonction : Auteur
Tania Marsset
Mirjam Uusõue
  • Fonction : Auteur
Walter Roest
Anne-Sophie Fanget
  • Fonction : Auteur
Maria-Angela Bassetti
  • Fonction : Auteur
Pierre Giresse
  • Fonction : Auteur
Germain Bayon

Résumé

Off French Guiana and Surinam, NADW and AABW oceanic currents contour the Demerara marginal plateau, which promotes the formation of contourites. We have studied these contourites thanks to a new compilation of high-resolution sub-bottom profiles calibrated by sedimentary cores. The echo-facies and isopach maps we constructed highlight a sedimentary distribution parallel to the isobaths. The presence of moats along the slope is confirmed by the observation of parallel, elongated, sedimentary depleted zones and echo-facies strongly affected by diffraction hyperbola and transparent echo-facies. We interpret these features to be related to eroded slopes and Mass Transport Deposits. In contrast, the sedimentary drifts we mapped are characterized by elongated and thick slope-parallel depocentres displaying bedded echo-facies with wave-like bedforms. According to our interpretation, they result from interactions between currents and the seafloor. Seismic wipe-outs frequently affect those drifts, possibly resulting from high water or organic contents.

Dates et versions

hal-04203342 , version 1 (11-09-2023)

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Citer

Cédric Tallobre, Lies Loncke, Laurence Droz, Tania Marsset, Mirjam Uusõue, et al.. Echofacies interpretation of Pleistocene to Holocene contourites on the Demerara plateau and abyssal plain. Interpretation-A Journal of Subsurface Characterization, 2021, 9 (2), pp.SB49-SB65. ⟨10.1190/INT-2020-0159.1⟩. ⟨hal-04203342⟩
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