Echofacies interpretation of Pleistocene to Holocene contourites on the Demerara plateau and abyssal plain
|Author(s)||Tallobre Cédric1, Loncke Lies1, Droz Laurence2, Marsset Tania3, Uusõue Mirjam4, Roest Walter3, Fanget Anne-Sophie1, Bassetti Maria-Angela1, Giresse Pierre1, Bayon Germain3|
|Affiliation(s)||1 : Université de Perpignan Via Domitia, Centre de Formation et de Recherche sur les Environnements Méditerranéens (CEFREM), UMR 5110, Perpignan, France..
2 : Université de Bretagne Occidentale (UBO)/UMR 6538 du CNRS Domaines Océaniques, Plouzané, France..
3 : IFREMER, Unité de Recherche Géosciences Marines, Plouzané, France..
4 : Tartu Observatory, Observatooriumi 1, Tõravere, 61602 Tartumaa, Estonia..
|Source||Interpretation-a Journal Of Subsurface Characterization (2324-8858) (Society of Exploration Geophysicists), 2021-05 , Vol. 9 , N. 2 , P. SB49-SB65|
|WOS© Times Cited||1|
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.