FN Archimer Export Format
PT J
TI Slope instabilities from echo-character mapping along the French Guiana transform margin and Demerara abyssal plain
BT 
AF LONCKE, L.
   DROZ, Laurence
   GAULLIER, V.
   BASILE, C.
   PATRIAT, Martin
   ROEST, Walter
AS 1:1;2:2;3:1;4:3;5:4;6:4;
FF 1:;2:;3:;4:;5:PDG-DOP-DCB-GM-LGG;6:PDG-DOP-DCB-GM-LGG;
C1 Univ Perpignan, Lab IMAGES, F-66860 Perpignan, France.
   Inst Univ Europeen Mer, CNRS, UMR 6538, F-29280 Plouzane, France.
   Univ Grenoble 1, CNRS, UMR 5025,Observ Sci Univers Grenoble, Lab Geodynam Chaines Alpines, F-38400 St Martin Dheres, France.
   IFREMER, DRO GM Geosci Marines, F-29280 Plouzane, France.
C2 UNIV PERPIGNAN, FRANCE
   UBO, FRANCE
   UNIV GRENOBLE, FRANCE
   IFREMER, FRANCE
SI BREST
SE PDG-DOP-DCB-GM-LES
   PDG-DOP-DCB-GM-LGG
IN WOS Ifremer jusqu'en 2018
   copubli-france
   copubli-univ-france
IF 1.684
TC 30
TU Centre national de la recherche scientifique
   Institut de recherche pour le développement
   Institut français de recherche pour l'exploitation de la mer
   Institut français des sciences et technologies des transports, de l'aménagement et des réseaux
   Service Hydrographique et Océanographique de la Marine
   Université de Bretagne Occidentale
   Université de Bretagne-Sud
   Université de Grenoble Alpes
   Université de Savoie
UR https://archimer.ifremer.fr/doc/2009/publication-6856.pdf
LA English
DT Article
CR GUYAPLAC
BO L'Atalante
DE ;Structural heritage;Fluids;Creeping;Transform margin;Slope instabilities
AB The French Guiana transform margin and Demerara abyssal plain have been recently surveyed in the framework of the EXTRAPLAC French Program of extension of the continental shelf (Guyaplac survey, Ifremer-IFP-SHOM-IPEV). Based on the interpretation of some of the data collected during the Guyaplac survey (Simrad-EM12 multibeam bathymetric data, backscatter imagery, and 3.5 kHz profiles), the area can be divided into three morphostructural domains. (1) The western Guiana margin, including a part of the Demerara plateau, an important bathymetric relief prolonging the continental platform off Guiana and Surinam. This domain is bounded by (1a) the NWSE trending northern border of the Demerara plateau which appears quite steep and corresponds to a transform segment of the margin, (1b) the N-S eastern border of the Demerara plateau which corresponds to a divergent segment of the margin. The Demerara plateau shows a segmented morphology, low slope gradients, and a very rough surface (ripples perpendicular to the slope direction). NNW-SSE structural steps seem to correspond to collapses of 100 km long blocs towards the east. Slumps initiate along these directions. The observed rough bathymetry seems to be related to creeping processes. At a greater scale (seismic data), this part of the margin has been totally destabilized (numerous imbricate transparent masses rooted at about 0.5 s.t.w.t.t. below seafloor). The NW-SE trending northern border of the Demerara plateau corresponds to a cliff-like continental slope, probably slightly smoother than other transform margins (Ghana/cote d'Ivoire margin). The N-S eastern border of Demerara plateau is characterized by numerous small-scale imbricate slumps. Some of these failures seem to be emplaced in the prolongation of the NNW-SSE structural steps identified on the Demerara plateau. (2) The eastern Guiana margin corresponds to a NW-SE oriented gullied transform margin segment. The associated continental slope is very steep and characterized by numerous imbricate slumps and related debris flows. Some undulated masses, probably corresponding to creeping sediments or to older mass-wasting events are still imprinted on bathymetry. This transform margin segment is nearly entirely destabilized and eroded. (3) The Demerara abyssal plain. This domain is characterized eastwards by channels belonging to the Amazon turbidite system and westwards, at the foot of Demerara continental slope, by sediment waves probably created by contour currents. To conclude, it seems that there is a strong relationship between the structure (transform and divergent segments) and the emplacement of recurrent slope instabilities. These are probably related to the steepness of the slopes but also to subsidence histories generating in some cases huge deep-seated collapses of the whole margin. Fluid ascents are common everywhere in the area, probably enhancing slope instability. Their origin is not constrained but the black shales or Cretaceous organic-rich layers could be good candidates.
PY 2009
PD MAY
SO Marine and Petroleum Geology
SN 0264-8172
PU Elsevier
VL 26
IS 5
UT 000266756500008
BP 711
EP 723
DI 10.1016/j.marpetgeo.2008.02.010
ID 6856
ER

EF