Mass Movements in a Transform Margin Setting: The Example of the Eastern Demerara Rise

France Pattier (1, 2) , Lies Loncke (2) , Virginie Gaullier (2) , Bruno Vendeville (3) , Agnès Maillard (4) , Christophe Basile (5) , Martin Patriat (1) , Walter R. Roest (1) , Benoît Loubrieu (1)

1 GM - Unité Géosciences Marines
2 CEFREM - Centre de formation et de recherche en environnement marin
3 Géosystèmes - FRE 3298
4 LMTG - Laboratoire des Mécanismes et Transfert en Géologie
5 Tectonique reliefs et bassins

The eastern Demerara Rise located offshore French Guiana was surveyed in 2003 (GUYAPLAC cruise, part of the French EXTRAPLAC program) using multibeam bathymetry and imagery, 6-channel seismic data and 3-5 kHz echosounding. Analysis of seismic data shows that the flank of the Demerara Rise endures repetitive sliding of its Paleogene to Neogene sedimentary cover towards the ocean. Fluid escapes seem to be closely associated with the activity of those slides and deep faults seems to impact the location of the main headscarp. We suspect fluid overpressures and the specific architecture of transform boundaries ("free border") to be key parameters in the development of wide MTD's retrogressively eroding the eastern Demerara Rise.

Mots clés: Transform margin; MTD's; Demerara Rise; Fluid escapes

Domaines: Géomorphologie

France Pattier, Lies Loncke, Virginie Gaullier, Bruno Vendeville, Agnès Maillard, et al.. Mass Movements in a Transform Margin Setting: The Example of the Eastern Demerara Rise. Yasuhiro Yamada, Kiichiro Kawamura, Ken Ikehara, Yujiro Ogawa, Roger Urgeles, David Mosher, Jason Chaytor and Michael Strasser. Submarine Mass Movements and Their Consequences, Springer, pp.331-339, 2012, Advances in Natural and Technological Hazards Research, Vol. 31, 978-94-007-2161-6. ⟨10.1007/978-94-007-2162-3_30⟩. ⟨insu-00682067⟩