Mass movements in a transform margin setting: The example of the eastern demerara rise

Abstract

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. © Springer Science+Business Media B.V. 2012.