Résumé
Geophysical data acquired in the southeastern Caribbean deep-marine area are used to investigate the deformation processes in a transition zone between a frontal subduction zone and a compressional transform system. This study shows the complexity of the connection between the active transform fault system of the south of the Caribbean plate and the active frontal accretionzone of the front of the Barbados accretionary prism. The hinge between the Barbados accretionary prism and the south Caribbean transform system is partitioned between a wide variety of recently active tectonic superficial features developed over a largescale diffuse plate boundary. Multibeam and seismic data show sublinear ramp anticlines developing at the leading edge of the prism, whereas a complex arrangement of folds is apparent at the southern lateral border of the prism, with notably, interference features occurring between different anticline trends. Near the deformation front of the southernmost part of the prism, the fold-and-thrust system vanished out toward the south with an en-echelon geometry. Numerous active mud volcanoes are well developed notably along ramp anticlines.A sublinear fault zone crosscuts the Orinoco Delta obliquely with respect to the continental slope from the south of the Columbus basin to the Atlantic abyssal plain. This fault line is characterized by active east-northeast–west-southwest normal dextral en-echelon strikeslipfaults deforming the sea bottom at the vicinity of the South America Margin, whereas at depth, faulting mechanisms of deep earthquakes are characteristic of a sinistral movement. This characterizes a complete decoupling between the aseismic deformation of the upper part of sedimentary pile and the seismic deep lithospheric movements. We interpret this overall tectonic feature in the Orinoco delta fault zone as the consequence of a recent reactivation of the Guyana transform margin around the continent–ocean transition. This could be a consequence of a deep shearing of the lithosphere at the southern edge of the Atlantic subductingslab below the Caribbean plate.