Lateral Changes of Frontal Accretion and Mud Volcanism Processes in the Barbados Accretionary Prism and Some Implications

This paper focuses on tectonic, sedimentary, and hydrogeologic processes presently occurring at the eastern leading edge of the Barbados accretionary prism. Thrusts and folds develop over a dcollement hosted at the deformation front in weak and probably undercompacted sedimentary layers of Miocene age. The volume of the anticlinal potential traps is changing from north to south and is related to the thickness of accreted sediments, i.e., of the Neogene-Quaternary section. This thickness is increasing drastically from north to south as it approaches the South American continent and the Orinoco deep-sea fan. The middle and distal parts of this fan are now being incorporated into the prism, supplying the piggyback basins developing between the growing folds and the immediate foreland in front of the prism with deep-water clastic sediments. These potential reservoirs in the Neogene-Quaternary section are possible targets for future exploration, subject to their geophysical identification, in such areas where the seismic resolution may be altered seriously by the complexity of structures. The distribution of potential source rocks is poorly known, but marine middle–Late Cretaceous source rocks are widespread on the northern South American continent, and also may have been deposited in the near-deep marine environment. Efficient paths for the migration of hydrocarbons originating and expelled from such source rocks are provided by deep-water clastic layers, active faults, and widespread mud volcanoes. The success of efficient entrapment of hydrocarbons could, in some cases, be hampered seriously by the efficiency of these vertical conduits connecting deep stratigraphic layers and the sea bottom.