Abstract 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 décollement 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.

Abstract Geophysical and geological investigations suggest processes of sedimentary accretion and evolution of a forearc basin in the Southern Hispaniola region. Several different sedimentological and structural domains are defined on multichannel seismic reflection lines offshore. Other domains, including pelagic abyssal plain, trench, accretionary wedge, and forearc basin, are identified in the onshore outcrops in Southern Hispaniola. Onland deposits of the pelagic and trench domains (Southern Peninsula and Enriquillo trough), located north of Beata Ridge, are considered slightly different from the offshore ones because of collision between the thick crusts of Beata Ridge and the Central Cordillera. Accretionary wedge and forearc basin domains (Sierra de Neiba, Sierra El Numero, San Cristobal basin) provide sedimentlogical and stratigraphical data concerning the evolution of the margin. Widespread distribution of Oligocene heterometric and polymicritic conglomerates indicate an “erosional crisis,” which could date the beginning of collision processes to the west.

Abstract Multichannel seismic reflection surveys across the North Venezuelan margin between 64 and 70° W provide new data on the three major structural elements of the area; the Venezuelan Basin margin along the Curacao Ridge, the episutural Falcon and Bonaire Basins, and the southern Guyana Shield continental crust. The Curacao Ridge consists of a thick, elongated belt of deformed sediments; it resulted from Neogene underthrusting of Venezuelan Basin crust. The formation of the onshore Falcon and offshore Bonaire Basins appears to have begun in Middle or Late Eocene. Structures observed in these basins suggest regional compression with attendant folding, faulting, and differential vertical movement. Northern elements of the Guyana Shield, including the Merida Andes to the west, appear to have been involved to some extent in tectonic movements of the margin in Cretaceous to Pliocene times.

Abstract Southeast Asia is located at the junction of four plates: the Eurasian, Indian Ocean/Australian, Pacific, and Philippine Sea plates. Their interaction during Tertiary times resulted in a complex active margin composed of a mosaic of small geotectonic units such as microcontinental blocks, island arcs, and marginal seas. The Sulu Sea is an example of a marginal sea with two distinct basins of different types: (1) the Outer Sulu Sea basin, formed inside an old island arc, the Palawan arc; (2) the Inner Sulu Sea, a basin with an oceanic crust. It is fringed to the southeast and the east by an active margin, supposedly the remains of a larger active margin which during Tertiary times extended along the western side of the Philippines from Luzon to Negros and perhaps from the Sulu Archipelago to the northeastern part of Sabah.