PETROLEUM POTENTIAL OF SOUTHERN HISPANIOLA P. Mann* and S. R. Lawrence** The island of Hispaniola (Dominican Republic and Haiti) lies within the North Caribbean strike- slip plate boundary zone. The post-Eocene history of Hispaniola is marked by strike-slip accretion of crustal fragments onto a Late Cretaceous-Eocene island arc. Three onshore Neogene clastic basins have been the focus of petroleum exploration in Hispaniola. Oil production was achieved by drilling surface anticlines in the Azua Basin in South- Central Hispaniola (Dominican Republic) during World War II (Maleno and Higuerito fields). More modern seismic exploration has been carried out in the Enriquillo, San Juan and Cibao Basins, but has not resulted in production. Recent surface and seismic stratigraphic mapping has elucidated the geologic history of Southern Hispaniola. It consists of several Late Cretaceous-Eocene oceanic and island-arc terranes separated by E-W to NW/SE-striking “ramp “ or thrust-bound clastic basins of Neogene age (San Juan, Azua and Enriquillo). Basin edges are marked by either basinward-verging thrust or reverse faults, or strike-slip faults. Basin centres are characterised by gentle folds at shallow depths and high-angle faults and associated folds at greater depths. The easternmost area of the three ramp basins (Azua and eastern Enriquillo) has been overprinted by more intense shortening caused by local NE-ward “indentation” of the Beata Ridge, an area of elevated Caribbean seafloor South of Hispaniola. The stratigraphy of Southern Hispaniola is characterised, by two depositional phases. During the first phase, deep-water pelagic sedimentary rocks of Eocene to Middle Miocene age accumulated on the leading-edge of the intra-oceanic Caribbean Plate. Following Early Miocene transpressional juxtaposition of the intra-oceanic plate with the Cretaceous-Eocene island-arc core of the island, Late Miocene-Early Pliocene clastic rocks derived from the island-arc core filled the developing Azua-San Juan ramp basin system. In the Plio-Pleistocene, shallow-marine/ lagoonal sediments filled the Enriquillo Basin, while residual fluvio-deltaic sedimentation continued in the Azua Basin. Oil-prone source rocks are predicted in deep-water carbonate rocks of the Sombrerito Formation (Early Miocene) and hemi-pelagic mudstones of the Trinchera Formation (Middle to Late Miocene). Reservoirs occur in carbonates of the Sombrerito Formation and sandstones of the Trinchera and Arroyo Blanco Formations. Maturity modelling shows that hydrocarbon generation largely pre-dates Plio-Pleistocene folding and uplift. Shallow. Late-formed structural traps in the Azua Basin have been charged by remigrated hydrocarbons. Unrecognised and undrilled deeper parent structures are predicted at depth in the Azua Basin, but require modern seismic data to confirm their existence. Existing seismic data identify undrilled prospects in the Enriquillo and San Juan Basins. Journal of Petroleum Geology, vol. 14 (3), July 1991, pp. 291-308 291 * Institute for Geophysics, University of Texas at Austin, 8701 Mopac Blvd., Austin, Texas, USA 78759. ** Quad Consulting Ltd.. Meadowbank. Bourne End, Bucks, SL8 5AJ, UK