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GEOLOGIC AND HYDROCARBON EVOLUTION OF BARBADOS
Author(s) -
Speed R. C.,
Barker L. H.,
Payne P. L. B.
Publication year - 1991
Publication title -
journal of petroleum geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.725
H-Index - 42
eISSN - 1747-5457
pISSN - 0141-6421
DOI - 10.1111/j.1747-5457.1991.tb00315.x
Subject(s) - geology , accretionary wedge , forearc , allochthon , paleontology , trough (economics) , prism , diapir , neogene , geochemistry , thrust fault , geomorphology , structural basin , fault (geology) , subduction , tectonics , nappe , physics , macroeconomics , optics , economics
Barbados island has risen above sea‐level in the last one million years as a pinnacle on the structural high of the extensive Barbados accretionary prism. The island provides by outcrop and many wells a glimpse of the structural history of the oldest and thickest realm of the prism, and a model for evolution of oil and gas in an accretionary terrane rich in quartz sanaktones and muddy temgenous and hemipelagic rocks that are moderately rich in organic substances. The island contains four major tectonostratigraphic units: basal complex of Eocene accretionary origin: prism cover: the Oceanic allochthon, of marly forearc basin strata, that was thrust over the basal complex and prism cover: and mud‐matrix mélange diapirs. Oil and gas are sourced chiefly from the basal complex at depths below 7 km, the minimum maturation depth. Oil reservoirs are in sandstones of the basal complex in fault‐fold structures. Seals are provided by mudstones of the basal complex and, more regionally, by thick, impermeable successions of prism cover and the Oceanic allochthon. Current oil reservoirs probably evolved mainly in Late Neogene time during a late stage of deformations. Oil reservoirs are best known in southern Barbados, in the Woodboume Trough, where sealing conditions were optimized. Barbados' marine territory also includes an extensive fold‐thrust belt for some 50 km west of the island. This belt includes rocks of both the Barbados accretionary prism and strata of the Tobago Trough forearc basin. The thrusting is due to the westward wedging of the prism into the forearc basin between roof and floor detachments.