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Tectonic Evolution of the South Florida Basin, Eastern Gulf of Mexico


Crustal extension, from the breakup of Pangea and opening of the Gulf of Mexico (GoM) basin during Late Triassic to Early Jurassic time, deformed the basement rock, and controlled the deposition of Jurassic reservoir rocks. Much is known in the western and northern regions of the GoM; however, the Eastern Gulf of Mexico (EGoM) is relatively understudied. The EGoM's thin salt deposits allow for better imaging and definition of the basement geometry. Researchers understand more about basins in the northeastern GoM than the South Florida Basin in the southeastern GoM. Investigation of the Mesozoic section through seismic interpretation and the construction of cross sections in the South Florida Basin help clarify the rifting style, origin of opening, and basement geometry, as well as aid in the development of preliminary conclusions regarding the sedimentary evolution of the basin. Interpretation of twelve seismic reflection profiles indicates that the South Florida Basin developed as a graben from Triassic NW-SE extension due to rifting of North American Plate from South America. Subsequent NE-SW extension, beginning in Early to Mid Jurassic, created large normal faults orthogonal to earlier extension. These extensional faults are present in the basement rocks throughout the EGoM and in the South Florida Basin. Previous workers conclude that extension in the southeastern GoM occurred from Late Jurassic to Early Cretaceous due to rifting and rotation of the Yucatan block. Because extensional faulting does not extend into the Lower Cretaceous section in the South Florida Basin, extension and rotation must have stopped before this time. Lack of well control in the southeastern GoM prevents stratigraphic correlation with the northern EGoM; however, similar depositional packages are observed and are correlated northward to the Tampa Embayment. The Mesozoic Smackover and Norphlet formations, which are the primary source and reservoir rocks, may have equivalents present in the South Florida Basin. Synrift deposits are Middle Jurassic in age in the southeastern GoM and are younger than those found in the northern basins due to a longer duration of rifting to the south. Little salt is present; however, carbonate rock is dominant. These interpretations are consistent with previous work done within the South Florida Basin.