Jurassic-Cretaceous Stratigraphic and Structural Evolution of the Northern Yucatan Margin, Gulf of Mexico Basin
Steier, Andrew 1990-
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The Gulf of Mexico (GOM) basin formed during Triassic-late Jurassic rifting as the Yucatan continental block rifted to the southeast away from its northern GOM conjugate margin. During a second, late Jurassic-earliest Cretaceous drift phase, the Yucatan block rotated counter-clockwise to its current location and produced an eastward-narrowing wedge of oceanic crust beneath the central GOM. The stratigraphy and structural evolution of the Florida margin is much better understood than its northern Yucatan conjugate because previous hydrocarbon exploration has been more extensive on the Florida margin. In the northeastern GOM, the late Jurassic section near DeSoto Canyon records late Jurassic-Cretaceous gravity sliding of rafted blocks over distances of 25-40 km along a basinward-dipping layer of salt. This study uses a 117,000 km2 grid of 2D seismic data tied to published regional seismic lines and wells to describe a previously unrecognized and coeval area of widespread, gravity sliding along the less-studied, northern Yucatan margin. I define three structural domains based on their distinctive salt structures and associated deformation: 1) the northeastern study area consists of relatively undeformed, late Jurassic-Cretaceous section underlain by 0-300 m-thick salt; 2) areas in the central and southwestern study area contain late Mesozoic gravity slides defined by normal faults rooted onto a 1-4° basinward-dipping salt detachment that controlled overlying, sedimentary growth wedges separated by intervening, 300-600 m-thick salt rollers; and 3) the distal margin of the western and central study area exhibits large salt diapirs up to 6 km tall that penetrate overlying units as young as the Pleistocene. In the central study area containing late Mesozoic gravity slides, a sedimentary unit equivalent to the productive, Oxfordian Norphlet sandstone of the deep-water northeastern GOM is identified based on its similar seismic character. Reconstructing the Norphlet-equivalent unit to its location during Oxfordian deposition places it adjacent to an extensive area of deep-water Norphlet sandstone mapped in a previous study. The reconstruction suggests an 84,000 km2 fairway of potential aeolian, Jurassic reservoirs on the Yucatan and Campeche margins that includes areas of productive reservoirs in the southeastern Bay of Campeche which previous authors correlated with the Norphlet Formation.