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Coeval Structural Evolution of Late Mesozoic Gravity Slides on the Northern Yucatan and Northeast Gulf of Mexico Conjugate Margins With Implications for Late Jurassic Reservoir Distribution


Gravity slides on salt detachments that link updip extension with downdip compression have been described from the northern and western margins of the Gulf of Mexico (GOM). In the northeastern GOM, the late Jurassic section near Desoto Canyon has undergone late Jurassic-Cretaceous gravity sliding and downdip dispersal of rafted blocks along a basinward-dipping layer of Louann salt. This study uses a grid of 2D seismic data tied to nine wells to describe a previously unrecognized and coeval area of late Mesozoic gravity sliding from the conjugate margin of the northeastern GOM along the northern Yucatan. We divide the length of the northern Yucatan margin into three structural provinces: 1) a 225-km-long, northeastern province consisting of a relatively undeformed, late Jurassic-Cretaceous section that is not underlain by salt, contains no gravity sliding features, and exhibits sub-horizontal dips; 2) a 120-km-long, north-central province with gravity slides defined by an updip, shelf-edge to slope, 80-km-wide zone of normal faults linked along a detachment to a base-of-slope, 50-km-wide zone of folds and thrust faults; the slide area exhibits discontinuous blocks that, similar to those on the northeastern GOM conjugate, have slid 20-35 km basinward upon a 3°-dipping detachment and are separated by intervening 0-500 ms thick salt rollers; growth wedges adjacent to listric, normal faults suggest a gradual, downdip motion of rigid fault blocks throughout much of the late Mesozoic similar to its conjugate margin in the northeastern GOM rather than a more rapid collapse; and 3) a 150-km-long, southwestern province with the thickest accumulation of salt up to 5 s in time thickness; diapirism is more prevalent than in the north-central province and penetrates into units as young as the Pleistocene. In the north-central province, a sedimentary unit equivalent to the productive Norphlet sandstone of the deepwater northeastern GOM is identified based on its remarkably similar seismic expression. Reconstructing the Oxfordian, pre-drift location of mapped Norphlet-equivalent of the Yucatan margin places it adjacent to the deepwater Norphlet sandstone in the northeastern GOM as mapped by previous authors. The reconstruction indicates a potential expansion of the reservoir fairway by 11,000 km2 along the north-central structural province of the Yucatan margin.