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Minibasin Stratigraphy and Related Trapping Styles in Salina del Istmo Basin, Gulf of Mexico, Mexico: New Insights From 3-D Seismic Stratigraphy and Geomorphology Interpretation


The geometry of intra-minibasin strata can provide a tectonostratigraphic record of salt movement and other structural controls during the evolution of salt-dominated sedimentary basins. Hence, characterizing and understanding minibasin stratigraphy is key when exploring salt basins. In this study, we analyzed a 3D wide-azimuth, broadband depth-imaged seismic reflection volume acquired between 2015 and 2017 in water depths ranging from 250 m to 3750 m. This regional-scale 3D seismic data covers 71,000 sq. km of the, hitherto, underexplored Salina del Istmo Basin in the Gulf of Mexico, offshore Mexico. Basinwide analysis of the seismic geomorphology suggests that clastic input into the basin was provided from three main directions, south, southwest and west indicating sediment provenance from Sierra Madre Oriental and the Chiapas massif. We recognize deepwater depositional systems (i.e., turbidites) since the Eocene extending for 370 km from the present-day shelf margin. Salina del Istmo Basin is characterized by a complex structural evolution controlled by gravity-driven extension, salt tectonics, onshore uplift and orogenic-driven shortening. In relatively less-deformed areas, our analysis of minibasin stratigraphy reveals that intra-Eocene -and -Oligocene sedimentation was locally controlled by salt movement, leading to lateral and frontal confinement of deepwater depositional systems within minibasins. Orogenically-driven shortening in the Miocene led to minibasin tilting, and intra-minibasin folding and thrusting, resulting in local uplift and segmentation of depositional systems and the development of structural and combined traps. Shortening-induced minibasins provided confinement for the successive intra-Miocene deepwater sedimentation with depositional systems onlapping the salt-cored highs and defining pinch-out trapping along the minibasin flanks. Our findings have direct implications for hydrocarbon exploration in Salina del Istmo Basin and describe previously undocumented salt-sediment interactions and trapping styles in the Gulf of Mexico, offshore Mexico.