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Spatial, Temporal, and Detachment-Level Variations in Thin-Skinned Deformation, Gulf Basin, USA and Mexico


The Gulf Basin has been characterized by a complex history of thin-skinned deformation since the Late Jurassic. In this overview, I examine both salt- and shale-detached extension and contraction in the conjugate margins of the northern and southern Gulf Basins (NGB and SGB). Gravity gliding above the Louann and Campeche salts dominated the early history due to thermal subsidence of oceanic crust and the consequent basinward tilt of the margins. Upper Jurassic to Cretaceous proximal extension and basinward translation were convergent due to the arcuate nature of the margins and resulted in emplacement of allochthonous nappes over oceanic crust, especially in the central NGB. Movement was divergent where the Yucatan Platform switches from from a N-S to NE-SW trend. Convergent-margin tectonics had major effects on deformation in the Gulf Basin from Paleogene to early Neogene time. First, orogenic shortening propagated basinward along the autochthonous salt detachments, slightly in the western NGB during the Eocene to Oligocene and more in the SGB beginning during the Eocene and culminating in the middle Miocene, NE-directed Chiapaneca event. Second, the orogeny generated abundant siliciclastics that prograded into the basin and drove gravity spreading of the margins that continued to the present, but with variable timing and detachment level moving around the margin: 1. There was effectively no Cenozoic extension or contraction in the northeast due to a lack of sediment loading; 2. In the east-central NGB, there was little Paleogene deposition, and Miocene extension at the Louann level was balanced by the Atwater foldbelt; 3. In the central NGB, failure was at the Louann level in the early history and switched mostly to shallow levels after Eo-Oligocene canopy emplacement; 4. In the northwest, Paleocene to Eocene failure was detached on the Louann salt, whereas Oligo-Miocene failure was detached first on a complex mixture of canopy and shale detachments (East Breaks, Port Isabel, and Kama foldbelts) and then back to the deep salt level (Perdido foldbelt); 5. There was no salt in the west, so upper Eocene to Oligocene shales formed the detachment for Miocene to recent extension and the Mexican Ridges foldbelt; 6. In the south, upper Miocene to present, NW-vergent, Campeche-detached raft tectonics created the Macuspana and Comalcalco troughs and was balanced by deepwater contraction, with the detachment ramping up to Eocene shales at the distal edge of the salt basin.