Emplacement and evolution of the Mahogany salt body, central Louisiana outer shelf, northern Gulf of Mexico

We used three- and two-dimensional seismic data, well and biostratigraphic constraints, and structural restorations to evaluate the evolution of the M ahogany salt body and surrounding strata on the central Louisiana outer she lf of the northern Gulf of Mexico. The history of emplacement and subsequen t modification of the Mahogany salt body is divided into six stages: (1) gr owth of a basinward-leaning salt ridge sourced from a deep allochthonous sa lt sheet prior to 7.5 Ma; (2) loading-induced evacuation of a large volume of salt from the sheet and ridge through a narrow feeder, resulting in rapi d salt flow and consequent radial growth of a bulb-shaped salt stock betwee n 7.5 and 4.3 Ma; (3) gravitational collapse of the inflated salt stock aft er depletion of the deep source layer, leading to basinward extrusion of a subhorizontal salt tongue and its rafted overburden between 4.3 and 3.65 Ma ; (4) burial of the composite salt body during a period of slow sedimentati on between 3.65 and 1.95 Ma; (5) basinward translation of the overburden re sulting from gravity gliding/spreading on the upper slope between 1.95 and 0.5 Ma, causing extension, reactive diapirism, and matching contraction; an d (6) cessation of lateral translation once the shelf margin prograded past the salt body, and subsequent loading of the salt driving active diapirism in the footwalls of normal faults. The Mahogany salt body provides an exce llent case study that illustrates both the value and limitations of publish ed simple models for allochthonous salt, and the reconstructed evolution yi elds insights into the complex interactions between salt deformation and se dimentation. The results also suggest that the Mahogany salt body did not i nfluence the trap style of the subsalt Mahogany field or hydrocarbon migrat ion into the pay sands but that it did affect sediment transport pathways a nd, to a lesser degree, reservoir facies distribution.