Centrifuged models of Gulf of Mexico profiles

Abstract

Physical models dynamically scaled in a centrifuge are used to explore the importance of slope progradation in driving internal salt structures much further horizontally than they rise. Large increments of ductile plastic overburden added at normal gravity values simulated primary clastic sedimentary progradation of a clastic slope over a layer of buoyant fluid simulating salt. During load increments at a nominal 800 g in a centrifuge, this ductile topographic slope spread over the ductile décollement. Except for down to basin growth faults, all the structures considered to be distinctive in the northern Gulf of Mexico are simulated in the models that are scaled such that 1 mm and 60 s in the model correspond to 1–1.5 km and 2–6 Ma in the prototype. Ratios of the rate of advance to the rate of rise of the shelf break, compared with the rate of advance and increase in relief of salt structures, control how much of the deep autochthonous salt is squeezed ahead of the advancing shelf and the paths this salt takes to shallow structural levels. The few three-dimensional diapiric stocks which developed from many two-dimensional mullions in the models spread stock canopies which advanced huge distances before some became tongue canopies by climbing over clastic sediments already aggraded in front of them. The models emphasize the significance of ductile spreading of the clastic sediments now being discerned by backstripping.