Two centrifuged models are used to study the segmentation and emplacement of allochthonous salt sheets. In the first model, a uniformly thick buoyant silicone layer simulating salt with a horizontal lower boundary, was overlain by a uniformly thick layer of anisotropically layered overburden (brittle-ductile microlaminates). During centrifuging, the model was allowed to extend at one end, termed the basin. As a result, the buoyant layer flowed basinward, resulting in extension at the toe and faulting of the overburden units as individual blocks. The buoyant material was then segmented by the sinking overburden blocks and penetrated the overburden through the faulted zones.
The second model consisted of a buoyant wedge of silicone, with a dipping lower boundary simulating an asymmetrically spreading salt sheet. This sheet was overlain by several wedges of anisotropic microlaminate overburden at different times. Simulating a progradational wedge in nature, the overburden produced a pressure difference ranging from 144 Pa at the rear to 80 Pa at the toe. The buoyant layer flowed basinward due to higher loading at the rear relative to the toe area. Sequential addition of overburden wedges resulted in flow of the buoyant layer up through the stratigraphic section and formation of secondary sheets basinward. During further addition of overburden wedges, these secondary sheets were progressively segmented by deforming overburden which display extensional structures at the rear and contractional structures (folding and thrusting) at the toe. A similar deformation pattern is reported from the Gulf of Mexico.
Comparison of model results suggests that differential loading and presence of a slope at the lower contact of the buoyant layer (or abrupt lateral margin) are two essential factors in the flow of the buoyant material up through the stratigraphic section, its segmentation, and formation of secondary buoyant sheets.
GCSSEPM Foundation , 1992, 13. 135-142 p.