Physical models constructed of plasticine and silicone putty are deformed in a centrifuge at 4000 g in an investigation of the influence of lateral facies boundaries (simulating the margins of carbonate platforms) on the evolution of superimposed fold-thrust structures. Initial configurations represent vertically aggraded, prograded, or retrograded platform margins, and the fold-thrust deformation is directed either from the basin toward the platform or from the platform toward the basin. The effects of mechanical layering in the platform facies, the strength of the basal dcollement, and more complex facies distributions are also investigated.

With the basin on the hinterland side of the platform, shortening first propagates across the basin facies, but an anomalous anticlinal structure tends to form along the facies boundary at an early stage of shortening. After the fold-thrust shortening has propagated across the facies boundary and into the platform facies, the anticline at the margin evolves into a large, foreland-verging structure that carries the basin facies over the platform margin. With the basin on the foreland side of the platform, the first compressional structure is an anticline situated in the basin facies along the facies boundary, even though this is distant from the hinterland end of the system. Shortening by folding propagates from this structure across the basin facies toward the foreland. Subsequently, the platform facies also undergoes foreland-propagating shortening. The dip of the boundary controls whether the platform facies is thrust over, under, or into the basin facies. The strength of the basal dcollement within prereef strata affects the style and symmetry of structures in both the basin and platform facies and also affects the timing and size of the margin-related structure.

A structure that develops early in the shortening process may be a prospective exploration target, because it has the potential to retain an early hydrocarbon charge. The geometry (facing and dip) of the facies boundary controls whether the localized structure is a fold or major thrust and whether it is foreland- or hinterland-vergent. Therefore, knowing the geometry of a facies boundary may aid explorationists in predicting the geometry of target structures associated with it. Conversely, the structural configuration may aid us in interpreting the original distribution of lithofacies.