High resolution fault displacement mapping from three-dimensional seismic data: evidence for dip linkage during fault growth

Detailed mapping using high resolution three-dimensional seismic data has revealed a number of sub-horizontal anomalies in the distribution of vertical displacement (throw) on the planes of growth faults in the Gulf of Mexico. Recognition of these anomalies is highly sensitive to the interval at which the fault displacements are sampled, because they represent local decreases in throw which are confined to small, discrete parts of the fault planes. The distribution of the anomalies is inconsistent with model displacement fields of quasi-elliptical concentric contours and is therefore incompatible with models of fault growth by uniform slip distribution and radial tip-line propagation. An alternative model is proposed, whereby the evolution of a fault plane is established by the propagation and linkage of precursor fault segments in the dip direction—‘dip linkage’. Overlap and linkage of fault tips in the dip direction results in relay structures that are sub-parallel to fault strike and therefore displacement minima that are sub-horizontal on normal and thrust faults. However, since they are orthogonal to the main slip direction on the fault, these structures have a low preservation potential and are therefore unlikely to be well resolved on cross-sectional seismic profiles.