Relations between fault surface morphology and volume structure: 3-D seismic attribute analysis deepwater Niger Delta fold and thrust belt.

摘要

Studies have shown that faults exhibit complex geometries that are often highly simplified and cross sections may not be sufficient to highlight the spatial variation of fault surface topography and the complex relationship with the wall rock. The main contributions of this thesis to structural geology are novel methods for investigating links between fault shape and wall rock structure. ududCurvature plots of sixteen faults show that thrust faults in deepwater Niger Delta exhibit corrugations on a range of wavelength and amplitude. The corrugations are characterized by large-scale anticlastic and synclastic geometries parallel to fault transport direction. The structure of the volumes in the immediate vicinity of the faults was investigated using slices of seismic attribute data sampled parallel and adjacent to thirteen faults. In half of the faults the hanging wall is more disrupted than the footwall, while in the other half the footwall is more disrupted than the hanging wall, implying that thrust zones exhibit complex geometries that existing models have yet to address. In addition, disruptions near fault surfaces may be related to discrete zones of intense fault surface maximum curvature, anomalous surface gradient and change in pattern of anticlastic and synclastic fault Gaussian surface curvature in the fault transport direction. No significant wall rock disruption was observed where fault surface curvature is planar.ud