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Fault Populations and Geometric Analyses |
Bullard Laboratories, University of Cambridge, Madingley Road, Cambridge CB3 OEZ, UK
The principal features of a general kinematic method which uses the shapes of deformed strata to calculate normal fault geometries at depth in two and three dimensions are summarized here. This method assumes that hanging-wall deformation can be represented by arbitrarily inclined bulk simple shear and it should be applicable to faults at any scale. In two-dimensional modelling, deformation is assumed to occur within the plane of section. Deformation in three dimensions is parameterized by the three Euler angles which describe the horizontal component of the slip vector, the rake (i.e. pitch) angle and the inclination of shear planes. Differential compaction is included in both cases. Since we use inverse theory to determine fault geometries, the quality of our solutions is easily investigated. Both two- and three-dimensional algorithms have been rigorously tested on synthetic data, on sand-box experiments, and on depth-converted and interpreted seismic reflection profiles. Modifications of this approach can be used to calculate fault geometries which have changed shape during or after fault displacement. A similar approach is applicable to reverse faulting.
