Flexural-Slip Based Restoration in 3-D
; A New Approach
KANE S. J., G. D. WILLIAMS, T. S. BUDDIN, S. S. EGAN, and D. HODGETTS
Restoration of cross-sections in two dimensions is commonly used for the
validation of complex geological structures. Three restoration techniques which
are commonly applied are: vertical shear construction; inclined shear
construction and a flexural slip construction based on Suppe (1983). Extension
of existing flexural constructions to three dimensions (3-D
) proves difficult
due to the need to predetermine
3-D
axial surfaces related to complex fault
bends prior to deformation.
Research has recently concentrated the development of truly 3-D
flexural-type
constructions. The model invokes fore- and back-shear of the hangingwall during
deformation according to the nature of the fault bend folds. The angular shear
and geometry of the
3-D
axial surfaces do not have to be pre-calculated. Volume
in the hangingwall, and the surface areas of interfaces, are conserved between
restored and deformed states. The lack of pre-determined geometrical constraints
significantly reduces the amount of processing time required to run the models,
and allows complex fault surfaces to be considered. The method is particularly
applicable to interpretations from
3-D
seismic data sets. As the method is truly
3-D
we have the ability to model all modes of deformation including
contractional, extensional, wrench and oblique slip. Non plane-strain will
ultimately be introduced into the models to allow for the strains associated
with, for example, oblique ramps or tip zones on faults with lateral and
down-dip displacement gradients.