Print this pageQuantification of Extension and Inversion Using Generalised
Three
Dimensional Volume Balance
WILLIAMS G. D,, T. S. SUDDIN, S. J. KANE, S. S. EGAN, D. HODGETTS, G. R. PEACE, and A. J. RICHARDS
The ability to manipulate volumetric data using computer workstations has
enabled the generalisation of three dimensional balancing techniques in order to
analyse areas with complex faulting histories. In regions that have undergone
extensional faulting producing accommodation space filled by a syn-rift
megasequence, followed by contractional inversion, it is possible to quantify
the relative amount of each deformation mode using volume balance. Generalised
three dimensional volume balance permits the analysis of reactivated faults with
displacement gradients and it allows the modelling of dip-slip, oblique-slip and
wrench faulting.
In this contribution we explain the concepts and methodology of three
dimensional volume balance using complex kinematic models. In areas where fault
surfaces are non planar, it is possible to obtain important information on fault
movement direction by comparing the shapes of footwall and hanging wall cut offs
on plan view -- the 'jigsaw fit' method. This parameter is vital in constraining
the three dimensional faulting model. The volume of a syn-rift megasequence that
fills fault generated accommodation space is used to calculate an extensional
heave profile for the model and the volume of material above regional after
inversion is used for the contractional heave profile. A combination of the two
heave profiles yields a net profile that describes the present day fault
configuration.
Case studies based on interpretations of seismic data cubes will be used to
illustrate the three dimensional
volume balance method and kinematic histories
for regions which exhibit basin inversion will be presented.