Forward and Backward modelling : the Simple Shear hypothesis

@inproceedings{Galera1999a,
 abstract = { ln order to define the prospects to be drilled, structural geologists have to take
into account ail available data to approach the true 3D geometry of an area. Usually
these data consist of seismic images (2D and/or 3D), wells and surface data. Olten
the study has two steps: first to build coherent markers (horizons and faults) based on
the most reliable data and then to restore them. The interest of restoration is to test
the existence of an acceptable deformation path from a realistic initial geometry to the
current one. In 2D as in 3D, the main hypothesis is that of mass conservation which
can be specified by length and/or surface deformation depending on the deformation
mode of the mate rial (Dahlstrom, 1969). Various deformation modes have been
documented that can be correlated to the competence of the material: flexural slip for
highly competent layers, simple shear for recent poorly compacted sediment and flow
for ductil layers such as shaly decollement level and salt (Moretti & Larrère, 1989).
Rigid rotation also exists in extensive crustal domain (tilted block and domino style
area). In extensive domain, like those along margins, where early tilting of the
base ment is followed by fast sedimentation, growth faults and rollovers are created by
simple shear deformation which affects the sediments.
To help structuralists in such a context, we developed a new set of tools to build
geologically coherent 3D block diagram based on the simple shear criteria and then
applied this criteria to model the deformation (Galera et al. 1999). A first presented
tool allows us to entirely construct a listric fault given the initial geometry of a horizon,
the final one and the fault segment between the two positions. Another one enables us
to construct the final (resp. initial) horizon knowing the listric fault, the throw and the
initial (resp. final) horizon. The third one is a modeling of a rollover evolution versus
time while sedimentation and fault displacement are coeval. },
 author = { Galéra, Cyril AND Bennis, Chakib AND Moretti, Isabelle AND Mallet, Jean-Laurent },
 booktitle = { $19^th$ Gocad Meeting Proceedings },
 title = { Forward and Backward modelling : the Simple Shear hypothesis },
 year = { 1999 }
}