Characterising fold geometries from structural data: application to implicit modelling

Folds present a challenge for implicit interpolation because
the information associated with the geometry of the structure is not explicit
in the orientation of the folded foliation. Traditional implicit approaches
involve interpolating between observations from orientation measurements and
stratigraphic contacts. To constrain the geometry of folds, the user is
generally required to draw fold profiles on cross sections or level maps using
bedding structural elements. A new method allows for more structural elements
(e.g. foliations, intersection lineations) and overprinting relationships to be
incorporated into the modelling process. 
Each generation of folding is successively modelled, starting with the
most recent folding event. At each stage, several scalar and vector fields are
interpolated to represent the axial surfaces, the fold axis and vergence of
each fold. The geometry of each fold generations are defined by structural
parameters. These parameters need to be derived from available data and specified
to the interpolator. We present an adaptation of geostatistical tools to
structural geology for quantifying fold geometry.