A least-squares method for multisurface unfolding

Geologic structures are mostly known from scattered data, and structures such as folds or faults are drawn in between by using interpolation, which is often based on geologically poor assumptions, such as smoothness. The need for more accuracy leads to restoration techniques in which more realistic assumptions are introduced. In this context, we have tested a multisurface unfolding procedure. We use a least-squares formulation involving the following criteria: initial horizontality, bed-length conservation (during slip on bedding) and local volume conservation. Weighted optimization of these criteria gives a compromise between them if they are conflicting. We have succesfully tested the method on various theoretical examples and on an analog model: the ‘paperback experiment’.