Influence of pre- or post-diapiric deformation on the foliation and strain pattern of a diapiric ridge

Foliation and total strain patterns of diapiric structures are very sensitive to pre- or post-diapiric deformation. This is illustrated quantitatively by superimposing homogeneous pure and simple shear on Mareschal and West's (1977) finite-element model of an antiformal diapiric ridge.

In models with post-diapiric homogeneous deformation (type 1) the foliation patterns typical for diapirism are obliterated. In models with pre-diapiric homogeneous deformation (type 2) diapiric deformation was too weak to overprint pre-diapiric foliation patterns. However, total strain patterns can be used successfully for identifying a diapiric component in the deformation history of both type 1 and type 2 models provided post- or pre-diapiric deformation is not too high.