Finite strains in transpression zones with no boundary slip

A mathematical model describing finite strains has been developed for transpression zones where no slip is allowed in any direction at the zone boundaries. This has been adapted to model transpression zones where the boundaries are inclined. The model can also be used to describe finite-strain patterns where material is incorporated into the deforming zone from one or both sides after the initiation of deformation, so that the deforming zone remains at a constant width, thus allowing large transpressional strains to be accommodated without the deforming zone closing to zero thickness. This model of ‘steady-state’ transpression can be used to explain some of the features of the South Mayo Trough, a late Silurian transpression zone in the west of Ireland.