Under sustained stretching stress, extensional forced folds were formed in the overlying formations of salt beds due to their differential subsidence.

It is suggested that the classification of extensional folds incorporates both axial trend and mechanism of folds.

In this paper we present the results of a fine structural geometric analyses of the seismic reflection profiles across the Dongying depression, where half-graben structures display the features of kink-band deformation and extensional fault-bend fold.

Fault-bend folds and fault-propagation folds are typical structural styles in the foreland thrust belts.