Benefits and limitations of different 2D algorithms used in cross-section restoration of inverted extensional faults: application to physical experiments

Abstract

In recent years, 2D restoration techniques have been systematically used to restore cross-sections through inverted basins. The accuracy of these techniques, and in particular which method better restores the inverted extensional faults to previous stages, is uncertain and difficult to assess in natural examples. To address this drawback, the applicability of flexural slip and vertical/oblique slip restoration techniques, executed with section restoration software, is tested through restoration of physical experiments of inverted extensional faults to their pre-inversion stage. The experiments chosen consist of simple listric and planar faults in which: (1) the original state and the kinematic path followed by the rocks to reach the final state is known, (2) the boundary conditions are known, (3) erosion is absent, and (4) the orientation of extension and compression vectors is equal. Comparing the restored sections with their corresponding actual pre-inversion stage reveals that flexural slip is the best restoration method, whereas the combination of different slip angles method gives the worst results. The accuracy of these techniques depends, to a great extent, on the master fault geometry, the coefficient of friction along it and the amount of inversion. The best results are obtained for a physical model that consists of a listric fault with 60° dip at the top of the rigid footwall, a shallow detachment, low coefficient of friction along the fault and mild amount of inversion. Since the deformation mechanisms and the geometry of the inverted structures are non-identical in physical experiments and in natural examples, the results obtained in our study should be cautiously applied to cross-sections across natural inverted basins.