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

In recent years, 2D restoration techniques have been systematically used to restore cross-sections through inverted basins. The accuracy of these tech niques, and in particular which method better restores the inverted extensi onal faults to previous stages, is uncertain and difficult to assess in nat ural examples. To address this drawback, the applicability of flexural slip and vertical/oblique slip restoration techniques, executed with section re storation software, is tested through restoration of physical experiments o f inverted extensional faults to their pre-inversion stage. The experiments chosen consist of simple listric and planar faults in which: (1) the origi nal state and the kinematic path followed by the rocks to reach the final s tate is known, (2) the boundary conditions are known, (3) erosion is absent , and (4) the orientation of extension and compression vectors is equal. Co mparing the restored sections with their corresponding actual pre-inversion stage reveals that flexural slip is the best restoration method, whereas t he combination of different slip angles method gives the worst results. The accuracy of these techniques depends, to a great extent, on the master fau lt geometry, the coefficient of friction along it and the amount of inversi on. The best results are obtained for a physical model that consists of a l istric fault with 60 degrees dip at the top of the rigid footwall, a shallo w detachment, low coefficient of friction along the fault and mild amount o f inversion. Since the deformation mechanisms and the geometry of the inver ted structures are non-identical in physical experiments and in natural exa mples, the results obtained in our study should be cautiously applied to cr oss-sections across natural inverted basins. (C) 1999 Elsevier Science B.V. All rights reserved.