| Abstrakt: |
Two modern models of thin-skinned thrust tectonics, by Elliott (1976) and Chapple (1978), are reviewed and found to be of restricted application. Following possible variations of surface and basal slope and based on published Alpine cross-sections, eight elementary, two-dimensional, mechanical models are set up. These include the possibility of a weak basal layer, a common feature of Alpine thrust sheets and an externally applied, subhorizontal compression. Six of these have two variants, depending on if the maximum shear stress in the sheet attains the yield stress, in which case there is permanent deformation and the sheet changes shape, perhaps to that of a different elementary model. The long ignored analysis by Goguel (1948) of stresses in a relaxed plastic material, at depth below an inclined surface, is outlined. Stress components resulting from this analysis are used, together with supplementary stresses derived by Hafner (1951) to represent an externally applied, subhorizontal compression, to suggest ways in which décollement possibilities of the models can be investigated. Some specific examples are considered. |
