Surface dynamics of inversion tectonics systems through analogue modelling (BSc thesis)
MetadataShow full item record
High resolution 4D monitoring using dynamic-photogrammetry was deployed to monitor the surface deformation of a series of analogue modelling experiments with variable angles of inversion (0 ° < α < 75°) in both the brittle and brittle-ductile regimes. This technique allowed for the compilation of a magnitude of valuable datasets to accurately extrapolate both timing and magnitude of the model deformation. This monitoring techniques was coupled with advanced 3D and 4D observational techniques that include fully textured 3D model web-rendering, modern room-scale Virtual reality (VR) which was used to inspect fully textured 3D models including cross section, and finally 3D color printing was used to print the surface topography including cross-sections. It was found that reactivation in the form of reverse dip-slip is a selective process and occurs at both low and high angle normal faults. High angle normal faults are mostly reactivated during the initial steps of inversion. This reactivation is paired with rotation of the fault towards the vertical axis, which puts the fault close to an oblique angel to the principal stress axis, which locks the faults from being further reactivated. Moderate to high angel normal faults are reactivated in the purely brittle environment when faults are very steep or if enough confining pressure is present to prevent the fault plane from locking due to brittle decay. This decay can be attributed to the low cohesion of the sediments under low pressure conditions which causes the sediments making up the fault plane to fracture, rotate and slip in irregular ways, greatly increasing the coefficient of internal friction of the fault. The reactivation occurs manly within the graben infill where the sediment cover is thick and the confining pressure is highest. No low-angle normal fault reactivation occurred in the purely brittle experiments. Most of the low-angle normal fault reactivation occurred in the brittle-ductile models at the rift basin border normal faults that were decoupled from the basement and pushed upwards by the convex flowing ductile layer towards the graben borders that led to the formation of salt walls and minor diapirism. Reactivation in the form of strike-slip deformation occurred in the brittle models mainly at the rift basin border fault in the hanging-wall, however, significant reactivation also occurred in the rotated blocks within the graben. PIV analysis showed that strike-slip reactivation is progressively filtered out and converted to oblique displacement towards the footwall due to the principal stress axis rotation and the lack of instantaneous differential stress necessary for the reactivation to initiate. Hard-linked rift border faults in the ductile regime are the main absorbers of strike-slip displacement followed by the soft-linked opposing listric border fault. It was found that the highest magnitude of vertical reverse slip occurred at a 75° inversion angle for the brittle regime experiments and at a 45° in the ductile regime experiments.