The linkage between fault throw and footwall scarp erosion patterns: an example from the Bremstein Fault Complex,offshore Mid‐Norway |
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| Authors: | Gavin M Elliott Paul Wilson Christopher A‐L Jackson Robert L Gawthorpe Lisa Michelsen Ian R Sharp |
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| Institution: | 1. Department of Earth Science & Engineering, Imperial College London, , London, UK;2. Basin Studies & Petroleum Geoscience, SEAES, University of Manchester, , Manchester, UK;3. Department of Earth Sciences, University of Bergen, , Bergen, Norway;4. Statoil ASA, , Harstad, Norway;5. Statoil Research Centre, , Bergen, Norway |
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| Abstract: | Studies of normal fault systems in modern extensional regimes (e.g. Basin and Range), and in exhumed, ancient rift basins (e.g. Gulf of Suez Rift) have shown a link between the evolution of fault‐related footwall topography and associated erosional drainage systems. In this study, we use 3D seismic reflection data to image the footwall crest of a gravity‐driven fault system developed during late Middle Jurassic to Early Cretaceous rifting on the Halten Terrace, offshore Mid‐Norway. This 22‐km‐long fault system lacks significant footwall uplift, with hangingwall subsidence accommodating throw accumulation on the fault system. Significant erosion has occurred along the length of the footwall crest and is defined by 96 catchments characterized by erosional channels. These erosional channels consist of small, linear systems up to 750 m long located along the front of the fault footwall. Larger, dendritic channel systems extend further back (up to 3 km normal to fault strike) into the footwall. These channels are up to 7 km long, up to 50 m deep and up to 1 km wide. Fault throw varies along strike, with greatest throw in the centre of the fault decreasing towards the fault tips; localized throw minima are interpreted to represent segment linkage points, which were breached as the fault grew. Comparison of the catchment location to the throw distribution shows that the largest catchments are in the centre of the fault and decrease in size to the fault tips. There is no link between the location of the breached segment linkage points and the location and size of the footwall catchments, suggesting that the first‐order control on footwall erosion patterns is the overall fault‐throw distribution. |
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