The dataset employed comprises 3D seismic, electrical log, core and biostratigraphic data; the seismic coverage encompassing >60 km of the northern end of the half-garben bounding Late Jurassic Strathspey-Brent-Statfjord fault system. Seismic interpretation of fault segments and their abandoned palaeo-tips, and investigation of displacement-length scaling relationships were employed to reconstruct the temporal and spatial evolution of the fault population in the study half-graben. The timing of activity on individual segments was determined from stratigraphic evidence. An initial population comprising a large number of short, low displacement fault segments is identified; these faults defined a graben-like geometry. As the rift event progressed, strain was concentrated on fewer structures and, after ~10 Ma, on the Strathspey-Brent-Statfjord fault alone; hence the basin subsequently evolved an half-graben geometry. As the number of active faults in the basin decreased with strain localisation so the rates of displacement increased. The evolution of the fault population strongly influenced the distribution and stratal architecture of syn-rift sediments. During the initial stages of rifting (deposition of the Tarbert and Heather formations), the rate of sediment supply largely kept pace with the rate of tectonic subsidence. Sediment was sourced externally from the southward retreating Brent detail complex. In the rift climax phase the basin was sediment starved (deposition of the Kimmeridge Clay Formation), rates of tectonic subsidence greatly outpaced rates of sediment supply. The dominant process of sedimentation was hemipelagic settling; a secondary external source of sediment supplied an axial turbidite system during the Kimmeridgian. The impact of sediment starvation was the establishment of a submarine fault bounded range front that had an elevation locally in excess of 750 m. This bathymetric high was denuded by gravity driven sliding, controlled by the rheology of the pre-rift geologies exposed in the scarp; the products are preserved both mounted on the footwall scarp (the fault scarp degradation complex) and in the proximal hangingwall.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:657057 |
| Date | January 2000 |
| Creators | McLeod, Aileen Elizabeth |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/11141 |
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