--> --> Abstract: Extensional Faulting and Related Fold Evolution along the Oseberg Ost Fault System, Norwegian North Sea, by de Boer, Jord P.; Gawthorpe, Robert; Jackson, Christopher A.; Sharp, Ian; Whipp, Paul; #90163 (2013)
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Extensional Faulting and Related Fold Evolution along the Oseberg Øst Previous HitFaultNext Hit System, Norwegian North Sea

de Boer, Jord P.; Gawthorpe, Robert; Jackson, Christopher A.; Sharp, Ian; Whipp, Paul

Interaction between normal faulting and associated propagation folding has implications for the understanding of hangingwall trap geometries and syn-rift reservoir distribution. Three dimensional seismic and well data are used to understand the geometry and evolution of the Oseberg Øst normal Previous HitfaultNext Hit system from the Jurassic North Sea rift. Integrated structural and stratigraphic analysis permits the reconstruction of initiation, growth, interaction and linkage of normal Previous HitfaultNext Hit segments and highlights the role of Previous HitfaultNext Hit-related folding in the development of a normal Previous HitfaultNext Hit system. The 11 km long, planar normal Previous HitfaultNext Hit system dips to the W, has up to 550 m displacement, and has a dominantly NNW-SSE strike, although prominent NNE-trending Previous HitfaultNext Hit ‘jogs' are present. Overall, displacement and associated drag increases towards the southern end of the Previous HitfaultNext Hit system. Local displacement minima occur at the linkage point between incipient Previous HitfaultNext Hit segments.

Analysis of sequential isopachs, stratal geometries and displacement distribution show that isolated Previous HitfaultNext Hit-parallel synclinal depocentres formed in the hangingwall of the propagating Previous HitfaultNext Hit segments during a Late Bajocian - Bathonian rift initiation stage. The depocentres were associated with Previous HitfaultNext Hit-parallel monoclinal folds above buried normal Previous HitfaultNext Hit tips and their lengths were related to the length of the underlying, blind Previous HitfaultNext Hit segments. In contrast, Previous HitfaultNext Hit-perpendicular hangingwall anticlines located adjacent to the present day Previous HitfaultNext Hit jogs and local displacement minima separated the synclinal Previous HitfaultNext Hit-parallel depocentres along strike. The individual Previous HitfaultNext Hit segments subsequently linked along-strike by breaching of existing relay ramps to form a single laterally extensive hangingwall depocentre during the rift climax (Middle-Late Oxfordian).

Resulting from the evolving Previous HitfaultNext Hit system inferences can be made on geometries of hangingwall traps, the timing and origin of sediment sources, main sediment transport system(s) and the deposition of syn-rift reservoirs: (I) the orientations and interactions of normal faults and folds define the location of the hangingwall depocentres, (II) displacement minima are areas of segment linkage (e.g. breached relay ramps) result in intra-basinal highs, and (III) the Previous HitfaultNext Hit scarp-related sediment input and the associated relay ramps defined the local pathways for coarse grained clastic sediments that have been delivered into the adjacent Previous HitfaultTop-parallel hangingwall depocentres.

 

AAPG Search and Discovery Article #90163©2013AAPG 2013 Annual Convention and Exhibition, Pittsburgh, Pennsylvania, May 19-22, 2013