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Rob L. Gawthorpe1, John R. Underhill2, Ian Sharp3, Ian Carr1, Mike Young1, Aileen McLeod2
(1) The University of Manchester, Manchester, United Kingdom
(2) Edinburgh University, Edinburgh, United Kingdom
(3) Norsk Hydro ASA, Bergen, Norway

Abstract: Fault array evolution as a control on syn-rift stratigraphy and play development: examples from the Gulf of Suez and North Sea

Field data from the exceptionally-exposed, Oligo-Miocene Suez rift, Egypt, and interpretation of well-constrained 3D seismic data from the Late Jurassic of the North Sea illustrate the interplay between fault array development, landscape evolution and syn-rift stratigraphy. The development of fault arrays is characterised by three main phases: i) an initiation phase characterised by isolated segments, ii) a stage where fault growth and interaction are dominant, and iii) a final stage characterised by major crustal-scale fault blocks. Each phase has a distinctive stratigraphic response and sequence architecture.

Depocentres in the initiation phase are isolated growth synclines, a few kilometres long and up to 2 km wide, located in the hangingwalls of blind fault segments. At this stage sequences are dominated by non-marine and shallow marine facies and are strongly influenced by growth folding above propagating faults. During the interaction phase some depocentres enlarge by segment linkage, while others become inactive. Relay ramps become the loci for coarse-grained sediment input along border fault zones. Due to propagation and linkage of fault segments, the locus of maximum displacement migrates, which strongly affects the temporal and spatial development of coarse-grained facies. By the localisation phase, major crustal-scale fault-blocks are dominant physiographic features, and deformation is focused on border faults. Major sequence variation around these fault-blocks is related to spatial variations in subsidence and uplift.

Reconstructing the propagation and linkage history of normal fault segments can increase predictive capability for subtle stratigraphic plays in rifts in general.

AAPG Search and Discovery Article #90914©2000 AAPG Annual Convention, New Orleans, Louisiana