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Regional Case Studies |
1 Oil Search Ltd., NIC Haus, PO Box 1031, Champion Parade, Port Moresby, Papua New Guinea
2 Department of Geology and Geophysics, The University of Edinburgh, Grant Institute, West Mains Road, Edinburgh, UK
4 Department of Geology, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
3 Esso Exploration and Production UK Ltd, Mailpoint 508, Esso House, Victoria Street, London SW1E 5JW, UK
The geometric and kinematic evolution of salt-related structures in the Central North Sea has been studied using structural restoration and balancing techniques. Strain associated with fault displacements, compaction and isostasy has been systematically removed, thus producing a graphical representation of the temporal and spatial distribution of salt structures through time. The results clearly demonstrate that the Central North Sea can be sub-divided into three structural provinces based on the type of salt structure present: (1) the Central Graben which is characterized by large offset extensional faults with broad salt swells and tall salt diapirs, (2) the Eastern platform comprising the Norwegian-Danish Basin which is dominated by symmetrical salt swells that are typically welded in intervening lows and deeply buried, and (3) the Western platform which is characterized by salt swells and gravity-driven, thin-skinned extension. By restoring the deformation at both a local and a regional scale, it becomes apparent that the Permian salt has controlled the development of structures throughout the Mesozoic and Tertiary in the Central Graben region and the Western Platform, whereas on the Eastern Platform the salt was primarily active during the Triassic only. This has led to a variation in the evolution of structural styles across the Central North Sea. The restorations also suggest that salt dissolution has not been a significant feature during the development of diapirs in this area.
