H漫画

Geological problems with offshore Nova Scotia are associated with complex salt deformation beneath the shelf and slope. Features in this area record highly variable tectono-sedimentary environments with high rates of sedimentation and progradation during the Jurassic and Early Cretaceous. These features have impacted petroleum exploration; particularly seismic imaging and hampers the structural interpretation of basement morphology beneath the rift-related salt basins. To address these problems innovative structural modelling techniques were coupled with interpretation of public seismic data from offshore Nova Scotia. Dynamically scaled analogue models consisting silica sand and silicone rubber simulate sedimentation, salt mobilization and deformation of the brittle overburden sediments and ductile salt.

Experimental results have led to three fundamental concepts. 1) The dominant mechanism for initial salt mobilization in rift basins with thick salt is channel flow within the salt layer driven by passive downbuilding of the landward salt withdrawal basins. 2) Initial landward mobilization and position of basinward salt inflation depends mainly on salt thickness controlled by the basin floor geometry, rather than the geometry of the basinward rift shoulder. 3) The timing and extent of allochthonous salt nappe advancement depends on the efficiency of early salt evacuation in the landward salt basin and sediment progradation on top of the inflated salt complex. When applied to public seismic data, it is clear that Subprovinces III and IV containing the Abenaki and Sable Subbasins have a basement floor geometry that results in highly variable salt thickness. With more in depth studies of seismic data these new concepts will make it possible to refine basement structure and its effect on reservoir development, migration systems and potential plays for hydrocarbons.

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