Abstract

ABSTRACT

The post-Jurassic bathymetric and subsidence history of the Mid-Norwegian Atlantic margin (Møre and Vøring basins) has been investigated using the technique of 3D-flexural backstripping. Eleven mapped horizons from seabed to the Base Cretaceous have been sequentially backstripped to produce a suite of palaeobathymetry and palaeostructure maps for all horizons at all time stages. Backstripping has incorporated thermal subsidence in response to (1) an initial rift event at c. 140 Ma and (2) a subsequent rift-to-break-up event in the latest Cretaceous/early Tertiary. Transient dynamic uplift of the margin during the Paleocene is also incorporated, having a particular impact on palaeobathymetric predictions at this time.

In an exploration context, the palaeobathymetric maps were used predictively to investigate sediment dispersal and deposition through time; the subsurface palaeostructure maps were used for maturation modelling and identification of hydrocarbon-migration pathways, while all of the maps contribute to an understanding of hydrocarbon-trap development through time. The backstripped maps yield considerable information on the regional structural evolution of the margin. After regionally distributed extension of both the Møre and Vøring basins during the Late Jurassic/Early Cretaceous, map restorations of the two basins show contrasting structural histories. There is no younger fault-controlled overprint on the Møre Basin, whereas the inner Vøring Basin was extended again in the mid-Cretaceous and the outer Vøring Basin was extended in the latest Cretaceous/Paleocene.

Three-dimensional backstripping also confirms an active compressional origin, rather than a wholly passive loading origin, for the post-break-up Tertiary domes located along the margin. This is the first time that a temporal analysis of the domes' formation has been possible in 3D map form rather than 2D section form. The technique of 3D flexural backstripping has wide application to the study of rifts and continental margins elsewhere.

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