Tectonic Analysis of a Viking Graben Border Fault

Abstract

The Viking graben has been proven to be an aulacogen on a passive continental margin. The rifting started in the Late Permian and had numerous episodes throughout the Mesozoic. The strongest tectonic events occurred in the Late Jurassic and in the Early Cretaceous, namely in the late Cimmerian phases. Toward the end of the Cretaceous, the taphrogeny ceased and the graben became part of a rigid continental margin. A Laramian phase, however, did occur. The Tertiary basins had their depocenters close to the Viking and the Central graben axes, but the outline of these smooth and rounded basins were independent of the graben border faults. However, in one area, in the central part of the North Sea, a Viking graben border fault was reactivated in the Paleocene-Eocene. This rejuvenation has resulted in such structural features as flower structures and normal faults along the old Cimmerian Viking graben border fault. The tensional features are found along one border fault dogleg trend, and the compressive features are found along another. This is explained as a response to strike-slip reactivation of the old fault. The transient movements coincide with the incipient sea-floor spreading in the Norwegian-Greenland Sea area and may be related to consequent rotation of the Shetland platform relative to the Fennoscandian shield.