What role does structural inheritance play in controlling the geometry of rifted basins during multiple phases of extension? A case study from the Northern North Sea

Abstract:

In multiphase rift systems pre-existing crustal structures, which typically lie within crystalline basement, may influence the nucleation, growth and linkage of overlying normal faults. However, our understanding of the physical and kinematic linkage between basement and cover structures is limited, since deep structures are commonly poorly imaged in seismic reflection data. The North Sea Rift is an ideal natural laboratory to study the role of structural inheritance on the geometry of rifts, having undergone multiple phases of contractional (Ordovician-Devonian) and extensional (Devonian, Permian-Triassic and Middle Jurassic-Early Cretaceous) deformation. In this study we constrain the influence of pre-existing crustal structures on the evolution of Permian-Triassic and Middle Jurassic-to-Early Cretaceous normal fault systems. To achieve this we utilize 2D and 3D seismic reflection and borehole data from the Northern North Sea, covering the eastern margin of North Viking Graben. We show that pre-existing basement structures control the first-order rift geometry, including the location and the strike of the main Permian-Triassic bounding faults and intrabasement highs. In detail, however, the link is more complex, with some Permian-Triassic rift-related normal faults seemingly unrelated in terms of location or strike to intrabasement structures. Similar complexity is observed between Permian-Triassic and Middle Jurassic-to-Early Cretaceous rift related faults. We show that the importance of pre-existing structures on rift geometry decreases over time, with these structures having a major influence on the geometry of Permian-Triassic rift basin, but a more subdued influence on the Middle Jurassic-to-Early Cretaceous rift.