Multi-phase reactivations and inversions of Paleozoic–Mesozoic extensional basins during the Wilson cycle: case studies from the North Sea (UK) and the Northern Apennines (Italy)

The Caledonian-Variscan orogens in Northern Europe and the Alpine-age Apennine range of Italy are classical examples of thrust belts that were developed at the expense of formerly rifted, passive continental margins that subsequently experienced various degrees of post-orogenic collapse and extension. The outer zones of orogenic belts and their adjoining foreland domains and regions where the effects of superposed deformations are mild-to-very mild, making it possible to recognise and separate structures produced at different times and to correctly establish their chronology and relationships. In this paper we integrate subsurface data (2- and 3D seismic reflection and well-logs), mainly from the North Sea, and structural field evidence, mainly from the Apennines, with the aim to reconstruct and refine the structural evolution of these two provinces that, in spite of their different ages and present-day structural framework, share repeated pulses of alternating extension and compression. The main outcome of this investigation is that in both scenarios, during repeated episodes of inversion that are a characteristic feature of the Wilson Cycle, inherited basement structures were effective in controlling stress localisation along faults affecting younger sedimentary cover rocks.