Pre-inversion normal fault geometry controls inversion style and magnitude, Farsund Basin, offshore southern Norway Thomas B. Phillips1, Christopher A-L. Jackson2, James R. Norcliffe2 1Department of Earth Sciences, Durham University, Science Labs, Durham, DH1 3LE, UK 5 2Basins Research Group (BRG), Imperial College, London, SW7 2BP, UK Correspondence to: Thomas B. Phillips (
[email protected]) Abstract. Inversion Compressional stresses may localise along pre-existing structures within the lithosphere, far from the plate boundaries along which the causal stress is greatest. Inversion The style and magnitude of the related contraction is expressed in different ways, depending on the geometric and mechanical properties of the pre-existing structure. A three-dimensional 10 approach is thus required to understand how inversion compression may be partitioned and expressed along structures in space and time. We here examine how inversionpost-rift compressional stresses is expressed manifest along the northern margin of the Farsund Basin during Late Cretaceous inversion and Paleogene-Neogene pulses of uplift. At the largest scale, strain stress localises along the lithosphere-scale Sorgenfrei-Tornquist Zone, where it; this is expressed in the upper crust as hangingwall folding, reverse reactivation of the basin-bounding normal fault, and bulk regional uplift. The geometry of the northern margin 15 of the basin varies along-strike, with a normal fault system passing eastward into an unfaulted ramp. Late Cretaceous compressive stresses, originating from the Alpine Orogeny convergence between Africa, Iberia and Europe to the south, selectively reactivated geometrically simple, planar sections of the fault, producing hangingwall anticlines and causing long- wavelength folding of the basin fill.