Cenozoic structures in the eastern North Sea Basin — A case for salt tectonics

Local and scattered deformations of the Cenozoic succession in the eastern North Sea Basin have often been used to infer the importance of regional events related to major plate tectonic processes such as the Alpine Orogeny or the opening of the North Atlantic. Here we integrate published and new interpretations from conventional and high resolution seismic data and outcrops in the entire eastern North Sea Basin (onshore as well as offshore) and unravel the kinematic history and the tectonic implications. The analysis shows Paleogene inversion along selected fault trends in the Central Graben and the Sorgenfrei–Tornquist Zone, superimposed onto thermal subsidence centered in the central North Sea. Minor Paleogene and Neogene differential subsidence across reactivated N–S striking basement faults could be invoked as having a tectonic origin, but differential compaction of the underlying thick Mesozoic succession provides a simpler explanation. Our analysis demonstrates that the main mechanism that caused deformation of the Cenozoic succession in the eastern North Sea Basin was reactivation of the Zechstein salt. Cenozoic salt reactivation was a consequence of differential loading by prograding Cenozoic sequences acting on Mesozoic salt structures and salt deposits of varying thickness, controlled by Permian topographic highs. ► Decompacting Cenozoic successions enable a detailed timing of tectonic activity. ► 2 Paleogene inversion phases are identified in the central North Sea. ► Cenozoic structures along the Ringkøbing-Fyn High are controlled by halokinetics. ► The halokinetics were triggerd by differential load imposed by clinoform deposition. ► No structural observations require Neogene inversion nor uplift of the hinterland.