The Permian to Jurassic stratigraphy and structural evolution of the central Cheshire Basin

Abstract

New seismic reflection data reveal details of the Permo-Triassic basin fill in the central Cheshire Basin. The seismic stratigraphy indicates that the Permian and Triassic succession is far thicker than previously estimated. Seismic data and backstripping of the preserved Permian to early Jurassic sedimentary succession suggest that at least two phases of fault-controlled subsidence occurred, in early Permian and early Triassic times. An intra-Triassic unconformity is seen on the seismic data near the top of the Sherwood Sandstone Group. This may equate with the Hardegsen Unconformity. It is possible that this unconformity was generated by syn-extensional regional uplift accompanying lithospheric thinning. The gross morphology and location of the faults on the eastern margin of the Cheshire Basin are interpreted to be, at least locally, controlled by extensional re-activation of a westwards-dipping reverse fault, possibly an extension of the Pontesford–Linley lineament.