A review of Alpine deformation and stresses in southern England

Abstract

Southern England is in the foreland of the Tertiary Alpine deformation, being ∼700 km from the main orogenic zone. The main Alpine deformation in southern England involved maximum compressive stress (σ1) orientated approximately N-S and with the least compressive stress (σ3) being vertical. This generally caused gentle folding, but deformation is relatively intense around reverse-reactivated faults. This stress system changed so the intermediate compressive stress (σ2) became vertical, causing strike-slip faults that are conjugate about N-S. This probably reflects the reduction of the Alpine compression and the reduction of E-W compressive stresses during Atlantic spreading. The maximum horizontal compressive stress (σH) became perturbed to ∼NW-SE across much of north-western Europe, probably during the Neogene, as indicated by the dominant orientation of joints.