Cenozoic inversion and uplift of southern Britain

Abstract

AbstractWhereas significant exhumation of northern Britain took place during Paleocene time, probably as a consequence of uplift caused by a mantle plume, Paleogene basin inversion and uplift in southern Britain appears to be a consequence of Alpine tectonism. Recent publications demonstrate that inversion of Mesozoic basins across southern Britain was accompanied by subsidence of flanking basins in areas that had previously remained stable. Structures observed on seismic sections across the Weald Basin in SE England reveal that inversion occurred locally by north-directed reverse movements on pre-existing normal faults that cut down at a low angle deep into the basement. The overall effect of inversion of the Weald Basin, however, is a bulk deformation that produced a domal uplift, flanked by subsidence of the London and Hampshire-Dieppe basins. A 2D finite element thermomechanical model of continental lithosphere containing a region of reduced strength in the crust simulates Jurassic-Early Cretaceous extension to form the Weald Basin, followed by compression during the Tertiary to produce its inversion and the flanking basins. The timing of tectonic events across southern Britain correlates with times when Alpine stresses were transmitted into the foreland to the north sufficiently well to link them. Through most of Tertiary time, the landscape of southern England was of relatively low elevation and low-energy surface processes. However, late Neogene uplift, generally greater in the west, appears to have been part of a larger-scale uplift of land areas with hard rock at surface, which has no obvious tectonic explanation.