Cenozoic inversion and uplift of southern Britain
Published:January 01, 2002
Derek J. Blundell, 2002. "Cenozoic inversion and uplift of southern Britain", Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration, A. G. Doré, J. A. Cartwright, M. S. Stoker, J. P. Turner, N. White
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Whereas 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 lowenergy 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.
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Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration
Northwest Europe has undergone repeated episodes of exhumation (the exposure of formerly buried rocks) due to such factors as post-orogenic unroofing, rift-shoulder uplift, hotspot activity, compressive tectonics, eustatic sea-level change, glaciation and isostatic readjustment. The main observational legacy of this exhumation around the North Atlantic is preserved in the comparatively young (Mesozoic and Cenozoic) geological record of this region. Despite a rapid increase in the understanding of the exhumation of this area, there are still many unknowns: the relative intensity of the various phases and their geographical variation; mechanisms of uplift; primary causes of exhumation. Tied to these problems is the larger-scale question of whether the circum-North Atlantic is unique or whether its behaviour is typical for passive margins.
There have been several attempts in recent years to bring together researchers to address these questions, but these have often focused on one particular geographical area or one particular exhumation phase. Before an integrated story can emerge, disciplines that have traditionally remained apart need to come together: geomorphology and offshore seismic interpretation; Palaeogene and Neogene studies; Scandinavian and British-Irish research schools. This volume represents a first step in this direction by providing an inter-disciplinary set of studies over a wide latitudinal range of the NW European margin.
The studies presented here are based on a variety of techniques that have been employed to address the main concerns of North Atlantic exhumation history, including timing, mechanisms and the sedimentary response of the continental margin. The 25 papers presented in this volume have been arranged in four sections to reflect the highly varied approach to this subject and the commercial implications. Part 1 is concerned with exhumation mechanisms, focusing primarily on the Iceland Plume. Parts 2 and 3 present ongoing research on the continental margin record offshore Scandinavia, Britain, Ireland and the Faroes. The papers in these two parts illustrate the communication that is now occurring between the two regional research schools and the acknowledgement of a multiphase Cenozoic denudation chronology for both areas. Part 4 contains five papers describing the significant changes to the hydrocarbon systems that occur in exhumed basins, detailing the implications for hydrocarbon-bearing basins.
Exhumation of the North Atlantic Margin: Timing, Mechanisms and Implications for Petroleum Exploration is the most up-to-date and complete volume integrating all aspects of the Mesozoic-Cenozoic exhumation of North Atlantic borderlands. Itwill be of interest to those within the oil industry, geomorphologists and other workers with an interest in NW European regional geology.