Late Neogene development of the UK Atlantic margin
Published:January 01, 2002
M. S. Stoker, 2002. "Late Neogene development of the UK Atlantic margin", 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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The late Neogene (Pliocene–Holocene) interval witnessed a significant change in sedimentation style across the UK Atlantic margin that culminated in its present morphological expression. The onset of change is marked by the creation of a regional, angular, erosional unconformity that can be traced from the Hebrides and West Shetland margins into the adjacent deep-water basins of the Rockall Trough and Faeroe-Shetland Channel. In the Rockall Trough, the unconformity is a submarine erosion surface that is dated as early Pliocene in age, between c. 3.85 and 4.5 Ma. On the Hebrides and West Shetland margins, the dating of the unconformity is slightly less well constrained and spans the latest Miocene(?)–early Pliocene (c. 5.5-3.8 Ma) interval. The formation of this unconformity may have resulted from the seaward tilting and subsidence of the shelf margin, which may have further modified the oceanographic circulation pattern in the adjacent basins. The sedimentary response to this event was relatively quick in the deep-water basins, which preserve a record of early Pliocene (post 3.85 Ma) to Holocene sediment-drift accumulation, albeit with a shift in the focus of sedimentation relative to the underlying strata. In contrast, major prograding wedges, which have contributed extensively to the construction of the Hebrides and West Shetland margins and to a lesser extent the Rockall Bank, date essentially from late Pliocene time and largely correlate with the influx of ice-rafted material to the margin. However, indications for a restricted lower Pliocene component to the shelf-margin succession suggest that this apparent delay or lag in sedimentation, relative to the basins, may be a natural response to the rate of denudation of the adjacent landmasses. The regional observations off NW Britain support the concept of Neogene tectonic uplift.
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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.