Present and past influence of the Iceland Plume on sedimentation
Published:January 01, 2002
Stephen M. Jones, Nicky White, Benjamin J. Clarke, Eleanor Rowley, Kerry Gallagher, 2002. "Present and past influence of the Iceland Plume on sedimentation", 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 Cenozoic development of the North Atlantic province has been dramatically influenced by the behaviour of the Iceland Plume, whose striking dominance is manifest by long-wavelength free-air gravity anomalies and by oceanic bathymetric anomalies. Here, we use these anomalies to estimate the amplitude and wavelength of present-day dynamic uplift associated with this plume. Maximum dynamic support in the North Atlantic is 1.5-2 km at Iceland itself. Most of Greenland is currently experiencing dynamic support of 0.5-1 km, whereas the NW European shelf is generally supported by < 0.5 km. The proto-Iceland Plume had an equally dramatic effect on the Early Cenozoic palaeogeography of the North Atlantic margins, as we illustrate with a study of plume-related uplift, denudation and sedimentation on the continental shelf encompassing Britain and Ireland. We infer that during Paleocene time a hot subvertical sheet of asthenosphere welled up beneath an axis running from the Faroes through the Irish Sea towards Lundy, generating a welt of magmatic underplating of the crust which is known to exist beneath this axis. Transient and permanent uplift associated with this magmatic injection caused regional denudation, and consequently large amounts of clastic sediment have been shed into surrounding basins during Cenozoic time. Mass balance calculations indicate agreement between the volume of denuded material and the volume of Cenozoic sediments deposited offshore in the northern North Sea Basin and the Rockall Trough. The volume of material denuded from Britain and Ireland is probably insufficient to account for the sediment in the Faroe-Shetland Basin and an excess of sediment has been supplied to the Porcupine Basin. We emphasize the value of combining observations from both oceanic and continental realms to elucidate the evolution of the Iceland Plume through space and time.
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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.