HR: 1330h
AN: V12B-0596    [PDF]
TI: Constraining the Temporal and Spatial Evolution of Mantle Plumes Using the Stratigraphic Record
AU: * Mackay, L M
EM: mackay@esc.cam.ac.uk
AF: Bullard Laboratories, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: Jones, S M
AF: Department of Geology, Trinity College, Dublin, 2 Ireland
AU: White, N
AF: Bullard Laboratories, Madingley Rise, Madingley Road, Cambridge, CB3 0EZ United Kingdom
AU: White, N
AF: Department of Geology, Trinity College, Dublin, 2 Ireland
AB: Gravitational and tomographic studies provide a snap-shot of mantle plumes at the present day. However, these techniques are unable to constrain how mantle plumes have evolved, temporally and spatially, to their present day structures. A mantle plume will generate vertical motions in the overlying plate. These vertical motions will be recorded in the stratigraphic record of the region, enabling the size and planform of the mantle plume to be mapped out over time. During Cenozoic times, anomalous uplift and subsidence occurred throughout the North Atlantic region. These vertical motions most likely result from temporal and spatial variations of Iceland Plume activity. Quantifying uplift generated by the convective support of the Iceland Plume enables the extent of the Iceland Plume head to be mapped out. Here, we describe the record of activity of the southern half of the Iceland Plume head, which affected a region encompassing the British Isles, southern Greenland and eastern Canada. This record is based on stratigraphy along the extensional margins which fringe the North Atlantic Ocean. A detailed study has been carried out on the Moray Firth Basin, part of the North Sea rift system, using backstripped well-log data. The effect of tectonic subsidence has been removed from the basement subsidence profiles of 50 wells, enabling anomalous residual uplift and subsidence to be isolated. A transient Paleocene uplift-subsidence event, with a duration of approximately 15 Ma, is recorded throughout the Moray Firth Basin. The magnitude of peak uplift is 150--500 m. This transient uplift event has previously been identified in basins surrounding the British Isles, including the Faroe-Shetland Basin, the Porcupine Basin and the North Viking Graben. The initiating Iceland Plume provided dynamic support to the overlying plate and generated uplift. As the effect of the Iceland Plume in the British Isles region waned, subsidence occurred. These results from subsidence analysis agree with estimates of dynamic support from the palaeotopographic reconstruction of the coastline of the British Isles at the Paleocene/Eocene boundary. The stratigraphic record of the North Atlantic region yields information about the temporal and spatial evolution of the Iceland Plume during Cenozoic time. Such records of mantle plume evolution will provide important new constraints for models of mantle convection.
DE: 8105 Continental margins and sedimentary basins
DE: 8121 Dynamics, convection currents and mantle plumes
DE: 9325 Atlantic Ocean
DE: 9604 Cenozoic
SC: Volcanology, Geochemistry, Petrology [V]
MN: 2003 Fall Meeting