HR: 11:20h
AN: T22C-05    [Abstracts]
TI: The influence of plate boundary deformation on regional intraplate exhumation: evidence from the Irish Sea basin system, western UK
AU: * Holford, S P
EM: sph184@bham.ac.uk
AF: School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B152TT United Kingdom
AU: Turner, J P
EM: j.p.turner@bham.ac.uk
AF: School of Geography, Earth & Environmental Sciences, University of Birmingham, Edgbaston, Birmingham, B152TT United Kingdom
AU: Green, P F
EM: mail@geotrack.com.au
AF: Geotrack International Pty Ltd, 37 Melville Road West Brunswick, Melbourne, 3055 Australia
AU: Williams, G A
EM: gwil@bgs.ac.uk
AF: British Geological Survey, Kingsley Dunham Centre, Keyworth, NG125GG United Kingdom
AB: Elucidating the causes of exhumation within intraplate regions and passive margin settings is an outstanding problem with global tectonic significance. The application of thermochronological tools such as apatite fission-track analysis (AFTA) across apparently stable intraplate regions (e.g. NW Europe, SW Australia, Southern Africa) has repeatedly revealed evidence for extensive phases of km-scale exhumation, often with no obvious causal mechanisms. Here we present results from a study of the exhumation history of the Irish Sea basin system (western UK) using palaeothermal (AFTA and VR), compactional and seismic reflection data which highlights the dominant control that plate boundary processes exert over the uplift and exhumation of continental interiors. This intraplate Mesozoic-Cenozoic basin system occupies the transition between the European Alpine deformation front and the NE Atlantic passive margin. Numerous studies have identified this area as one of the most severely exhumed in NW Europe. Much of this exhumation has been ascribed to Palaeocene epeirogeny caused by the Iceland Plume. However, our results reveal an exhumation history of far greater complexity with major exhumation episodes during the early Cretaceous (120-115 Ma) and Neogene (<20 Ma) removing up to 3 km and 1.5 km of Mesozoic-Cenozoic sediments from this region respectively. Mapping of early Cenozoic exhumation patterns reveals major heterogeneities in exhumation magnitudes at intra-basinal (<10 km) and regional (<100 km) scales which cannot be ascribed to a purely epeirogenic process such as plume-driven uplift. These regional phases of intraplate exhumation are coincident with important phases of deformation at preexisting or incipient plate boundaries. Early Cretaceous exhumation was coeval with the onset of seafloor spreading in Bay of Biscay. Neogene exhumation was coincident with the late Alpine orogenesis, with abundant evidence for Neogene compressional shortening in this study area. These observations imply that, despite the often large distances (>1000 km) between the exhumed intraplate regions and the most proximal plate boundaries, plate boundary processes exert the dominant control on the exhumation histories of plate interiors through (i) the far-field transmission of stresses (compressional shortening/inversion) and (ii) rift-flank uplift associated with continental rifts and pull-apart basins. In NW Europe, the influence of boundary-independent phenomena such as plume-related uplift appears to be subsidiary to that of plate boundary deformation.
DE: 1033 Intra-plate processes (3615, 8415)
DE: 1140 Thermochronology
DE: 8102 Continental contractional orogenic belts and inversion tectonics
DE: 8169 Sedimentary basin processes
SC: Tectonophysics [T]
MN: Fall Meeting 2005