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Dangosydd eitem ddigidol (DOI)

  • James Scourse
    College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn, 9 TR10 9EZ, UK.
  • Margot Saher
  • Katrien Van Landeghem
  • Edward Lockhart
  • Catriona Purcell
  • Sarah Louise Callard
    Durham University
  • Zoe Roseby
    School of Ocean Sciences, Bangor UniversityNational Oceanography Centre, SouthamptonFaculty of Natural and Environmental Sciences, University of Southampton, Southampton, UK.
  • Ben Allison
    School of Ocean Sciences, Bangor University
  • Anna Pieńkowski
    University Centre in Svalbard (UNIS), Department of Arctic Geology, N-9171 Longyearbyen, Svalbard, Norway
  • Colm Ó Cofaigh
    Department of Geography, Durham University, Lower Mountjoy, South Road, Durham, DH1 3LE, UK
  • Daniel Praeg
    OGS (Istituto Nazionale di Oceanografia e di Geofisica Sperimentale), Borgo Grotta Gigante, 34010 Trieste, ItalyLaboratório de Geologia Marinha, Universidade Federal Fluminense, Brazil
  • Sophie Ward
  • R.C. Chiverrell
    School of Environmental Sciences, University of Liverpool, Liverpool, UK
  • Steven Moreton
    Natural Environment Research Council, Radiocarbon Facility, East Kilbride, Scotland, G75 OQF, UK
  • Derek Fabel
    Scottish Universities Environmental Research Centre
  • Chris Clark
    Department of Geography, Sheffield University, Sheffield, S10 2TN, UK
The dynamics of the British-Irish Ice Sheet (BIIS) during the Last Glacial were conditioned by marine-based ice streams, the largest of which by far was the Irish Sea Ice Stream (ISIS) which drained southwest across the Celtic shelf. The maximum extent and timing of the ISIS have been constrained by onshore evidence from the UK and Ireland, and by glacigenic sediments encountered in a small suite of vibrocores from the UK-Irish continental shelf, from which a single radiocarbon date is available. These data have long supported ice advance to at least the mid-shelf, while recent results suggest the ISIS may have extended 150 km farther seaward to the shelf edge. The glacigenic sequences have not been placed within a secure seismic-stratigraphic context and the relationship between glaciation and the linear sediment megaridges observed on the outer shelf of the Celtic Sea has remained uncertain. Here we report results of sedimentological, geochemical, geochronological and micropalaeontological analyses combined with a seismic-stratigraphic investigation of the glacigenic sequences of the Celtic Sea with the aims of establishing maximum extent, depositional context, timing and retreat chronology of ISIS. Eight lithofacies packages are identified, six of which correlate with seismic facies. Lithofacies LF1 and LF2 correlate to a seafloor seismic facies (SF1) that we interpret to record the postglacial and Holocene transgressive flooding of the shelf. Lithofacies LF10 (till), LF3, LF4 and LF8 (glacimarine) correlate to different seismic facies that we interpret to be of glacigenic origin based on sedimentological, geotechnical and micropalaeontological evidence, and their distribution, supported by geochemical evidence from lithofacies LF8 and LF10 indicate extension of ISIS as far as the Celtic Sea shelf break. New radiocarbon ages on calcareous micro- and macrofauna constrain this advance to be between 24 and 27 cal ka BP, consistent with pre-existing geochronological constraints. Glacimarine lithofacies LF8 is in places glacitectonically contorted and deformed, indicating ice readvance, but the nature and timing of this readvance is unclear. Retreat out of the Celtic Sea was initially rapid and may have been triggered by high relative sea-levels driven by significant glacio-isostatic depression, consistent with greater ice loads over Britain and Ireland than previously considered.

Allweddeiriau

Iaith wreiddiolSaesneg
Tudalennau (o-i)53-68
CyfnodolynMarine Geology
Cyfrol412
Dyddiad ar-lein cynnar16 Maw 2019
Dynodwyr Gwrthrych Digidol (DOIs)
StatwsCyhoeddwyd - 1 Meh 2019

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Nid oes data ar gael
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