A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors

Edward A. Lockhart, James D Scourse, Daniel Praeg, Katrien J J Van Landeghem, Claire Mellett, Margot Saher, Louise Callard, Richard Chiverrell, S. Benetti, Colm Ó Cofaigh, Chris D Clark

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

The Celtic Sea contains the world's largest continental shelf sediment ridges. These megaridges were initially interpreted as tidal features formed during post-glacial marine transgression, but glacigenic sediments have been recovered from their flanks. We examine the stratigraphy of the megaridges using new decimetric-resolution geophysical data correlated to sediment cores to test hypothetical tidal vs glacial modes of formation. The megaridges comprise three main units, 1) a superficial fining-upward drape that extends across the shelf above an unconformity. Underlying this drape is 2), the Melville Formation (MFm) which comprises the upper bulk of the megaridges, sometimes displaying dipping internal acoustic reflections and consisting of medium to coarse sand and shell fragments; characteristics consistent with either a tidal or glacifluvial origin. The MFm unconformably overlies 3), the Upper Little Sole Formation (ULSFm), previously interpreted to be of late Pliocene to early Pleistocene age, but here shown to correlate to Late Pleistocene glacigenic sediments forming a precursor topography. The superficial drape is interpreted as a product of prolonged wave energy as tidal currents diminished during the final stages of post-glacial marine transgression. We argue that the stratigraphy constrains the age of the MFm to between 24.3 and 14 ka BP, based on published dates, coeval with deglaciation and a modelled period of megatidal conditions during post-glacial marine transgression. Stratigraphically and sedimentologically, the megaridges could represent preserved glacifluvial features, but we suggest that they comprise post-glacial tidal deposits (MFm) mantling a partially-eroded glacial topography (ULSFm). The observed stratigraphy suggests that ice extended to the continental shelf-edge.
LanguageEnglish
Pages156-170
JournalQuaternary Science Reviews
Volume198
Early online date10 Sep 2018
DOIs
Publication statusPublished - 15 Oct 2018

Fingerprint

Postglacial
transgression
stratigraphy
continental shelf
topography
Pleistocene
shelf sediment
shelf break
tidal current
deglaciation
wave energy
unconformity
sediment
sediment core
Pliocene
acoustics
shell
ice
sand
sea

Keywords

  • Holocene
  • Late Pleistocene
  • Western Europe
  • Celtic Sea
  • Stratigraphy
  • Glaciation
  • Tidal Sand Ridges
  • Irish Sea Ice Stream

Cite this

Lockhart, E. A., Scourse, J. D., Praeg, D., Van Landeghem, K. J. J., Mellett, C., Saher, M., ... Clark, C. D. (2018). A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors. Quaternary Science Reviews, 198, 156-170. https://doi.org/10.1016/j.quascirev.2018.08.029
Lockhart, Edward A. ; Scourse, James D ; Praeg, Daniel ; Van Landeghem, Katrien J J ; Mellett, Claire ; Saher, Margot ; Callard, Louise ; Chiverrell, Richard ; Benetti, S. ; Ó Cofaigh, Colm ; Clark, Chris D. / A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors. In: Quaternary Science Reviews. 2018 ; Vol. 198. pp. 156-170.
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abstract = "The Celtic Sea contains the world's largest continental shelf sediment ridges. These megaridges were initially interpreted as tidal features formed during post-glacial marine transgression, but glacigenic sediments have been recovered from their flanks. We examine the stratigraphy of the megaridges using new decimetric-resolution geophysical data correlated to sediment cores to test hypothetical tidal vs glacial modes of formation. The megaridges comprise three main units, 1) a superficial fining-upward drape that extends across the shelf above an unconformity. Underlying this drape is 2), the Melville Formation (MFm) which comprises the upper bulk of the megaridges, sometimes displaying dipping internal acoustic reflections and consisting of medium to coarse sand and shell fragments; characteristics consistent with either a tidal or glacifluvial origin. The MFm unconformably overlies 3), the Upper Little Sole Formation (ULSFm), previously interpreted to be of late Pliocene to early Pleistocene age, but here shown to correlate to Late Pleistocene glacigenic sediments forming a precursor topography. The superficial drape is interpreted as a product of prolonged wave energy as tidal currents diminished during the final stages of post-glacial marine transgression. We argue that the stratigraphy constrains the age of the MFm to between 24.3 and 14 ka BP, based on published dates, coeval with deglaciation and a modelled period of megatidal conditions during post-glacial marine transgression. Stratigraphically and sedimentologically, the megaridges could represent preserved glacifluvial features, but we suggest that they comprise post-glacial tidal deposits (MFm) mantling a partially-eroded glacial topography (ULSFm). The observed stratigraphy suggests that ice extended to the continental shelf-edge.",
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Lockhart, EA, Scourse, JD, Praeg, D, Van Landeghem, KJJ, Mellett, C, Saher, M, Callard, L, Chiverrell, R, Benetti, S, Ó Cofaigh, C & Clark, CD 2018, 'A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors', Quaternary Science Reviews, vol. 198, pp. 156-170. https://doi.org/10.1016/j.quascirev.2018.08.029

A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors. / Lockhart, Edward A.; Scourse, James D; Praeg, Daniel; Van Landeghem, Katrien J J ; Mellett, Claire; Saher, Margot; Callard, Louise; Chiverrell, Richard; Benetti, S.; Ó Cofaigh, Colm; Clark, Chris D.

In: Quaternary Science Reviews, Vol. 198, 15.10.2018, p. 156-170.

Research output: Contribution to journalArticle

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T1 - A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors

AU - Lockhart, Edward A.

AU - Scourse, James D

AU - Praeg, Daniel

AU - Van Landeghem, Katrien J J

AU - Mellett, Claire

AU - Saher, Margot

AU - Callard, Louise

AU - Chiverrell, Richard

AU - Benetti, S.

AU - Ó Cofaigh, Colm

AU - Clark, Chris D

N1 - ‘Open Access funded by Natural Environment Research Council’

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N2 - The Celtic Sea contains the world's largest continental shelf sediment ridges. These megaridges were initially interpreted as tidal features formed during post-glacial marine transgression, but glacigenic sediments have been recovered from their flanks. We examine the stratigraphy of the megaridges using new decimetric-resolution geophysical data correlated to sediment cores to test hypothetical tidal vs glacial modes of formation. The megaridges comprise three main units, 1) a superficial fining-upward drape that extends across the shelf above an unconformity. Underlying this drape is 2), the Melville Formation (MFm) which comprises the upper bulk of the megaridges, sometimes displaying dipping internal acoustic reflections and consisting of medium to coarse sand and shell fragments; characteristics consistent with either a tidal or glacifluvial origin. The MFm unconformably overlies 3), the Upper Little Sole Formation (ULSFm), previously interpreted to be of late Pliocene to early Pleistocene age, but here shown to correlate to Late Pleistocene glacigenic sediments forming a precursor topography. The superficial drape is interpreted as a product of prolonged wave energy as tidal currents diminished during the final stages of post-glacial marine transgression. We argue that the stratigraphy constrains the age of the MFm to between 24.3 and 14 ka BP, based on published dates, coeval with deglaciation and a modelled period of megatidal conditions during post-glacial marine transgression. Stratigraphically and sedimentologically, the megaridges could represent preserved glacifluvial features, but we suggest that they comprise post-glacial tidal deposits (MFm) mantling a partially-eroded glacial topography (ULSFm). The observed stratigraphy suggests that ice extended to the continental shelf-edge.

AB - The Celtic Sea contains the world's largest continental shelf sediment ridges. These megaridges were initially interpreted as tidal features formed during post-glacial marine transgression, but glacigenic sediments have been recovered from their flanks. We examine the stratigraphy of the megaridges using new decimetric-resolution geophysical data correlated to sediment cores to test hypothetical tidal vs glacial modes of formation. The megaridges comprise three main units, 1) a superficial fining-upward drape that extends across the shelf above an unconformity. Underlying this drape is 2), the Melville Formation (MFm) which comprises the upper bulk of the megaridges, sometimes displaying dipping internal acoustic reflections and consisting of medium to coarse sand and shell fragments; characteristics consistent with either a tidal or glacifluvial origin. The MFm unconformably overlies 3), the Upper Little Sole Formation (ULSFm), previously interpreted to be of late Pliocene to early Pleistocene age, but here shown to correlate to Late Pleistocene glacigenic sediments forming a precursor topography. The superficial drape is interpreted as a product of prolonged wave energy as tidal currents diminished during the final stages of post-glacial marine transgression. We argue that the stratigraphy constrains the age of the MFm to between 24.3 and 14 ka BP, based on published dates, coeval with deglaciation and a modelled period of megatidal conditions during post-glacial marine transgression. Stratigraphically and sedimentologically, the megaridges could represent preserved glacifluvial features, but we suggest that they comprise post-glacial tidal deposits (MFm) mantling a partially-eroded glacial topography (ULSFm). The observed stratigraphy suggests that ice extended to the continental shelf-edge.

KW - Holocene

KW - Late Pleistocene

KW - Western Europe

KW - Celtic Sea

KW - Stratigraphy

KW - Glaciation

KW - Tidal Sand Ridges

KW - Irish Sea Ice Stream

U2 - 10.1016/j.quascirev.2018.08.029

DO - 10.1016/j.quascirev.2018.08.029

M3 - Article

VL - 198

SP - 156

EP - 170

JO - Quaternary Science Reviews

T2 - Quaternary Science Reviews

JF - Quaternary Science Reviews

SN - 0277-3791

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