Marine geophysical evidence for Late Pleistocene ice sheet extent and recession off northwest Ireland

C O´ Cofaigh, P Dunlop, S Benetti

Research output: Contribution to journalArticle

64 Citations (Scopus)

Abstract

Multibeam swath bathymetry data collected through the Irish National Seabed Survey provides direct evidence for extensive glaciation of the continental shelf off northwest Ireland. Streamlined subglacial bedforms on the inner shelf record former offshore-directed ice flow. The major glacial features, however, consist of well developed, nested arcuate moraines which mark the position of former ice sheet margins on the shelf. Distal to these moraines, on the outermost shelf, prominent zones of iceberg ploughmarks give way into a well developed system of gullies and canyons which incise the continentalslope. The large-scale, nested, arcuate moraines record the episodic retreat, probably punctuated by minor readvances or oscillations, of a lobate grounded ice sheet across this sector of the continental shelf during deglaciation. Initial retreat from the outer shelf was associated with an episode of ice sheet breakup and calving as recorded by extensive zones of iceberg ploughmarks distal to the outermost moraine. It is conceivable that this initial phase of retreat could have been driven by rising sea level. The data indicate a major reorganisation of the Irish Ice Sheet on the northwest shelf during deglaciation; an initial elongate ice sheet configuration extending along the shelf edge changed to a pronounced lobate form during retreat. Consideration of dated, marine stratigraphic records from the wider northwest margin suggests that ice sheet advance to the shelf edge likely occurred at about 29–27 cal ka BP, but that retreat from this shelf edge position did not take place until after 24 cal ka BP. Large-scale contrasts in continental margin morphology west of Ireland, from trough mouth fans in the north to gully/canyon systems further to south, reflects a combination of factors including spatial variations in sediment flux related to palaeo-glaciology.
LanguageEnglish
Pages147-159
JournalQuaternary Science Reviews
Volume44
DOIs
Publication statusPublished - Jun 2012

Fingerprint

recession
Ireland
ice sheet
ice
Pleistocene
fan
shelf break
reorganization
evidence
iceberg
icebergs
gully
deglaciation
canyons
canyon
continental shelf
glacial feature
glaciology
swath bathymetry
marine record

Keywords

  • Moraines
  • British Irish Ice Sheet
  • Drumlins
  • Continental shelf

Cite this

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abstract = "Multibeam swath bathymetry data collected through the Irish National Seabed Survey provides direct evidence for extensive glaciation of the continental shelf off northwest Ireland. Streamlined subglacial bedforms on the inner shelf record former offshore-directed ice flow. The major glacial features, however, consist of well developed, nested arcuate moraines which mark the position of former ice sheet margins on the shelf. Distal to these moraines, on the outermost shelf, prominent zones of iceberg ploughmarks give way into a well developed system of gullies and canyons which incise the continentalslope. The large-scale, nested, arcuate moraines record the episodic retreat, probably punctuated by minor readvances or oscillations, of a lobate grounded ice sheet across this sector of the continental shelf during deglaciation. Initial retreat from the outer shelf was associated with an episode of ice sheet breakup and calving as recorded by extensive zones of iceberg ploughmarks distal to the outermost moraine. It is conceivable that this initial phase of retreat could have been driven by rising sea level. The data indicate a major reorganisation of the Irish Ice Sheet on the northwest shelf during deglaciation; an initial elongate ice sheet configuration extending along the shelf edge changed to a pronounced lobate form during retreat. Consideration of dated, marine stratigraphic records from the wider northwest margin suggests that ice sheet advance to the shelf edge likely occurred at about 29–27 cal ka BP, but that retreat from this shelf edge position did not take place until after 24 cal ka BP. Large-scale contrasts in continental margin morphology west of Ireland, from trough mouth fans in the north to gully/canyon systems further to south, reflects a combination of factors including spatial variations in sediment flux related to palaeo-glaciology.",
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Marine geophysical evidence for Late Pleistocene ice sheet extent and recession off northwest Ireland. / O´ Cofaigh, C; Dunlop, P; Benetti, S.

Vol. 44, 06.2012, p. 147-159.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Marine geophysical evidence for Late Pleistocene ice sheet extent and recession off northwest Ireland

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AU - Dunlop, P

AU - Benetti, S

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AB - Multibeam swath bathymetry data collected through the Irish National Seabed Survey provides direct evidence for extensive glaciation of the continental shelf off northwest Ireland. Streamlined subglacial bedforms on the inner shelf record former offshore-directed ice flow. The major glacial features, however, consist of well developed, nested arcuate moraines which mark the position of former ice sheet margins on the shelf. Distal to these moraines, on the outermost shelf, prominent zones of iceberg ploughmarks give way into a well developed system of gullies and canyons which incise the continentalslope. The large-scale, nested, arcuate moraines record the episodic retreat, probably punctuated by minor readvances or oscillations, of a lobate grounded ice sheet across this sector of the continental shelf during deglaciation. Initial retreat from the outer shelf was associated with an episode of ice sheet breakup and calving as recorded by extensive zones of iceberg ploughmarks distal to the outermost moraine. It is conceivable that this initial phase of retreat could have been driven by rising sea level. The data indicate a major reorganisation of the Irish Ice Sheet on the northwest shelf during deglaciation; an initial elongate ice sheet configuration extending along the shelf edge changed to a pronounced lobate form during retreat. Consideration of dated, marine stratigraphic records from the wider northwest margin suggests that ice sheet advance to the shelf edge likely occurred at about 29–27 cal ka BP, but that retreat from this shelf edge position did not take place until after 24 cal ka BP. Large-scale contrasts in continental margin morphology west of Ireland, from trough mouth fans in the north to gully/canyon systems further to south, reflects a combination of factors including spatial variations in sediment flux related to palaeo-glaciology.

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