Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation.

Louise Callard, Colm Ó Cofaigh, S. Benetti, Richard Chiverrell, Katrien J J Van Landeghem, Margot Saher, Jenny A Gales, David Small, Chris D Clark, Stephen J Livingstone, Derek Fabel, Steven G Moreton

Research output: Contribution to journalArticle

8 Citations (Scopus)

Abstract

During the Last Glacial Maximum (LGM) the marine-terminating Barra Fan Ice Stream (BFIS), a major conduit of the British Irish Ice Sheet (BIIS), drained much of western Scotland and northwest Ireland with ice streaming onto the continental shelf of the Malin Sea. The extent and retreat history of this ice stream across the shelf, until now, is not well known. In particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. To understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. Here, we present new geophysical data, marine sediment cores and over forty radiocarbon dates to provide important constraints on maximum extent of the BFIS, as well as the timing and pattern of retreat back across the Malin Shelf. Dated moraines and grounding-zone wedges (GZW) seen in seafloor sub-bottom profiles provide evidence that the BFIS reached the Malin Shelf edge during the LGM and was at its maximum extent around 26.7 ka BP. The presence of two sets of GZWs suggests that the style of retreat was episodic. The new radiocarbon chronology shows that retreat from the shelf edge was underway by 25.9 ka BP, with the majority of the continental shelf ice free by 23.2 ka BP, and that glacimarine conditions were present in the Sea of Hebrides by 20.2 ka BP at the latest. Collectively, these results indicate that the majority of the Malin Shelf was free of grounded ice by ~21.5-20 ka BP, which is up to 4,000 years earlier than previously reconstructed. We attribute this early deglaciation to high relative sea level caused by glacial isostatic depression when the BIIS reached its maximum extent promoting ice shelf and grounding line instability. Two deep troughs, forming reverse bed slopes, aided the continued retreat of the BFIS. This suggests that local ice loading and bed morphology can be significant controls on the destabilisation of a marine-terminating ice stream and can override the influence of ocean and atmospheric temperatures.
LanguageEnglish
Pages280-302
JournalQuaternary Science Reviews
Volume201
Early online date26 Oct 2018
DOIs
Publication statusPublished - 1 Dec 2018

Fingerprint

ice stream
Northern Ireland
last glaciation
glaciation
fan
Scotland
ice
history
shelf break
deglaciation
Last Glacial Maximum
ice sheet
Ireland
continental shelf
grounding line
Barra
History
Retreat
ice shelf
marine sediment

Keywords

  • British-Irish Ice Sheet
  • glacimarine
  • Last Glacial Maximum
  • radiocarbon dating
  • ice-sheet retreat
  • grounding-zone wedges

Cite this

Callard, Louise ; Ó Cofaigh, Colm ; Benetti, S. ; Chiverrell, Richard ; Van Landeghem, Katrien J J ; Saher, Margot ; Gales, Jenny A ; Small, David ; Clark, Chris D ; Livingstone, Stephen J ; Fabel, Derek ; Moreton, Steven G. / Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation. In: Quaternary Science Reviews. 2018 ; Vol. 201. pp. 280-302.
@article{e05de740349f4e188af2d4694fc41e01,
title = "Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation.",
abstract = "During the Last Glacial Maximum (LGM) the marine-terminating Barra Fan Ice Stream (BFIS), a major conduit of the British Irish Ice Sheet (BIIS), drained much of western Scotland and northwest Ireland with ice streaming onto the continental shelf of the Malin Sea. The extent and retreat history of this ice stream across the shelf, until now, is not well known. In particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. To understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. Here, we present new geophysical data, marine sediment cores and over forty radiocarbon dates to provide important constraints on maximum extent of the BFIS, as well as the timing and pattern of retreat back across the Malin Shelf. Dated moraines and grounding-zone wedges (GZW) seen in seafloor sub-bottom profiles provide evidence that the BFIS reached the Malin Shelf edge during the LGM and was at its maximum extent around 26.7 ka BP. The presence of two sets of GZWs suggests that the style of retreat was episodic. The new radiocarbon chronology shows that retreat from the shelf edge was underway by 25.9 ka BP, with the majority of the continental shelf ice free by 23.2 ka BP, and that glacimarine conditions were present in the Sea of Hebrides by 20.2 ka BP at the latest. Collectively, these results indicate that the majority of the Malin Shelf was free of grounded ice by ~21.5-20 ka BP, which is up to 4,000 years earlier than previously reconstructed. We attribute this early deglaciation to high relative sea level caused by glacial isostatic depression when the BIIS reached its maximum extent promoting ice shelf and grounding line instability. Two deep troughs, forming reverse bed slopes, aided the continued retreat of the BFIS. This suggests that local ice loading and bed morphology can be significant controls on the destabilisation of a marine-terminating ice stream and can override the influence of ocean and atmospheric temperatures.",
keywords = "British-Irish Ice Sheet, glacimarine, Last Glacial Maximum, radiocarbon dating, ice-sheet retreat, grounding-zone wedges",
author = "Louise Callard and {{\'O} Cofaigh}, Colm and S. Benetti and Richard Chiverrell and {Van Landeghem}, {Katrien J J} and Margot Saher and Gales, {Jenny A} and David Small and Clark, {Chris D} and Livingstone, {Stephen J} and Derek Fabel and Moreton, {Steven G}",
year = "2018",
month = "12",
day = "1",
doi = "10.1016/j.quascirev.2018.10.002",
language = "English",
volume = "201",
pages = "280--302",
journal = "Quaternary Science Reviews",
issn = "0277-3791",
publisher = "Elsevier",

}

Callard, L, Ó Cofaigh, C, Benetti, S, Chiverrell, R, Van Landeghem, KJJ, Saher, M, Gales, JA, Small, D, Clark, CD, Livingstone, SJ, Fabel, D & Moreton, SG 2018, 'Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation.', Quaternary Science Reviews, vol. 201, pp. 280-302. https://doi.org/10.1016/j.quascirev.2018.10.002

Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation. / Callard, Louise; Ó Cofaigh, Colm; Benetti, S.; Chiverrell, Richard; Van Landeghem, Katrien J J ; Saher, Margot; Gales, Jenny A; Small, David; Clark, Chris D; Livingstone, Stephen J; Fabel, Derek; Moreton, Steven G.

In: Quaternary Science Reviews, Vol. 201, 01.12.2018, p. 280-302.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Extent and retreat history of the Barra Fan Ice Stream offshore western Scotland and northern Ireland during the last glaciation.

AU - Callard, Louise

AU - Ó Cofaigh, Colm

AU - Benetti, S.

AU - Chiverrell, Richard

AU - Van Landeghem, Katrien J J

AU - Saher, Margot

AU - Gales, Jenny A

AU - Small, David

AU - Clark, Chris D

AU - Livingstone, Stephen J

AU - Fabel, Derek

AU - Moreton, Steven G

PY - 2018/12/1

Y1 - 2018/12/1

N2 - During the Last Glacial Maximum (LGM) the marine-terminating Barra Fan Ice Stream (BFIS), a major conduit of the British Irish Ice Sheet (BIIS), drained much of western Scotland and northwest Ireland with ice streaming onto the continental shelf of the Malin Sea. The extent and retreat history of this ice stream across the shelf, until now, is not well known. In particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. To understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. Here, we present new geophysical data, marine sediment cores and over forty radiocarbon dates to provide important constraints on maximum extent of the BFIS, as well as the timing and pattern of retreat back across the Malin Shelf. Dated moraines and grounding-zone wedges (GZW) seen in seafloor sub-bottom profiles provide evidence that the BFIS reached the Malin Shelf edge during the LGM and was at its maximum extent around 26.7 ka BP. The presence of two sets of GZWs suggests that the style of retreat was episodic. The new radiocarbon chronology shows that retreat from the shelf edge was underway by 25.9 ka BP, with the majority of the continental shelf ice free by 23.2 ka BP, and that glacimarine conditions were present in the Sea of Hebrides by 20.2 ka BP at the latest. Collectively, these results indicate that the majority of the Malin Shelf was free of grounded ice by ~21.5-20 ka BP, which is up to 4,000 years earlier than previously reconstructed. We attribute this early deglaciation to high relative sea level caused by glacial isostatic depression when the BIIS reached its maximum extent promoting ice shelf and grounding line instability. Two deep troughs, forming reverse bed slopes, aided the continued retreat of the BFIS. This suggests that local ice loading and bed morphology can be significant controls on the destabilisation of a marine-terminating ice stream and can override the influence of ocean and atmospheric temperatures.

AB - During the Last Glacial Maximum (LGM) the marine-terminating Barra Fan Ice Stream (BFIS), a major conduit of the British Irish Ice Sheet (BIIS), drained much of western Scotland and northwest Ireland with ice streaming onto the continental shelf of the Malin Sea. The extent and retreat history of this ice stream across the shelf, until now, is not well known. In particular, geochronological constraints on the history of this ice stream have thus far been restricted to deep-sea cores or terrestrial cosmogenic nuclide dating onshore, with ages across the shelf absent. To understand the possible external forcing factors acting on this marine terminating ice stream during retreat, improved geochronological constraint on its deglaciation is necessary. Here, we present new geophysical data, marine sediment cores and over forty radiocarbon dates to provide important constraints on maximum extent of the BFIS, as well as the timing and pattern of retreat back across the Malin Shelf. Dated moraines and grounding-zone wedges (GZW) seen in seafloor sub-bottom profiles provide evidence that the BFIS reached the Malin Shelf edge during the LGM and was at its maximum extent around 26.7 ka BP. The presence of two sets of GZWs suggests that the style of retreat was episodic. The new radiocarbon chronology shows that retreat from the shelf edge was underway by 25.9 ka BP, with the majority of the continental shelf ice free by 23.2 ka BP, and that glacimarine conditions were present in the Sea of Hebrides by 20.2 ka BP at the latest. Collectively, these results indicate that the majority of the Malin Shelf was free of grounded ice by ~21.5-20 ka BP, which is up to 4,000 years earlier than previously reconstructed. We attribute this early deglaciation to high relative sea level caused by glacial isostatic depression when the BIIS reached its maximum extent promoting ice shelf and grounding line instability. Two deep troughs, forming reverse bed slopes, aided the continued retreat of the BFIS. This suggests that local ice loading and bed morphology can be significant controls on the destabilisation of a marine-terminating ice stream and can override the influence of ocean and atmospheric temperatures.

KW - British-Irish Ice Sheet

KW - glacimarine

KW - Last Glacial Maximum

KW - radiocarbon dating

KW - ice-sheet retreat

KW - grounding-zone wedges

U2 - 10.1016/j.quascirev.2018.10.002

DO - 10.1016/j.quascirev.2018.10.002

M3 - Article

VL - 201

SP - 280

EP - 302

JO - Quaternary Science Reviews

T2 - Quaternary Science Reviews

JF - Quaternary Science Reviews

SN - 0277-3791

ER -