Cosmogenic 10Be chronology of the last deglaciation of western Ireland, and implications for sensitivity of the Irish Ice Sheet to climate Change

Clark, Jorie; McCabe, Anne; Schnabel, Christoph; Clark, Peter U.; McCarron, Stephen; Freeman, Stewart P.H.T.; Maden, C.; Xu, Sheng

doi:10.1130/b26288.1

Cited by 13 publications

(34 citation statements)

References 31 publications

(34 reference statements)

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“…Conversely, the aggregated TCN mean age for Glencolumbkille in south‐west Donegal [17.2 ± 0.6 ka (17.0 ± 1.4 ka)], the single TCN age for Kilcar (18.0 ± 1.7 ka) and the minimum deglaciation age represented by postglacial rockslide debris at nearby Slieve League [17.3 ± 0.6 ka (17.1 ± 1.5 ka)] suggest that southern Donegal lay within the limits of the readvance that produced the DBM. Similarly, the five ‘younger’ TCN ages [mean = 16.6 ± 0.6 ka (16.7 ± 1.5 ka)] reported by Clark et al () for the Twanywaddyduff moraine system of the northern Ox Mountains (Fig. ; Table ) indicate persistence of ice cover along the inner part of Donegal Bay after ∼17 ka.…”

Section: Discussionmentioning

confidence: 99%

Deglaciation chronology of the Donegal Ice Centre, north‐west Ireland

Wilson

Ballantyne

Benetti

et al. 2018

J Quaternary Science

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During the Last Glacial Maximum, Donegal in north‐west Ireland functioned as an independent centre of ice dispersal that separated and fed into the Donegal Bay Ice Lobe (sourced in the Irish Midlands) to the south and the Hebrides/Malin Sea Ice Stream to the north. We report geochronological data that demonstrate marked contrasts in the timing and rate of deglaciation in northern and southern Donegal. In northern Donegal, which occupied an inter‐ice‐stream/lobe location, decoupling from the Hebrides/Malin Sea Ice Stream resulted in formation of a marine embayment along the north coast by ∼22–21 ka, and subsequent slow (∼4 ± 1 m a−1) climatically driven inland retreat of the ice margin to mountain source areas by ∼17 ka. By contrast, in southern Donegal, which lay near the axis of the Donegal Bay Ice Lobe, deglaciation was delayed until ∼18 ka following readvance of ice to a moraine in outer Donegal Bay. The ice margin subsequently underwent net retreat, apparently uninterrupted by readvances, at a net rate of ∼ 18 ± 6 m a−1. A mean terrestrial cosmogenic nuclide age of ∼15.0 ka obtained for samples from the foothills of the Blue Stack Mountains in south‐east Donegal indicates that ice persisted in valley heads and cirques at the beginning of the Lateglacial Interstadial, suggesting that these and nearby mountains supported the last remnants of the Irish Ice Sheet before complete deglaciation of Ireland, and that almost all the shrinkage of the ice sheet in this sector occurred under stadial conditions before the onset of interstadial warming at ∼14.7 ka.

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Section: Discussionmentioning

confidence: 99%

Deglaciation chronology of the Donegal Ice Centre, north‐west Ireland

Wilson

Ballantyne

Benetti

et al. 2018

J Quaternary Science

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“…Thermomechanically coupled numerical models driven by proxy climate parameters retrodict major volume loss of the last BIIS between 19.4 ka and 17.2 ka, with reduction of the ice sheet to an ice cap over the Scottish Highlands and smaller ice caps over peripheral upland areas by 15.7 ka (Hubbard et al, 2009; 'ka' is here employed to imply thousands of calendar years before present). This pattern is broadly supported by recent research involving surface exposure dating of glacially deposited boulders and exposed bedrock surfaces in several locations, notably in Ireland (Ballantyne et al, , 2007Clark et al, 2009aClark et al, , 2009b, around the Irish Sea basin (McCarroll et al, 2010) and northwest Scotland (Ballantyne and Stone, 2012;Fabel et al, 2012;Small et al, 2012) An interesting but hitherto unresolved question concerns the timing of the final disappearance of the last ice sheet from upland source areas. Several researchers have suggested that glacier ice persisted in favourable locations such as high corries or plateaus in the Scottish Highlands throughout the Lateglacial Interstade (% Greenland Interstade 1 (GI-1) of Lowe et al, 2008;ca.…”

Section: Introductionmentioning

confidence: 57%

Section: Introductionmentioning

confidence: 99%

Deglaciation chronology of the Galloway Hills Ice Centre, southwest Scotland

Ballantyne

Rinterknecht

Gheorghiu

2013

J Quaternary Science

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During the last glacial maximum, the Galloway Hills in southwest Scotland acted as a major centre of ice dispersion within the last British-Irish Ice Sheet (BIIS). Six new or recalibrated 10 Be exposure ages for samples obtained from boulders near the former ice divide yielded uncertainty-weighted mean ages of 15.15 AE 0.72 ka (Lm scaling), or 15.33 AE 0.74 ka (Du scaling). These ages indicate that the former ice dome centred over the Galloway Hills had almost (or completely) disappeared by ca. 15 ka, imply prior deglaciation of all of southwest Scotland and refute suggestions that ice cover persisted in this area during the Lateglacial Interstade. They strongly support recent models advocating extensive deglaciation of all areas occupied by the last BIIS (apart from the Scottish Highlands) prior to warming at the onset of the Lateglacial Interstade (ca. 14.7 ka). Three samples obtained from boulders on a large latero-terminal moraine (Tauchers moraine) near the former ice divide yielded a weighted mean age of 11.91 AE 0.77 ka (Lm scaling) or 12.01 AE 0.78 ka (Du scaling), confirming that the moraine is of Loch Lomond (Younger Dryas) Stadial age, and suggesting that the moraine was deposited 200-500 years before the end of the stade.

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“…At Furnace Lough, moraine ridges composed of angular sandstone boulders mark a recessional ice limit (McCabe et al ., ). Comogenic beryllium‐10 ( 10 Be) dating of boulders within the moraine suggest it was formed at 17–14 kyr bp (Clark et al ., ), which matches with chlorine‐36 ( 36 Cl) ages on exposed bedrock surfaces immediately outside of this limit in the Nephin Beg Mountains (Ballantyne et al ., ). On the south side of the bay, the drift limit also declines steeply from east to west (Synge, , ) and glacigenic sediments form moraines, terraces and aprons on bedrock mountain slopes (Coxon, ).…”

Section: Introductionmentioning

confidence: 99%

Subglacial processes from drumlins in Clew Bay, western Ireland

Knight

2015

Earth Surf Processes Landf

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Interpretation of subglacial processes and environments can be usefully informed by the stratigraphy and structures of sediments preserved within drumlins, and the down-ice variability of these sediments. Drumlins in Clew Bay, western Ireland, were formed by westward late Pleistocene ice flow onto the Atlantic shelf, but the depositional processes and environments of these sediments remain uncertain. This study describes and interprets the drumlin stratigraphy and sediment properties and structures from two drumlins on the south side of Clew Bay. Drumlin sediments are dominated by massive to stratified diamicton deposited subglacially by deformation of flows of varying rheology. Folds, shears and clastic dikes within the sediments suggest active subglacial water flow related to variations in ice flow and ice-bed coupling. The distal ends of the drumlins are dominated by stratified diamicton and gravel units with sandy interbeds. These sediments reflect deposition in a leeside subglacial cavity formed coevally with bedform development. A model is proposed that can account for sediment stratigraphic patterns and drumlin formation.

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Cosmogenic 10Be chronology of the last deglaciation of western Ireland, and implications for sensitivity of the Irish Ice Sheet to climate Change

Cited by 13 publications

References 31 publications

Deglaciation chronology of the Donegal Ice Centre, north‐west Ireland

Deglaciation chronology of the Donegal Ice Centre, north‐west Ireland

Deglaciation chronology of the Galloway Hills Ice Centre, southwest Scotland

Subglacial processes from drumlins in Clew Bay, western Ireland

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