European Ice Sheet Complex evolution during the Last Glacial Maximum (29–19 ka)

Hughes, Anna L.C.; Winsborrow, Monica; Greenwood, Sarah L.

doi:10.1016/b978-0-12-823498-3.00038-8

Cited by 2 publications

(2 citation statements)

References 86 publications

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“…We take the glacial setting as described in Section 5.2 as a starting point: the Rogen plateau, situated near a collapsing ice saddle, develops into an onset zone at 10.6–10.8 ka bp . Because there is no consensus on when and where the bed may have thawed (Borgström, 1999; Hughes et al, 2022), we distinguish between two possible options for what the initial basal thermal regime may have been. A choice for either option has implications for our subsequent understanding of how meltwater can reach overpressure at the bed: Most of the Rogen plateau is cold‐based and topographic lows are occupied by a flat, frozen till sheet. Topographic lows are temperate, while highs are cold‐based. …”

Section: Discussionmentioning

confidence: 99%

“…We take the glacial setting as described in Section 5.2 as a starting point: the Rogen plateau, situated near a collapsing ice saddle, develops into an onset zone at 10.6-10.8 ka BP. Because there is no consensus on when and where the bed may have thawed (Borgström, 1999;Hughes et al, 2022) Sarala, 2007), initiating (subtemperate) sliding (Mantelli et al, 2019). The frozen till sheet was more competent than the overlying ice and the till sheet began to fracture (Hättestrand, 1997), allowing direct meltwater delivery to the bedrock surface, and into bedding planes through pre-existing bedrock fractures.…”

Section: Initial Conditionsmentioning

confidence: 99%

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Late erosion pulse triggered by rapid melt in the cold‐based interior of the last Fennoscandian Ice Sheet, an example from Rogen

Boeckel

Boeckel²,

Hall

2022

Earth Surf Processes Landf

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Ice sheet interiors are conventionally regarded as non-erosive. Yet subglacial conditions may be transformed during deglaciation by the arrival of large volumes of meltwater at the ice sheet bed. The development of a dynamic meltwater drainage system and the onset of basal sliding have potential to increase erosion rates in bedrock and sediment. Here, we examine the impact of late deglacial thawing on the Rogen plateau, located near the former ice divide of the Fennoscandian Ice Sheet.We provide new maps of glacial and glacifluvial landforms which we combine with existing data on Quaternary sediments and landforms. Cross-cutting and overlapping relations allow for an event sequence to be established of the deglaciation period. In the Early Holocene (< 11 ka), an ice lobe onset zone developed at the Rogen plateau.In places where meltwater reached the bed and where pressures rose to overpressure, it caused fracture dilation in horizontally bedded sandstones and rock brecciation. The onset of sliding and application of drag resulted in the mobilization of bedrock sheets. The establishment of meltwater corridors led to fluidization of sediments at the bed, dissection and modification of ribbed moraines and formation of murtoos and hummock corridors. During final stagnation of the ice sheet, meltwater drained through channels forming axial eskers. Bedrock erosion during deglaciation reached depths up to 4 m, and in conjunction with some recycling of till, generated $ 317 km 2 of boulder cover. The average erosion depths by removal and reworking of sediment are $ 0.9-1.1 m across areas below 900 m elevation. This study shows that when the cold-based interiors of ice sheets become briefly activated by large subglacial meltwater delivery late in deglaciation, there can be significant reworking and erosion of rock and sediment.

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Section: Discussionmentioning

confidence: 99%

Section: Initial Conditionsmentioning

confidence: 99%

Late erosion pulse triggered by rapid melt in the cold‐based interior of the last Fennoscandian Ice Sheet, an example from Rogen

Boeckel

Boeckel²,

Hall

2022

Earth Surf Processes Landf

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Millennial-scale fluctuations of palaeo-ice margin at the southern fringe of the last Fennoscandian Ice Sheet

Tylmann,

Wysota,

Rinterknecht

et al. 2024

The Cryosphere

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Abstract. The paper presents the first terrestrial record of millennial-scale palaeo-ice margin oscillations at the southern fringe of the last Fennoscandian Ice Sheet (FIS) during the last glacial cycle. The study area is located in northern Poland close to the last FIS maximum limit. The chronology and dynamics of palaeo-ice margin oscillations at the southern fringe of the FIS are based on combined luminescence and 10Be surface exposure dating. Optically stimulated luminescence (OSL) was used to date sandy deposits (fluvioglacial sediments and aeolian deposits filling fossil periglacial wedges) intercalating basal till layers. The most likely age of the tills was constrained by Bayesian modelling of the sequence of OSL ages and lithostratigraphy. 10Be surface exposure dating was used on erratic boulders left during the final retreat of the last FIS and resting on the surface of glacial landforms. Our results, which are mainly based on OSL chronology and Bayesian modelling, indicate millennial-scale oscillations of the last FIS in northern Poland between ∼19 and ∼17 ka. The last FIS retreated and re-advanced over a relatively short period of time (2–3 ka), leaving lithostratigraphic records (basal tills) of three ice re-advances over a millennial-scale cycle: 19.2±1.1, 17.8±0.5 and 16.9±0.5 ka. Despite 10Be surface exposure ages obtained for 14 erratic boulders being poorly clustered, the main mode of age distribution occurs at ∼18 ka and indicates a possible signal of the ice sheet retreat after one of the re-advances. We explore the dynamics of these oscillations and compare the proposed cycles of the southern FIS advances and retreats with existing patterns of the last deglaciation and millennial-scale fluctuations of the last FIS inferred from marine records.

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European Ice Sheet Complex evolution during the Last Glacial Maximum (29–19 ka)

Cited by 2 publications

References 86 publications

Late erosion pulse triggered by rapid melt in the cold‐based interior of the last Fennoscandian Ice Sheet, an example from Rogen

Late erosion pulse triggered by rapid melt in the cold‐based interior of the last Fennoscandian Ice Sheet, an example from Rogen

Millennial-scale fluctuations of palaeo-ice margin at the southern fringe of the last Fennoscandian Ice Sheet

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