Geomorphic signature of the presence and breakup of large ice-sheet derived multi-keeled tabular icebergs

Dowdeswell, Julian A.; Ottesen, Dag

doi:10.1016/j.margeo.2022.106889

Cited by 4 publications

(2 citation statements)

References 27 publications

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“…Secondly, the lineations in the southern portion of the Bear Lake Ice Stream (Fs-65; Figure 6H, mid-image) display a transition from straight and highly parallel MSGLs at higher elevations to a series of sinuous, sometimes paired ridges with cross-cutting relationships at lower elevations near the Keith Arm of Great Bear Lake (Figure 7). We interpret the lineations at higher elevations as forming beneath grounded ice while the lower elevation lineations formed later by groove-ploughing from ice keels beneath the partially floating Bear Lake Ice Stream while the ice margin was lightly grounded, following ice margin retreat and the development of Glacial Lake McConnell (Figure 8; Clark et al, 2003;Piasecka et al, 2018;Dowdeswell and Ottesen, 2022).…”

Section: Timeslice 145 Kamentioning

confidence: 99%

Ice flow dynamics of the northwestern Laurentide Ice Sheet during the last deglaciation

Stoker,

Dulfer,

Stokes

et al. 2024

Preprint

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Abstract. Reconstructions of palaeo-ice stream activity provide an insight into the processes governing ice stream evolution over millennial timescales. The northwestern sector of the Laurentide Ice Sheet experienced a period of rapid retreat driven by warming during the Bølling–Allerød (14.7 – 12.9 ka) which may have contributed significantly to global mean sea level rise during this time. It therefore provides an opportunity to investigate ice sheet dynamics during a phase of rapid ice sheet retreat. Here, we classify coherent groups of ice flow parallel lineations into 326 flowsets and then categorise them as ice stream, deglacial, inferred deglacial or event type flowsets. Combined with ice marginal landforms and a new ice margin chronology (Dalton et al., 2023), we present the first reconstruction of ice flow dynamics of the northwestern Laurentide Ice Sheet at 500-year timesteps through the last deglaciation. At the local Last Glacial Maximum (17.5 ka), the ice stream network was dominated by large, marine-terminating ice streams (>1000 km long) that were fed by the Laurentide-Cordilleran ice saddle to the south and the Keewatin Ice Dome to the east. As the ice margin retreated onshore, the drainage network was characterised by shorter, land-terminating ice streams (<200 km long), with the exception of the Bear Lake and Great Slave Lake ice streams (~600 km long) that terminated in large glacial lakes. Rapid reorganisation of the ice drainage network, from predominantly northerly ice flow to westerly ice flow, occurred over ~2000 years, coinciding with a period of rapid ice sheet surface lowering in the ice saddle region. We note a peak in ice stream activity during the Bølling–Allerød that we suggest is a result of increased ablation and a steepening of the ice surface slope in ice stream onset zones and the increase in driving stresses which contributed to rapid ice drawdown. The subsequent cessation of ice stream activity by the end of the Bølling–Allerød was a result of ice drawdown lowering the ice surface profile, reducing driving stresses and leading to widespread ice stream shut-down.

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Section: Timeslice 145 Kamentioning

confidence: 99%

Ice flow dynamics of the northwestern Laurentide Ice Sheet during the last deglaciation

Stoker,

Dulfer,

Stokes

et al. 2024

Preprint

View full text Add to dashboard Cite

show abstract

“…Iceberg ploughmarks up to a few hundred metres wide and in water depths down to ~600 m suggest that numerous, large, tabular icebergs calved from the ice shelves of the Scandinavian Ice Sheet during its deglacial retreat across the mid-Norwegian margin 22,56,100 .…”

Section: For Publication In Naturementioning

confidence: 99%