Mega‐scale glacial lineations formed by ice shelf grounding in the Canadian Beaufort Sea during multiple glaciations

Riedel, Michael; Dallimore, S. R.; Wamsteeker, Michael L.; Taylor, Gary G.; King, E.L.; Rohr, Kristin M. M.; Hong, Jong Kuk; Jin, Young Keun

doi:10.1002/esp.5125

Cited by 5 publications

(1 citation statement)

References 86 publications

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“…In the Mackenzie Delta region, early reconstructions suggested that the ice sheet did not extend offshore and placed the LGM extent at moraines related to the Sitidgi Stade (Rampton, 1982(Rampton, , 1988. However, offshore geophysical surveys have revealed at least two, undated, advances to the shelf break, the most recent of which has been proposed to relate to the last glaciation (Batchelor et al, 2013(Batchelor et al, , 2014Riedel et al, 2021). Consequently, the Sitidgi Stade has been reinterpreted as a deglacial ice-margin position (Dalton et al, 2023) as part of a series of well-established deglacial limits (e.g.…”

Section: Regional Glacial Historymentioning

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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