A framework for the timing of the final meltwater outbursts from glacial Lake Agassiz-Ojibway

Brouard, Étienne; Roy, Martin; Godbout, Pierre‐Marc; Veillette, J J

doi:10.1016/j.quascirev.2021.107269

Cited by 19 publications

(21 citation statements)

References 73 publications

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“…However, due to disagreement between continental and marine records, the timing, duration and number of freshwater fluxes remain debated (e.g. Carlson and Clark, 2012;Brouard et al, 2021). The most common explanation for the trigger of the event has been one large outburst of freshwater from LAO, as documented by a red marker bed in Hudson Strait sediment cores and dated to 8.47 ± 0.3 ka cal BP (Barber et al, 1999).…”

Section: Timing and Durationmentioning

confidence: 99%

“…Ellison et al, 2006;Hillaire-Marcel et al, 2007;Lochte et al, 2019), arguing for a more complex drainage history. A recent study proposes that the 8.2 ka event was triggered by two distinct drainage events: a subglacial drainage at 8.22 ± 0.02 ka cal BP and the final drainage of LAO at 8.16 ± 0.02 ka cal BP (Brouard et al, 2021). The timing of the first meltwater pulse is based on an annual chronology from well-defined varve records, whilst the timing of the second meltwater pulse was determined by using the minimumand maximum-limiting 14 C ages of continental records that showed clear evidence of the termination of glaciolacustrine conditions (Brouard et al, 2021).…”

Section: Timing and Durationmentioning

confidence: 99%

“…A recent study proposes that the 8.2 ka event was triggered by two distinct drainage events: a subglacial drainage at 8.22 ± 0.02 ka cal BP and the final drainage of LAO at 8.16 ± 0.02 ka cal BP (Brouard et al, 2021). The timing of the first meltwater pulse is based on an annual chronology from well-defined varve records, whilst the timing of the second meltwater pulse was determined by using the minimumand maximum-limiting 14 C ages of continental records that showed clear evidence of the termination of glaciolacustrine conditions (Brouard et al, 2021). The subglacial drainage coincides with the onset of the 8.2 ka event in the δ 18 O in the NGRIP ice core (8.25 ± 0.05 ka; Thomas et al, 2007), and the final drainage appears in the central part of the event, coinciding with the lowest δ 18 O values in the NGRIP ice core (Fig.…”

Section: Timing and Durationmentioning

confidence: 99%

“…This test shows all ages for the onset of the event to be statistically from the same population (MSWD = 1.16, p = 0.33), yielding an error-weighted mean age of 8.23 ± 0.03 ka, suggesting that the onset of the event was synchronous. Performing the test on all the ages from the end of the event gives a low probability of fit (p = 0.04), Brouard et al, 2021); NGRIP ice core record (North Grip Ice Core Project Members, 2004); speleothem records of SIR-14 (this study), GARO1 (La Garma Cave; Baldini et al, 2019), LV5 (Kaite Cave;Domínguez-Villar et al, 2009), GdL2016-1 (Galeria das Lâminas; Benson et al, 2021) and Cha-1 (Chaara Cave; Ait Brahim et al, 2019). The intervals of slow growth in SIR-14 (9.9-9.1 and 7.9-6.7 ka) are shown as dotted lines, as they are representative of drip-specific effects and not regional climate variability.…”

Section: Timing and Durationmentioning

confidence: 99%

“…An alternative cause, a freshwater outburst from the collapsing ice saddle over Hudson Bay, has also been proposed (Gregoire et al, 2012;Matero et al, 2017). Additionally, there is evidence for multiple meltwater fluxes prior to and/or during the event (Hillaire-Marcel et al, 2001;Ellison et al, 2006;Lochte et al, 2019;Brouard et al, 2021). Whilst the exact trigger is still debated, the volume and routing of freshwater entering the North Atlantic Ocean was apparently sufficient to disrupt the Atlantic Meridional Overturning Circulation (AMOC), which transports heat from the tropics to the Arctic region (Barber et al, 1999;Ellison et al, 2006).…”

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confidence: 99%

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The 8.2 ka event in northern Spain: timing, structure and climatic impact from a multi-proxy speleothem record

Kilhavn

Couchoud²,

Drysdale³

et al. 2022

Clim. Past

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Abstract. The 8.2 ka event is regarded as the most prominent climate anomaly of the Holocene and is thought to have been triggered by a meltwater release to the North Atlantic that was of sufficient magnitude to disrupt the Atlantic Meridional Overturning Circulation (AMOC). It is most clearly captured in Greenland ice-core records, where it is reported as a cold and dry anomaly lasting ∼ 160 years, from 8.25 ± 0.05 until 8.09 ± 0.05 ka (Thomas et al., 2007). It is also recorded in several archives in the North Atlantic region; however, its interpreted timing, evolution and impacts vary significantly. This inconsistency is commonly attributed to poorly constrained chronologies and/or inadequately resolved time series. Here we present a high-resolution speleothem record of early Holocene palaeoclimate from El Soplao Cave in northern Spain, a region pertinent to studying the impacts of AMOC perturbations on south-western Europe. We explore the timing and impact of the 8.2 ka event on a decadal scale by coupling speleothem stable carbon and oxygen isotopic ratios, trace element ratios (Mg / Ca and Sr / Ca), and growth rate. Throughout the entire speleothem record, δ18O variability is related to changes in effective recharge. This is supported by the pattern of changes in δ13C, Mg / Ca and growth rate. The 8.2 ka event is marked as a centennial-scale negative excursion in El Soplao δ18O, starting at 8.19 ± 0.06 ka and lasting until 8.05 ± 0.05 ka, suggesting increased recharge at the time. Although this is supported by the other proxies, the amplitude of the changes is minor and largely within the realm of variability over the preceding 1000 years. Further, the shift to lower δ18O leads the other proxies, which we interpret as the imprint of the change in the isotopic composition of the moisture source, associated with the meltwater flux to the North Atlantic. A comparison with other well-dated records from south-western Europe reveals that the timing of the 8.2 ka event was synchronous, with an error-weighted mean age for the onset of 8.23 ± 0.03 and 8.10 ± 0.05 ka for the end of the event. This compares favourably with the North Greenland Ice Core Project (NGRIP) record. The comparison also reveals that the El Soplao δ18O is structurally similar to the other archives in south-western Europe and the NGRIP ice-core record.

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Section: Timing and Durationmentioning

confidence: 99%

Section: Timing and Durationmentioning

confidence: 99%

Section: Timing and Durationmentioning

confidence: 99%

Section: Timing and Durationmentioning

confidence: 99%

mentioning

confidence: 99%

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The 8.2 ka event in northern Spain: timing, structure and climatic impact from a multi-proxy speleothem record

Kilhavn

Couchoud²,

Drysdale³

et al. 2022

Clim. Past

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Climatic control on the retreat of the Laurentide Ice Sheet margin in easternmost Québec–Labrador (Canada) revealed by cosmogenic nuclide exposure dating

Couette

Ghienne

Lajeunesse

et al. 2023

J Quaternary Science

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The Laurentide Ice Sheet (LIS) was the largest ice sheet in the Northern Hemisphere during the last glacial cycle. The effects of its demise on global climate and sea‐level changes during the subsequent deglaciation are unequivocal. Understanding the interplay between ice sheets and long‐term or short‐term (e.g. abrupt) climatic events is therefore crucial for predicting future rates of ice sheet melting and their potential contribution to sea‐level changes. Here, we present 37 new 10Be surface exposure ages from easternmost Québec–Labrador that allow us to identify close ties between regional deglaciation history and climate. These results reveal that the LIS was disconnected from the Newfoundland Ice Cap by ~14.1 ka. Samples collected from moraine boulders indicate that this event was followed by five major stillstands and/or readvance stages of the LIS margin. Integrating our new moraine ages with those of earlier studies allows us to depict a temporal framework including events at ~12.9, ~11.5, ~10.4, ~9.3 and ~8.4–8.2 ka. These moraine ages highlight a strong sensitivity of the LIS to temperature changes in the Northern Hemisphere, as the documented continental ice margin stabilizations coincide with abrupt cooling events recorded in Greenland ice cores. These observations support the idea of a negative feedback mechanism induced by meltwater forcings into the North Atlantic Ocean which, in turn, provoked repeated cold reversals during the Younger Dryas and early Holocene.

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Configuration and timing of the postglacial marine incursion along the eastern Ungava Peninsula (Nunavik, Canada): implications for deglaciation models

Lefebvre‐Fortier,

Roy,

Dubé‐Loubert

et al. 2024

J Quaternary Science

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The final deglaciation stages of the Laurentide Ice Sheet in northern Quebec–Labrador were marked by the incursion of the d'Iberville Sea into the coastal areas of Ungava Bay. Remote and field mapping of raised marine strandlines along the Ungava Peninsula east coast show that the maximum marine limit decreases from south (165 m) to north (100 m), reflecting differential uplift linked to an ice mass remnant located to the southwest of the bay. Reconstruction of the uppermost marine limit in two east–west transects extending into the Peninsula interior reveals distinct sea‐level stands with limited extents towards the west, indicating that the early stages of the marine incursion occurred in contact with the ice margin. The reconstruction also identifies the maximum eastward extent of ice‐dammed lakes that occupied the Arnaud River and Aux‐Feuilles River valleys. 10Be surface exposure dating of marine strandlines yielded consistent 10Be ages that indicate a rapid deglaciation of Ungava Bay between 8900 ± 200 a (north) and 7900 ± 200 a (south). These results provide constraints on the position of the Labrador Sector eastern and western ice margins during the late deglaciation, in addition to the timing of ice and meltwater discharges from the Ungava Bay region.

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A framework for the timing of the final meltwater outbursts from glacial Lake Agassiz-Ojibway

Cited by 19 publications

References 73 publications

The 8.2 ka event in northern Spain: timing, structure and climatic impact from a multi-proxy speleothem record

The 8.2 ka event in northern Spain: timing, structure and climatic impact from a multi-proxy speleothem record

Climatic control on the retreat of the Laurentide Ice Sheet margin in easternmost Québec–Labrador (Canada) revealed by cosmogenic nuclide exposure dating

Configuration and timing of the postglacial marine incursion along the eastern Ungava Peninsula (Nunavik, Canada): implications for deglaciation models

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