Chronological constraints on Cordilleran Ice Sheet glaciomarine sedimentation from core MD02-2496 off Vancouver Island (western Canada)

Cosma, T.; Hendy, I. L.; Chang, Alice S.

doi:10.1016/j.quascirev.2008.01.013

Cited by 48 publications

(48 citation statements)

References 78 publications

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“…Although surface water reservoir ages appear to have increased during the late glacial from 807 ± 50 years to >1,400 years [ Cosma et al , 2008], we reject local changes in reservoir ages as a radiocarbon plateau generating mechanism for the following reasons. First terrestrial organic carbon delivery to the site was greatest when the CIS was proximal [ Cosma et al , 2008] and should have been coincident with the radiocarbon plateaus if terrestrial organic carbon had significantly impacted the 14 C of marine p CO 2 . Second the addition of 14 C depleted carbon to the marine environment would have a greater impact on surface waters than deep resulting in decreased benthic‐planktonic foraminiferal age differences, which is inconsistent with results from a nearby sediment core [ McKay et al , 2005].…”

Section: Radiocarbon Plateausmentioning

confidence: 99%

“…Radiocarbon plateaus within sediment cores can be generated by a number of processes including, mixing with a secondary source of radiogenic carbon, instantaneous deposition of a thick package of sediment, and global changes in 14 C production and partitioning in carbon reservoirs. On the basis of δ 13 C organic carbon , 50 to 70% of late glacial total organic carbon accumulation has been estimated to be terrestrial in origin [ Cosma et al , 2008 ; McKay et al , 2004], potentially carrying an infinite radiocarbon age such that bulk organic carbon radiocarbon ages are <4 ka older than the planktonic foraminiferal carbonate when the CIS was proximal to the site [ Cosma et al , 2008]. As well the CIS might have increased 14 C depleted CO 2 delivery to surface waters through meltwater [ Hutchinson et al , 2004; Kovanen and Easterbrook , 2002].…”

Section: Radiocarbon Plateausmentioning

confidence: 99%

“…As well the CIS might have increased 14 C depleted CO 2 delivery to surface waters through meltwater [ Hutchinson et al , 2004; Kovanen and Easterbrook , 2002]. Although surface water reservoir ages appear to have increased during the late glacial from 807 ± 50 years to >1,400 years [ Cosma et al , 2008], we reject local changes in reservoir ages as a radiocarbon plateau generating mechanism for the following reasons. First terrestrial organic carbon delivery to the site was greatest when the CIS was proximal [ Cosma et al , 2008] and should have been coincident with the radiocarbon plateaus if terrestrial organic carbon had significantly impacted the 14 C of marine p CO 2 .…”

Section: Radiocarbon Plateausmentioning

confidence: 99%

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Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events

Hendy

Cosma

2008

Paleoceanography

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[1] We present the first high-resolution record of iceberg calving on the continental slope of Vancouver Island, British Columbia (MD02-2496, 48°58N, 127°02W, 1243 m water depth), through the last glacial from the Cordilleran Ice Sheet (CIS). These previously unknown ice-rafted debris (IRD) events representing significant retreat of the western margin of the CIS out of marine waters show little correspondence with local climate change. High-resolution radiocarbon dating indicates that the younger IRD events coincide with global radiocarbon age plateaus that allow direct correlation with distal climate records where the same plateaus have been identified. The coincidence of episodic shedding of IRD from the CIS with North Atlantic climate events (i.e., North Atlantic Deep Water shutdown, and Heinrich events) begs the question: What drove CIS destabilization? Forcing appears to be external to CIS dynamics perhaps resulting from either eustatic sea level rise or episodes of atmospheric warming over the North American continent.Citation: Hendy, I. L., and T. Cosma (2008), Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events, Paleoceanography, 23, PA2101,

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Section: Radiocarbon Plateausmentioning

confidence: 99%

Section: Radiocarbon Plateausmentioning

confidence: 99%

Section: Radiocarbon Plateausmentioning

confidence: 99%

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Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events

Hendy

Cosma

2008

Paleoceanography

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“…Ice reached the edge of the British Columbia continental shelf 17,000 years ago and began to retreat about 16,200 years ago, based on a rapid reduction in ice-rafted debris in deep-sea cores to the west (Cosma et al, 2008). The chronology of retreat of the east margin of the Cordilleran Ice Sheet remains poorly constrained.…”

mentioning

confidence: 99%

Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

Clague

2017

CIG

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“…Deglacial estimates include 700 years from associated wood and marine carbonates from SW British Columbia [ Kovanen and Easterbrook , ], and 600–700 years from marine tephrochronology off SE of Japan during the Bolling‐Allerod [ Ohkushi et al ., ; Ikehara et al ., ]. Using radiocarbon plateau “tuning,” LGM to deglacial estimates of Δ R are ~1400 years off Vancouver Island [ Cosma et al ., ] and 800–3200 years in the subarctic Pacific [ Sarnthein et al ., ]. In this latter study, the wide range in radiocarbon ventilation age estimates from just three sediment cores clearly points to the need for more studies that evaluate the Δ R changes across the North Pacific during the LGM and deglaciation.…”

Section: Methodsmentioning

confidence: 99%

Radiocarbon profiles of the NW Pacific from the LGM and deglaciation: Evaluating ventilation metrics and the effect of uncertain surface reservoir ages

Cook

Keigwin

2015

Paleoceanography

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During the last deglaciation, the ventilation of the subarctic Pacific is hypothesized to have changed dramatically, including the rejuvenation of a poorly ventilated abyssal water mass that filled the deep ocean, and fluctuations in the strength of North Pacific intermediate and deep water formation at millennial timescales. Foraminiferal radiocarbon reconstructions of past ventilation changes in the Pacific are valuable but are hampered by poor carbonate preservation, low sediment accumulation rates, bias from bioturbation, and poorly constrained past surface reservoir age. In this study, we present paired benthic-planktonic radiocarbon measurements from the Okhotsk Sea and Emperor Seamounts. We take advantage of large contemporaneous peaks in benthic abundances from the last glacial maximum, Bolling-Allerod (BA), and early Holocene to produce time slices of radiocarbon from 1 to 4 km water depth. We explore the impact of uncertain surface reservoir age and evaluate several approaches to quantifying past ocean radiocarbon distribution using our NW Pacific data and a compilation of published data from the North Pacific. Both the calendar age and the absolute value of an ocean radiocarbon estimate depend on the assumed surface reservoir age. But for a time slice from a small geographical area with radiocarbon-independent stratigraphic correlation between cores, the shape of a water column profile is independent of surface reservoir age. The NW Pacific profiles are similar in shape to the compilation profiles for the entire North Pacific, which suggests that deglacial surface reservoir age changes across the N Pacific did not diverge dramatically across the areas sampled. The Last Glacial Maximum (LGM) profile >2 km spans a wide range of values, ranging from values similar to today to lower than today. However, by the BA the profile has a similar shape to today. Ultimately, local surface reservoir ages, end-member water mass composition, and mixing ratios must each be constrained before a radiocarbon activity reconstruction can be used to confidently infer ventilation changes.

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Chronological constraints on Cordilleran Ice Sheet glaciomarine sedimentation from core MD02-2496 off Vancouver Island (western Canada)

Cited by 48 publications

References 78 publications

Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events

Vulnerability of the Cordilleran Ice Sheet to iceberg calving during late Quaternary rapid climate change events

Deglaciation of the Cordillera of Western Canada at the end of the Pleistocene

Radiocarbon profiles of the NW Pacific from the LGM and deglaciation: Evaluating ventilation metrics and the effect of uncertain surface reservoir ages

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