Radiocarbon dates pertinent to defining the last glacial maximum for the Laurentide and Innuitian ice sheets

Dyke, A S; Andrews, JT; Clark, P. U.; England, JH; Miller, Gifford H.; Shaw, J; Veillette, J J

doi:10.4095/212843

Cited by 13 publications

(13 citation statements)

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“…Also, dates on terrestrial plants confirm that this area was ice-free by ~12,500 14 C yr BP; in calibrated years, this corresponds to an age range of 15,600-14,200 cal BP, as reported by Dyke et al (2001).…”

Section: Fire Frequency Determined From Ams 14 C Dating At Bear Flatsupporting

confidence: 48%

“…The oldest continuous charcoal layer at 386-cm depth yields an age of 10,530 ± 100 14 C yr BP, which gives a calibrated range of 10,780-10,306 BC (1 σ) and 10,845-10,198 BC (2 σ). This age postdates the age range of 15,600-14,200 BP of Dyke et al (2001) of a minimum age of Glacial Lake Peace. Our study does not solve this deglacial landscape issue, but provides additional data for consideration.…”

Section: Resultsmentioning

confidence: 99%

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Over 16,000 Years of Fire Frequency Determined from AMS Radiocarbon Dating of Soil Charcoal in an Alluvial Fan at Bear Flat, Northeastern British Columbia

Jull

Geertsema²

2006

Radiocarbon

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ABSTRACT. We present results of radiocarbon dating of charcoal from paleosols and buried charcoal horizons in a unique sequence, which potentially records the last 36,000 yr, from a fan at Bear Flat, British Columbia (BC) (56°16′51″N, 121°13′39″W). Evidence for forest-fire charcoal is found over the last 13,500 ± 110 14 C yr before present (BP) or 16,250 ± 700 cal BP. The study area is located east of the Rocky Mountains in an area that was ice-free at least 13,970 ± 170 14 C yr BP (17,150 cal BP) ago. The latest evidence of fire is during the Medieval Warm Period (MWP). The charcoal ages show a periodicity in large fires on a millennial scale through the Holocene-an average of 4 fires per thousand years. Higher fire frequencies are observed between 2200 to 2800 cal BP, ~5500 and ~6000 cal BP, ~7500 to 8200 cal BP, and 9000 to 10,000 cal BP. These intervals also appear to be times of above-average aggradation of the fan. We conclude that fire frequency is related to large-scale climatic events on a millennial time scale.

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Section: Fire Frequency Determined From Ams 14 C Dating At Bear Flatsupporting

confidence: 48%

Section: Resultsmentioning

confidence: 99%

Over 16,000 Years of Fire Frequency Determined from AMS Radiocarbon Dating of Soil Charcoal in an Alluvial Fan at Bear Flat, Northeastern British Columbia

Jull

Geertsema²

2006

Radiocarbon

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“…The lack of any unambiguously finite radiocarbon ages on marine shells between about 12 and 40 cal ka from anywhere on Baffin Island (Dyke et al, 2001) suggests that the NE sector of the LIS was near its maximum configuration from at least 40 ka until nearly 12 ka, although recent 10 Be CE dates suggest deglaciation of the coastal reaches began by 15 ka (Briner et al, , 2006b. By 10 ka, most of Clyde Inlet was ice free (Briner et al, 2006b), by which time the high-elevation summits near the fiord heads should have been ice-free.…”

Section: In Situ 14 C Exposure Agesmentioning

confidence: 99%

Limited ice-sheet erosion and complex exposure histories derived from in situ cosmogenic 10Be, 26Al, and 14C on Baffin Island, Arctic Canada

Miller

Briner

Lifton

et al. 2006

Quaternary Geochronology

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Discordant cosmogenic nuclide exposure ages derived from 10 Be, 26 Al, and 14 C extracted from quartz in rocky summits along the eastern rim of the central Baffin Island plateau provide constraints on the efficiency of erosion by the Laurentide Ice Sheet (LIS) and on the timing and duration of ice-free conditions in the eastern Canadian Arctic. In situ 14 C records the duration of exposure during the present interglaciation; any previously acquired 14 C decayed below detection limits beneath thick LIS during the last glaciation. The in situ 14 C exposure ages for two samples adjacent to a cold-based local ice cap are significantly less than for a nearby ice-free summit, suggesting that an expanded local ice cap shielded the ice-adjacent sites for at least 800 years, longer than the duration of the Little Ice Age. Disequilibrium between 10 Be and 26Al concentrations in the same samples can be realistically explained by brief (ca. 10 kyr) intervals of exposure during peak interglacials (MIS 11, 9, 7, 5e, and 1), separated by long (ca. 50-100 kyr) intervals of complete shielding by the LIS. The lack of glacial erosion for at least the past 400 kyr suggests that the LIS was frozen to its bed across much of Baffin Island throughout the Middle and Late Quaternary. r

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“…Samples from the dune bases also make it possible to constrain the timing of the initiation of eolian deposition on the postglacial landscape. Because of the relative scarcity of organic material containing datable radiocarbon, the retreat of the Laurentice Ice Sheet from western Canada has been difficult to constrain (Dyke et al, 2001(Dyke et al, , 2002(Dyke et al, , 2003Munyikwa et al, 2011a). The timing of the initiation of eolian deposition however, can by inference be used to constrain the timing of the retreat of the ice sheet from the region (Wolfe et al, 2004(Wolfe et al, , 2007Munyikwa et al, 2011a).…”

Section: Discussionmentioning

confidence: 99%

Delineating stratigraphic breaks at the bases of postglacial eolian dunes in central Alberta, Canada using a portable OSL reader

Munyikwa

Brown

Kitabwalla

2012

Earth Surf Processes Landf

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Temporal constraints for the Late Pleistocene deposition of eolian dunes that occur in central and northern Alberta, Canada can be provided by dating sediments from the dune bases using luminescence techniques. In places, however, the postglacial dunes overlie glaciofluvial sands that resemble the eolian deposits in texture such that demarcating the bases of the dunes is often problematic. In this study we address the problem by employing a portable optically stimulated luminescence (OSL) reader to construct luminescence profiles that depict luminescence signal variation with depth. With the portable OSL reader, measurement can be performed on bulk sediments, negating the need for laborious separation procedures to isolate pure mineral fractions, as is required in regular luminescence dating. Measurements can also be carried out in the field, permitting quicker decision making during sample collection. Results from this study, presented as depth variations of feldspar derived infrared stimulated luminescence (IRSL) signals and predominantly quartz‐generated post‐IR blue OSL signals, show that luminescence profiling enables one to distinguish between eolian deposits that make up the dunes from the underlying non‐eolian sands. The identification of such cryptostratigraphic interfaces is made possible by differences in the dosimetric histories of the sediments. The delineation of the dune bases allows targeted sampling that yields best luminescence age approximations for the initiation of postglacial eolian deposition in the region. Luminescence profiling of eolian sequences would also, in theory, permit the identification of depositional breaks of extended duration. Copyright © 2012 John Wiley & Sons, Ltd.

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Radiocarbon dates pertinent to defining the last glacial maximum for the Laurentide and Innuitian ice sheets

Cited by 13 publications

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Over 16,000 Years of Fire Frequency Determined from AMS Radiocarbon Dating of Soil Charcoal in an Alluvial Fan at Bear Flat, Northeastern British Columbia

Over 16,000 Years of Fire Frequency Determined from AMS Radiocarbon Dating of Soil Charcoal in an Alluvial Fan at Bear Flat, Northeastern British Columbia

Limited ice-sheet erosion and complex exposure histories derived from in situ cosmogenic 10Be, 26Al, and 14C on Baffin Island, Arctic Canada

Delineating stratigraphic breaks at the bases of postglacial eolian dunes in central Alberta, Canada using a portable OSL reader

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