Younger Dryas ice margin retreat in Greenland: new evidence from southwestern Greenland

Younger Dryas ice margin retreat in Greenland: new evidence from southwestern Greenland

To date the final stage in deglaciation of the Greenland shelf, when a contiguous ice sheet margin on the inner shelf transitioned to outlet glaciers in troughs with intervening ice-free areas, we generated cosmogenic 10Be dates from bedrock knobs on six outlying islands along a stretch of 300 km of...

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Bibliographic Details
Published in:Climate of the past Vol. 17; no. 2; pp. 587 - 601
Main Authors: Funder, Svend, Sørensen, Anita H. L, Larsen, Nicolaj K, Bjørk, Anders A, Briner, Jason P, Olsen, Jesper, Schomacker, Anders, Levy, Laura B, Kjær, Kurt H
Format: Journal Article
Language:English
Published: Katlenburg-Lindau Copernicus GmbH 04-03-2021
European Geosciences Union
Copernicus Publications
Subjects:
Advection
Bedrock
Beryllium 10
Chronology
Climate change
Coasts
Deglaciation
Geofag: 450
Geosciences: 450
Glacial drift
Glaciation
Glaciers
Greenland ice sheet
Heredity
Ice
Ice cores
Ice sheets
Inheritances
Knobs
Kvartærgeologi, glasiologi: 465
Laboratories
Landforms
Matematikk og Naturvitenskap: 400
Mathematics and natural science: 400
Meltwater
Moraines
Quartz
Quaternary geology, glaciology: 465
Records
Seasonal variations
Seasonality
Sediments
Spectrum analysis
Subsurface water
Troughs
VDP
Younger Dryas
Greenland
Denmark
Aarhus Denmark
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Summary:To date the final stage in deglaciation of the Greenland shelf, when a contiguous ice sheet margin on the inner shelf transitioned to outlet glaciers in troughs with intervening ice-free areas, we generated cosmogenic 10Be dates from bedrock knobs on six outlying islands along a stretch of 300 km of the southwestern Greenland coast. Despite 10Be inheritance influencing some dates, the ages generally support a Greenland Ice Sheet (GrIS) margin that retreated off the inner shelf during the middle Younger Dryas (YD) period. Published 10Be- and 14C-dated records show that this history of the GrIS margin is seen in other parts of Greenland but with large variations in the extent and speed of retreat, sometimes even between neighbouring areas. Areas with a chronology extending into the Allerød period show no marked ice margin change at the Allerød–YD transition except in northernmost Greenland. In contrast, landforms on the shelf (moraines and grounding zone wedges) have been suggested to indicate YD readvances or long-lasting ice margin stillstands on the middle shelf. However, these features have been dated primarily by correlation with cold periods in the ice core temperature records. Ice margin retreat during the middle and late YD is explained by advection of warm subsurface water at the ice margin and by increased seasonality. Our results therefore point to the complexity of the climate–ice margin relation and to the urgent need for direct dating of the early deglaciation history of Greenland.
Bibliography:Climate of the Past
ISSN:1814-9332
1814-9324
1814-9332
DOI:10.5194/cp-17-587-2021