Glacial history of Inglefield Land, north Greenland from combined in situ 10Be and 14C exposure dating

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Determining the sensitivity of the Greenland Ice Sheet (GrIS) to Holocene climate changes is a key prerequisite for understanding the future response of the ice sheet to global warming. In this study, we present new information on the Holocene glacial history of the GrIS in Inglefield Land, north Greenland. We use Be-10 and in situ C-14 exposure dating to constrain the timing of deglaciation in the area and radiocarbon dating of reworked molluscs and wood fragments to constrain when the ice sheet retreated behind its presentday extent. The Be-10 ages are scattered ranging from ca. 92.7 to 6.8 ka, whereas the in situ C-14 ages range from ca. 14.2 to 6.7 ka. Almost half of the apparent Be-10 ages predate the Last Glacial Maximum and up to 89% are to some degree affected by nuclide inheritance. Based on the few reliable Be-10 ages, the in situ C-14 ages and existing radiocarbon ages from Inglefield Land, we find that the deglaciation along the coast commenced at ca. 8.6-8.3 ka cal BP in the western part and ca. 7.9 ka in the central part, following the opening of Nares Strait and arrival of warm waters. The ice margin reached its present-day position at ca. 8.2 ka at the Humboldt Glacier and ca. 6.7 ka in the central part of Inglefield Land. Radio-carbon ages of reworked molluscs and wood fragments show that the ice margin was behind its present-day extent from ca. 5.8 to 0.5 ka cal BP. After 0.5 ka cal BP, the ice advanced towards its Little Ice Age position. Our results emphasize that the slowly eroding and possibly cold-based ice in north Greenland makes it difficult to constrain the deglaciation history based on Be-10 ages alone unless they are paired with in situ C-14 ages. Further, combining our findings with those of recently published studies reveals distinct differences between deglaciation patterns of northwest and north Greenland. Deglaciation of the land areas in northwest Greenland occurred earlier than in north Greenland, and periods of restricted ice extent were longer, spanning the Middle and Late Holocene. Overall, this highlights past ice sheet sensitivity to Holocene climate changes in an area where little information was available just a few years ago.

Original languageEnglish
JournalClimate of the Past
Issue number5
Pages (from-to)1999-2015
Number of pages17
Publication statusPublished - 2020

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