A Late Paleocene age for Greenland's Hiawatha impact structure
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The ~31-km-wide Hiawatha structure, located beneath Hiawatha Glacier in northwestern Greenland, has been proposed as an impact structure that may have formed after the Pleistocene inception of the Greenland Ice Sheet. To date the structure, we conducted 40Ar/39Ar analyses on glaciofluvial sand and U-Pb analyses on zircon separated from glaciofluvial pebbles of impact melt rock, all sampled immediately downstream of Hiawatha Glacier. Unshocked zircon in the impact melt rocks dates to ~1915 million years (Ma), consistent with felsic intrusions found in local bedrock. The 40Ar/39Ar data indicate Late Paleocene resetting and shocked zircon dates to 57.99 ± 0.54 Ma, which we interpret as the impact age. Consequently, the Hiawatha impact structure far predates Pleistocene glaciation and is unrelated to either the Paleocene-Eocene Thermal Maximum or flood basalt volcanism in east Greenland. However, it was contemporaneous with the Paleocene Carbon Isotope Maximum, although the impact's exact paleoenvironmental and climatic significance awaits further investigation.
Originalsprog | Engelsk |
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Artikelnummer | eabm2434 |
Tidsskrift | Science Advances |
Vol/bind | 8 |
Udgave nummer | 10 |
Antal sider | 11 |
ISSN | 2375-2548 |
DOI | |
Status | Udgivet - 2022 |
Bibliografisk note
Funding Information:
Fieldwork was supported by Geocenter Denmark project ?Dating of the Little Ice Age? (?DALIA?) (K.H.K.). The NordSIMS facility is supported by the Swedish Research Council and the Swedish Museum of Natural History; Swedish Research Council (Vetenskapsr?det) infrastructure grant no. 2017-00671 (M.J.W.). Quadlab is supported by the Villum Foundation and the Natural History Museum of Denmark; Villum Foundation grant no. 7408 (M.S.). This work was also supported by Swedish Research Council (Vetenskapsr?det) starting grant no. 2020-04862 (G.G.K.), European Union Horizon 2020 research and innovation program Marie Sk?odowska-Curie Individual Fellowship grant agreement no. 792030 (G.G.K.), Aarhus University Research Foundation grant no. 2017-9-33 (N.K.L.), and Independent Research Fund Denmark grant no. 0135-00163B (N.K.L.).
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Copyright © 2022 The Authors
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