University of Sussex
Browse

File(s) not publicly available

Identification of Younger Dryas outburst flood path from Lake Agassiz to the Arctic Ocean

journal contribution
posted on 2023-06-07, 17:21 authored by Julian MurtonJulian Murton, Mark D Bateman, Scott R Dallimore, James T Teller, Zhirong Yang
The melting Laurentide Ice Sheet discharged thousands of cubic kilometres of fresh water each year into surrounding oceans, at times suppressing the Atlantic meridional overturning circulation and triggering abrupt climate change1, 2, 3, 4. Understanding the physical mechanisms leading to events such as the Younger Dryas cold interval requires identification of the paths and timing of the freshwater discharges. Although Broecker et al. hypothesized in 1989 that an outburst from glacial Lake Agassiz triggered the Younger Dryas1, specific evidence has so far proved elusive, leading Broecker to conclude in 2006 that our inability to identify the path taken by the flood is disconcerting2. Here we identify the missing flood pathevident from gravels and a regional erosion surfacerunning through the Mackenzie River system in the Canadian Arctic Coastal Plain. Our modelling of the isostatically adjusted surface in the upstream Fort McMurray region, and a slight revision of the ice margin at this time, allows Lake Agassiz to spill into the Mackenzie drainage basin. From optically stimulated luminescence dating we have determined the approximate age of this Mackenzie River flood into the Arctic Ocean to be shortly after 13,000years ago, near the start of the Younger Dryas. We attribute to this flood a boulder terrace near Fort McMurray with calibrated radiocarbon dates of over 11,500years ago. A large flood into the Arctic Ocean at the start of the Younger Dryas leads us to reject the widespread view that Agassiz overflow at this time was solely eastward into the North Atlantic Ocean.

History

Publication status

  • Published

Journal

Nature

ISSN

0028-0836

Publisher

Nature Publishing Group

Issue

7289

Volume

464

Page range

740-743

Pages

4.0

Department affiliated with

  • Geography Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2012-02-06

Usage metrics

    University of Sussex (Publications)

    Categories

    No categories selected

    Exports

    RefWorks
    BibTeX
    Ref. manager
    Endnote
    DataCite
    NLM
    DC