Greenland ice sheet hides huge ‘impact crater’

Posted: November 15, 2018 by oldbrew in Analysis, Geology, History, research

Topographic map of Greenland


Something creating a 19-mile wide dent in the Earth’s surface would clearly have been a major strike. If confirmed it would be the most northerly impact crater on Earth.

What looks to be a large impact crater has been identified beneath the Greenland ice sheet, reports BBC News.

The 31km-wide depression came to light when scientists examined radar images of the island’s bedrock.

Investigations suggest the feature was probably dug out by a 1.5km-wide iron asteroid sometime between about 12,000 and three million years ago.

But without drilling through nearly 1km of ice to sample the bed directly, scientists can’t be more specific.

“We will endeavour to do this; it would certainly be the best way to get the ‘dead fish on the table’ (acknowledge the issue, rather than leaving it), so to speak,” Prof Kurt Kjær, from the Danish Museum of Natural History, told BBC News.

If confirmed, the crater would be the first of any size that has been observed under one of Earth’s continental ice sheets.

The discovery is reported in the journal Science Advances.

What does the crater look like?

The putative impact crater is located right on the northwest margin of the Greenland Ice Sheet, underneath what is known as Hiawatha Glacier.

Additional high-resolution radar imagery gathered by Prof Kjær’s team clearly shows a circular structure that is elevated at its rim and at its centre – both classic traits. But because the depression is covered by up to 980m of ice, the scientists have so far had to rely on indirect studies.

What is the supporting evidence?

Meltwaters running out from under Hiawatha Glacier into the Nares Strait carry sediments from the depression. In these sediments are quartz grains which have been subjected to enormous shock pressures, of the type that would be experienced in an impact.

Continued here.

In Pictures: The Giant Crater Beneath Greenland Explained | Space.com

Comments
  1. Curious George says:

    Is this science coming from the IPCC?

  2. oldbrew says:

    It’s a Danish study.

    A large impact crater beneath Hiawatha Glacier in northwest Greenland
    http://advances.sciencemag.org/content/4/11/eaar8173

  3. Bill In Oz says:

    An impact like that would also generate a huge amount of steam and vapor..And maybe subsequent global warming…Could this be the smoking gun which ended the last ice age ?

  4. Phi32 says:

    Does the impact crater imply that some or all of Greenland’s land mass might have been the result of the impact?

  5. Graeme No.3 says:

    Wasn’t 12,000 years ago about the time of the disappearance of the Clovis culture and the mega beasts in North America? Also roughly the time of the Younger Dryas?

  6. oldbrew says:

    Graeme – yes, it seems arguable on the face of it.

    The Younger Dryas impact hypothesis or Clovis comet hypothesis originally proposed that a large air burst or earth impact of one or more comets initiated the Younger Dryas cold period about 12,900 BP calibrated (10,900 14C uncalibrated) years ago.
    https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis

    But there are various claimed snags with impact theories.
    https://en.wikipedia.org/wiki/Younger_Dryas_impact_hypothesis#Criticism

    A 26-author study in favour of impact…

    Evidence for an extraterrestrial impact 12,900 years ago that contributed to the megafaunal extinctions and the Younger Dryas cooling
    https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1994902/

  7. hunter says:

    Great find and very interesting article.
    It will be fascinating to see the value of the recoverable metals from this bolide.

  8. oldbrew says:

    From Cosmic Tusk:

    What a week. The announcement of the Hiawatha Crater is hands down the most important development in the eight year history of the Tusk. Lest I remind you, when your blog’s tagline is “Exploring abrupt climate change induced by comets and asteroids during human history”, and Science publishes a feature article titled: Ice Age Impact: A large asteroid struck Greenland in the time of humans. How did it affect the planet? — times are good!

    Times are not so good for the shrinking band of reckless, uninformed critics of the Younger Dryas Impact Hypothesis.

    https://cosmictusk.com/9992-2/

    Bos Bet
    https://cosmictusk.com/boslough_bet_greenland_crater_younger_dryas/

  9. oldbrew says:

    Could an impact have generated a lot of new icebergs?
    – – –
    Greenland icebergs may have triggered the Younger Dryas
    September 15, 2013

    Just as the last Ice Age was drawing to a close, Greenland icebergs changed the temperature in the Atlantic and triggered a 1,000-year-long extension of the Ice Age.

    By: Kristian Sjøgren

    When the last Ice Age ended, meltwater and icebergs from Greenland triggered the 1,000-year-long cold spell we know as the Younger Dryas, new research reveals.

    Some 13,000 years ago, as the last Ice Age seemed to lose its cold grip on the Earth, the temperature suddenly plunged again.
    . . .
    …our studies of the seabed in the Labrador Sea, located between the two ice caps, show that the sediments deposited just prior to the Younger Dryas originated from Greenland, not Canada.
    [bold added]

    http://sciencenordic.com/greenland-icebergs-may-have-triggered-younger-dryas

  10. oldbrew says:

    See Science Advances video with 3 of the authors, here…

    https://cosmictusk.com/carolina_bays_cosmic_tusk_george_howard/