Huge crater discovered in Greenland from impact that rocked Northern Hemisphere

November 14, 2018, University of Kansas
Geomorphological and glaciological setting of Hiawatha Glacier, northwest Greenland. (A) Regional view of northwest Greenland. Inset map shows location relative to whole of Greenland. Magenta box identifies location of panels B-D. (B) 5-m ArcticDEM mosaic over eastern Inglefield Land. Colors are ice surface velocity. Blue line illustrates an active basal drainage path inferred from radargrams. (C) Hillshade surface relief based on the ArcticDEM mosaic which illustrates characteristics such as surface undulations. Dashed red lines are the outlines of the two subglacial paleo-channels. Blue lines are catchment outlines, i.e., solid blue line is subglacial and hatched is supraglacial. (D) Bed topography based on airborne radar sounding from 1997-2014 NASA data and 2016 AWI data. Black triangles represent elevated rim picks from the radargrams and the dark purple circles represent peaks in the central uplift. Hatched red lines are field measurements of the strike of ice-marginal bedrock structures. Black circles show location of the three glaciofluvial sediment. Credit: University of Kansas

A survey of ice in Greenland has uncovered evidence suggesting a kilometer-wide iron asteroid slammed into that island, perhaps as recently as 12,000 years ago during the end of the Pleistocene. The resulting 19-mile-wide impact crater has remained hidden under a half-mile-thick ice sheet until now. It recently was exposed by an ultra-wideband chirp radar system developed at the Center for the Remote Sensing of Ice Sheets (CReSIS) headquartered at the University of Kansas.

The impact beneath the Hiawatha Glacier in remote northwest Greenland is detailed in a new paper in Science Advances published today.

It was identified with data collected between 1997 and 2014 by KU for NASA's Program for Arctic Regional Climate Assessment and Operation IceBridge, and supplemented with more data collected in May 2016 using the Multichannel Coherent Radar Depth Sounder (MCoRDS) developed at KU.

"We've collected lots of radar-sounding data over the last couple of decades, and glaciologists put these radar-sounding datasets together to produce maps of what Greenland is like underneath the ice," said co-author John Paden, courtesy associate professor of & computer science at KU and associate scientist at CReSIS. "Danish researchers were looking at the map and saw this big, craterlike depression under the and looked at satellite imagery and—because the crater is on edge of the ice sheet—you can see a circular pattern there as well. The two combined made a really strong case for this being an impact-crater site. Based on this discovery, a detailed radar survey was conducted in May 2016 using a new state-of-the-art radar designed and built by KU for the Alfred Wegener Institute in Germany."

Photo illustration of the airplane during the survey, radar waves and the actual radar image. Credit: NASA

Paden, who helped develop the MCoRDS radar signal processing software, participated in low-altitude flights in a grid pattern over the impact crater to detail its dimensions.

"You can see the rounded structure at the edge of the ice sheet, especially when flying high enough," he said. "For the most part the crater isn't visible out the airplane window. It's funny that until now nobody thought, 'Hey, what's that semicircular feature there?' From the airplane it is subtle and hard to see unless you already know it's there. Using satellite imagery taken at a low sun angle that accentuates hills and valleys in the ice sheet's terrain—you can really see the circle of the whole crater in these images."

Video taken by University of Kansas researcher John Paden during a radar survey of the impact crater in Greenland. Credit: John Paden/University of Kansas

To confirm the satellite and radar findings, the research team performed subsequent ground-based studies of glaciofluvial sediment from the largest river draining the crater. The work showed the presence of "shocked quartz and other impact-related grains" that include glass. The research team believes these rocks and glassy grains are likely produced from impact melting of grains in the meta-sedimentary bedrock.

Work remains to determine with more precision the timing of the asteroid impact on Greenland. The authors write evidence "suggests that the Hiawatha impact crater formed during the Pleistocene, as this age is most consistent with inferences from presently available data." However, even this broad range in time remains "uncertain." Southwest of the crater, the team has found a region rich in possible debris ejected from the impact, which could help to narrow the date range.

An artist’s depiction of a possible impact into the Greenland Ice Sheet. The iron meteorite penetrated seven kilometers into the Earth’s crust, creating a crater that was initially 20 kilometers wide and collapsed within minutes into the final 31 kilometer crater we see today. Credit: Carl Toft
"There would have been debris projected into the atmosphere that would affect the climate and the potential for melting a lot of ice, so there could have been a sudden freshwater influx into the Nares Strait between Canada and Greenland that would have affected the ocean flow in that whole region," Paden said. "The evidence indicates that the impact probably happened after the Greenland Ice Sheet formed, but the research team is still working on the precise dating."

Other KU personnel involved in the research that revealed the impact crater include Rick Hale, Spahr Professor and chair of the Department of Aerospace Engineering and associate director of CReSIS; Carl Leuschen, associate professor of electrical engineering & computer science and director of CReSIS, and Fernando Rodriguez-Morales, courtesy assistant professor of electrical engineering & computer science. The KU researchers collaborated closely with colleagues from the University of Copenhagen and the Alfred Wegener Institute in Germany.

Map of the bedrock topography beneath the ice sheet and the ice-free land surrounding the Hiawatha impact crater. The structure is 31 kilometers wide, with a prominent rim surrounding the structure. In the central part of the impact structure, an area with elevated terrain is seen, which is typical for larger impact craters. Calculations show that in order to generate an impact crater of this size, the Earth was struck by a meteorite more than one kilometer wide. Credit: Natural History Museum of Denmark, Cryospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, USA

Paden said during the three years between the crater discovery and publication of the team's findings, it was gratifying and exciting to be part of the exclusive group of scientists that knew of the massive .

"It was really cool—it was the kind of thing where I went home and told my kids about it," Paden said. "I said, 'Look at this! It's underneath the ice.' It's one of those fun moments. They were impressed. A lot of times, my research isn't that interesting to them, but this was something they could connect to."

Map of bedrock topography, but with the view towards the Nares Strait, the narrow sea that links Baffin Bay and the Arctic Ocean. Credit: Natural History Museum of Denmark, Cryospheric Sciences Lab, NASA Goddard Space Flight Center, Greenbelt, MD, USA
Map of Greenland showing the location of the Hiawatha impact crater in Inglefield Land, along the northwest margin of the Greenland Ice sheet. Credit: The Natural History Museum of Denmark.

Explore further: NASA support key to glacier mapping efforts

More information: K.H. Kjær el al., "A large impact crater beneath Hiawatha Glacier in northwest Greenland," Science Advances (2018). DOI: 10.1126/sciadv.aar8173 , advances.sciencemag.org/content/4/11/eaar8173

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17 comments

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Bogey
5 / 5 (3) Nov 14, 2018
I guess that's the one that changed human history, big style.
Genava
3.9 / 5 (7) Nov 14, 2018
Sciencemag did a better review of this discovery. It is interesting because it could explain the strange Bølling-Allerød and Younger Drias but anyway, the estimated range for the data is far to wide for the moment.

I'm pretty sure climate deniers will distort this news to serve their agenda
Mark Thomas
5 / 5 (7) Nov 14, 2018
a kilometer-wide iron asteroid


Time for a little prospecting!

Regarding the effects, it sounds like it is a very good fit for causing the Younger Dryas.

https://www.scien...ars-ago/
https://en.wikipe...er_Dryas
https://www.daily...ion.html
https://www.scrib...s-Mining
torbjorn_b_g_larsson
4.3 / 5 (6) Nov 14, 2018
Oy, not this bullshit again! The only reason to suggest 12 kyrs is because University of Kansas.is the origin of its Merlott et al "Dryas impact" theory.

"Why won't this debate about an ancient cold snap die? ... Radiocarbon dating for such old events is challenging regardless of calibration, Marlon says. That's why she analyzed and compared her sites in several different ways, yet still found no unusual peak at 12,800 years. In fact, she says, many of the sites show no signs of burning at that time.""

https://www.scien...old-snap

I note in passing that the purported Clovis extinction claim was thoroughly rejected by no less than 3 [!] separate genome studies as recent as last week.

[tbctd]
torbjorn_b_g_larsson
3 / 5 (6) Nov 14, 2018
[ctd] The bolide impact frequency of this size is fairly comparable to the perhaps 100 kyrs window the fringe "Dryas impact" theorists scour for fitting patterns, perhaps every 0.5 Myrs or so https://en.wikipe...ct_event .

So one Northern hemisphere impact would not be unlikely to be eventually found.

'Nuff said, this fringe is boring. A 10 km impact crater, not so much.
Mark Thomas
5 / 5 (9) Nov 14, 2018
For what it is worth, the graphic shows a 31 km impact crater, which probably had some non-trivial effect on the atmosphere. I suppose the Torbjorn's question is whether there is any real evidence supporting the 12 kyrs age estimate other than trying to fit the even to some data. I suppose time will tell.
Shootist
5 / 5 (2) Nov 14, 2018
There was a Younger Dryas event, whether or not an impact was involved is seriously debatable.
Da Schneib
3.8 / 5 (6) Nov 14, 2018
Yeah, @torbjorn, I was a little suspicious about this 12 kya figure too coming from KU. And you're right, it's not a very big crater as such things go. Minor effects over a limited area. Bigger than any hydrogen bomb we've ever made, though, if it was a near-vertical impact at the average 70 km/s speeds of most meteors. Still, nothing like the Chixulub impactor, by orders of magnitude.
Solon
1.8 / 5 (5) Nov 14, 2018
Wow, that's some impressive electrical discharge pit. Where is the impact debris field? Glacier push it all into the ocean? The truth will out, eventually.
Whydening Gyre
5 / 5 (4) Nov 14, 2018
Wow, that's some impressive electrical discharge pit. Where is the impact debris field? Glacier push it all into the ocean? The truth will out, eventually.

I think an electrical discharge would also have a debris field...
Shootist
5 / 5 (4) Nov 15, 2018
Turns out the age bars are 3 million to 12000 years old.

Retracted article re: Hiawatha

https://www.scien...18301577
jonesdave
4.5 / 5 (8) Nov 15, 2018
Wow, that's some impressive electrical discharge pit. Where is the impact debris field? Glacier push it all into the ocean? The truth will out, eventually.

I think an electrical discharge would also have a debris field...


Not to mention that there is no mechanism that could cause an electrical discharge of that size!
torbjorn_b_g_larsson
5 / 5 (7) Nov 15, 2018
Turns out the age bars are 3 million to 12000 years old.

Retracted article re: Hiawatha

https://www.scien...18301577


FWIW, the authors have retracted - they are trying publishing elsewhere.

Yes, I just saw a thorough article on this, with the suggested date span 100 - 12 kyrs, as well as a glaciologist claiming it may well be millions of years old matching the impactor frequency. (I was a bit high,) https://www.scien...e-humans

"Yet no one can be sure of the timing. ... An external trigger [to Yunger Dryas] may be unnecessary in any case, ... Hiawatha's full story will come down to its age. ... . "Somebody's got to go drill in there," Keigwin says. "That's all there is to it.""

torbjorn_b_g_larsson
5 / 5 (7) Nov 15, 2018
So I was a bit high on the impact frequency as I noted, but come to think about it I was correct on the time window that the Dryas people is looking into due to the glacial cycles.

¯\_(ツ)_/¯

Also "Younger Dryas".
Nik_2213
5 / 5 (1) Nov 15, 2018
Possible coincidence ?
If the feature is 100~120 MY age, it falls remarkably close to the then-location of the 'hot-spot' which migrated SE beneath Greenland, is now feeding Iceland...
Solon
1 / 5 (1) Nov 15, 2018
Wow, that's some impressive electrical discharge pit. Where is the impact debris field? Glacier push it all into the ocean? The truth will out, eventually.

I think an electrical discharge would also have a debris field...


A large scale ion beam erosion process perhaps.

Not to mention that there is no mechanism that could cause an electrical discharge of that size!


If the Sun produces a major ion storm then such a discharge would be possible, perhaps during a period when the magnetosphere was very weak or collapsed.
Da Schneib
5 / 5 (2) Nov 15, 2018
@Nik, isn't Iceland on or near the Mid-Atlantic Ridge? I don't recall it being a hotspot, though I may be wrong.

On edit, yeah, I was right. Found this map: http://staff.imsa...es5.html

Apparently it's at the northern end.

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