A 400 kilometer-wide impact zone from a huge meteorite that broke in two moments before it slammed into the Earth has been found in Central Australia
From Australian National University:
A 400 kilometre-wide impact zone from a huge meteorite that broke in two moments before it slammed into the Earth has been found in Central Australia.
The crater from the impact millions of years ago has long disappeared. But a team of geophysicists has found the twin scars of the impacts – the largest impact zone ever found on Earth – hidden deep in the earth’s crust.
Lead researcher Dr Andrew Glikson from The Australian National University (ANU) said the impact zone was discovered during drilling as part of geothermal research, in an area near the borders of South Australia, Queensland and the Northern Territory.
“The two asteroids must each have been over 10 kilometres across – it would have been curtains for many life species on the planet at the time,” said Dr Glikson, from the ANU School of Archaeology and Anthropology.
The revelation of such ancient violent impacts may lead to new theories about the Earth’s history.
“Large impacts like these may have had a far more significant role in the Earth’s evolution than previously thought,” Dr Glikson said.
The exact date of the impacts remains unclear. The surrounding rocks are 300 to 600 million years old, but evidence of the type left by other meteorite strikes is lacking.
For example, a large meteorite strike 66 million years ago sent up a plume of ash which is found as a layer of sediment in rocks around the world. The plume is thought to have led to the extinction of a large proportion of the life on the planet, including many dinosaur species.
However, a similar layer has not been found in sediments around 300 million years old, Dr Glikson said.
“It’s a mystery – we can’t find an extinction event that matches these collisions. I have a suspicion the impact could be older than 300 million years,” he said.
A geothermal research project chanced on clues to the impacts while drilling more than two kilometres into the earth’s crust.
The drill core contained traces of rocks that had been turned to glass by the extreme temperature and pressure caused by a major impact.
Magnetic modelling of the deep crust in the area traced out bulges hidden deep in the Earth, rich in iron and magnesium, corresponding to the composition of the Earth mantle.
“There are two huge deep domes in the crust, formed by the Earth’s crust rebounding after the huge impacts, and bringing up rock from the mantle below,” Dr Glikson said.
The two impact zones total more than 400 kilometres across, in the Warburton Basin in Central Australia. They extend through the Earth’s crust, which is about 30 kilometres thick in this area.
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This is always a fun one to plug in the numbers-looks like Richter 9.6 shock form a single 10km chunk.
The impact effects calculator:
http://impact.ese.ic.ac.uk/ImpactEffects/
Just be careful about distance though or you get “Your position is inside the fireball”. Oh goody. 😉
shame it didn’t happen a bit later 😉
Just maybe, the Cambrian Explosion may not have happened had the bolide not impacted. All just speculation, and irrelevant as well.
It’s definitely not that old.
If you assume that asteroid impacts are essentially random in distribution, and given that 70% of the earth is covered by water, it would be reasonable to assume that for every old impact you find on continental crust there were probably 2.3 that occurred in the oceans some where.
Would make for an interesting day at the beach.
Larry Ledwick
March 23, 2015 at 3:41 pm
Much of today’s exposed-to-the-atmosphere continental rock is fairly recent: Only a few areas around Australia, Africa and the central Canadian tundra are “original rock” in that they’ve been exposed to bombardment for 3.7 billion years or more. The rest of today’s continents are ex-seafloor moved around, bumped up and submerged and piled into mountains chains, etc. The seafloor is also fairly new: The oldest rocks under the heavy cover of debris and whale poop are getting jammed under the continental rocks in the trenches at the edge of the continents.
http://en.wikipedia.org/wiki/Crust_%28geology%29
Other areas around ocean floor expanding points (the Atlantic’s east and west coastlines) for example, may have comet impact craters – but they’ve been buried under 1 kilometers of more whale and shark poop.
“but they’ve been buried under 1 kilometers of more whale and shark poop.”
Perhaps the MIA heat is in a giant compost pile at the bottom of the sea. I knew it was some form of manure. (-;
I hope CERN is on the night time tariff this time
Quite interesting – BUT WHY ON EARTH do they drill for geothermal energy in the middle of Australia’s outback ???
Do the Kangaroos there feel to cold or what? Well, in that case it would be much cheaper to solve the problem this way:
http://learnenglishkids.britishcouncil.org/en/jokes/sheep-with-kangaroo
Because earlier oil and gas drilling showed that the region was geothermally hot, and that’s where most of the onshore drill rigs are concentrated.
Ciao
John
Thank you for this information.
OFF TOPIC:
Scott Adams of Dilbert’s fame is discussing Climate Change Science in his blog. He has a huge and educated readership.
http://blog.dilbert.com/post/114402236396/who-is-more-anti-science
If someone here wants to throw some light there…
Why are asteroids in space on fire? I thought WUWT was into accurate pictures?
It’s an artists illustration of an asteroid with a coma.
http://www.universetoday.com/81576/asteroid-sheila-sprouts-a-tail-and-coma/
The fire is in your imagination.
Oh yes, asteroids are full of surprises.
http://www.nasa.gov/sites/default/files/14-060-asteroid-disintegration_1.jpg
“The Keck Observatory showed us this thing was worth looking at with Hubble,” Jewitt said. “With its superior resolution, space telescope observations soon showed there were really 10 embedded objects, each with comet-like dust tails. The four largest rocky fragments are up to 400 yards in diameter, about four times the length of a football field.”
trafamadore,
You seem very unhappy here. You never have a good or positive thing to say. Why not post elsewhere?
Asteroids are visible because of their brightness; that is also how the size is estimated.
“Size estimates: Object diameters are rough approximations derived by standard formula from H, an object’s “absolute magnitude” (brightness), where higher numbers represent dimmer (thus usually smaller) objects.”
It’s not bright, it’s burning up. Like after it hits the atmosphere, but it’s still way out in space. You could say it’s a comet, but the tail is pointed towards the sun, also wrong, and anyway, they are talking about asteroids.
And db, it is WUWT that loves to complain about photoshopped polar bears, not me.
trafamadore,
Yes. Readers here object to that kind of dishonest photoshopping — while you apparently approve.
When someone becomes a climate alarmist, they must check their ethics at the door.
@trafamadore
Artists’ concept work is a problem of mine also, in many cases. (:
trafamdore found us out, I guess we will have to give up our plans for world domination.
DavidA
I suggest he avoid astronomy news if he doesn’t care for artists’ concept renderings.
black holes
https://www.google.com/search?q=neutron+star&client=opera&hs=jhy&source=lnms&tbm=isch&sa=X&ei=VvYQVZfPAoKfoQTRmYLYBw&ved=0CAcQ_AUoAQ&biw=1241&bih=600#tbm=isch&q=black+holes&imgdii=xHpsy2BjmFNRgM%3A%3Bv7S2evVD3hwjkM%3BxHpsy2BjmFNRgM%3A
neutron star
http://www.esa.int/var/esa/storage/images/esa_multimedia/images/2007/02/fast-spinning_neutron_star/9517599-4-eng-GB/Fast-spinning_neutron_star.jpg
…and here I was ready to capitulate, and admit that this post was about something that could cause climate change I could believe in.
Massive asteroid/meteor impacts are not clamatic “tipping points” because they are not caused by human activity.
Now see how you are? (:
But ass-steroids make him feel better. (People do what they do because there is always a payoff.)
Tread warily where Dr. Glikson is concerned. As Jo Nova demonstrated a few years back, his musts, mays and coulds need to be taken with the proverbial grain of salt.
He lost all credibility hanging out with the Flim Flam man.
Well this explains the kangaroos, poor mutated buggers.
Why would such a large object break in two ‘moments’ before impact? Surely the thermal shock would be superficial over such a brief encounter with the atmosphere.
(The Thunderbolts folks would probably say that there was a large voltage differential between the earth and the object, and upon nearing the earth, quickly increasing internal electrical stresses causes the break-up, similar to an exploding over-charged capacitor.)
Max Photon
But look at the 20+ objects that comet shoemaker-levy busted up into during just one loop around Jupiter prior to its fatal impact – and that impact was spread out over some 15 days, only 1-1/2 years after the original comet was slung around the planet. These things are not necessarily all that well glued together into single round solid objects.
Which is why I question severely (laugh at) any thoughts and plans of actually getting a remote-controlled, 15 minutes lag time-between-phone-calls-radio-signals to control a “lander on a spinning irregular-shaped irregularly cemented-together “comet” and attach a “lanyard” exactly on the “south pole” to “pull it” away from the future earth’s orbit intercept point. A pipe dream.
Thanks for that. I just investagoogled Shoemaker-Levy; I didn’t realize it was a Jupiter-orbiting comet. Trippy.
As for comet abatement, what better way to burn copious green funding than with a pipe dream?
Here’s mission control …
http://www.celebstoner.com/assets/images/pages/2013/csnews13/CheechChong_UIS.jpg
“Why would such a large object break in two ‘moments’ before impact?”
It would have happened slightly earlier when it crossed the Roche limit. At ordinary orbital speeds that would be 5-10 minutes before impact. Many asteroids ar “rubble piles” only held together by gravity.
This must be due to climate change. Let’s see if the climate modelers can hindcast and predict the time and place of impact!
Could it be from trying to remember the meaning of your non de plume?
To take a sobering count of just how “likely” a continent-sized (or planet-sized!) blast cloud can be, consider that in less than 20 years, 25 huge impacts have been photographed on Jupiter alone. (21 from comet Shuemaker-Levy-9, and 4 additional impacts)
None were expected. Only the comet was seen before impact – and that only because as a comet, it did become bright enough to see by telescope. Yes, Jupiter has a huge gravitation field, and yes, it is closer to the asteroid belt. But ….
See this Wkipedia page for links to each of the other impacts.
http://en.wikipedia.org/wiki/List_of_Jupiter_events
Impacts
September 2012 Jupiter impact event[2]
August 2010 Jupiter impact event[2]
June 2010 Jupiter impact event
2009 Jupiter impact event
Comet Shoemaker–Levy 9 (1994 impact event)
Not only some of the largest, but some of the oldest and some of those can be barely seen from the ground because they have, literally, been worn away by erosion over time.
Reblogged this on Utopia – you are standing in it!.
For those who ponder if the Deccan Traps flood basalts were due to to the Chicxulub impact, please see the link.
/www.sci-news.com/geology/science-deccan-traps-volcanism-dinosaur-extinction-02345.html
or if you have an account (paywall)
Blair Schoene et al. U-Pb geochronology of the Deccan Traps and relation to the end-Cretaceous mass extinction. Science, published online December 11, 2014; doi: 10.1126/science.aaa0118
Briefly, more exact rock dating has placed a beginning date for the eruptions at 250,000 years prior to the impact and extending 500,000 years after. I would say that there is strong evidence that they are neither linked either by time or process.
If rocks ~300MY were affected, the impact would have been younger. If the surface layers at the time of impact have been removed by later erosion, the age of the unconformity between affected rock and over burden without signs of impact will give the oldest possible date for the impact. In view of the global effects expected, I’d look at the Permo-Triassic boundary at 252 mya as a possible impact date.
A quiet time at ANU……the vice chancellor has a ring around ….”anybody got anything interesting for an announcement ?
Well we’ve got this impact stuff…announced it a couple of years ago but no one will remember
Good stuff, get on with it Andy…
https://web.archive.org/web/20130303083341/http://www.google.com/hostednews/afp/article/ALeqM5hKA11RSxMWXNDCylkruMp8ArUxLQ?docId=CNG.1bb4b4734767ea26f972911ed32c4387.4a1
The earlier comment about bolides was mistaken: the fracture of a meteor in the atmosphere has little to do with heating (although there is plenty of heat). The meteor is supersonic and thus creates a shockwave ahead of itself. There is a high overpressure behind the shockwave, in front of the meteor, where the incoming airflow “stagnates” or comes nearly to rest relative to the meteor. This constitutes an axial compression load against the meteor (overpressure vs. inertia). Once the compression strength of the meteor is exceeded, it fractures (releasing compression strain energy in the process). If it is a small meteor (bolide), this manifests as an apparent “explosion,” even though nothing actually explodes (like TNT).
This fracture mechanism could have happened to the Australian monster collider, but it requires a determination of how fast the speed of sound was within the material body of the meteor, since pressure effects are communicated basically at the speed of sound within a material. It is not clear how they come to this conclusion of a fractured body at impact, since the fragments would not have had significant time to separate.
There is a further twist to this scenario. As the impact proceeds, the first thing to occur will be the high-speed contact of the shockwave with the surface of the Earth. This will cause a reflection of the shockwave, and the pressure ratio across the shockwave will be the square of what it was coming in. This will create a very high-pressure seismic spike into the Earth. The reflected wave will travel back and reflect again off the meteor, where the pressure ratio across the shockwave squares yet again. It is at least plausible that if the meteor had not fractured in response to the original shockwave, it might well fracture in response to this sudden fourth-power increase of the shockwave pressure ratio, just before impact.
An impact like this might be even worse than building the Keystone Pipeline!!
The impact of one of these strikes on a major ocean basin would be almost as devastating as political climate change over reach. Either way the unsuspecting populations in the way of these policy-caused and natural events are helpless.