Earth’s oldest asteroid crater found in Australia

Posted: January 22, 2020 by oldbrew in Ice ages, News, research
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Credit: earth.com


Theories abound, but the inevitable carbon dioxide one pops up at the end.

Scientists have identified the world’s oldest asteroid crater in Australia, adding it may explain how the planet was lifted from an ice age, reports BBC News.

The asteroid hit Yarrabubba in Western Australia about 2.2 billion years ago – making the crater about half the age of Earth, researchers say.

Their conclusion was reached by testing minerals found in rocks at the site.

The scientists say the find is exciting because it could account for a warming event during that era.

The Curtin University research was published in the journal Nature Communications on Wednesday.

How did they date it?

The crater was discovered in the dry outback in 1979, but geologists had not previously tested how old it was.

Due to billions of years of erosion, the crater is not visible to the eye. Scientists mapped scars in the area’s magnetic field to determine its 70km (43 miles) diameter.

“The landscape is actually very flat because it’s so old, but the rocks there are distinctive,” researcher Prof Chris Kirkland told the BBC.

To determine when the asteroid hit Earth, the team examined tiny zircon and monazite crystals in the rocks. They were “shocked” in the strike and now can be read like “tree rings”, Prof Kirkland said.

These crystals hold tiny amounts of uranium. Because uranium decays into lead at a consistent pace, the researchers were able to calculate how much time had passed.

It is at least 200 million years older than the next most ancient impact structure – the Vredefort Dome in South Africa.

“We were interested in the area because the Western Australian landscape is very old but we didn’t expected [the crater] to be as old as this,” Prof Kirkland said.

“It’s absolutely possible that there’s an older crater out there just waiting to be discovered, but the difficulty is in finding the crust before it erodes and you lose that early Earth history”.

Could it have ended an ice age?

The timing of the impact could also explain why the world warmed around this time, according to the researchers.

Scientists believe the planet was previously in one of its “Snowball Earth” periods, when it was largely covered in ice. At some point, the ice sheets melted and the planet began to rapidly warm.

“The age of the [crater] corresponds pretty precisely with the end of a potential global glacial period,” Prof Kirkland said.

“So the impact may have had significant changes to our planetary climate.”

Full report here.

See also: Asteroid that smashed Earth 2.2 billion years ago may have thawed the planet [cnet.com]

Comments
  1. Jim says:

    Interesting. But shy in the conclusions. How do you create global warming? By limiting the sun’s influence? Or attracting the heat to the ground? This study says limit the sun. Clouds keep the heat in the air, reflecting the sun back to space. Making the ground cooler. Cooler ground, ice age. Water vapor, absorbs the heat, dust if darker in color, absorbs heat, all reradiating in the atmosphere which is cold, create a winter effect. Not conducive to life as we know it.
    The study is interesting, but, this creates an illusion of cooperation, there are other ways to influence the creation of a proper world, this is one of the weakest ways. It more likely helped extend a snowball earth.

  2. Phoenix44 says:

    “The age of the [crater] corresponds pretty precisely with the end of a potential global glacial period,”

    Total b******s.

    The resolution of both events is in millions of years. So the two could be two million years apart without any problem. Now two million years apart in geological time is close, but not in terms of climate.

  3. Gamecock says:

    I’ve told you a million times not to exaggerate!

    ‘Scientists have identified the world’s oldest asteroid crater’

    ‘It’s absolutely possible that there’s an older crater out there just waiting to be discovered’

    Lapse in continuity.

    ‘Scientists have identified the world’s oldest asteroid crater in Australia’

    More likely dumbass BBC writers identified it as the oldest. Being journalists the distinction is beyond their intellect.

  4. oldbrew says:

    ‘Oldest known crater’ would be nearer the mark.

  5. JB says:

    “To determine when the asteroid hit Earth, the team examined tiny zircon and monazite crystals in the rocks. They were “shocked” in the strike and now can be read like “tree rings”, Prof Kirkland said.

    These crystals hold tiny amounts of uranium. Because uranium decays into lead at a consistent pace, the researchers were able to calculate how much time had passed.”

    How in the world can they correlate atomic decay with an impact? Are they assuming the uranium is extraterrestrial? Isn’t there an assumption of uniformitarianism embedded in the concept of atomic decay and errosion? How could they know that far back there were no cosmic events accelerating the decay of uranium, or other catastrophic events accelerating errosion? And how do “shocked” mineral crystals have anything to do with uranium?

    As for the existence of massive ice sheets, the idea is a 19th century speculation never proved. Just one sample from Allan & Delair’s 1997 tome:

    “Data from the Faeroe islands, even farther north, cast further doubts on the very existence of former extensive ice-sheets in the North Sea region. Deposits attributed to ice action have been interpreted there as due to local ice, “…rather than to an ice-sheet advancing from the north or having contact with the Norwegian mer de glace “.
    On mainland Britain, several ‘drift’-less areas in northern England – south of York, for example – reinforce the general picture now emerging, as does the apparent failure of any ice to have crossed the North Sea to terrain north of the Humber.
    During so-called Weichselian times the Norwegian mountains were supposedly the centre of a regular mer de glace which, at its maximum, stretched south-Westwards to embrace not only the Faeroes, Shetlands and Orkneys, mainland Scotland and Wales, all but southernmost England and the entire North Sea area, but also the whole of Eire. As previously noted, many parts of this extensive region were apparently never glaciated at all – a detail paralleled by the absence of detectable glaciation on the Lofoten islands(68°N, 15°E) and the unglaciated character of innumerable jagged rocks off Norway’s western coast. Moreover, the lower deposits occupying the adjacent Norwegian deep-sea trench are also apparently nonglacial.
    Why is glacial evidence absent from parts of mainland Britain and the bed of the North Sea if an ice-sheet allegedly mantled that entire region? Was it because, as intimated earlier, glacial action actually never occurred there?” pp41-42 Cataclysm!

    This sure looks like speculation cloaked in scientism and zero proof by falsification.

  6. Graeme No.3 says:

    JB:
    The further back in time you go, the more uncertain the position of land masses becomes, and the ease of ignoring contrary evidence to one’s pet theory becomes greater.
    I have an old (time) geologist friend who thinks that Uranium/Lead analyses might be OK back to 100 million years ago ±5 million years. These people are projecting 25 times that time.

  7. Dan says:

    “To determine when the asteroid hit Earth, the team examined tiny zircon and monazite crystals in the rocks. They were “shocked” in the strike and now can be read like “tree rings”, Prof Kirkland said.”

    Because the shocked crystals can be read like tree rings, I applied Mann’s methodology and am confident in saying that the temperature in that area was absolutely static for millions of years until the asteroid impact released megatons of CO2, causing rapid warming. Hence the wildfires now.

  8. oldbrew says:

    Before the asteroid hit…

    JANUARY 23, 2020 REPORT
    Computer model shows ancient Earth with an atmosphere 70 percent carbon dioxide

    A team of researchers from the University of Washington has found evidence that the Earth’s atmosphere approximately 2.7 billion years ago might have been up to 70 percent carbon dioxide. In their paper published in the journal Science Advances, the group describes their study of micro-meteorites and what they learned from them.

    https://phys.org/news/2020-01-ancient-earth-atmosphere-percent-carbon.html
    – – –
    up to 70 percent carbon dioxide
    But 0.04% CO2 today is too much – a terrible problem, say alarmists 😂

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