Tau.Neutrino said:
Yarrabubba crater in WA outback world’s oldest recognised impact structure
Around 2 billion years ago when Earth was covered in ice, a meteorite slammed into what is now outback Western Australia.
The impact left a 70-kilometre-wide scar on the land known as Yarrabubba impact crater.
Key points
Precise dating of melted crystals indicate a meteorite slammed into the Yarrabubba crater 2.229 billion years ago
This time coincided with the end of the first ‘snowball’ Earth
Modelling by the scientists suggests this may have helped end the deep freeze, but other experts are sceptical
more…
According to wikipedia, it’s only 30 km in diameter. In this wikipedia table, the date is given as “1130–2600” million years ago. Other confirmed large crates have confirmed dates out to 2023 million years and tentative dates out to 2100 million years.
So yes, at 2229 Ma, Yarrabubba crater is definitely the oldest.
> How do you date a crater?
> he sifted through kilograms of rock picking out tiny crystals of zircon and monazite with a steady hand and a good set of tweezers.
Hey, yes. Zircon and monazite contain radioactive uranium and thorium. Monazite is a primary ore of thorium.
> Mineral grains that trap uranium turn into clocks because uranium over time turns to lead and we know the rate of that change. By being able to precisely target these shocked grains, we’ve been able to get a much more precise handle on when this event occurred.
I’m convinced. Good work. For a date that early, darn good.