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4.4 Billion Year Old Piece of Earth's Crust, Oldest Yet, Found

| 24 Feb 2014 14:38

Scientists have analyzed a zircon crystal taken from Australia's Jack Hills region and determined it is approximately 4.4 billion years old, making it the oldest known piece of Earth's crust.

At 4.375 billion years old, give or take six million years, a zircon crystal from Australia's Jack Hills has been found to be the oldest piece of Earth's crust discovered yet. The scientists that dated the ancient crystal have also used a technique that they hope will put an end to the long-running debate over the accuracy of dating these minerals.

"We've proved that the chemical record inside these zircons is trustworthy," said John Valley, lead study author and a geochemist at the University of Wisconsin, Madison. The findings were published yesterday in the journal Nature Geoscience.

Studying these ancient zircons is important to understanding early Earth, because inclusions within them tell us about the conditions of their environment during their formation. Earth is 4.54 billion years old, and zircons from Australia's Jack Hills region range from 3 billion to 4.4 billion years in age. However, the age of these ancient crystals has always been suspect due to the radiation damage that can occur during natural processes. Valley and his co-authors used a recently developed technique called atom-probe tomography to prove that the radiation damage to their analyzed zircon crystal does not render their dating inaccurate.

"We've demonstrated this zircon is a closed geochemical system, and we've never been able to do that before," Valley said. "There's no question that many zircons do suffer radiation damage, but I think relative to these zircons, this should settle it once and for all," Valley told Live Science's Our Amazing Planet.

Source: Fox News
Image source: Wikimedia Commons

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