4.3 billion-year-old crust found on surface | daily-sun.com

4.3 billion-year-old crust found on surface

    21 March, 2017 12:00 AM printer

4.3 billion-year-old crust found on surface

EARTH is just shy of 4.6 billion years old and roughly a couple hundred million years later the planetary blob began to cool enough for it to form its first crust, reports agency.

 

Astonishingly, scientists believe they have discovered a piece of that very early crust on the Earth’s surface, dating back some 4.3 billion years. A vast majority of our planet’s first crust has been destroyed through subduction (the tectonic plates sliding under each other) and recycling back into the mantle, however some slivers of the ancient rock record remain.

And geologists believe they have found a piece of it along the eastern shore of the Hudson Bay in Northwestern Quebec, in Canada.

 

The extraordinary discovery was made by a pair of geologists led by Jonathan O’Neil at the University of Ottawa and since published in the journal Science.

 

“I think that it’s a piece of the original crust. It was cooked, but I think it’s still very close to what it used to be,” Mr O’Neil told Popular Mechanics.

 

Previously, the oldest crust samples we have on record date back to 2.7 billion years but pieces of earlier crust have remained elusive.

 

The geologists discovered the chunk of rock enveloped by granite in an area known as “The Canadian Shield” which forms the ancient geological core of the North American continent.

 

The roughly 4.3 billion-year-old volcanic rock is basalt and Mr O’Neil believes was once underneath the Earth’s first oceans.

 

The researchers were able to date the rock using a new technique that has only existed for about the last decade. By measuring an isotope that was only produced within the Earth’s first 500 million years, called neodymium-142, researchers were able to determine that the sliver of Earth had formed between 4.2 billion and 4.3 billion years ago.


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