Earth's first example of recycling -- its own crust!
Rock samples from northeastern Canada retain chemical signals that help explain what Earth’s crust was like more than 4 billion years ago, reveals new work from Carnegie’s Richard Carlson and Jonathan O’Neil of the University of Ottawa. Their work is published by Science.
There is much about Earth’s ancient crust that scientists don’t understand. This is because most of the planet’s original crust simply isn’t around any longer to be studied directly—it has either sunk back into the planet’s interior due to the action of plate tectonics or been transformed by geological activity at Earth’s surface to make new, younger rocks.
“Finding remnants of this ancient crust has proven difficult, but a new approach offers the ability to detect the presence of truly ancient crust that has been reworked into ‘merely’ really old rocks,” Carlson said.
The approach employed in this study examined variations in the abundance of an isotope of the element neodymium, which is created by the radioactive decay of a different element, samarium.
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Image credit: Jonathan O'Neil via Carnegie Institute for Science.