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The good earth recycles its crust

A Rutgers geologist at the State University of New Jersey, has come up with evidence that the earth practices recycling on a grand scale.

india Updated: Dec 01, 2006 11:23 IST

A Rutgers geologist at the State University of New Jersey, has come up with evidence that the earth practices recycling on a grand scale.

In his report in the journal Nature, Claude Herzberg offers new evidence that parts of the earth’s crust that long ago dove hundreds or thousands of kilometres into the earth’s interior, have resurfaced in the hot lava flow of Hawaiian volcanoes.

“This concept has been a big issue in the earth sciences. While it had been proposed earlier by some geologists, the profession hasn’t embraced it because evidence until now remained sketchy. Many geologists felt that when the earth’s crust was forced deep into the mantle, a process called subduction, it would simply stay there,” said Herzberg.

Herzberg said tell-tale chemical evidence of this was found upon studying the lava at Mauna Kea where pieces of this submerged crust had been forced up through plumes.

“The low calcium in the Hawaiian magma pegs it as crust that had melted and been forced to the surface. The calcium levels in traditional magma, which comes from melting the earth’s mantle layer below the crust, are much higher,” he said.

The research in Hawaii doesn’t end here. The chemical findings will be useful in understanding the makeup and action of other volcanoes around the world.

These findings extend beyond calcium and include sulphur, along with isotopes of the heavier elements hafnium and lead that are tracers for clays and other materials that originated close to the surface prior to subduction,” he added.