BEIJING, Sept. 21 (Xinhuanet) -- Recent research recreating the crushing, searing conditions inside the Earth's lower mantle suggests a portion of the mantle about 620 to 1,365 miles (1,000 to 2,200 kilometers) deep is a "transitional zone" where rock turns into an incredibly dense state.

"Scientists trying to develop an accurate model of the Earth's interior will need these findings," said Viktor Struzhkin, an earth scientist at Carnegie Institution in Washington, D.C., and co-author of the new study detailed in the Sept. 21 issue of the journal Science.

Struzhkin said the lower mantle's crushing pressures ─ at least 230,000 times that at Earth's surface ─ cause electrons in iron-containing minerals such as ferropericlase, the second most common mantle material, to act strangely.

"The deeper you go, the higher the pressures and temperatures become," Struzhkin said. His team crushed and heated ferropericlase to mantle-like conditions with diamond anvils and an intense laser beam generated at Argonne National Laboratory in Illinois.

"Argonne is one of the only places where we could have done this experiment," he told LiveScience, noting that his team achieved temperatures of 3,140 degrees F (1,727 degrees C) and pressures about 940,000 times greater than on Earth's surface.

He said the pressure was so great under such conditions that "spinning electrons in iron ... are forced to pair up." When the electrons did so, he noted that the material's density increased about 30 percent.

Struzhkin explained the compacted minerals help speed up energy waves, such as seismic waves, moving through Earth's interior. The researchers only studied one common mantle mineral, however, and need to see how others behave.

"This paper solves only part of the puzzle," Struzhkin said. "We know there are more surprises to come."

(Agencies)