Submarine ridge off Brazil: piece of sole original continent?

 

(Reuters) - Brazilian and Japanese researchers say a granite formation deep off the coast of Brazil could be a piece of an original continent that existed before the Americas, Africa, Europe and other major land masses drifted apart.

After a month long expedition using a research submarine, the scientists say the so-called Rio Grande Elevation, a rise on the ocean floor about 1,500 km (932 miles) southeast of Rio de Janeiro, features granite and minerals, including iron, manganese, and cobalt, that differentiate it from the rest of the surrounding seabed.

As such, the researchers believe, the formation could be a lost piece of Pangaea, the sole continent that geologists say existed before today's continents began to drift apart hundreds of millions of years ago.

While the hypothesis must still be tested through further research, the lost piece "could revolutionize our understanding of the formation and evolution of the Earth's crust," said Roberto Ventura, a director at the Brazilian Geological Service and a member of the team that announced the discovery on Monday.

The research was conducted aboard the Shinkai 6500, a Japanese submarine currently deployed as part of a joint mission by the Brazilian Geological Service, the Oceanographic Institute of the University of Sao Paulo and the Japan Agency for Marine-Earth Science and Technology.

The mission, which will resume after a break in Rio, is gathering geological and biological samples collected in various portions of the South Atlantic.

(Reporting By Paulo Prada; Editing by Sandra Maler)

 

 

TOKYO (Reuters) - Vast deposits of rare earth minerals, crucial in making high-tech electronics products, have been found on the floor of the Pacific Ocean and can be readily extracted, Japanese scientists said on Monday.

"The deposits have a heavy concentration of rare earths. Just one square kilometer (0.4 square mile) of deposits will be able to provide one-fifth of the current global annual consumption," said Yasuhiro Kato, an associate professor of earth science at the University of Tokyo.

The discovery was made by a team led by Kato and including researchers from the Japan Agency for Marine-Earth Science and Technology.

They found the minerals in sea mud extracted from depths of 3,500 to 6,000 meters (11,500-20,000 ft) below the ocean surface at 78 locations. One-third of the sites yielded rich contents of rare earths and the metal yttrium, Kato said in a telephone interview.

The deposits are in international waters in an area stretching east and west of Hawaii, as well as east of Tahiti in French Polynesia, he said.

He estimated rare earths contained in the deposits amounted to 80 to 100 billion metric tons, compared to global reserves currently confirmed by the U.S. Geological Survey of just 110 million tonnes that have been found mainly in China, Russia and other former Soviet countries, and the United States.

Details of the discovery were published on Monday in the online version of British journal Nature Geoscience.

The level of uranium and thorium -- radioactive ingredients that are usually contained in such deposits that can pose environmental hazards -- was found to be one-fifth of those in deposits on land, Kato said.

A chronic shortage of rare earths, vital for making a range of high-technology electronics, magnets and batteries, has encouraged mining projects for them in recent years.

 

China, which accounts for 97 percent of global rare earth supplies, has been tightening trade in the strategic metals, sparking an explosion in prices.

Japan, which accounts for a third of global demand, has been stung badly, and has been looking to diversify its supply sources, particularly of heavy rare earths such as dysprosium used in magnets.

Kato said the sea mud was especially rich in heavier rare earths such as gadolinium, lutetium, terbium and dysprosium.

"These are used to manufacture flat-screen TVs, LED (light-emitting diode) valves, and hybrid cars," he said.

Extracting the deposits requires pumping up material from the ocean floor. "Sea mud can be brought up to ships and we can extract rare earths right there using simple acid leaching," he said.

"Using diluted acid, the process is fast, and within a few hours we can extract 80-90 percent of rare earths from the mud."

The team found that sites close to Hawaii and Tahiti were especially rich in rare earths, he said.

He gave no estimate of when extraction of the materials from the seabed might start.

(Reporting by El Tan in Hong Kong and Yuko Inoue in Tokyo; Editing by Michael Watson)