Japanese scientists to use giant undersea drill to reach Earth’s mantle.

Earth’s elusive mantle is too much to resist for a team of Japanese scientists who plan to be the first to reach it. The team will use a giant drill to reach the molten rock, located six kilometers (3.7 miles) beneath the planet’s surface.

“If we dig into the mantle we will know the whole Earth history, that’s our motivation to search,” researcher Natsue Abe, who is involved in the project, told CNN.

Japan’s Agency for Marine-Earth Science and Technology (JAMSTEC) are undertaking the massive project that will see a drill dropped four kilometers into the ocean, before drilling through six kilometers of the planet’s crust to reach its destination.

“We don’t know the exact (composition) of the mantle yet. We have only seen some mantle materials — the rock is very beautiful, it’s kind of a yellowish green,” Abe said.

The mantle has been observed before by scientists, extruding from ocean ridges and in areas of the ocean where crust is missing, but JAMSTEC’s research will be the first time it has been viewed directly at such a depth.

Three locations in the Pacific Ocean are being scouted for the expedition, planned to start before 2030. A location in Hawaii will be used for preliminary research in September, which will use sound waves to study the thickness and temperature of the crust, reported The Yomiuri Shimbun.

When the drilling begins JAMSTEC will enlist the help of the Chikyū, a Japanese scientific drilling ship designed to drill deeper into the Earth than any ship before it.

“It’s the biggest drilling ship of our science area, so the drilling capability is three times longer, or deeper, than the previous,”Abe said.

There are four objectives to the project, according to Abe, the first of which is to access the mantle.

“The second aim is we want to investigate the boundary between the oceanic crust and the mantle,” she said. “The third one is we want to know how the oceanic crust formed.”

The fourth objective is to examine how life exists inside the planet and see if it has any limitations.



Posted on 2014/11/25


New findings by a Johns Hopkins University-led team reveal long unknown details about carbon deep beneath the Earth’s surface and suggest ways this subterranean carbon might have influenced the history of life on the planet.

The team also developed a new, related theory about how diamonds form in the Earth’s mantle.

For decades scientists had little understanding of how carbon behaved deep below the Earth’s surface even as they learned more and more about the element’s vital role at the planet’s crust. Using a model created by Johns Hopkins geochemistDimitri Sverjensky, Sverjensky, Vincenzo Stagno of the Carnegie Institution of Washington and Fang Huang, a Johns Hopkins graduate student, became the first to calculate how much carbon and what types of carbon exist in fluids at 100 miles below the Earth’s surface at temperatures up to 2,100 degrees F.

In an article published this week in the journal Nature Geoscience, Sverjensky and his team demonstrate that in addition to the carbon dioxide and methane already documented deep in subduction zones, there exists a rich variety of organic carbon species that could spark the formation of diamonds and perhaps even become food for microbial life.

“It is a very exciting possibility that these deep fluids might transport building blocks for life into the shallow Earth,” said Sverjensky, a professor in the Department of Earth and Planetary Sciences. “This may be a key to the origin of life itself.”

Sverjensky’s theoretical model, called the Deep Earth Water model, allowed the team to determine the chemical makeup of fluids in the Earth’s mantle, expelled from descending tectonic plates. Some of the fluids, those in equilibrium with mantle peridotite minerals, contained the expected carbon dioxide and methane. But others, those in equilibrium with diamonds and eclogitic minerals, contained dissolved organic carbon species including a vinegar-like acetic acid.

These high concentrations of dissolved carbon species, previously unknown at great depth in the Earth, suggest they are helping to ferry large amounts of carbon from the subduction zone into the overlying mantle wedge where they are likely to alter the mantle and affect the cycling of elements back into the Earth’s atmosphere.

The team also suggested that these mantle fluids with dissolved organic carbon species could be creating diamonds in a previously unknown way. Scientists have long believed diamond formation resulted through chemical reactions starting with either carbon dioxide or methane. The organic species offer a range of different starting materials, and an entirely new take on the creation of the gemstones.

The research is part of a 10-year global project to further understanding of carbon on Earth called the Deep Carbon Observatory. The work is funded by the Alfred P. Sloan Foundation.