Featured Research

from universities, journals, and other organizations

Carbon cycle reaches Earth's lower mantle: Evidence of carbon cycle found in 'superdeep' diamonds From Brazil

Date:
September 15, 2011
Source:
American Association for the Advancement of Science
Summary:
The carbon cycle, upon which most living things depend, reaches much deeper into Earth than generally supposed -- all the way to the lower mantle, researchers report.

Like an insect in amber, mineral inclusions trapped in diamonds can reveal much about the Earth's deep interior. The study by Walter et al. in Science reveals mineral inclusions that originated in oceanic crust subducted into the lower mantle.
Credit: Image Science/AAAS

The carbon cycle, upon which most living things depend, reaches much deeper into Earth than generally supposed -- all the way to the lower mantle, researchers report.

Related Articles


The findings, which are based on the chemistry of an unusual set of Brazilian diamonds, will be published online by the journal Science, at the Science Express Web site, on 15 September. Science is published by AAAS, the non-profit, international science society.

"This study shows the extent of Earth's carbon cycle on the scale of the entire planet, connecting the chemical and biological processes that occur on the surface and in the oceans to the far depths of Earth's interior," said Nick Wigginton, associate editor at Science.

"Results of this kind offer a broader perspective of planet Earth as an integrated, dynamic system," he said.

The carbon cycle generally refers to the movement of carbon through the atmosphere, oceans, and the crust. Previous observations suggested that the carbon cycle may even extend to the upper mantle, which extends roughly 400 kilometers into Earth. In this region, plates of ocean crust -- bearing a carbon-rich sediment layer -- sink beneath other tectonic plates and mix with the molten rock of the mantle.

Seismological and geochemical studies have suggested that oceanic crust can sink all the way to the lower mantle, more than 660 kilometers down. But actual rock samples with this history have been hard to come by.

Michael Walter of the University of Bristol and colleagues in Brazil and the United States analyzed a set of "superdeep" diamonds from the Juina kimberlite field in Brazil. Most diamonds excavated at Earth's surface originated at depths of less than 200 kilometers. Some parts of the world, however, have produced rare, superdeep diamonds, containing tiny inclusions of other material whose chemistry indicates that the diamonds formed at far greater depths.

The Juina-5 diamonds studied by Walter and colleagues contain inclusions whose bulk compositions span the range of minerals expected to form when basalt melts and crystallizes under the extreme high pressures and temperatures of the lower mantle.

Thus, these inclusions probably originated when diamond-forming fluids incorporated basaltic components from oceanic lithosphere that had descended into the lower mantle, the researchers have concluded.

If this hypothesis is correct, then the carbon from which the diamonds formed may have been deposited originally within ocean crust at the seafloor. A relative abundance of light carbon isotopes in the Juina-5 diamonds supports this idea, since this lighter form of carbon is found at the surface but not generally in the mantle, the authors say.

The diamond inclusions also include separate phases that appear to have "unmixed" from the homogenous pool of material. This unmixing likely happened as the diamonds traveled upward hundreds of kilometers into the upper mantle, the researchers say.

After the diamonds formed in the lower mantle, they may have been launched back near the surface by a rising mantle plume, Walter and colleagues propose.

This research was supported by the Natural Environment Research Council and the National Science Foundation.


Story Source:

The above story is based on materials provided by American Association for the Advancement of Science. Note: Materials may be edited for content and length.


Journal Reference:

  1. M. J. Walter, S. C. Kohn, D. Araujo, G. P. Bulanova, C. B. Smith, E. Gaillou, J. Wang, A. Steele, S. B. Shirey. Deep Mantle Cycling of Oceanic Crust: Evidence from Diamonds and their Mineral Inclusions. Science, 2011; DOI: 10.1126/science.1209300

Cite This Page:

American Association for the Advancement of Science. "Carbon cycle reaches Earth's lower mantle: Evidence of carbon cycle found in 'superdeep' diamonds From Brazil." ScienceDaily. ScienceDaily, 15 September 2011. <www.sciencedaily.com/releases/2011/09/110915141227.htm>.
American Association for the Advancement of Science. (2011, September 15). Carbon cycle reaches Earth's lower mantle: Evidence of carbon cycle found in 'superdeep' diamonds From Brazil. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2011/09/110915141227.htm
American Association for the Advancement of Science. "Carbon cycle reaches Earth's lower mantle: Evidence of carbon cycle found in 'superdeep' diamonds From Brazil." ScienceDaily. www.sciencedaily.com/releases/2011/09/110915141227.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Ivory Trade Boom Swamps Law Efforts

Ivory Trade Boom Swamps Law Efforts

Reuters - Business Video Online (Dec. 17, 2014) Demand for ivory has claimed the lives of tens of thousands of African elephants and now a conservation report says the illegal trade is overwhelming efforts to enforce the law. Amy Pollock reports. Video provided by Reuters
Powered by NewsLook.com
Indictments in West Virginia Chemical Spill Case

Indictments in West Virginia Chemical Spill Case

AP (Dec. 17, 2014) A grand jury indicted four former executives of Freedom Industries, the company at the center of the Jan. 9, 2014 chemical spill in Charleston, West Virginia. The spill contaminated the Elk River and the water supply of 300,000 people. (Dec. 17) Video provided by AP
Powered by NewsLook.com
Uphill Battle to Tackle Indonesian Shark Fishing

Uphill Battle to Tackle Indonesian Shark Fishing

AFP (Dec. 17, 2014) Sharks are hauled ashore every day at a busy market on the central Indonesian island of Lombok, the hub of a booming trade that provides a livelihood for local fishermen but is increasingly alarming environmentalists. Duration: 00:42 Video provided by AFP
Powered by NewsLook.com
France's Sauternes Wine Threatened by New Train Line

France's Sauternes Wine Threatened by New Train Line

AFP (Dec. 16, 2014) Winemakers in southwestern France's Bordeaux are concerned about a proposed high speed train line that could affect the microclimate required for the region's sweet wine. Duration: 01:06 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

More Coverage


Journey to the Lower Mantle and Back: Minerals from Ocean-Floor Rocks Are Found in Ultra-Deep Diamonds

Sep. 15, 2011 Mineral inclusions discovered in diamonds prove that surface rocks can be subducted into the deep part of the Earth's mantle. The isotopic composition of the diamonds confirms that recycling of ... read more

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins