Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Noble gases hitch a ride on hydrous minerals

17.06.2013
The noble gases get their collective moniker from their tendency toward snobbishness.

The six elements in the family, which includes helium and neon, don't normally bond with other elements and they don't dissolve into minerals the way other gases do. But now, geochemists from Brown University have found a mineral structure with which the nobles deign to fraternize.


The mineral amphibole is made up of tetrahedral and octahedral structures linked together in a way that creates a series of rings. New research suggests those rings -- called A-sites -- could dissolve noble gases, which are not generally thought to dissolve in minerals. The findings could explain how noble gases are cycled from deep within the Earth to the surface and back again.

Credit: Parman Lab / Brown University

Researchers led by Colin Jackson, a graduate student in geological sciences, have found noble gases to be highly soluble in amphibole, a mineral commonly found in oceanic crust. "We found remarkably high solubility," said Stephen Parman, assistant professor of geological sciences at Brown and Jackson's Ph.D. adviser. "It was three or four orders of magnitude higher than in any other mineral than had been measured."

The findings, which are published in Nature Geoscience, are a step toward answering puzzling questions about how noble gases are cycled between the atmosphere and the depths of the Earth.

Completing the cycle

Gases in the air we breathe are on a geological conveyor belt of sorts, cycled from the Earth's mantle to the atmosphere and back again. Carbon dioxide, water vapor and other gases are released into the atmosphere and oceans from molten magma during volcanic eruptions, and then returned to depths through subduction, when one tectonic plate slides underneath another. The subducting crust is injected deep into the mantle, taking water and any other volatiles it may carry along for the ride.

Noble gases are also released during volcanic activity, but the amount of those gases returned to the mantle through subduction was long thought to be minimal. After all, if noble gases don't dissolve in minerals, they would lack a vehicle to make the trip. Recent research, however, has suggested that some noble gases are indeed recycled, leaving scientists at a loss to find a mechanism for it. By showing definitively that noble gases are soluble in amphibole, Jackson and his colleagues have shown how noble gases could be carried in subducting slabs.

The key to amphibole's ability to dissolve noble gases, the researchers say, is its lattice structure. Amphibole and other silicate minerals are made up of tetrahedral and octahedral structures linked together in a way that creates a series of rings. It's those rings, called A-sites, that provide a home for otherwise finicky noble gases, the research suggests.

Jackson performed a series of experiments to see if the number of empty rings in different types of amphibole were correlated to its ability to dissolve noble gases. He placed cut amphibole gems into a tube with helium or neon under high pressure and temperature, and then used a mass spectrometer to see how much of the gas had dissolved in each gem over the duration of each experiment. The experiments showed that noble gas solubility was highest in types of amphibole with the most unoccupied ring structures.

"This was the meat of the paper," Parman said. "It's telling us a specific site where we think the noble gases are. It might be the first time anyone has made a positive identification of where noble gases are going into a mineral."

Importantly, the researchers said, amphibole isn't the only crustal mineral with these ring structures. Ring structures are actually quite common in crustal minerals, and could provide a wide variety of potential vehicles that could take noble gases back to the depths via subduction.

A high-fidelity fingerprint

Understanding how noble gases are cycled between the Earth's surface and interior could shed new light on how other volatiles are recycled, the researchers said.

Scientists are particularly interested in tracking the cycling of water and carbon. Water is obviously vital for life, and carbon cycling has an important impact on the climate. Scientists try to track the cycle by looking at isotope ratios, which can provide a fingerprint that helps to identify where elements originated. Butarbon and the hydrogen in water have only a few isotopes that scientists can use for tracking, and in the case of hydrogen, the isotope ratios are easily thrown off by all kinds of natural processes.

The noble gases, on the other hand, have lots of isotopes, giving scientists ways to track them with great specificity. So if noble gases are cycled in the same minerals that cycle other volatiles like water and carbon, they could be used as a marker to track those other volatiles. "It's a very high-fidelity fingerprint because you have so many isotopes to play with," Jackson said.

There's more work to be done before noble gases could be used as such a fingerprint, but this work does provide a first step: showing which kinds of minerals could be responsible for noble gas recycling.

Other authors on the paper were Simon Kelley of The Open University in the United Kingdom and Reid Cooper, professor of geological sciences at Brown. The work was funded by the National Science Foundation's Division of Earth Sciences (1019229).

Editors:

Brown University has a fiber link television studio available for domestic and international live and taped interviews, and maintains an ISDN line for radio interviews. For more information, call (401) 863-2476.

Kevin Stacey | EurekAlert!
Further information:
http://www.brown.edu

More articles from Earth Sciences:

nachricht New research calculates capacity of North American forests to sequester carbon
16.07.2018 | University of California - Santa Cruz

nachricht Scientists discover Earth's youngest banded iron formation in western China
12.07.2018 | University of Alberta

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Subaru Telescope helps pinpoint origin of ultra-high energy neutrino

16.07.2018 | Physics and Astronomy

Barium ruthenate: A high-yield, easy-to-handle perovskite catalyst for the oxidation of sulfides

16.07.2018 | Life Sciences

New research calculates capacity of North American forests to sequester carbon

16.07.2018 | Earth Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>