Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rust under pressure could explain deep Earth anomalies

09.06.2016

Using laboratory techniques to mimic the conditions found deep inside the Earth, a team of Carnegie scientists led by Ho-Kwang "Dave" Mao has identified a form of iron oxide that they believe could explain seismic and geothermal signatures in the deep mantle. Their work is published in Nature.

Iron and oxygen are two of the most geochemically important elements on Earth. The core is rich in iron and the atmosphere is rich in oxygen, and between them is the entire range of pressures and temperatures on the planet.


An artwork depicting the decomposition of FeOOH in lower mantle conditions. The cycle starts from α-FeOOH (blue dot on the top) to its high-pressure form (brown dot), to FeO2 (center crystal) and hydrogen (cyan bubbles), and finally produce other minerals (bubbles on the left side).

Courtesy of Ms. Xiaoya

"Interactions between oxygen and iron dictate Earth's formation, differentiation--or the separation of the core and mantle--and the evolution of our atmosphere, so naturally we were curious to probe how such reactions would change under the high-pressure conditions of the deep Earth," said Mao.

The research team--Qingyang Hu, Duck Young Kim, Wenge Yang, Liuxiang Yang, Yue Meng, Li Zhang, & Ho-Kwang Mao--put ordinary rust, or FeOOH, under about 900,000 times normal atmospheric pressure and at about 3200 degrees Fahrenheit and were able to synthesize a form of iron oxide, FeO2, that structurally resembles pyrite, also known as fool's gold. The reaction gave off hydrogen in the form of H2.

FeOOH is found in iron ore deposits that exist in bogs, so it could easily move into the deep Earth at plate tectonic boundaries, as could samples of ferric oxide, Fe2O3, which along with water will also form the pyrite-like iron oxide under deep lower mantle conditions.

Why does this interest the researchers? For one thing, this type of reaction could have started in Earth's infancy, and understanding it could inform theories of our own planet's evolution, as well as its current geochemistry.

Furthermore, the H2 released in this reaction would work its way upward, possibly reacting with other materials on its way. Meanwhile, the iron oxide would settle planet's depths and form reservoirs of oxygen there, particularly if one of these patches of iron oxide moved upward along the pressure gradient to the middle part of the mantle and separated into iron and O2.

"Pools of free oxygen under these conditions could create many reactions and chemical phases, which might be responsible for seismic and geochemical signatures of the deep Earth," Mao explained.

"Our experiments mimicking mantle conditions demonstrate that more research is needed on this pyrite-like phase of iron oxide." Hu added.

The research team believes their findings could even offer an alternate explanation for the Great Oxygenation Event that changed Earth's atmosphere between 2 and 2.5 billion years ago. The rise of bacteria performing photosynthesis, which releases oxygen as a byproduct, is often considered the source of the rapid increase in atmospheric oxygen, which had previously been scarce. But releases of oxygen from upwelling of deep mantle FeO2 patches could provide an abiotic explanation for the phenomenon, they say.

###

Researchers were supported by the NSF and the National Natural Science Foundation of China.

Measurements were performed at the High Pressure Collaborative Access Team, Advanced Photon Source, Argonne National Laboratory, and the BL15U1 beamline, Shanghai Synchrotron Radiation Facility in China. Parts of the experiments were performed at the 13BM-C experimental station of the GeoSoilEnviroCARS facility at the APS. HPCAT operations are supported by the DOE-NNSA and by the DOE-BES, with partial instrumentation funding by the NSF. 13BM-C operation is supported by COMPRES through the Partnership for Extreme Crystallography (PX2) project, under an NSF Cooperative Agreement. APS is supported by the DOE-BES.

The Carnegie Institution for Science is a private, nonprofit organization headquartered in Washington, D.C., with six research departments throughout the U.S. Since its founding in 1902, the Carnegie Institution has been a pioneering force in basic scientific research. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

Media Contact

Ho-Kwang "Dave" Mao
hmao@carnegiescience.edu

 @carnegiescience

https://carnegiescience.edu/ 

Ho-Kwang "Dave" Mao | EurekAlert!

Further reports about: Atmosphere Earth's mantle Oxygen atmospheric pressure ferric oxide iron oxide

More articles from Earth Sciences:

nachricht Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments
22.01.2018 | Duke University

nachricht World’s oldest known oxygen oasis discovered
18.01.2018 | Eberhard Karls Universität Tübingen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>