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 Climate satellite: Tracking methane with robust laser technology
22.06.2017 | Fraunhofer-Gesellschaft

nachricht How reliable are shells as climate archives?
21.06.2017 | Leibniz-Zentrum für Marine Tropenforschung (ZMT)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Climate satellite: Tracking methane with robust laser technology

Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.

Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...

Im Focus: How protons move through a fuel cell

Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.

As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...

Im Focus: A unique data centre for cosmological simulations

Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.

With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...

Im Focus: Scientists develop molecular thermometer for contactless measurement using infrared light

Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine

Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...

Im Focus: Optoelectronic Inline Measurement – Accurate to the Nanometer

Germany counts high-precision manufacturing processes among its advantages as a location. It’s not just the aerospace and automotive industries that require almost waste-free, high-precision manufacturing to provide an efficient way of testing the shape and orientation tolerances of products. Since current inline measurement technology not yet provides the required accuracy, the Fraunhofer Institute for Laser Technology ILT is collaborating with four renowned industry partners in the INSPIRE project to develop inline sensors with a new accuracy class. Funded by the German Federal Ministry of Education and Research (BMBF), the project is scheduled to run until the end of 2019.

New Manufacturing Technologies for New Products

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Plants are networkers

19.06.2017 | Event News

Digital Survival Training for Executives

13.06.2017 | Event News

Global Learning Council Summit 2017

13.06.2017 | Event News

 
Latest News

A new technique isolates neuronal activity during memory consolidation

22.06.2017 | Life Sciences

Plant inspiration could lead to flexible electronics

22.06.2017 | Materials Sciences

A rhodium-based catalyst for making organosilicon using less precious metal

22.06.2017 | Materials Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>