Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Why Huge Bands of Iron Formed Billions of Years Ago on Earth’s Surface

18.11.2009
No one knows why massive formations of banded iron — some ultimately hundreds of kilometers long, like a sleeping giant’s suspenders — mysteriously began precipitating on Earth’s surface about 3.5 billion years ago. Or why, almost 2 billion years later, the precipitation ceased.

Because these deposits carry information about early Earth’s surface conditions and climate changes, as well as provide much of modern industry’s iron resources, interested researchers have cast a wide net in trying to explain why and how these bands formed. But attempts to explain their existence based on seasonal variations, surface temperature changes and episodic seawater mixing all have foundered on assumptions requiring the unexplained oscillations of external forces.

None of these theories could satisfactorily explain all the observations made by geologists, particularly the existence of alternating structural bands of silica-rich layers with iron-rich layers in these deposits.

A new approach proposed in an October issue of Nature Geoscience by Sandia National Laboratories principal investigator Yifeng Wang and colleagues elsewhere may have the answer.

A key component of the process, the researchers found in computer simulations, may have been the absence of aluminum in early oceanic rocks. That absence chemically favored the formation of banded iron formations. The continual enrichment of oceanic crust by aluminum as Earth evolved ultimately ended the era of iron band formation.

A complete thermodynamic explanation by the research team suggests that iron- and silicon-rich fluids were generated by hydrothermal action on the seafloor. The team’s calculations show that the formation of bands was generated by internal interactions of the chemical system, rather than from external forcing by unexplained changes such as ocean surface temperature variations.

“This concept of the self-organizational origin of banded iron formations is very important,” said Wang. “It allows us to explain a lot of things about them, like their occurrence and band thickness.”

Wang’s Ph.D. advisor, Enrique Merino at Indiana University, may have been the first to consider banded iron formations as formed through self-organization, Wang said: “We started to work on the issue about 15 years ago.” But difficulties in pinning down an actual mechanism persisted.

“Last year, Huifang Xu [at the University of Wisconsin at Madison] and I happened to talk about his work on astrobiology and then we talked about banded iron formations,” said Yifeng. “After that, I got interested again in the topic. Luckily, I came across a very recent publication on silicic acid interactions with metals. With these new data, I did thermodynamic calculations. I looked at the results and talked to both Huifang and Enrique. The whole banded-iron-formation puzzle started to fit together nicely.”

Merino and Xu coauthored the paper with Wang, along with Hironomi Konishi, also at the University of Wisconsin at Madison.

“Our work has two interesting implications,” said Wang. “The Earth’s surface can be divided into four interrelated parts: atmosphere, hydrosphere, biosphere and lithosphere. Our work shows that the lithosphere, that is, the solid rock part, plays a very important role in regulating the surface evolution of the Earth. This may have an implication on the studies of other planets such as Mars. Our work also shows that to understand such evolution requires a careful consideration of nonlinear interactions among different components in the system. Such consideration is important for prediction of modern climatic cycles.”

“After all,” he said, “Earth’s system is inherently complex and the involved processes couple with each other in nonlinear fashion.”

Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, an autonomous Lockheed Martin company, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.

Neal Singer | Newswise Science News
Further information:
http://www.sandia.gov

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: Can we see monkeys from space? Emerging technologies to map biodiversity

An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.

Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...

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)...

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

Quantum thermometer or optical refrigerator?

23.06.2017 | Physics and Astronomy

A 100-year-old physics problem has been solved at EPFL

23.06.2017 | Physics and Astronomy

Equipping form with function

23.06.2017 | Information Technology

VideoLinks
B2B-VideoLinks
More VideoLinks >>>