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 Water - as the underlying driver of the Earth’s carbon cycle
17.01.2017 | Max-Planck-Institut für Biogeochemie

nachricht Modeling magma to find copper
13.01.2017 | Université de Genève

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: How gut bacteria can make us ill

HZI researchers decipher infection mechanisms of Yersinia and immune responses of the host

Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...

Im Focus: Interfacial Superconductivity: Magnetic and superconducting order revealed simultaneously

Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.

While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...

Im Focus: Studying fundamental particles in materials

Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales

Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...

Im Focus: Designing Architecture with Solar Building Envelopes

Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.

As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...

Im Focus: How to inflate a hardened concrete shell with a weight of 80 t

At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).

Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

12V, 48V, high-voltage – trends in E/E automotive architecture

10.01.2017 | Event News

2nd Conference on Non-Textual Information on 10 and 11 May 2017 in Hannover

09.01.2017 | Event News

Nothing will happen without batteries making it happen!

05.01.2017 | Event News

 
Latest News

A big nano boost for solar cells

18.01.2017 | Power and Electrical Engineering

Glass's off-kilter harmonies

18.01.2017 | Materials Sciences

Toward a 'smart' patch that automatically delivers insulin when needed

18.01.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>