Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Rich ore deposits linked to ancient atmosphere

23.11.2009
Much of our planet's mineral wealth was deposited billions of years ago when Earth's chemical cycles were different from today's.

Using geochemical clues from rocks nearly 3 billion years old, a group of scientists including Andrey Bekker and Doug Rumble from the Carnegie Institution have made the surprising discovery that the creation of economically important nickel ore deposits was linked to sulfur in the ancient oxygen-poor atmosphere.

These ancient ores -- specifically iron-nickel sulfide deposits -- yield 10% of the world's annual nickel production. They formed for the most part between two and three billion years ago when hot magmas erupted on the ocean floor. Yet scientists have puzzled over the origin of the rich deposits. The ore minerals require sulfur to form, but neither seawater nor the magmas hosting the ores were thought to be rich enough in sulfur for this to happen.

"These nickel deposits have sulfur in them arising from an atmospheric cycle in ancient times. The isotopic signal is of an anoxic atmosphere," says Rumble of Carnegie's Geophysical Laboratory, a co-author of the paper appearing in the November 20 issue of Science.

Rumble, with lead author Andrey Bekker (formerly Carnegie Fellow and now at the University of Manitoba), and four other colleagues used advanced geochemical techniques to analyze rock samples from major ore deposits in Australia and Canada. They found that to help produce the ancient deposits, sulfur atoms made a complicated journey from volcanic eruptions, to the atmosphere, to seawater, to hot springs on the ocean floor, and finally to molten, ore-producing magmas.

The key evidence came from a form of sulfur known as sulfur-33, an isotope in which atoms contain one more neutron than "normal" sulfur (sulfur-32). Both isotopes act the same in most chemical reactions, but reactions in the atmosphere in which sulfur dioxide gas molecules are split by ultraviolet light (UV) rays cause the isotopes to be sorted or "fractionated" into different reaction products, creating isotopic anomalies.

"If there is too much oxygen in the atmosphere then not enough UV gets through and these reactions can't happen," says Rumble. "So if you find these sulfur isotope anomalies in rocks of a certain age, you have information about the oxygen level in the atmosphere."

By linking the rich nickel ores with the ancient atmosphere, the anomalies in the rock samples also answer the long-standing question regarding the source of the sulfur in the ore minerals. Knowing this will help geologists track down new ore deposits, says Rumble, because the presence of sulfur and other chemical factors determine whether or not a deposit will form.

"Ore deposits are a tiny fraction of a percent of the Earth's surface, yet economically they are incredibly important. Modern society cannot exist without specialized metals and alloys," he says. "But it's all a matter of local geological circumstance whether you have a bonanza -- or a bust."

The Carnegie Institution (www.CIW.edu) has been a pioneering force in basic scientific research since 1902. It is a private, nonprofit organization with six research departments throughout the U.S. Carnegie scientists are leaders in plant biology, developmental biology, astronomy, materials science, global ecology, and Earth and planetary science.

Douglas Rumble | EurekAlert!
Further information:
http://www.ciw.edu

More articles from Earth Sciences:

nachricht Sediment from Himalayas may have made 2004 Indian Ocean earthquake more severe
26.05.2017 | Oregon State University

nachricht Devils Hole: Ancient Traces of Climate History
24.05.2017 | Universität Innsbruck

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 the immune system be boosted against Staphylococcus aureus by delivery of messenger RNA?

Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.

Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....

Im Focus: A quantum walk of photons

Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.

The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....

Im Focus: Turmoil in sluggish electrons’ existence

An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.

We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...

Im Focus: Wafer-thin Magnetic Materials Developed for Future Quantum Technologies

Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.

Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...

Im Focus: World's thinnest hologram paves path to new 3-D world

Nano-hologram paves way for integration of 3-D holography into everyday electronics

An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Marine Conservation: IASS Contributes to UN Ocean Conference in New York on 5-9 June

24.05.2017 | Event News

AWK Aachen Machine Tool Colloquium 2017: Internet of Production for Agile Enterprises

23.05.2017 | Event News

Dortmund MST Conference presents Individualized Healthcare Solutions with micro and nanotechnology

22.05.2017 | Event News

 
Latest News

How herpesviruses win the footrace against the immune system

26.05.2017 | Life Sciences

Water forms 'spine of hydration' around DNA, group finds

26.05.2017 | Life Sciences

First Juno science results supported by University of Leicester's Jupiter 'forecast'

26.05.2017 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>