Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Path to Oxygen in Earth's Atmosphere: Long Series of Starts and Stops

07.12.2011
Rock cores from Northwest Russia provide new insights

The appearance of oxygen in the Earth's atmosphere probably did not occur as a single event, but as a long series of starts and stops, according to geoscientists who investigated rock cores from the FAR DEEP project. The Fennoscandia Arctic Russia - Drilling Early Earth Project--FAR DEEP--took place during the summer of 2007 near Murmansk in Northwest Russia.


Panorama of Russia's Imandra/Varzuga Greenstone Belt where FAR DEEP drilling took place. Credit: Victor Melezhik, Geological Survey of Norway/University of Bergen

The project, part of the International Continental Scientific Drilling Program, drilled a series of shallow, two-inch diameter cores and, by overlapping them, created a record of stone deposited during the Proterozoic Eon--2,500 million to 542 million years ago.

"We've always thought that oxygen came into the atmosphere really quickly during an event," said Lee Kump, a geoscientist at Penn State University.

"We are no longer looking for an event. Now we're looking for when and why oxygen became a stable part of the Earth's atmosphere."

The researchers report in this week's issue of the journal Science Express that evaluation of these cores, in comparison with cores from Gabon previously analyzed by others, supports the conclusion that the Great Oxidation Event, the appearance of free oxygen in Earth's atmosphere, played out over hundreds of millions of years. Kump is the lead author of the Science Express paper.

Oxygen levels gradually crossed the low atmospheric oxygen threshold for pyrite--an iron sulfur mineral--oxidation by 2,500 million years ago, and the loss of what scientists call mass-independently fractionated (MIF) sulfur by 2,400 million years ago.

Then oxygen levels rose at an ever-increasing rate through the Paleoproterozoic, achieving about one percent of the present atmospheric level.

"The definition of when an oxygen atmosphere occurred depends on which threshold you are looking for," said Kump. "It could be when pyrite becomes oxidized, when sulfur MIF disappears, or when deep crustal oxidation occurs."

When the MIF sulfur disappeared, the air on Earth was still not breathable by animal standards.

When red rocks containing iron oxides appeared 2,300 million years ago, the air was still unbreathable.

"At about one percent oxygen, the groundwater became strongly oxidized, making it possible for water seeping through rocks to oxidize organic materials," said Kump.

Initially, any oxygen in the atmosphere, produced by the photosynthesis of single-celled organisms, was used up when sulfur, iron and other elements oxidized.

When sufficient oxygen accumulated in the atmosphere, it permeated the groundwater and began oxidizing buried organic material, oxidizing carbon to create carbon dioxide.

"Insights into Earth's carbon cycle offer tantalizing clues to the history of atmospheric oxygen levels, and Kump and others have revealed unrecognized details of the timing and mechanism of the Great Oxidation Event," said Enriqueta Barrera, program director in the National Science Foundation's Division of Earth Sciences, which funded the research.

The cores from the FAR-DEEP project were compared with samples from Gabon using the ratio of carbon isotopes, or variants, 13 and 12 to see if the evidence for high rates of oxygen accumulation existed worldwide.

Both the FAR-DEEP project's cores and the Gabon cores show large deposits of carbon in the form of fossilized petroleum.

Both sets of cores also show similar changes in carbon 13 through time, indicating that the changes in carbon isotopes occurred worldwide and that oxygen levels throughout the atmosphere were high.

"Although others have documented huge carbon isotope variations at later times in Earth history associated with stepwise increases in atmospheric oxygen, our results are less equivocal because we have many lines of data all pointing to the same thing," said Kump.

"These indications include not only carbon 13 isotope profiles in organic mater from two widely separated locations, but also supporting profiles in limestones and no indication that processes occurring since that time have altered the signal."

Working with Kump on the project were geoscientists Michael Arthur of Penn State; Christopher Junium of Syracuse University; Alex Brasier and Anthony Fallick of the Scottish Universities Environmental Research Centre; Victor Melezhik, Aivo Lepland and Alenka Crne at the Norwegian Geological Survey; and Genming Luo, China University of Geosciences.

The NASA Astrobiology Institute also supported the research.

Media Contacts
Cheryl Dybas, NSF (703) 292-7734 cdybas@nsf.gov
A'ndrea Elyse Messer, Penn State (814) 865-9481 aem1@psu.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2011, its budget is about $6.9 billion. NSF funds reach all 50 states through grants to nearly 2,000 universities and institutions. Each year, NSF receives over 45,000 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.

Cheryl Dybas | EurekAlert!
Further information:
http://www.nsf.gov
http://www.nsf.gov/news/news_summ.jsp?cntn_id=122418

More articles from Earth Sciences:

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

nachricht A close-up look at an uncommon underwater eruption
11.01.2018 | Woods Hole Oceanographic Institution

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

Let the good tubes roll

19.01.2018 | Materials Sciences

How cancer metastasis happens: Researchers reveal a key mechanism

19.01.2018 | Health and Medicine

Meteoritic stardust unlocks timing of supernova dust formation

19.01.2018 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>