Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Volcanoes key to Earth's oxygen atmosphere

30.08.2007
A switch from predominantly undersea volcanoes to a mix of undersea and terrestrial ones shifted the Earth's atmosphere from devoid of oxygen to one with free oxygen, according to geologists.

"The rise of oxygen allowed for the evolution of complex oxygen-breathing life forms," says Lee R. Kump, professor of geoscience, Penn State.

Before 2.5 billion years ago, the Earth's atmosphere lacked oxygen. However, biomarkers in rocks 200 million years older than that period, show oxygen-producing cyanobacteria released oxygen at the same levels as today. The oxygen produced then, had to be going somewhere.

"The absence of oxidized soil profiles and red beds indicates that oxidative weathering rates were negligible during the Archaean," the researchers report in today's (Aug. 30) issue of Nature.

The ancient Earth should have had an oxygen atmosphere but something was converting, reducing, the oxygen and removing it from the atmosphere. The researchers suggest that submarine volcanoes, producing a reducing mixture of gases and lavas, effectively scrubbed oxygen from the atmosphere, binding it into oxygen containing minerals.

"The Archaean more than 2.5 billion years ago seemed to be dominated by submarine volcanoes," says Kump. "Subaerial andesite volcanoes on thickened continental crust seem to be almost absent in the Archaean."

About 2.5 billion years ago at the Archaean/Proterozoic boundary, when stabilized continental land masses arose and terrestrial volcanoes appeared, markers show that oxygen began appearing in the atmosphere.

Kump and Mark E. Barley, professor of geology, University of Western Australia, looked at the geologic record from the Archaean and the Palaeoproterozoic in search of the remains of volcanoes. They found that the Archaean was nearly devoid of terrestrial volcanoes, but heavily populated by submarine volcanoes. The Palaeoproterozoic, however, had ample terrestrial volcanic activity along with continuing submarine vulcanism. Subaerial volcanoes arose after 2.5 billion years ago and did not strip oxygen from the air. Having a mix of volcanoes dominated by terrestrial volcanoes allowed oxygen to exist in the atmosphere.

Terrestrial volcanoes could become much more common in the Palaeoproterozoic because land masses stabilized and the current tectonic regime came into play.

The researchers looked at the ratio of submarine to subaerial volcanoes through time. Because submarine volcanoes erupt at lower temperatures than terrestrial volcanoes, they are more reducing. As long as the reducing ability of the submarine volcanoes was larger than the amounts of oxygen created, the atmosphere had no oxygen. When terrestrial volcanoes began to dominate, oxygen levels increased.

Andrea Elyse Messer | EurekAlert!
Further information:
http://www.psu.edu

More articles from Earth Sciences:

nachricht Ice cave in Transylvania yields window into region's past
28.04.2017 | National Science Foundation

nachricht Citizen science campaign to aid disaster response
28.04.2017 | International Institute for Applied Systems Analysis (IIASA)

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Fighting drug resistant tuberculosis – InfectoGnostics meets MYCO-NET² partners in Peru

28.04.2017 | Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

 
Latest News

Wireless power can drive tiny electronic devices in the GI tract

28.04.2017 | Medical Engineering

Ice cave in Transylvania yields window into region's past

28.04.2017 | Earth Sciences

Nose2Brain – Better Therapy for Multiple Sclerosis

28.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>