Featured Research

from universities, journals, and other organizations

Earth's core deprived of oxygen

Date:
November 24, 2011
Source:
Carnegie Institution
Summary:
Scientists know that the Earth's liquid outer core consists mainly of iron, but it is believed that small amounts of some other elements are also present. Oxygen is the most abundant element in the planet, so it is not unreasonable to expect oxygen might be one of the dominant "light elements" in the core. But new research proves otherwise. This has major implications for our understanding of the period when the Earth formed.

Planet Earth. The composition of Earth's core remains a mystery.
Credit: NASA

The composition of Earth's core remains a mystery. Scientists know that the liquid outer core consists mainly of iron, but it is believed that small amounts of some other elements are present as well. Oxygen is the most abundant element in the planet, so it is not unreasonable to expect oxygen might be one of the dominant "light elements" in the core. However, new research from a team including Carnegie's Yingwei Fei shows that oxygen does not have a major presence in the outer core. This has major implications for our understanding of the period when Earth formed through the accretion of dust and clumps of matter.

Related Articles


Their work is published Nov. 24 in Nature.

According to current models, in addition to large amounts of iron, Earth's liquid outer core contains small amounts of so-called light elements, possibly sulfur, oxygen, silicon, carbon, or hydrogen. In this research, Fei, from Carnegie's Geophysical Laboratory, worked with Chinese colleagues, including lead author Haijun Huang from China's Wuhan University of Technology, now a visiting scientist at Carnegie. The team provides new experimental data that narrow down the identity of the light elements present in Earth's outer core.

With increasing depth inside Earth, the pressure and heat also increase. As a result, materials act differently than they do on the surface. At Earth's center are a liquid outer core and a solid inner core. The light elements are thought to play an important role in driving the convection of the liquid outer core, which generates Earth's magnetic field.

Scientists know the variations in density and speed of sound as a function of depth in the core from seismic observations, but to date it has been difficult to measure these properties in proposed iron alloys at core pressures and temperatures in the laboratory.

"We can't sample the core directly, so we have to learn about it through improved laboratory experiments combined with modeling and seismic data," Fei said.

High-speed impacts can generate shock waves that raise the temperature and pressure of materials simultaneously, leading to melting of materials at pressures corresponding to those in the outer core. The team carried out shock-wave experiments on core materials, mixtures of iron, sulfur, and oxygen. They shocked these materials to the liquid state and measured their density and speed of sound traveling through them under conditions directly comparable to those of the liquid outer core.

By comparing their data with observations, they conclude that oxygen cannot be a major light element component of Earth's outer core, because experiments on oxygen-rich materials do not align with geophysical observations. This supports recent models of core differentiation in early Earth under more 'reduced' (less oxidized) environments, leading to a core that is poor in oxygen.

"The research revealed a powerful way to decipher the identity of the light elements in the core. Further research should focus on the potential presence of elements such as silicon in the outer core," Fei said.

Portions of this work were supported by grants from the National Natural Science Foundation of China, the Fundamental Research Funds for the Central Universities, and the National Basic Research of China, as well as the National Science Foundation and the Carnegie Institution for Science.


Story Source:

The above story is based on materials provided by Carnegie Institution. Note: Materials may be edited for content and length.


Journal Reference:

  1. Haijun Huang, Yingwei Fei, Lingcang Cai, Fuqian Jing, Xiaojun Hu, Hongsen Xie, Lianmeng Zhang, Zizheng Gong. Evidence for an oxygen-depleted liquid outer core of the Earth. Nature, 2011; 479 (7374): 513 DOI: 10.1038/nature10621

Cite This Page:

Carnegie Institution. "Earth's core deprived of oxygen." ScienceDaily. ScienceDaily, 24 November 2011. <www.sciencedaily.com/releases/2011/11/111123133137.htm>.
Carnegie Institution. (2011, November 24). Earth's core deprived of oxygen. ScienceDaily. Retrieved December 21, 2014 from www.sciencedaily.com/releases/2011/11/111123133137.htm
Carnegie Institution. "Earth's core deprived of oxygen." ScienceDaily. www.sciencedaily.com/releases/2011/11/111123133137.htm (accessed December 21, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Sunday, December 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Lava on Track to Hit Hawaii Market

Raw: Lava on Track to Hit Hawaii Market

AP (Dec. 19, 2014) Lava from an active volcano on Hawaii's Big Island slowed slightly but stayed on track to hit a shopping center in the small town of Pahoa. (Dec. 19) Video provided by AP
Powered by NewsLook.com
Birds Might Be Better Meteorologists Than Us

Birds Might Be Better Meteorologists Than Us

Newsy (Dec. 19, 2014) A new study suggests a certain type of bird was able to sense a tornado outbreak that moved through the U.S. a day before it hit. Video provided by Newsy
Powered by NewsLook.com
Navy Unveils Robot Fish

Navy Unveils Robot Fish

Reuters - Light News Video Online (Dec. 18, 2014) The U.S. Navy unveils an underwater device that mimics the movement of a fish. Tara Cleary reports. Video provided by Reuters
Powered by NewsLook.com
Arctic Warming Twice As Fast As Rest Of Planet

Arctic Warming Twice As Fast As Rest Of Planet

Newsy (Dec. 18, 2014) The Arctic is warming twice as fast as the rest of the planet, thanks in part to something called feedback. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Plants & Animals

Earth & Climate

Fossils & Ruins

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins