Featured Research

from universities, journals, and other organizations

Upside-down answer for deep mystery: What caused Earth to hold its last breath?

Date:
February 18, 2010
Source:
Rice University
Summary:
When Earth was young, it exhaled the atmosphere. During a period of intense volcanic activity, lava carried light elements from the planet's molten interior and released them into the sky. However, some light elements got trapped inside the planet. In a new study, scientists offer a new answer to a longstanding mystery: what caused Earth to hold its last breath?

Volcano eruption (Reunion island, Indian Ocean).
Credit: iStockphoto

When Earth was young, it exhaled the atmosphere. During a period of intense volcanic activity, lava carried light elements from the planet's molten interior and released them into the sky. However, some light elements got trapped inside the planet. In the journal Nature, a Rice University-based team of scientists is offering a new answer to a longstanding mystery: What caused Earth to hold its last breath?

Related Articles


For some time, scientists have known that a large cache of light elements like helium and argon still reside inside the planet. This has perplexed scientists because such elements tend to escape into the atmosphere during volcanism. However, because these elements are depleted in the Earth's upper mantle, Earth scientists are fairly certain the retained elements lie in a deeper portion of the mantle. Researchers have struggled to explain why some gases would be retained while others would rise and escape into the air. The dominant view has been that the lowermost mantle has been largely isolated from the upper mantle and therefore retains its primordial composition.

In the new study, a team of researchers from Rice, the University of Michigan and the University of California-Berkeley suggests that a particular set of geophysical conditions that existed about 3.5 billion years ago -- when Earth's interior was much warmer -- led to the formation of a "density trap" about 400 kilometers below the planet's surface. In the trap, a precise combination of heat and pressure led to a geophysical rarity, an area where liquids were denser than solids.

Today, liquids generated in the mantle are less dense than solids and therefore rise to the surface to form volcanoes. However, several billion years ago, a hotter mantle permitted deeper melting and generated dense liquids that stalled, crystallized and eventually sank to the bottom of the mantle.

"When something melts, we expect the gas to get out, and for that reason people have suggested that the trapped elements must be in a primordial reservoir that has never melted," said lead author Cin-Ty Lee, associate professor of Earth science at Rice. "That idea's become problematic in recent decades, because there's evidence that suggests all the mantle should have melted at least once. What we are suggesting is a mechanism where things could have melted but where the gas does not escape because the melted material never rises to the surface."

Lee said the rise of less dense, melted material from Earth's interior is the process that created Earth's crust. Suggesting that melted material might sink instead literally turns conventional wisdom on its head. But the "upside-down" model can explain several geochemical and geophysical oddities in addition to the trapped gases, which suggests that it is a plausible hypothesis.

"I hope this generates a lot of interest," Lee said. "There are seismic methods that can be used to test our idea. Even if we turn out to be wrong, the tests that would be needed to falsify our hypothesis would generate a lot of new information."

Research co-authors include Peter Luffi, Tobias Hφink and Rajdeep Dasgupta, all of Rice, Michigan's Jie Li and UC-Berkeley's John Hernlund. The research was supported by the Packard Foundation and the National Science Foundation.


Story Source:

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


Journal Reference:

  1. Cin-Ty A. Lee, Peter Luffi, Tobias Hφink, Jie Li, Rajdeep Dasgupta & John Hernlund. Upside-down differentiation and generation of a 'primordial' lower mantle. Nature, 2010; 463 (7283): 930 DOI: 10.1038/nature08824

Cite This Page:

Rice University. "Upside-down answer for deep mystery: What caused Earth to hold its last breath?." ScienceDaily. ScienceDaily, 18 February 2010. <www.sciencedaily.com/releases/2010/02/100217131140.htm>.
Rice University. (2010, February 18). Upside-down answer for deep mystery: What caused Earth to hold its last breath?. ScienceDaily. Retrieved October 25, 2014 from www.sciencedaily.com/releases/2010/02/100217131140.htm
Rice University. "Upside-down answer for deep mystery: What caused Earth to hold its last breath?." ScienceDaily. www.sciencedaily.com/releases/2010/02/100217131140.htm (accessed October 25, 2014).

Share This



More Earth & Climate News

Saturday, October 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

EU Gets Climate Deal, UK PM Gets Knock

EU Gets Climate Deal, UK PM Gets Knock

Reuters - Business Video Online (Oct. 24, 2014) — EU leaders achieve a show of unity by striking a compromise deal on carbon emissions. But David Cameron's bid to push back EU budget contributions gets a slap in the face as the European Commission demands an extra 2bn euros. David Pollard reports. Video provided by Reuters
Powered by NewsLook.com
Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Deep Sea 'mushroom' Could Be Early Branch on Tree of Life

Reuters - Innovations Video Online (Oct. 24, 2014) — Miniature deep sea animals discovered off the Australian coast almost three decades ago are puzzling scientists, who say the organisms have proved impossible to categorise. Academics at the Natural History of Denmark have appealed to the world scientific community for help, saying that further information on Dendrogramma enigmatica and Dendrogramma discoides could answer key evolutionary questions. Jim Drury has more. Video provided by Reuters
Powered by NewsLook.com
Raw: Tornado Rips Roofs in Washington State

Raw: Tornado Rips Roofs in Washington State

AP (Oct. 24, 2014) — A rare tornado ripped roofs off buildings, uprooted trees and shattered windows Thursday afternoon in the southwest Washington city of Longview, but there were no reports of injuries. (Oct. 24) Video provided by AP
Powered by NewsLook.com
Fast-Moving Lava Headed For Town On Hawaii's Big Island

Fast-Moving Lava Headed For Town On Hawaii's Big Island

Newsy (Oct. 24, 2014) — Lava from the Kilauea volcano on Hawaii's Big Island has accelerated as it travels toward a town called Pahoa. 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