Featured Research

from universities, journals, and other organizations

Earth's dynamic interior: Multiple compositional components of Earth's deep mantle carried up to surface

Date:
March 30, 2014
Source:
Arizona State University College of Liberal Arts and Sciences
Summary:
Seeking to better understand the composition of the lowermost part of Earth's mantle, located nearly 2,900 kilometers (1,800 miles) below the surface, researchers have developed new simulations that depict the dynamics of deep Earth. These could be used to explain the complex geochemistry of lava from hotspots such as Hawaii.

ASU graduate student Mingming Li in collaboration with ASU professors Allen McNamara and Ed Garnero developed new simulations that depict the dynamics of deep Earth. Here, Li stands in front of the massive computer clusters required for running the calculations.
Credit: Allen McNamara

Seeking to better understand the composition of the lowermost part of Earth's mantle, located nearly 2,900 kilometers (1,800 miles) below the surface, a team of Arizona State University researchers has developed new simulations that depict the dynamics of deep Earth. A paper published March 30 in Nature Geoscience reports the team's findings, which could be used to explain the complex geochemistry of lava from hotspots such as Hawaii.

Mantle convection is the driving force behind continental drift and causes earthquakes and volcanoes on the surface. Through mantle convection, material from the lowermost part of Earth's mantle could be carried up to the surface, which offers insight into the composition of the deep Earth. Earth's core is very hot (~4000 K) and rocks at the core mantle boundary are heated and expand to have a lower density. These hot rocks (also called mantle plumes) could migrate to the surface because of buoyancy.

Observations, modeling and predictions have indicated that the deepest mantle is compositionally complex and continuously churning and changing.

"The complex chemical signatures of hotspot basalts provide evidence that the composition of the lowermost part of Earth's mantle is different from other parts. The main question driving this research is how mantle plumes and different compositional components in Earth's mantle interact with each other, and how that interaction leads to the complex chemistry of hotspot basalts. The answer to this question is very important for us to understand the nature of mantle convection," explains lead author Mingming Li, who is pursuing his Ph.D. in geological sciences.

"Obviously, we cannot go inside of Earth to see what is happening there. However, the process of mantle convection should comply with fundamental physics laws, such as conservation of mass, momentum and energy. What we have done is to simulate the process of mantle convection by solving the equations which controls the process of mantle convection," says Li.

It has long been suggested that Earth's mantle contains several different compositional reservoirs, including an ancient more-primitive reservoir at the lowermost mantle, recycled oceanic crust and depleted background mantle. The complex geochemistry of lava found at hotspots such as Hawaii are evidence of this. The various compositional components in hotspot lava may be derived from these different mantle reservoirs. The components could become embedded in and carried to the surface by mantle plumes, but it is unclear how individual plumes could successively sample each of these reservoirs.

Joined by his advisor Allen McNamara, geodynamicist and associate professor in Arizona State University's School of Earth and Space Exploration, and seismologist and SESE professor Ed Garnero, Li and his collaborators' numerical experiments show that plumes can indeed carry a combination of different materials from several reservoirs.

According to the simulations, some subducted oceanic crust is entrained directly into mantle plumes, but a significant fraction of the crust -- up to 10 percent -- enters the more primitive reservoirs. As a result, mantle plumes entrain a variable combination of relatively young oceanic crust directly from the subducting slab, older oceanic crust that has been stirred with ancient more primitive material and background, depleted mantle. Cycling of oceanic crust through mantle reservoirs can therefore explain observations of different recycled oceanic crustal ages and explain the chemical complexity of hotspot lavas.

"Our calculations take a long time -- more than one month for one calculation -- but the results are worth it," says Li.


Story Source:

The above story is based on materials provided by Arizona State University College of Liberal Arts and Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. Mingming Li, Allen K. McNamara, Edward J. Garnero. Chemical complexity of hotspots caused by cycling oceanic crust through mantle reservoirs. Nature Geoscience, 2014; DOI: 10.1038/ngeo2120

Cite This Page:

Arizona State University College of Liberal Arts and Sciences. "Earth's dynamic interior: Multiple compositional components of Earth's deep mantle carried up to surface." ScienceDaily. ScienceDaily, 30 March 2014. <www.sciencedaily.com/releases/2014/03/140330151238.htm>.
Arizona State University College of Liberal Arts and Sciences. (2014, March 30). Earth's dynamic interior: Multiple compositional components of Earth's deep mantle carried up to surface. ScienceDaily. Retrieved September 1, 2014 from www.sciencedaily.com/releases/2014/03/140330151238.htm
Arizona State University College of Liberal Arts and Sciences. "Earth's dynamic interior: Multiple compositional components of Earth's deep mantle carried up to surface." ScienceDaily. www.sciencedaily.com/releases/2014/03/140330151238.htm (accessed September 1, 2014).

Share This




More Earth & Climate News

Monday, September 1, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Washington Wildlife Center Goes Nuts Over Baby Squirrels

Reuters - US Online Video (Aug. 30, 2014) An animal rescue in Washington state receives an influx of orphaned squirrels, keeping workers busy as they nurse them back to health. Rough Cut (no reporter narration). Video provided by Reuters
Powered by NewsLook.com
Raw: Volcano Erupts on Papua New Guinea

Raw: Volcano Erupts on Papua New Guinea

AP (Aug. 29, 2014) Several communities were evacuated and some international flights were diverted on Friday after one of the most active volcanos in the region erupts. (Aug. 29) Video provided by AP
Powered by NewsLook.com
Raw: Small Volcanic Eruption in Iceland

Raw: Small Volcanic Eruption in Iceland

AP (Aug. 29, 2014) Icelandic authorities briefly raised the aviation warning code to red on Friday during a small eruption at the Holuhraun lava field in the Bardabunga volcano system. (Aug. 29) Video provided by AP
Powered by NewsLook.com
As Drought Continues LA "water Police" Fight Waste

As Drought Continues LA "water Police" Fight Waste

AFP (Aug. 29, 2014) In the midst of a historic drought, Los Angeles is increasing efforts to go after people who waste water. Five water conservation "cops" drive around the city every day educating homeowners about the drought. Duration: 02:17 Video provided by AFP
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:
from the past week

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