Featured Research

from universities, journals, and other organizations

Plate Tectonics May Grind To A Halt, Then Start Again

Date:
January 7, 2008
Source:
Carnegie Institution
Summary:
Plate tectonics, the geologic process responsible for creating the Earth's continents, mountain ranges, and ocean basins, may be an on-again, off-again affair. Scientists have assumed that the shifting of crustal plates has been slow but continuous over most of the Earth's history, but a new study suggests that plate tectonics may have ground to a halt at least once in our planet's history -- and may do so again.

When an ocean plate collides with another ocean plate or with a plate carrying continents, one plate will bend and slide under the other. This process is called subduction. As the subducting plate plunges deep into the mantle, it gets so hot it melts the surrounding rock. The molten rock rises through the crust and erupts at the surface of the overriding plate.
Credit: Woods Hole Oceanographic Institution

Plate tectonics, the geologic process responsible for creating the Earth's continents, mountain ranges, and ocean basins, may be an on-again, off-again affair. Scientists have assumed that the shifting of crustal plates has been slow but continuous over most of the Earth's history, but a new study from researchers at the Carnegie Institution suggests that plate tectonics may have ground to a halt at least once in our planet's history--and may do so again.

Related Articles


A key aspect of plate tectonic theory is that on geologic time scales ocean basins are transient features, opening and closing as plates shift. Basins are consumed by a process called subduction, where oceanic plates descend into the Earth's mantle. Subduction zones are the sites of oceanic trenches, high earthquake activity, and most of the world's major volcanoes.

Writing in the January 4 issue of Science, Paul Silver of the Carnegie Institution's Department of Terrestrial Magnetism and former postdoctoral fellow Mark Behn (now at Woods Hole Oceanographic Institution) point out that most of today's subduction zones are located in the Pacific Ocean basin. If the Pacific basin were to close, as it is predicted to do about in 350 million years when the westward-moving Americas collide with Eurasia, then most of the planet's subduction zones would disappear with it.

This would effectively stop plate tectonics unless new subduction zones start up, but subduction initiation is poorly understood. "The collision of India and Africa with Eurasia between 30 and 50 million years ago closed an ocean basin known as Tethys," says Silver. "But no new subduction zones have initiated south of either India or Africa to compensate for the loss of subduction by this ocean closure."

Silver and Behn also present geochemical evidence from ancient igneous rocks indicating that around one billion years ago there was a lull in the type of volcanic activity normally associated with subduction. This idea fits with other geologic evidence for the closure of a Pacific-type ocean basin at that time, welding the continents into a single "supercontinent" (known to geologists as Rodinia) and possibly snuffing out subduction for a while. Rodinia eventually split apart when subduction and plate tectonics resumed.

Plate tectonics is driven by heat flowing from the Earth's interior, and a stoppage would slow the rate of the Earth's cooling, just as clamping a lid on a soup pot would slow the soup's cooling. By periodically clamping the lid on heat flow, intermittent plate tectonics may explain why the Earth has lost heat slower than current models predict. And the buildup of heat beneath stagnant plates may explain the occurrence of certain igneous rocks in the middle of continents away from their normal locations in subduction zones.

"If plate tectonics indeed starts and stops, then continental evolution must be viewed in an entirely new light, since it dramatically broadens the range of possible evolutionary scenarios," says Silver.


Story Source:

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


Cite This Page:

Carnegie Institution. "Plate Tectonics May Grind To A Halt, Then Start Again." ScienceDaily. ScienceDaily, 7 January 2008. <www.sciencedaily.com/releases/2008/01/080103144448.htm>.
Carnegie Institution. (2008, January 7). Plate Tectonics May Grind To A Halt, Then Start Again. ScienceDaily. Retrieved December 18, 2014 from www.sciencedaily.com/releases/2008/01/080103144448.htm
Carnegie Institution. "Plate Tectonics May Grind To A Halt, Then Start Again." ScienceDaily. www.sciencedaily.com/releases/2008/01/080103144448.htm (accessed December 18, 2014).

Share This


More From ScienceDaily



More Earth & Climate News

Thursday, December 18, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

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
Ivory Trade Boom Swamps Law Efforts

Ivory Trade Boom Swamps Law Efforts

Reuters - Business Video Online (Dec. 17, 2014) Demand for ivory has claimed the lives of tens of thousands of African elephants and now a conservation report says the illegal trade is overwhelming efforts to enforce the law. Amy Pollock reports. Video provided by Reuters
Powered by NewsLook.com
Indictments in West Virginia Chemical Spill Case

Indictments in West Virginia Chemical Spill Case

AP (Dec. 17, 2014) A grand jury indicted four former executives of Freedom Industries, the company at the center of the Jan. 9, 2014 chemical spill in Charleston, West Virginia. The spill contaminated the Elk River and the water supply of 300,000 people. (Dec. 17) Video provided by AP
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