Study Reconciles Long-Standing Contradiction of Deep-Earth Dynamics

August 25, 2005
Study Reconciles Long-Standing Contradiction of Deep-Earth Dynamics

Scientists at Columbia University's Lamont-Doherty Earth Observatory (LDEO) have solved a long-standing contradiction about the workings of the deep Earth.

Image: The chemical composition of ocean-island lavas support the idea that the Earth's deep mantle has been continually moving and mixing. Credit: LDEO

While some geochemists have argued that parts of the deep mantle have remained unchanged since the formation of the Earth, some geophysicists and others have believed that the entire mantle has been moving throughout geologic time. The question of whether the deep-Earth changes is central to scientists' understanding of the process of heat loss from deep beneath the surface.

LDEO earth scientists Cornelia Class and Steven Goldstein now show that the evidence favors a moving mantle, with the deepest parts of the Earth affected by the same tectonic processes that occur at the surface. The study appears in the Aug. 25 issue of the journal Nature.

"For 30 years scientists have debated whether there is a layer of the mantle that has remained unchanged since the formation of the Earth," said Class. "We found the strongest evidence yet that indicates the opposite is true."

Class and Goldstein's re-evaluation of this concept of the inner Earth is based on their work with two new databases: the Petrological Database of Ocean Floor Basalts (PetDB) and Geochemistry of Rocks from the Oceans and Continents (GEOROC).

Scientists have known that upper mantle basalt found at mid-ocean ridges, formed by sea-floor spreading, comes from previously formed oceanic and continental crust. The new global data synthesis demonstrates that ocean island lavas, chemically most like mid-ocean ridge basalt, were previously processed by plate tectonics, say Class and Goldstein, indicating that the deep mantle has been continually moving and mixing.

This result adds to growing evidence "that most of Earth's mantle has been subject to the same forces that drive the movements of Earth's crust," said Sonia Esperanca, a program director in the National Science Foundation (NSF)'s Division of Earth Sciences, which funded the research.

Source: NSF

Explore further: First measurements taken of South Africa's Iron Age magnetic field history

Related Stories

What is the Haleakala Volcano?

July 13, 2015

Hawaii is famous for its lovely mountains, tropical climate, and majestic oceanfront vistas. Another thing it is famous for is the string of volcanoes that dot its islands. As a land that sits atop a geographic hot spot – ...

Scientists make new estimates of the deep carbon cycle

June 19, 2015

Over billions of years, the total carbon content of the outer part of the Earth—in its upper mantle, crust, oceans, and atmospheres—has gradually increased, scientists reported this month in the journal Proceedings ...

Recommended for you

How bees naturally vaccinate their babies

July 31, 2015

When it comes to vaccinating their babies, bees don't have a choice—they naturally immunize their offspring against specific diseases found in their environments. And now for the first time, scientists have discovered how ...

Image: Hubble sees a dying star's final moments

July 31, 2015

A dying star's final moments are captured in this image from the NASA/ESA Hubble Space Telescope. The death throes of this star may only last mere moments on a cosmological timescale, but this star's demise is still quite ...

Earth flyby of 'space peanut' captured in new video

July 31, 2015

NASA scientists have used two giant, Earth-based radio telescopes to bounce radar signals off a passing asteroid and produce images of the peanut-shaped body as it approached close to Earth this past weekend.

Exoplanets 20/20: Looking back to the future

July 31, 2015

Geoff Marcy remembers the hair standing up on the back of his neck. Paul Butler remembers being dead tired. The two men had just made history: the first confirmation of a planet orbiting another star.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.