Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

MELT data sheds new and surprising light on birth of oceanic plates

09.09.2005


The East Pacific Rise, a vast volcanic mountain range submerged in the eastern Pacific Ocean, is one of the fastest seafloor factories on the planet. Here, along a rocky spine that runs about 1,000 miles west of South America, oceanic crust is created from magma bubbling up from deep within Earth’s interior.



Forces that shape these young oceanic plates have come into clearer focus through research conducted by scientists at the Woods Hole Oceanographic Institution, Brown University and the Japan Agency for Marine-Earth Science and Technology.

The research represents the first time that seismic and electromagnetic data were analyzed in tandem from 1995 Mantle Electromagnetic and Tomography, or MELT, Experiment. MELT employed 51 ocean-bottom seismometers and 30 magnetotelluric receivers two miles under the sea to measure sound waves and magnetic fields along the East Pacific Rise, making it one of the largest marine geophysical experiments ever conducted.


In a paper published in Nature, the team notes that in rock down to a depth of about 60 kilometers below the ocean floor, electrical currents conduct poorly and sound waves travel rapidly. Deeper down, beyond 60 kilometers, there is a dramatic increase in electrical conductivity, and sound waves travel at their slowest.

A switch in seismic and electrical properties with depth was expected. Researchers were surprised, however, at how close to the East Pacific Rise this structure develops and how little it changes with increasing distance from the rise.

Brown marine geophysicist Donald Forsyth said the team, led by Robert Evans from the Woods Hole Oceanographic Institution, has a theory about the cause of the sudden compositional changes at 60 kilometers: dehydration.

As magma migrates to the surface to form crust at the rise, it leaves behind a dry, residual layer about 60 kilometers thick. This change from “dry” surface rock to “damp” rock below it increases electrical conductivity and slows seismic velocity, the researchers write.

Here is what they did not expect: These changes occur, the team found, less than 100 kilometers away from the highest point on the ridge. And the seismic and electrical measurements remained nearly constant at least about 500 kilometers away from the crest.

Separating seafloor guides magma up to mid-ocean ridges such as the East Pacific Rise, where the molten rock erupts, fans out along the ocean floor and cools to form new crust. Cooling allows sound waves and electrical currents to travel faster. But scientists thought this cooling – and the resulting changes in the rock – would be gradual.

“About two-thirds of the Earth’s surface is oceanic crust – and it is all formed at ridges,” Forsyth said. “So this work helps us better understand the basic processes of how this crust is formed.”

The National Science Foundation funded MELT and the latest research.

Wendy Lawton | EurekAlert!
Further information:
http://www.brown.edu

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Unraveling the nature of 'whistlers' from space in the lab

A new study sheds light on how ultralow frequency radio waves and plasmas interact

Scientists at the University of California, Los Angeles present new research on a curious cosmic phenomenon known as "whistlers" -- very low frequency packets...

Im Focus: New interactive machine learning tool makes car designs more aerodynamic

Scientists develop first tool to use machine learning methods to compute flow around interactively designable 3D objects. Tool will be presented at this year’s prestigious SIGGRAPH conference.

When engineers or designers want to test the aerodynamic properties of the newly designed shape of a car, airplane, or other object, they would normally model...

Im Focus: Robots as 'pump attendants': TU Graz develops robot-controlled rapid charging system for e-vehicles

Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.

Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....

Im Focus: The “TRiC” to folding actin

Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.

Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...

Im Focus: Lining up surprising behaviors of superconductor with one of the world's strongest magnets

Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur

What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Within reach of the Universe

08.08.2018 | Event News

A journey through the history of microscopy – new exhibition opens at the MDC

27.07.2018 | Event News

2018 Work Research Conference

25.07.2018 | Event News

 
Latest News

Staying in Shape

16.08.2018 | Life Sciences

Diving robots find Antarctic seas exhale surprising amounts of carbon dioxide in winter

16.08.2018 | Earth Sciences

Protein droplets keep neurons at the ready and immune system in balance

16.08.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>