Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

New Observations on Shape of Ocean Mountain Ranges Turn an Old Idea Upside Down

23.06.2004


Figure 1. Perspective view from the south of the mid-ocean ridge off the coast of Central America (far distance) showing how the morphology of this spreading ridge changes across transform faults and smaller ridge offsets. Note how the more westerly segments (offset in the direction of ridge migration) are shallower and broader than their neighbors. Image credit: Bill Haxby


Figure 2. Close-up perspective view from figure above showing how the shape and height of the ridge axis changes across a major transform fault. Image credit: Bill Haxby


New findings suggest that surface geometry determines volcanic activity

What causes the peaks and valleys of the world’s great mountains? For continental ranges like the Appalachians or the Northwest’s Cascades, the geological picture is clearer. Continents crash or volcanoes erupt, then glaciers erode away. Yet scientists are still puzzling out what makes the highs high and the lows low for the planet’s largest mountain chain, the 55,000-mile-long Mid-Ocean Ridge.

This week in the journal Nature, scientists at Columbia University’s Lamont Doherty Earth Observatory describe new findings that challenge current thinking about how the silhouette of the mile’s high deepwater ridge is formed.



The long string of mountains that zig-zags across the ocean floor define the boundaries of the crustal plates that make up the Earth’s surface. At the center of the Mid-Ocean Ridge is a continuous fissure in which hot magma bubbles up from below and cools to become new crust material added to the plates on either side. For decades, the most popular explanation for the ridge’s distinct undulating topography has been that magma flows upward from the mantle interior in directed streams of differing sizes. Larger magma flows lead to higher, broader peaks, while a magma trickle or drought is reflected in lower, more narrow valleys.

But after analyzing thousands of miles of the Mid-Ocean Ridge, Lamont marine geologist Suzanne Carbotte and co-authors Christopher Small and Katie Donnelly disagree. They discovered that the height and width of underwater mountains are highly correlated to the direction that the ridge and connecting plates move across the surface of the planet.

“Our observations indicate that these variations in ridge height reflect a top down rather than a bottom up process,” said Carbotte. “The motion of the plates seems to be the important factor, not the mantle.”

The twelve crustal plates that make up the surface of the Earth are constantly jostling each other as some grow in size and others shrink. In response, the Mid-Ocean Ridge migrates very slowly, moving at a rate of about an inch a decade in relation to fixed hot areas of the mantle below. Each underwater range in the mountain chain can be offset from the next by up to hundreds of miles, connected by a long perpendicular fault line. This geometry creates distinct ridge segments jutting back and forth.

Their results have implications for geologists concerned with crust and mantle structure, as well as for biologists interested in life around hydrothermal vents. Previously, many scientists believed that the structure of the upper mantle must be both physically and chemically diverse in order to explain the peaks and valleys along the Mid-Ocean Ridge. This implied that ridge segment would spend time above both high and low magma streams as it travels over the mantle.

“Our findings suggest that the upper mantle could be quite uniform and still produce a varied topography due solely to plate migration,” said Carbotte. “This has all sorts of implications. For example, if certain ridge segments are just more volcanically active than others due simply to their geometry, those locations may host hydrothermal communities over very long periods of time.”

This study was funded by The National Science Foundation.

The Lamont-Doherty Earth Observatory, a member of The Earth Institute at Columbia University, is one of the world’s leading research centers examining the planet from its core to its atmosphere, across every continent and every ocean. From global climate change to earthquakes, volcanoes, environmental hazards and beyond, Observatory scientists provide the basic knowledge of Earth systems needed to inform the future health and habitability of our planet. For more information, visit www.ldeo.columbia.edu.

The Earth Institute at Columbia University is among the world’s leading academic centers for the integrated study of Earth, its environment, and society. The Earth Institute builds upon excellence in the core disciplines—earth sciences, biological sciences, engineering sciences, social sciences and health sciences—and stresses cross-disciplinary approaches to complex problems. Through its research training and global partnerships, it mobilizes science and technology to advance sustainable development, while placing special emphasis on the needs of the world’s poor.

Mary Tobin | EurekAlert!
Further information:
http://www.earth.columbia.edu

More articles from Earth Sciences:

nachricht Climate change weakens Walker circulation
20.10.2017 | MARUM - Zentrum für Marine Umweltwissenschaften an der Universität Bremen

nachricht Shallow soils promote savannas in South America
20.10.2017 | Senckenberg Forschungsinstitut und Naturmuseen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Neutron star merger directly observed for the first time

University of Maryland researchers contribute to historic detection of gravitational waves and light created by event

On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...

Im Focus: Breaking: the first light from two neutron stars merging

Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.

Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....

Im Focus: Smart sensors for efficient processes

Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).

When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...

Im Focus: Cold molecules on collision course

Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.

How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...

Im Focus: Shrinking the proton again!

Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.

It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ASEAN Member States discuss the future role of renewable energy

17.10.2017 | Event News

World Health Summit 2017: International experts set the course for the future of Global Health

10.10.2017 | Event News

Climate Engineering Conference 2017 Opens in Berlin

10.10.2017 | Event News

 
Latest News

Terahertz spectroscopy goes nano

20.10.2017 | Information Technology

Strange but true: Turning a material upside down can sometimes make it softer

20.10.2017 | Materials Sciences

NRL clarifies valley polarization for electronic and optoelectronic technologies

20.10.2017 | Interdisciplinary Research

VideoLinks
B2B-VideoLinks
More VideoLinks >>>