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 Hundreds of bubble streams link biology, seismology off Washington's coast
22.03.2019 | University of Washington

nachricht Atmospheric scientists reveal the effect of sea-ice loss on Arctic warming
11.03.2019 | Institute of Atmospheric Physics, Chinese Academy of Sciences

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: The taming of the light screw

DESY and MPSD scientists create high-order harmonics from solids with controlled polarization states, taking advantage of both crystal symmetry and attosecond electronic dynamics. The newly demonstrated technique might find intriguing applications in petahertz electronics and for spectroscopic studies of novel quantum materials.

The nonlinear process of high-order harmonic generation (HHG) in gases is one of the cornerstones of attosecond science (an attosecond is a billionth of a...

Im Focus: Magnetic micro-boats

Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.

The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...

Im Focus: Self-healing coating made of corn starch makes small scratches disappear through heat

Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.

Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...

Im Focus: Stellar cartography

The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.

A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...

Im Focus: Heading towards a tsunami of light

Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.

"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

International Modelica Conference with 330 visitors from 21 countries at OTH Regensburg

11.03.2019 | Event News

Selection Completed: 580 Young Scientists from 88 Countries at the Lindau Nobel Laureate Meeting

01.03.2019 | Event News

LightMAT 2019 – 3rd International Conference on Light Materials – Science and Technology

28.02.2019 | Event News

 
Latest News

Solving the efficiency of Gram-negative bacteria

22.03.2019 | Life Sciences

Bacteria bide their time when antibiotics attack

22.03.2019 | Life Sciences

Open source software helps researchers extract key insights from huge sensor datasets

22.03.2019 | Information Technology

VideoLinks
Science & Research
Overview of more VideoLinks >>>