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Mountains and volcanoes in the Mediterranean rise due to pressure from mantle below

Date:
June 3, 2010
Source:
University of Southern California
Summary:
Some mountains in "mobile belts" -- regions of crustal fragments, such as in the Mediterranean, the Rockies, and the Himalayas -- can rise due to upward pressure from the semi-liquid mantle. The study proposes a model for predicting uplift and likely volcanic hotspots in such regions.
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Kotor Bay in Montenegro. A new study suggests that volcanoes and mountains in the Mediterranean can grow from the pressure of the semi-liquid mantle pushing on Earth's crust from below.
Credit: iStockphoto/Micha Krakowiak

If tectonic plate collisions cause volcanic eruptions, as every fifth grader knows, why do some volcanoes erupt far from a plate boundary?

A study in Nature suggests that volcanoes and mountains in the Mediterranean can grow from the pressure of the semi-liquid mantle pushing on Earth's crust from below.

"The rise and subsidence of different points of the earth is not restricted to the exact locations of the plate boundary. You can get tectonic activity away from a plate boundary," said study co-author Thorsten Becker of the University of Southern California.

The study connects mantle flow to uplift and volcanism in "mobile belts": crustal fragments floating between continental plates.

The model should be able to predict uplift and likely volcanic hotspots in other mobile belts, such as the North American Cordillera (including the Rocky Mountains and Sierra Nevada) and the Himalayas.

"We have a tool to be able to answer these questions," Becker said.

Scientists previously had suggested a connection between mantle upwelling and volcanism, Becker said. The Nature study is the first to propose the connection in mobile belts.

Becker and collaborator Claudio Faccenna of the University of Rome believe that small-scale convection in the mantle is partly responsible for shaping mobile belts.

Mantle that sinks at the plate boundary flows back up farther away, pushing on the crust and causing uplift and crustal motions detectable by global positioning system, the authors found.

The slow but inexorable motions can move mountains -- both gradually and through earthquakes or eruptions.

The study identified two mountain ranges raised almost entirely by mantle flow, according to the authors: the southern Meseta Central plateau in Spain and the Massif Central in France.

Becker and Faccenna inferred mantle flow from interpreting seismic mantle tomography, which provides a picture of the deep earth just like a CAT scan, using seismic waves instead of X-rays.

Assuming that the speed of the waves depends mainly on the temperature of crust and mantle (waves travel slower through warmer matter), the authors used temperature differences to model the direction of mantle convection.

Regions of upward flow, as predicted by the model, mostly coincided with uplift or volcanic activity away from plate boundaries.

"Mantle circulation … appears more important than previously thought, and generates vigorous upwellings even far from the subduction zone," the authors wrote.

The study culminates work started 13 years ago when Becker was a graduate student at Harvard University and Faccenna was a visiting scholar. Becker now is associate professor of earth sciences in USC's College of Letters, Arts and Sciences.

The National Science Foundation and USC's High Performance Computing Center supported the research.


Story Source:

The above story is based on materials provided by University of Southern California. Note: Materials may be edited for content and length.


Journal Reference:

  1. Claudio Faccenna, Thorsten W. Becker. Shaping mobile belts by small-scale convection. Nature, 2010; 465 (7298): 602 DOI: 10.1038/nature09064

Cite This Page:

University of Southern California. "Mountains and volcanoes in the Mediterranean rise due to pressure from mantle below." ScienceDaily. ScienceDaily, 3 June 2010. <www.sciencedaily.com/releases/2010/06/100602131346.htm>.
University of Southern California. (2010, June 3). Mountains and volcanoes in the Mediterranean rise due to pressure from mantle below. ScienceDaily. Retrieved May 28, 2015 from www.sciencedaily.com/releases/2010/06/100602131346.htm
University of Southern California. "Mountains and volcanoes in the Mediterranean rise due to pressure from mantle below." ScienceDaily. www.sciencedaily.com/releases/2010/06/100602131346.htm (accessed May 28, 2015).

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