Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Curvy Mountain Belts

02.07.2012
Mountain belts on Earth are most commonly formed by collision of one or more tectonic plates.
The process of collision, uplift, and subsequent erosion of long mountain belts often produces profound global effects, including changes in regional and global climates, as well as the formation of important economic resources, including oil and gas reservoirs and ore deposits. Understanding the formation of mountain belts is thus a very important element of earth science research.

One common but poorly understood aspect of mountain belts are the many examples of curved (arcuate) mountain ranges. The Appalachian range in Pennsylvania, the Rocky Mountains in central Montana, the Blue Mountains in Oregon, the Bolivian Andes of South America, and the Cantabrian Arc in Spain and northern Africa are among many examples of noticeably curved mountain belts.
The cause of these curvy mountains is among the oldest topics of research in geology, and there is still extensive debate on what mechanisms are most important for making a curvy mountain range.

A common question is whether these presently curvy mountain ranges were originally straight and then later bent or whether they were uplifted in more or less their present shape.

Another important aspect of the origin of these curved mountain ranges is the thickness of the rock units involved in their formation. Some workers have proposed that these ranges are composed of relatively thin slices of crustal rocks (limited to several kilometers in thickness), while others have argued that at least some of these curvy ranges involve the entire thickness of the lithospheric plates (30 to 100 km thick). One of the most promising ways to answer these questions utilizes comparisons of the orientation of structural features in rocks (fault planes and joints), records of the ancient magnetic field directions found in rocks, and the timing of deformation and uplift of the mountain belts.

An international group of researchers from Spain, Canada, and the United States, led by Dr. Gabriel Gutiérrez-Alonso, have presented a compelling study of one of the best examples of curved mountain ranges: the Cantabrian Arc in Spain and northern Africa. They have compiled an extensive collection of fault and joint orientation data and directions of the ancient geomagnetic field recorded by Paleozoic rocks collected in Spain.

The Cantabrian Arc was formed during the collision of a southern set of continents (Gondwanaland [present day Africa-South America-Australia-India-Antarctica]) with a northern set of continents (Laurentia [present day North America and Eurasia]) to produce the supercontinent Pangea. In a nutshell, their combined study has found that the curved pattern of the Cantabrian Arc was produced by the bending of an originally straight mountain range.

The main line of evidence supporting this view is the patterns of rotation that are obtained from the directions of the ancient geomagnetic field recorded by the rocks of these mountain ranges. Combined with an analysis of the faults and joints in the rocks, and the ages of rocks that have variations in the amount of rotation indicated by the magnetic directions, the age of the bending of the Cantabrian Arc is confined to a relatively narrow window of geological time between 315 and 300 million years ago.

Gutiérrez-Alonso and colleagues compare the age range of this mountain bending event to the ages of igneous activity and uplift of the region and propose that widespread changes in the deeper (mantle) portion of the lithospheric plate in the area are coeval, and likely linked to, the rotation of the Cantabrian Arc to produce its characteristic sharp curviness. Based on this linkage, they propose that this, and perhaps many other, curvy mountain ranges are produced by rotation of entire portions of the lithosphere of tectonic plates, rather than just thin slices of crustal rocks.

This article is online now at www.geosociety.org/gsatoday/archive/22/7/. GSA Today articles are open access online; for a print copy, please contact Kea Giles at kgiles@geosociety.org. Please discuss articles of interest with the authors before publishing stories on their work, and please make reference to GSA Today in articles published.

Buckling an orogen: The Cantabrian Orocline
G. Gutiérrez-Alonso et al., Depto. de Geología, Universidad de Salamanca, Plaza de los Caídos s/n, 37008 Salamanca, Spain. Posted online 27 June 2012; doi: 10.1130/GSATG141A.1.

GSA Today is The Geological Society of America's science and news magazine for members and other earth scientists. Refereed lead science articles present exciting new research or synthesize important issues in a format understandable to all in the earth science community. GSA Today often features a refereed "Groundwork" article — a tightly focused paper on issues of import to earth science policy, planning, funding, or education. All GSA Today articles are open access at www.geosociety.org/pubs/.

The July 2012 GSA Today science article is now online at www.geosociety.org/gsatoday/archive/22/7/

Kea Giles | EurekAlert!
Further information:
http://www.geosociety.org

More articles from Earth Sciences:

nachricht Colorado River's connection with the ocean was a punctuated affair
16.11.2017 | University of Oregon

nachricht Researchers create largest, longest multiphysics earthquake simulation to date
14.11.2017 | Gauss Centre for Supercomputing

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: A “cosmic snake” reveals the structure of remote galaxies

The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.

Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...

Im Focus: Visual intelligence is not the same as IQ

Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.

That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...

Im Focus: Novel Nano-CT device creates high-resolution 3D-X-rays of tiny velvet worm legs

Computer Tomography (CT) is a standard procedure in hospitals, but so far, the technology has not been suitable for imaging extremely small objects. In PNAS, a team from the Technical University of Munich (TUM) describes a Nano-CT device that creates three-dimensional x-ray images at resolutions up to 100 nanometers. The first test application: Together with colleagues from the University of Kassel and Helmholtz-Zentrum Geesthacht the researchers analyzed the locomotory system of a velvet worm.

During a CT analysis, the object under investigation is x-rayed and a detector measures the respective amount of radiation absorbed from various angles....

Im Focus: Researchers Develop Data Bus for Quantum Computer

The quantum world is fragile; error correction codes are needed to protect the information stored in a quantum object from the deteriorating effects of noise. Quantum physicists in Innsbruck have developed a protocol to pass quantum information between differently encoded building blocks of a future quantum computer, such as processors and memories. Scientists may use this protocol in the future to build a data bus for quantum computers. The researchers have published their work in the journal Nature Communications.

Future quantum computers will be able to solve problems where conventional computers fail today. We are still far away from any large-scale implementation,...

Im Focus: Wrinkles give heat a jolt in pillared graphene

Rice University researchers test 3-D carbon nanostructures' thermal transport abilities

Pillared graphene would transfer heat better if the theoretical material had a few asymmetric junctions that caused wrinkles, according to Rice University...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Ecology Across Borders: International conference brings together 1,500 ecologists

15.11.2017 | Event News

Road into laboratory: Users discuss biaxial fatigue-testing for car and truck wheel

15.11.2017 | Event News

#Berlin5GWeek: The right network for Industry 4.0

30.10.2017 | Event News

 
Latest News

NASA detects solar flare pulses at Sun and Earth

17.11.2017 | Physics and Astronomy

NIST scientists discover how to switch liver cancer cell growth from 2-D to 3-D structures

17.11.2017 | Health and Medicine

The importance of biodiversity in forests could increase due to climate change

17.11.2017 | Studies and Analyses

VideoLinks
B2B-VideoLinks
More VideoLinks >>>