Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Geological demolition derby

17.11.2004


The spectacular rift valleys of the Tibetan plateau don’t all run north-south as previously thought, according to new research.


A satellite’s-eye-view of India and Tibet. Image from NASA’s Terra satellite. Photo credit: NASA



The rift valleys actually curve away -- some to the east, some to the west -- from the point where India is punching into the gut of Tibet. "Everyone looked at the rifts and said they went north-south," said Paul Kapp, assistant professor of geosciences at the University of Arizona in Tucson. "I looked and said -- they’re not." His work contradicts a leading theory that suggests the rifts are a consequence of Tibet flowing slowly out over India’s northern edge.

The new research indicates the Tibetan plateau is being compressed between the Indian subcontinent to the south and the solid wall of the North China block. As a result, Tibet is splitting much like an orange squeezed by a vise. Kapp’s research challenges the idea that the 16,000-foot-high Tibetan plateau, the highest-elevation region on Earth, is losing elevation. Previous research reported the Tibetan plateau reached its highest elevation eight million years ago and is now slowly deflating as it spreads out over India. "My hypothesis predicts that the plateau is getting higher. The other theory suggests the plateau is collapsing," he said. "We’re in a place where continents are slamming against each other. Instead of Tibet crumpling like an accordion, we see these rift valleys. The rifts are from the east-west stretching of the plateau."


The article, "India Punch Rifts Tibet," by Kapp and Jerome H. Guynn, a doctoral candidate in UA’s department of geosciences, is in the November issue of the journal Geology. Although the standard description says Tibet’s rift valleys run north-south, that didn’t square with what Kapp saw when he looked at topographic maps of the area. The problem nagged at him for years.

In fall of 2003, he was teaching structural geology. As he worked on the lecture about stress in the crust from continents colliding, he realized that collisional stress caused the pattern of Tibet’s rift valleys. He remembers thinking, "Yeah, that’s it!" "It took me eight years to recognize the pattern," he said. "It took me two days to come up with an explanation."

Geologists often use digital elevation models, or DEMs, that are developed from satellite imagery. Such maps, which look like a shaded relief map, show the Earth’s current surface in incredible detail. Kapp said that the detailed nature of such maps obscures the underlying pattern of the rifts.

So Kapp and Guynn used a computer to strip away the DEM’s superficial layers to expose the underlying structure of the plateau. Once they created a bare-bones map of the region, the curving patterns of the rifts were clear. "I took away all the secondary faults and then the pattern jumped out," Kapp said. Because India is crashing into Tibet, geologists call India "the indentor." Kapp says that because India is hitting Tibet head-on, the Tibetan plateau is developing splits, or rifts, that curve away from the axis of impact.

Once Kapp figured out what caused the rifts, he and Guynn created mathematical models to test the idea. According to the models, a head-on punch split the plateau just the way Kapp predicted. In addition to punching Tibet directly, a lower portion of the Indian subcontinent is sliding under Tibet and lifting the plateau, Kapp said. Measuring how much Tibet is moving up or down is extremely difficult, although the technology is getting better all the time. "I think there will be some serious arguing for probably the next five years."

The Himalayas and Tibet are an area of active research by many groups of geologists. Kapp said, "If you want to understand mountain-building, you go there." Kapp and Guynn are among them. This summer they’ll be there scanning the region’s rocks for more evidence to support their new theory.

Mari N. Jensen | EurekAlert!
Further information:
http://www.arizona.edu

More articles from Earth Sciences:

nachricht Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments
22.01.2018 | Duke University

nachricht World’s oldest known oxygen oasis discovered
18.01.2018 | Eberhard Karls Universität Tübingen

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Artificial agent designs quantum experiments

On the way to an intelligent laboratory, physicists from Innsbruck and Vienna present an artificial agent that autonomously designs quantum experiments. In initial experiments, the system has independently (re)discovered experimental techniques that are nowadays standard in modern quantum optical laboratories. This shows how machines could play a more creative role in research in the future.

We carry smartphones in our pockets, the streets are dotted with semi-autonomous cars, but in the research laboratory experiments are still being designed by...

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Thanks for the memory: NIST takes a deep look at memristors

22.01.2018 | Materials Sciences

Radioactivity from oil and gas wastewater persists in Pennsylvania stream sediments

22.01.2018 | Earth Sciences

Saarland University bioinformaticians compute gene sequences inherited from each parent

22.01.2018 | Life Sciences

VideoLinks Wissenschaft & Forschung
Overview of more VideoLinks >>>