Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Seismic CT scan points to rapid uplift of Southern Tibet

08.06.2017

Tomographic model indicates Southern Tibet formed within 10 million years

Using seismic data and supercomputers, Rice University geophysicists have conducted a massive seismic CT scan of the upper mantle beneath the Tibetan Plateau and concluded that the southern half of the "Roof of the World" formed in less than one-quarter of the time since the beginning of India-Eurasia continental collision.


The Tibetan Plateau as seen from Space Shuttle Challenger in October 1984.

Image courtesy NASA

The research, which appears online this week in the journal Nature Communications, finds that the high-elevation of Southern Tibet was largely achieved within 10 million years. Continental India's tectonic collision with Asia began about 45 million years ago.

"The features that we see in our tomographic image are very different from what has been seen before using traditional seismic inversion techniques," said Min Chen, the Rice research scientist who headed the project. "Because we used full waveform inversion to assimilate a large seismic data set, we were able to see more clearly how the upper-mantle lithosphere beneath Southern Tibet differs from that of the surrounding region. Our seismic image suggests that the Tibetan lithosphere thickened and formed a denser root that broke away and sank deeper into the mantle. We conclude that most of the uplift across Southern Tibet likely occurred when this lithospheric root broke away."

The research could help answer longstanding questions about Tibet's formation. Known as the "Roof of the World," the Tibetan Plateau stands more than three miles above sea level. The basic story behind its creation -- the tectonic collision between the Indian and Eurasian continents -- is well-known to schoolchildren the world over, but the specific details have remained elusive. For example, what causes the plateau to rise and how does its high elevation impact Earth's climate?

"The leading theory holds that the plateau rose continuously once the India-Eurasia continental collision began, and that the plateau is maintained by the northward motion of the Indian plate, which forces the plateau to shorten horizontally and move upward simultaneously," said study co-author Fenglin Niu, a professor of Earth science at Rice. "Our findings support a different scenario, a more rapid and pulsed uplift of Southern Tibet."

It took three years for Chen and colleagues to complete their tomographic model of the crust and upper-mantle structure beneath Tibet. The model is based on readings from thousands of seismic stations in China, Japan and other countries in East Asia. Seismometers record the arrival time and amplitude of seismic waves, pulses of energy that are released by earthquakes and that travel through Earth. The arrival time of a seismic wave at a particular seismometer depends upon what type of rock it has passed through. Working backward from instrument readings to calculate the factors that produced them is something scientists refer to as an inverse problem, and seismological inverse problems with full waveforms incorporating all kinds of usable seismic waves are some of the most complex inverse problems to solve.

Chen and colleagues used a technique called full waveform inversion, "an iterative full waveform-matching technique that uses a complicated numerical code that requires parallel computing on supercomputers," she said.

"The technique really allows us to use all the wiggles on a large number of seismographs to build up a more realistic 3-D model of Earth's interior, in much the same way that whales or bats use echo-location," she said. "The seismic stations are like the ears of the animal, but the echo that they are hearing is a seismic wave that has either been transmitted through or bounced off of subsurface features inside Earth."

The tomographic model includes features to a depth of about 500 miles below Tibet and the Himalaya Mountains. The model was computed on Rice's DAVinCI computing cluster and on supercomputers at the University of Texas that are part of the National Science Foundation's Extreme Science and Engineering Discovery Environment (XSEDE).

"The mechanism that led to the rise of Southern Tibet is called lithospheric thickening and foundering," Chen said. "This happened because of convergence of two continental plates, which are each buoyant and not easy to subduct underneath the other plate. One of the plates, in this case on the Tibetan side, was more deformable than the other, and it began to deform around 45 million years ago when the collision began. The crust and the rigid lid of upper mantle -- the lithosphere -- deformed and thickened, and the denser lower part of this thickened lithosphere eventually foundered, or broke off from the rest of the lithosphere. Today, in our model, we can see a T-shaped section of this foundered lithosphere that extends from a depth of about 250 kilometers to at least 660 kilometers."

Chen said that after the denser lithospheric root broke away, the remaining lithosphere under Southern Tibet experienced rapid uplift in response.

"The T-shaped piece of foundered lithosphere sank deeper into the mantle and also induced hot upwelling of the asthenosphere, which leads to surface magmatism in Southern Tibet," she said.

Such magmatism is documented in the rock record of the region, beginning around 30 million years ago in an epoch known as the Oligocene.

"The spatial correlation between our tomographic model and Oligocene magmatism suggests that the Southern Tibetan uplift happened in a relatively short geological span that could have been as short as 5 million years," Chen said.

###

Additional co-authors include Adrian Lenardic, Cin-Ty Lee, Wenrong Cao and Julia Ribeiro, all of Rice, and Jeroen Tromp of Princeton University.

The research was supported by a grant from the National Science Foundation (NSF), by the NSF's Extreme Science and Engineering Discovery Environment (XSEDE) program, and by the China Earthquake Administration's China Seismic Array Data Management Center. Rice's DAVinCI supercomputer is administered by Rice's Center for Research Computing and procured in partnership with the Ken Kennedy Institute for Information Technology.

The DOI of the Nature Communications paper is: 10.1038/NCOMMS15659

A copy of the paper, "Lithospheric Foundering and Underthrusting Imaged Beneath Tibet," is available at: https://www.nature.com/articles/ncomms15659

More information is available at:

Rice Earth Science: https://earthscience.rice.edu/

Rice Research Computing: https://oit.rice.edu/research-computing

Min Chen home page: https://sites.google.com/site/minchenresearch/

XSEDE: https://www.xsede.org/

TACC: https://www.tacc.utexas.edu/

This release can be found online at news.rice.edu.

Follow Rice News and Media Relations on Twitter @RiceUNews.

Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation's top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,879 undergraduates and 2,861 graduate students, Rice's undergraduate student-to-faculty ratio is 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for happiest students and for lots of race/class interaction by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger's Personal Finance. To read "What they're saying about Rice," go to http://tinyurl.com/RiceUniversityoverview.

Media Contact

David Ruth
david@rice.edu
713-348-6327

 @RiceUNews

http://news.rice.edu 

David Ruth | EurekAlert!

Further reports about: CT scan Seismic Tibetan collision lithosphere magmatism seismic stations seismic waves

More articles from Earth Sciences:

nachricht NASA, NOAA analyses reveal 2019 second warmest year on record
16.01.2020 | NASA/Goddard Space Flight Center

nachricht New assessment of gas locked in ice in European waters
16.01.2020 | University of Southampton

All articles from Earth Sciences >>>

The most recent press releases about innovation >>>

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

Im Focus: Miniature double glazing: Material developed which is heat-insulating and heat-conducting at the same time

Styrofoam or copper - both materials have very different properties with regard to their ability to conduct heat. Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the University of Bayreuth have now jointly developed and characterized a novel, extremely thin and transparent material that has different thermal conduction properties depending on the direction. While it can conduct heat extremely well in one direction, it shows good thermal insulation in the other direction.

Thermal insulation and thermal conduction play a crucial role in our everyday lives - from computer processors, where it is important to dissipate heat as...

Im Focus: Fraunhofer IAF establishes an application laboratory for quantum sensors

In order to advance the transfer of research developments from the field of quantum sensor technology into industrial applications, an application laboratory is being established at Fraunhofer IAF. This will enable interested companies and especially regional SMEs and start-ups to evaluate the innovation potential of quantum sensors for their specific requirements. Both the state of Baden-Württemberg and the Fraunhofer-Gesellschaft are supporting the four-year project with one million euros each.

The application laboratory is being set up as part of the Fraunhofer lighthouse project »QMag«, short for quantum magnetometry. In this project, researchers...

Im Focus: How Cells Assemble Their Skeleton

Researchers study the formation of microtubules

Microtubules, filamentous structures within the cell, are required for many important processes, including cell division and intracellular transport. A...

Im Focus: World Premiere in Zurich: Machine keeps human livers alive for one week outside of the body

Researchers from the University Hospital Zurich, ETH Zurich, Wyss Zurich and the University of Zurich have developed a machine that repairs injured human livers and keep them alive outside the body for one week. This breakthrough may increase the number of available organs for transplantation saving many lives of patients with severe liver diseases or cancer.

Until now, livers could be stored safely outside the body for only a few hours. With the novel perfusion technology, livers - and even injured livers - can now...

Im Focus: SuperTIGER on its second prowl -- 130,000 feet above Antarctica

A balloon-borne scientific instrument designed to study the origin of cosmic rays is taking its second turn high above the continent of Antarctica three and a half weeks after its launch.

SuperTIGER (Super Trans-Iron Galactic Element Recorder) is designed to measure the rare, heavy elements in cosmic rays that hold clues about their origins...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

11th Advanced Battery Power Conference, March 24-25, 2020 in Münster/Germany

16.01.2020 | Event News

Laser Colloquium Hydrogen LKH2: fast and reliable fuel cell manufacturing

15.01.2020 | Event News

„Advanced Battery Power“- Conference, Contributions are welcome!

07.01.2020 | Event News

 
Latest News

A new 'cool' blue

17.01.2020 | Life Sciences

EU-project SONAR: Better batteries for electricity from renewable energy sources

17.01.2020 | Power and Electrical Engineering

Neuromuscular organoid: It’s contracting!

17.01.2020 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>