Solving a Tibetan mystery

April 25, 2001

April 27, 2001 - It has often been called the "roof of the world," for its elevated plateau--probably the highest and the largest to exist on earth. As long as scientists have been studying Tibet, they have been puzzled by exactly how its plateau came to be so immense and raised. A University of Alberta physicist has helped to solve part of that age-old mystery.

"What we found is that the midcrust is like a big waterbed," said Dr. Martyn Unsworth from the Department of Physics. "That provides an explanation for how the whole of Tibet could possible rise up over millions and millions of years."

The study, which includes co-authors from China, Canada and the United States, is published in today's edition of the internationally renowned journal Science. The principle behind the discovery--which was made after three years of investigation--is that hot or molten rocks are less dense than cold rocks so the lower density hot rock rises up slowly, similar to how a hot air balloon works.

Since India rammed into Asia about 40 to 50 million years ago, many theories have been proposed for the origin of this immense thickness. Recently, computer simulations have been made about what the crust might look like. Unsworth's new research will help fill in some of the blanks.

"Tibet is the best example of what happens when two continents collide," he said, adding the research team used low-frequency radio waves to detect the fluid. "It's an obvious, natural laboratory to study...studies like our are important to give firm observations that can say which of the computer models might be correct."

It has taken this long to discover the fluid because Tibet was closed to foreign access until the 1980s. At that time French scientists first collaborated with Chinese scientists to study the plateau. As well, the instruments used to measure the electric and magnetic fields have advanced in the last decade, said Unsworth.

"With earth sciences, you can study processes that are active today and see how it affected the development of the continents," said Unsworth. "It's sort of like detective work, putting it all together."

Unsworth will return shortly to the Tibetan Plateau to try to solve more pieces of the puzzle.
The UofA in Edmonton, Alberta is one of Canada's premier teaching and research universities serving more than 30,000 students with 6,000 faculty and staff. It continues to lead the country with the most 3M Teaching Fellows, Canada's only national award recognizing teaching excellence.

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