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Scientists to get INDEPTH look at crust beneath the Himalayas
Collaboration on Tibetan plateau involves Syracuse, Cornell, Stanford and Columbia Universities, and Chinese Ministry of Geology and Mineral Resources
It's 1,000 kilometers (625 miles) across, averages 5,000 meters (3 miles) in height and is getting larger every year. Books have been written about it. Armies have fought over it. Climbers have died trying to reach the top. Now scientists are trying to get to the bottom of it.
It's the Himalaya-Tibet Plateau, where India has been crashing into the soft underbelly of Asia for the past 50 million years. With a $3.6 million grant from the Continental Dynamics Program of the National Science Foundation (NSF), scientists from China and several American universities are working to uncover this mystery through the use of "seismic profiling," a method that bounces sound waves off rock layers as deep as 150 kilometers within the earth. The NSF grant will be matched by funding from the Chinese Ministry of Geology and Mineral Resources and the Chinese National Natural Science Foundation.
The project, termed INDEPTH (INternational DEep Profiling of Tibet and the Himalaya), is a joint initiative of the Ministry of Geology and Mineral Resources of China and a group of earth scientists from several U.S. universities. The U.S. effort is led by principal investigator Douglas Nelson, associate professor of geology at Syracuse University and adjunct professor of geology at Cornell University, together with co- principal investigators Larry D. Brown, professor of geophysics at Cornell; Simon Klemperer, associate professor of geophysics at Stanford University; and John T. Kuo, Ewing and Worzel Professor Emeritus of Geophysics at Columbia University.
Professor Zhao Wenjin of the Chinese Academy of Geological Sciences is the primary coordinator of the Chinese effort. China's Ministry of Geology and Mineral Resources is providing a petroleum industry-type seismic reflection crew, with a complement of about 200 men and 50 trucks, including 20 truck-mounted drilling rigs. This crew will be used to acquire raw data for the project.
"We decided that if there was one place in the world where we would want to study an active collision between continents it would the Himalaya-Tibet Plateau," said Nelson. "Geologists will be able compare our data with that from other mountain belts like the Appalachians, the Rockies or the Alps and learn fundamental information about how the earth's continents were formed."
INDEPTH started as a pilot project in 1992 to determine if seismic profiling, which ultimately produces a sonogram-like image of the earth's crust, was technically feasible in a region where the crust is twice its usual thickness and the extreme elevation makes physical labor difficult.
Using sound waves produced from explosive charges equal to 110 pounds of dynamite, scientists were able to map out an image of buried rock interfaces in the earth's crust that has been useful in understanding the collision between India and Asia. A 6-kilometer-long wire with several thousand vibration sensors, or "geophones," attached to it was moved along in 200-meter steps for 100 kilometers to record the reflected sound energy and get the image.
The second phase of Project INDEPTH, to begin May 15 and run five months, will expand on the pilot project - extending the initial survey 200 kilometers north. This time a 12-kilometer-long array of geophones will be used along with larger charges. In addition to seismic profiling, the scientists will use a variety of other techniques to learn more about physical properties of the rock within the crust and exposed at the surface.
While the Chinese-American seismic profiling team works to produce a reflection image of the fault along which India underthrusts Tibet, Stanford geophysicists will use a second set of remotely placed instruments to collect a "wide angle" profile to measure the velocities of seismic signals from each test explosion. According to Stanford's Simon Klemperer, the data gathered will help scientists determine rock types and physical conditions deep in the Tibet Plateau. "This is a landmark project," said Klemperer. "My colleagues and I are proud to be associated with it."
William Kidd, professor and chairman of the Department of Earth Sciences at the State University of New York-Albany, will lead a team of American and Chinese geologists to map the surface geology along the route of the seismic surveys.
"INDEPTH promises to be a truly global collaboration, reflecting the great interest in this unique region by scientists all over the world," said Cornell's Larry D. Brown. "Currently, plans are being developed for German scientists to join in the field work this summer. Scientists from Canada, Britain, Switzerland and Japan have expressed interest in future activities."
According to Nelson, several theories exist to explain the
formation of the Himalaya-Tibet Plateau. One explains the formation as the result of compression of the Asian continent by the force of collision. Another holds that India is sliding underneath Asia, creating the plateau.
"We believe the INDEPTH pilot study provided us with evidence that India is actually sliding underneath at least the southernmost part of Asia," Nelson said. "Now we want to go back and see how far northward it extends beneath the plateau."
"The plateau is a natural laboratory for studying the archetype continent-continent collision, which is still a missing link in our understanding of plate tectonics," said Columbia's John T. Kuo. "The second phase of Project INDEPTH should provide clues on how far the southernmost portion of Asia has overthrust the northernmost portion of India and by what mechanisms."
The effort to undertake deep seismic profiling research in Tibet began more than 10 years ago. Nelson said now that the project is under way, it is likely to take another 10 years to complete.
This release was written by Gina M. Granozio of Syracuse University News Services.
Project INDEPTH contacts:
John Harvith, Director of National Media Relations
820 Comstock Ave.
Syracuse, NY 13244-5040
(315) 443-4152, fax (315) 443-5355
Douglas Nelson, Associate Professor of Geology
204 Heroy Geology Laboratory
Syracuse, NY 13244
(315) 443-3626, fax (315) 443-3363
Larry Bernard, Cornell News Service
840 Hanshaw Road
Ithaca, NY 14850-1548
(607) 255-3651, fax (607) 257-6397
Larry D. Brown, Professor of Geophysics
Department of Geological Sciences and Institute for the Study of the Continents
3124 Snee Hall
Ithaca, NY 14850
(607) 255-7357, fax (607) 254-4780
Janet Basu, Science Writer, Stanford News Service
Press Courtyard, Santa Teresa Street
Stanford, CA 94305-2245
(415) 723-7582; fax (415) 725-0247; (415) 641-7198 (home)
Simon Klemperer, Associate Professor of Geophysics
Department of Geophysics
Stanford, CA 94305
(415) 723-8214, fax (415) 725-7344
Robert J. Nelson, Senior Science Writer
Office of Public Information
304 Low Library
New York, NY 10027
(212) 854-5573, fax (212) 678-4817
John T. Kuo, Ewing and Worzel Professor Emeritus of Geophysics
834 S.W. Mudd Engineering Terrace
New York, NY 10027
(212) 854-2910, fax (212) 854-6508
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