Researchers Suggest Answer to Geological Puzzle

Contact: Ellen Mayou 214-768-7650
emayou@mail.smu.edu

November 15, 2000

SMU RESEARCHERS FIND ORDER IN THE DISTRIBUTION OF GEOLOGIC 'HOT
SPOTS'

DALLAS (SMU) -- Researchers at Southern Methodist University have discovered a symmetrical distribution for the "hot spots" on the Earth's surface.

Scientists have located 47 places on the Earth's surface where volcanic activity unrelated to plate tectonics occurs. These areas include Hawaii, Yellowstone, Iceland and the Galapagos Islands. These hot spots mark the sites of ancient "mantle plumes" where huge amounts of volcanic material rose from deep within the Earth. Today, residual material representing the tails of these mantle plumes still comes up at these hot spots.

Although previous studies have recognized that hot spots tend to occur in broad clusters, an orderly arrangement in their distribution had not been reported. SMU geologists Rebecca Ghent and Douglas Oliver studied the location of the major hot spots and determined that a disproportionate number occur at latitudes between 20 and 30 degrees north and south of the equator. Their observation became much more significant when the hot spots were weighted according to the amount of volcanic material that they produced. Statistical analysis shows that the likelihood of this distribution arising by chance is less than one percent.

"This hints that there is something going on deep within the Earth that hasn't been suspected before," Oliver said. Although it is widely accepted that mantle plumes rise due to buoyancy, Oliver said that if buoyancy were the only factor, this should result in a random distribution of hot spots. The symmetrical distribution of hot spots on either side of the equator suggests a process that channels material to the source region for the hot spots 1,800 miles below the surface. Oliver and Ghent are currently investigating processes within the Earth that may be responsible for this phenomena.

Oliver and Ghent said their observation may shed light on other geological phenomena, such as the development of superplumes, which are clusters of mantle plumes arriving together at the Earth's surface. Scientists believe that massive superplume events are responsible for some of the major changes that have occurred on the Earth, such as the breakup of the supercontinent known as Pangea into the present continents.

Ghent and Oliver presented their research Nov. 15 at the 112th annual meeting of the Geological Society of America in Reno, Nevada.

###

Note to editors: Illustrations are available upon request

00071-nr-11/15/00-em

Southern Methodist University news releases can be found on the World Wide Web at http://www.smu.edu/~newsinfo/nrindex.html