May 2001

From Washington University in St. Louis

St. Louis University, Washington University in St. Louis researchers uncover evidence that sheds light on origins of the planet

A Saint Louis University researcher has made a discovery near the Great Wall in China that could change the science of plate tectonics and provide some clues into how life might have developed on Earth.

The research, a collaborative effort involving Peking University and Washington University in St. Louis researchers, was published as a report in the May 11, 2001 issue of Science magazine.

It has been widely held that plate tectonics, or the motion of plates and continents, dates back 1.9 billion years. Timothy Kusky, Ph.D., professor of geology at St. Louis University, is part of a group of geologists who believe the plates began moving much sooner.

Kusky now believes he has the data to prove the theory. Last summer, he discovered the oldest complete section of oceanic sea floor on the planet, which is more than 500 million years older than previously documented. When he returned, he sought the assistance of Robert Tucker, Ph.D., associate professor of earth and planetary science at Washington University in St. Louis, to date the rare samples.

According to Tucker, the rocks are 2.5 billion years old and date back to Earthís earliest geologic time period, known as the Archean. The rocks are remarkably similar to much younger volcanic rocks that erupted on the sea floor in the process of sea floor spreading. For decades, geologists have debated whether plate tectonics operated in the Archean period. Those who have argued against that theory have cited the lack of any Archean ophiolites as their main line of evidence that plate tectonics did not occur on the early Earth. Ophiolites are rock structures formed on the sea floor when continents collide.

"This discovery shows that the plate tectonic forces that create oceanic crust on the Earth today were in operation more than 2.5 billion years ago," Kusky said.

Kusky said the findings could have a more far-reaching effect on theories related to the development of life on the planet. Scientists believe life on Earth during the Archean period consisted mainly of single-celled organisms in the oceans. Just when they evolved into more complex organisms has been contested for years.

"Because hot volcanic vents on the sea floor may have provided the nutrients and temperatures needed for life to flourish and develop, itís possible that life developed and diversified around these vents as plate tectonics began," Kusky said. Kusky and Dr. Jiang-Hai Li of Peking University in Beijing made the discovery in a mountain belt in the Eastern Hebei Province, which is located only a few miles from the Great Wall.

Saint Louis University is a leading Catholic, Jesuit, research institution ranked 24th in the nation on the U.S. News & World Report 2001 best buy list. Founded in 1818, the University strives to foster the intellectual and spiritual growth of its 11,000 students through a broad array of undergraduate, graduate and professional degree programs on campuses in St. Louis, Missouri, and Madrid, Spain.

Washington University in St. Louis, a medium-sized, independent university, is dedicated to challenging its faculty and students alike to seek new knowledge and greater understanding of an ever-changing, multicultural world. The University is counted among the world's leaders in teaching and research and draws students and faculty to St. Louis from all 50 states and more than 90 nations. The University is highly regarded for its commitment to excellence in learning. Its programs, administration, facilities, resources, and activities combine to further its mission of teaching, research, and service to society.












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