Scientists Decipher Forces Driving Mountain Formation

The world's longest mountain chain stretches along the entire west coast of South America, but scientists have been struggling to explain how it formed.

Published Dec. 1 in Nature, research led by Fabio Capitanio of Monash University's School of Geosciences, Dave Stegman of Scripps Institution of Oceanography at UC San Diego and others
describes new results of computer simulations showing how mountain ranges are built by plate tectonics.

Capitanio said existing theories of plate tectonics had failed to explain several features of how the Andes came into existence, and this motivated the researchers to develop a new approach. Capitanio said the traditional approach to plate tectonics, to work back from data, resulted in models with strong descriptive, but no predictive power.

"We knew that the Andes resulted from the subduction of one plate, under another; however, a lot was unexplained. For example, the subduction began 125 million years ago, but the mountains only began to form 45 million years ago. This lag was not understood," Capitanio said. "The model we developed explains the timing of the Andes formation and unique features such as the curvature of the mountain chain."

"The formation of the Andes has been a long-standing question, but almost all of the previous explanations have major flaws. This new model is much more viable, but needs further testing," said Dave Stegman, a geoophysicist at Scripps Institution of Oceanography at UC San Diego.

The new theory has only been applied to one subduction zone so far, but has broader applications.

Understanding the forces driving tectonic plates will ultimately allow researchers to predict shifts and their consequences, including the formation of mountain ranges, opening and closing of oceans, and earthquakes.

Collaborators on the project also included Claudio Faccenna of Universita Roma Tre and Sergio Zlotnik of UPC-Barcelona Tech. The researchers will continue to develop the model by applying it to other subduction zones. Stegman's research was supported by the G. Unger Vetlesen Foundation.